**Part 2**

**Public Health Data of Osteoporosis** 

78 Osteoporosis

Zioupos, P.; Currey, J.D. & Hamer, A.J. (1999). The role of collagen in the declining

*Research*, Vol. 45, Issue 2, pp. 108-116.

mechanical properties of ageing human cortical bone, *Journal of Biomedical Material* 

**4** 

**Self-Reported Prevalence** 

Tiffany K. Gill1, Anne W. Taylor1, Julie Black2 and Catherine L. Hill1

*1University of Adelaide,* 

*2Arthritis SA Australia* 

**of Osteoporosis in Australia** 

"Self-report" is generally the only method of determining the prevalence of non-registry based chronic diseases (Bergmann et al., 2004). However, there are difficulties in "case definition" associated with self-report and often the most effective means of identifying the presence of disease is to determine whether the chronic condition in question has been diagnosed by the doctor. Chronic conditions such as osteoporosis are often difficult to identify as they do not generally manifest themselves until after a bone fracture occurs. The aim of this chapter is to determine the self-reported prevalence of osteoporosis and associated demographic factors from a community dwelling sample aged 15 years and over across a 16 year period and compare this prevalence with that obtained from a biomedical study. Associated risk and demographic factors can be examined using these data. The issues around the use of self-reported, doctor-diagnosed osteoporosis to determine disease

Osteoporosis is a hidden condition. Bone loss due to osteoporosis is subtle but as there are no overt symptoms, it is generally not until a fracture occurs that osteoporosis may be identified (Australian Institute of Health and Welfare [AIHW] 2011; Rachner et al., 2011; Sànchez-Riera et al., 2010). However, with an ageing population, the related medical issues and socioeconomic impact will only increase (Rachner et al., 2011). Osteoporosis is a condition which affects both men and women although the greatest focus has generally been on post menopausal women (Cawthon, 2011). A meta-analysis identified that there was a five to eight fold increase in the risk of mortality due to all causes within the first three months following a hip fracture (Haentjens et al., 2010), which is a common fracture type associated with osteoporosis (Cooper, 1997). An increased annual mortality remains over time and it is generally higher for men compared to women (Center et al., 2011; Haentjens et al., 2010). Fractures consequently are a significant health issue which lead to not only premature mortality but also an increased level of disability and risk of future fracture

**1. Introduction** 

**2. Background** 

prevalence will also be discussed.

(Center et al., 2007; Center et al., 2011; Cooper, 1997).

## **Self-Reported Prevalence of Osteoporosis in Australia**

Tiffany K. Gill1, Anne W. Taylor1, Julie Black2 and Catherine L. Hill1 *1University of Adelaide, 2Arthritis SA Australia* 

### **1. Introduction**

"Self-report" is generally the only method of determining the prevalence of non-registry based chronic diseases (Bergmann et al., 2004). However, there are difficulties in "case definition" associated with self-report and often the most effective means of identifying the presence of disease is to determine whether the chronic condition in question has been diagnosed by the doctor. Chronic conditions such as osteoporosis are often difficult to identify as they do not generally manifest themselves until after a bone fracture occurs. The aim of this chapter is to determine the self-reported prevalence of osteoporosis and associated demographic factors from a community dwelling sample aged 15 years and over across a 16 year period and compare this prevalence with that obtained from a biomedical study. Associated risk and demographic factors can be examined using these data. The issues around the use of self-reported, doctor-diagnosed osteoporosis to determine disease prevalence will also be discussed.

### **2. Background**

Osteoporosis is a hidden condition. Bone loss due to osteoporosis is subtle but as there are no overt symptoms, it is generally not until a fracture occurs that osteoporosis may be identified (Australian Institute of Health and Welfare [AIHW] 2011; Rachner et al., 2011; Sànchez-Riera et al., 2010). However, with an ageing population, the related medical issues and socioeconomic impact will only increase (Rachner et al., 2011). Osteoporosis is a condition which affects both men and women although the greatest focus has generally been on post menopausal women (Cawthon, 2011). A meta-analysis identified that there was a five to eight fold increase in the risk of mortality due to all causes within the first three months following a hip fracture (Haentjens et al., 2010), which is a common fracture type associated with osteoporosis (Cooper, 1997). An increased annual mortality remains over time and it is generally higher for men compared to women (Center et al., 2011; Haentjens et al., 2010). Fractures consequently are a significant health issue which lead to not only premature mortality but also an increased level of disability and risk of future fracture (Center et al., 2007; Center et al., 2011; Cooper, 1997).

Self-Reported Prevalence of Osteoporosis in Australia 83

information related to economic, social, cultural and physical factors which are relevant to health can be provided. These factors can then be associated with the effects of public health and health promotion interventions and targeted campaigns. Data on health risk factors can also be obtained and support afforded to health related legislative programs and disease prevention actions, and regular surveillance can also evaluate the long term effects of health promotion campaigns. Also, future trends, the use of health resources and the emergence of any new health issues can be recognised (International Union for Health Promotion and Education World Alliance for Risk Factor Surveillance Global Working Group [IUHPE

Thus, while self-report underestimates osteoporosis prevalences, use of this method of data collection can improve the understanding and knowledge of the disease, in addition to assisting the identification of high risk groups (Werner, 2003). Self-report has been used in population surveys in South Australia (SA), Australia for approximately 20 years, with osteoporosis data being collected since 1995. Questions have been asked in the same way, using the same methodology annually, and while this timeframe is considered to be infrequent in terms of the surveillance timeframe spectrum (IUHPE WARFS GWG, 2011), aggregated data from these surveys possess the characteristics of a more regular surveillance system. Aggregation of these data provides the ability to analyse data over time and enables an assessment of changes in prevalence over the period of time under examination. It also provides evidence for the development of policy and an investigation of

The data presented in this chapter are derived from two different sources. The first is a faceto-face survey and the second, a telephone survey and clinical assessment conducted as part

The self-reported prevalence of osteoporosis has been collected in SA since 1995, using the SA Health Omnibus Survey (SAHOS) which is conducted annually, with data collection between September and December each year (spring to summer in Australia). Key uses of

• gaining information on perceptions towards, and acceptability of, services and

• explaining population perspectives, attitudes, values and behaviours associated with

• gaining information on the acceptability and uptake of new initiatives and programs;

• gaining information on knowledge, attitudes and behaviours;

• allowing the segmentation of problems and related issues; • identifying target groups for interventions and campaigns; • monitoring changes in health problems and disease trends;

• obtaining information on the aetiology of specific health problems;

WARFS GWG], 2011).

**3. Methods** 

the survey are:

the impact of these policies over time.

of a longitudinal cohort study.

**3.1 Health Omnibus Survey (HOS)** 

programs or organisations;

issues under investigation;

• provision of prevalence or incidence data;

• obtaining data to test hypotheses; and • evaluating interventions and programs.

Dual x-ray absorptiometry (DXA) is considered to be the gold standard for the diagnosis of osteoporosis (Keen, 2007). Guidelines have been developed and implemented to address effectively screening for osteoporosis (Rachner et al., 2011). In Australia, the guideline focuses on post menopausal women and older men (Royal Australian College of General Practitioners, 2010), as do other international guidelines (Compston et al., 2009; Hodgson et al., 2003). The guideline does not, however, come into effect until there has been a minimal trauma fracture (Royal Australian College of General Practitioners, 2010). Risk assessment tools have also been developed which combine clinical risk factors and DXA measurements (Borgström & Kanis, 2008; Unnanuntana et al., 2010). Thus DXA scans are only provided to those considered at risk of osteoporosis or in response to a minimal trauma fracture. Bone density screening is not provided to the population in a similar manner to breast cancer screening, as it is not considered cost effective, due to the cost of providing scans and limited availability (Davis et al., 2011).

A variety of data sources are used to determine the characteristics of osteoporosis within the Australian population and estimating the population prevalence can be difficult. Self– reported, doctor diagnosis of a condition is generally used in population surveys but these estimates do not generally reflect the true prevalence. This discrepancy with true prevalence has been demonstrated (Sacks et al., 2005) using arthritis information collected as part of the Behavioural Risk Factor Surveillance System (BRFSS) which is undertaken across the United States. In terms of osteoporosis, the prevalence is underestimated due to the absence of obvious symptoms until a diagnosis may occur following a minimal trauma fracture (AIHW, 2011; Werner, 2003). But even after a minimal trauma fracture, those with osteoporosis may be untreated or undiagnosed (Eisman et al., 2004) or the underlying disease may not be appropriately investigated (Elliot-Gibson et al., 2004).

Osteoporosis contributes to the global burden of disease. Chronic conditions (including osteoporosis), whether they are physical or mental, reduce quality living time, with the subsequent morbidity significantly impacting the population (McQueen, 2003). Regular surveillance allows the monitoring of health, demographic and other related data to assess trends and prevalence and also provide an explanation of demographic and exposure differences, the use of health services and evaluate if there is a response to health promotion and public health interventions (McQueen, 2003; Wilson, 2003). A system that monitors chronic disease and related risk factors does have some specific features which characterise it as "surveillance" (Campostrini, 2003). These include:


While it is considered most ideal to collect data across short timeframes (e.g. a day, a week or a month) in order to simulate as closely as possible a continuous data collection, this is not always practical or feasible (Campostrini, 2003; McQueen, 2003). However, if questions and methodology remain stable over time so that changes or trends that occur can be attributed to true population changes and not questionnaire changes, and data are collected at regular intervals (McQueen, 2003); the information provided is extremely powerful.

Developing a systematic approach to surveillance addresses many needs. These include: an estimation of the size of the problem, the geographic distribution, detection of an epidemic or definition of a problem, stimulation of research and research hypotheses, monitoring changes in disease patterns and providing assistance to planning. Population-based information related to economic, social, cultural and physical factors which are relevant to health can be provided. These factors can then be associated with the effects of public health and health promotion interventions and targeted campaigns. Data on health risk factors can also be obtained and support afforded to health related legislative programs and disease prevention actions, and regular surveillance can also evaluate the long term effects of health promotion campaigns. Also, future trends, the use of health resources and the emergence of any new health issues can be recognised (International Union for Health Promotion and Education World Alliance for Risk Factor Surveillance Global Working Group [IUHPE WARFS GWG], 2011).

Thus, while self-report underestimates osteoporosis prevalences, use of this method of data collection can improve the understanding and knowledge of the disease, in addition to assisting the identification of high risk groups (Werner, 2003). Self-report has been used in population surveys in South Australia (SA), Australia for approximately 20 years, with osteoporosis data being collected since 1995. Questions have been asked in the same way, using the same methodology annually, and while this timeframe is considered to be infrequent in terms of the surveillance timeframe spectrum (IUHPE WARFS GWG, 2011), aggregated data from these surveys possess the characteristics of a more regular surveillance system. Aggregation of these data provides the ability to analyse data over time and enables an assessment of changes in prevalence over the period of time under examination. It also provides evidence for the development of policy and an investigation of the impact of these policies over time.

### **3. Methods**

82 Osteoporosis

Dual x-ray absorptiometry (DXA) is considered to be the gold standard for the diagnosis of osteoporosis (Keen, 2007). Guidelines have been developed and implemented to address effectively screening for osteoporosis (Rachner et al., 2011). In Australia, the guideline focuses on post menopausal women and older men (Royal Australian College of General Practitioners, 2010), as do other international guidelines (Compston et al., 2009; Hodgson et al., 2003). The guideline does not, however, come into effect until there has been a minimal trauma fracture (Royal Australian College of General Practitioners, 2010). Risk assessment tools have also been developed which combine clinical risk factors and DXA measurements (Borgström & Kanis, 2008; Unnanuntana et al., 2010). Thus DXA scans are only provided to those considered at risk of osteoporosis or in response to a minimal trauma fracture. Bone density screening is not provided to the population in a similar manner to breast cancer screening, as it is not considered cost effective, due to the cost of providing scans and

A variety of data sources are used to determine the characteristics of osteoporosis within the Australian population and estimating the population prevalence can be difficult. Self– reported, doctor diagnosis of a condition is generally used in population surveys but these estimates do not generally reflect the true prevalence. This discrepancy with true prevalence has been demonstrated (Sacks et al., 2005) using arthritis information collected as part of the Behavioural Risk Factor Surveillance System (BRFSS) which is undertaken across the United States. In terms of osteoporosis, the prevalence is underestimated due to the absence of obvious symptoms until a diagnosis may occur following a minimal trauma fracture (AIHW, 2011; Werner, 2003). But even after a minimal trauma fracture, those with osteoporosis may be untreated or undiagnosed (Eisman et al., 2004) or the underlying

Osteoporosis contributes to the global burden of disease. Chronic conditions (including osteoporosis), whether they are physical or mental, reduce quality living time, with the subsequent morbidity significantly impacting the population (McQueen, 2003). Regular surveillance allows the monitoring of health, demographic and other related data to assess trends and prevalence and also provide an explanation of demographic and exposure differences, the use of health services and evaluate if there is a response to health promotion and public health interventions (McQueen, 2003; Wilson, 2003). A system that monitors chronic disease and related risk factors does have some specific features which characterise

• There is a focus on chronic or non-communicable diseases and related factors, and • Attention is also focused on the data management, collection, analysis, use and

While it is considered most ideal to collect data across short timeframes (e.g. a day, a week or a month) in order to simulate as closely as possible a continuous data collection, this is not always practical or feasible (Campostrini, 2003; McQueen, 2003). However, if questions and methodology remain stable over time so that changes or trends that occur can be attributed to true population changes and not questionnaire changes, and data are collected at regular intervals (McQueen, 2003); the information provided is extremely powerful. Developing a systematic approach to surveillance addresses many needs. These include: an estimation of the size of the problem, the geographic distribution, detection of an epidemic or definition of a problem, stimulation of research and research hypotheses, monitoring changes in disease patterns and providing assistance to planning. Population-based

disease may not be appropriately investigated (Elliot-Gibson et al., 2004).

it as "surveillance" (Campostrini, 2003). These include: • Time, which is a essential element of the data collection,

interpretation (Campostrini, 2003).

limited availability (Davis et al., 2011).

The data presented in this chapter are derived from two different sources. The first is a faceto-face survey and the second, a telephone survey and clinical assessment conducted as part of a longitudinal cohort study.

### **3.1 Health Omnibus Survey (HOS)**

The self-reported prevalence of osteoporosis has been collected in SA since 1995, using the SA Health Omnibus Survey (SAHOS) which is conducted annually, with data collection between September and December each year (spring to summer in Australia). Key uses of the survey are:


Self-Reported Prevalence of Osteoporosis in Australia 85

example, the starting point is 80 and the skip interval is 100, then the CDs which contain the 80th, 180th and 280th cumulative dwelling will be the first three CDs to be selected. Thus, once the skip interval has been determined, selection of an individual CD is dependent on the number of dwellings within that CD. In some cases, larger CDs may, in theory, be

The selection process of households is similar to the selection of CDs. Ten households per

Within households, the person who was last to have a birthday (aged 15 years or over) is selected to participate in the survey. The sample is a non-replacement sample, thus, if the selected person is not available, interviews are not conducted with any other household members. Generally up to six visits are made to each household to interview the selected participant, before the selected individual is classified as a non-contact, however in some cases more visits may be conducted. Selections that occur in hotels, motels, hospitals,

The randomly selected starting points and the skip intervals between selected CDs and selected households within CDs produce a systematic even spread of households across the

The self-weighting sampling procedure of HOS ensures that every household within each of the two strata (metropolitan Adelaide and the major country towns) have the same probability of being selected even though different probabilities of selection exist at each

The probability of selecting a household equals the probability of selecting a CD (i.e. the cumulative number of dwellings in the CD divided by the skip interval) multiplied by the probability of selecting a household, given that the CD was selected (i.e. the number of households required in each CD divided by the cumulative number of households in the

In line with other epidemiologically-based surveillance systems, a letter introducing SAHOS is sent to each selected household including a brochure outlining how the information is used. It has been shown that sending a letter informing a person of a survey can increase response rates (Frey, 1989; Robertson et al., 2000). If respondents have any questions about the survey, they are able to call a free call telephone number listed in the approach letter.

Ten percent of all respondents are re-contacted and re-interviewed using selected questions to ensure the validity of the original responses. Data entry is fully verified using a double

entry technique to ensure the accuracy of the final data.

selected CD are chosen using a fixed skip interval from a random starting point.

selected more than once.

**3.1.3 Systematic sample** 

**3.1.4 Self weighting sample** 

stage of the sampling process.

**3.1.5 Approach letter** 

**3.1.6 Validation** 

population.

CD).

**Stage 2 - Selection of households within CDs** 

**Stage 3 - Selection of individuals within households** 

nursing homes and other institutions are excluded from the survey.

Questions to be included in each survey are reviewed by a quality control committee, both before and after pilot testing, for appropriate wording and design. Approximately ten background demographic questions are included within the survey. SAHOS is a face-to-face survey, which is the original method and consequently the "gold standard" of interview techniques (Dillman, 1999; Dillman et al., 2009; Schonlau et al., 2002). Participation is voluntary. Interviewers read out the questions to participants and, if necessary, prompt cards are used to ensure that respondents remember all of the response categories. The questionnaire is designed to take approximately 30 to 40 minutes for respondents to complete. Prior to the main survey, a pilot study of 50 interviews is conducted to test questions, validate the survey instrument and assess survey procedures.

#### **3.1.1 Sample size**

The survey sample is a clustered, multi-stage, systematic, self-weighting, area sample. Each of these key sampling concepts is described in more detail below. Each survey usually samples 5,200 households. The SAHOS has been in operation since 1991 and since that time the observed response rate has generally ranged between approximately 60-70%, usually resulting in a minimum of 3,000 interviews being completed each year. This large sample size facilitates a high level of confidence that the results and trends obtained in response to the survey questions can be extrapolated to the South Australian population as a whole.

#### **3.1.2 Clustered sample**

Seventy-five percent of the sample is selected from from the metropolitan area of the capital, Adelaide, with the remaining sample being drawn from those country areas with a population of 1,000 or more (based on Australian Bureau of Statistics (ABS) Census information which is collected every five years in Australia). Country towns with smaller populations are not included within the sample frame because of the additional cost of interviewing people living in these remote areas. Within the selected metropolitan and country areas, the ABS Collection Districts (CDs) are the basis of the sample frame. A CD is a geographical area comprising approximately 200 dwellings. By using a cluster sampling technique, some, but not all, of these CDs are included in the sample. To achieve a sample of 5,200 households, 10 households are selected from each of 520 CDs.

#### **Stage 1 - Selection of CDs**

Based on ABS population estimates, 400 CDs are selected in metropolitan Adelaide, and 120 CDs from the selected country areas. All cities/towns in country SA with a population size of 10,000 or more are selected automatically with the balance of the country sample chosen from centres with a population of 1,000 or more. A randomly selected starting point and a fixed skip interval are used to determine which CDs are chosen from the sample frame. The skip interval is calculated as the number of households in metropolitan Adelaide (or country SA) divided by the number of CDs required for the metropolitan (or country) sector.

The process of selection is as follows. Firstly, all CDs in the sample frame are listed in numerical code order, along with the number of dwellings in that individual CD and the "cumulative number of dwellings" for that CD. The cumulative number of dwellings is defined as the total number of dwellings for a particular CD and all previously listed CDs. A random number between one and the skip number is chosen as the starting point for selections and the skip interval is then used to determine which CDs are selected. If, for

Questions to be included in each survey are reviewed by a quality control committee, both before and after pilot testing, for appropriate wording and design. Approximately ten background demographic questions are included within the survey. SAHOS is a face-to-face survey, which is the original method and consequently the "gold standard" of interview techniques (Dillman, 1999; Dillman et al., 2009; Schonlau et al., 2002). Participation is voluntary. Interviewers read out the questions to participants and, if necessary, prompt cards are used to ensure that respondents remember all of the response categories. The questionnaire is designed to take approximately 30 to 40 minutes for respondents to complete. Prior to the main survey, a pilot study of 50 interviews is conducted to test

The survey sample is a clustered, multi-stage, systematic, self-weighting, area sample. Each of these key sampling concepts is described in more detail below. Each survey usually samples 5,200 households. The SAHOS has been in operation since 1991 and since that time the observed response rate has generally ranged between approximately 60-70%, usually resulting in a minimum of 3,000 interviews being completed each year. This large sample size facilitates a high level of confidence that the results and trends obtained in response to the survey questions can be extrapolated to the South Australian population as a whole.

Seventy-five percent of the sample is selected from from the metropolitan area of the capital, Adelaide, with the remaining sample being drawn from those country areas with a population of 1,000 or more (based on Australian Bureau of Statistics (ABS) Census information which is collected every five years in Australia). Country towns with smaller populations are not included within the sample frame because of the additional cost of interviewing people living in these remote areas. Within the selected metropolitan and country areas, the ABS Collection Districts (CDs) are the basis of the sample frame. A CD is a geographical area comprising approximately 200 dwellings. By using a cluster sampling technique, some, but not all, of these CDs are included in the sample. To achieve a sample of

Based on ABS population estimates, 400 CDs are selected in metropolitan Adelaide, and 120 CDs from the selected country areas. All cities/towns in country SA with a population size of 10,000 or more are selected automatically with the balance of the country sample chosen from centres with a population of 1,000 or more. A randomly selected starting point and a fixed skip interval are used to determine which CDs are chosen from the sample frame. The skip interval is calculated as the number of households in metropolitan Adelaide (or country

The process of selection is as follows. Firstly, all CDs in the sample frame are listed in numerical code order, along with the number of dwellings in that individual CD and the "cumulative number of dwellings" for that CD. The cumulative number of dwellings is defined as the total number of dwellings for a particular CD and all previously listed CDs. A random number between one and the skip number is chosen as the starting point for selections and the skip interval is then used to determine which CDs are selected. If, for

SA) divided by the number of CDs required for the metropolitan (or country) sector.

questions, validate the survey instrument and assess survey procedures.

5,200 households, 10 households are selected from each of 520 CDs.

**3.1.1 Sample size** 

**3.1.2 Clustered sample** 

**Stage 1 - Selection of CDs** 

example, the starting point is 80 and the skip interval is 100, then the CDs which contain the 80th, 180th and 280th cumulative dwelling will be the first three CDs to be selected. Thus, once the skip interval has been determined, selection of an individual CD is dependent on the number of dwellings within that CD. In some cases, larger CDs may, in theory, be selected more than once.

### **Stage 2 - Selection of households within CDs**

The selection process of households is similar to the selection of CDs. Ten households per selected CD are chosen using a fixed skip interval from a random starting point.

### **Stage 3 - Selection of individuals within households**

Within households, the person who was last to have a birthday (aged 15 years or over) is selected to participate in the survey. The sample is a non-replacement sample, thus, if the selected person is not available, interviews are not conducted with any other household members. Generally up to six visits are made to each household to interview the selected participant, before the selected individual is classified as a non-contact, however in some cases more visits may be conducted. Selections that occur in hotels, motels, hospitals, nursing homes and other institutions are excluded from the survey.

### **3.1.3 Systematic sample**

The randomly selected starting points and the skip intervals between selected CDs and selected households within CDs produce a systematic even spread of households across the population.

### **3.1.4 Self weighting sample**

The self-weighting sampling procedure of HOS ensures that every household within each of the two strata (metropolitan Adelaide and the major country towns) have the same probability of being selected even though different probabilities of selection exist at each stage of the sampling process.

The probability of selecting a household equals the probability of selecting a CD (i.e. the cumulative number of dwellings in the CD divided by the skip interval) multiplied by the probability of selecting a household, given that the CD was selected (i.e. the number of households required in each CD divided by the cumulative number of households in the CD).

### **3.1.5 Approach letter**

In line with other epidemiologically-based surveillance systems, a letter introducing SAHOS is sent to each selected household including a brochure outlining how the information is used. It has been shown that sending a letter informing a person of a survey can increase response rates (Frey, 1989; Robertson et al., 2000). If respondents have any questions about the survey, they are able to call a free call telephone number listed in the approach letter.

### **3.1.6 Validation**

Ten percent of all respondents are re-contacted and re-interviewed using selected questions to ensure the validity of the original responses. Data entry is fully verified using a double entry technique to ensure the accuracy of the final data.

Self-Reported Prevalence of Osteoporosis in Australia 87

Fig. 1. Chronic Disease Continuum for Osteoporosis

using Computer Assisted Telephone Interview (CATI) technology.

All households in the northern and western areas of Adelaide, SA, with a telephone connected and a telephone number listed in the Electronic White Pages were eligible for selection in the NWAHS. Households were randomly selected and sent an approach letter and brochure informing them about the study. The person who was last to have their birthday within each household and aged 18 years and over was selected for interview. Interviews were conducted

During the telephone interview respondents were asked a range of health-related and demographic questions, and were invited to attend an assessment clinic for a 45 minute

**3.2.1 Stage one** 

### **3.1.7 Weighting**

All SAHOS data are weighted by age, sex, area of residence and the inverse of the probability of selection in the household to the most recent ABS Census or Estimated Residential Population data for SA.

### **3.1.8 Ethics approval**

Ethics approval for the methodology of the survey is provided by the Human Research Ethics Committee of the University of Adelaide and ethics approval for questions may be provided through the individual users' institutions, or if users do not have access to a committee, by the University of Adelaide.

### **3.1.9 Questions related to osteoporosis prevalence**

The methodology of the SAHOS has remained consistent over time and questions relating to self-reported, doctor diagnosed osteoporosis have been included since 1995, which enables examination of prevalence changes over time.

Questions within the SAHOS include demographic characteristics:


The question used to determine osteoporosis prevalence is "Have you ever been told by a doctor that you have osteoporosis? "

### **3.2 North West Adelaide Health Study**

The North West Adelaide Health Study (NWAHS) is a longitudinal cohort study of over 4,000 participants located in the northwest suburbs of Adelaide, SA, Australia.

The study focuses on priority health conditions and risk factors that have been identified due to the significant burden that is placed on the community in terms of social, health, quality of life and economic factors. By identifying and describing specific population groups at risk of chronic conditions, the effectiveness of strategies for the prevention, early detection, and management of chronic conditions may be maximised (Grant et al., 2006; Grant et al., 2009).

Participants were recruited to Stage 1 of the study between 2000 and 2003, and undertook a second assessment between 2004 and 2006. The initial objective of the study was to establish both baseline self-reported and biomedically measured information on chronic diseases and risk factors, in terms of those who may be at risk of these conditions, those who already had these conditions but had not been diagnosed, and those who had previously been diagnosed with the conditions. Identifying those categories of disease along a chronic disease continuum provides a view of disease burden and presents opportunities for effective interventions, improved health service use and development of health policy (Grant et al., 2006; Grant et al., 2009). When specifically considering osteoporosis, the chronic disease continuum can be described as presented in Figure 1.

All SAHOS data are weighted by age, sex, area of residence and the inverse of the probability of selection in the household to the most recent ABS Census or Estimated

Ethics approval for the methodology of the survey is provided by the Human Research Ethics Committee of the University of Adelaide and ethics approval for questions may be provided through the individual users' institutions, or if users do not have access to a

The methodology of the SAHOS has remained consistent over time and questions relating to self-reported, doctor diagnosed osteoporosis have been included since 1995, which enables

The question used to determine osteoporosis prevalence is "Have you ever been told by a

The North West Adelaide Health Study (NWAHS) is a longitudinal cohort study of over

The study focuses on priority health conditions and risk factors that have been identified due to the significant burden that is placed on the community in terms of social, health, quality of life and economic factors. By identifying and describing specific population groups at risk of chronic conditions, the effectiveness of strategies for the prevention, early detection, and management of chronic conditions may be maximised (Grant et al., 2006;

Participants were recruited to Stage 1 of the study between 2000 and 2003, and undertook a second assessment between 2004 and 2006. The initial objective of the study was to establish both baseline self-reported and biomedically measured information on chronic diseases and risk factors, in terms of those who may be at risk of these conditions, those who already had these conditions but had not been diagnosed, and those who had previously been diagnosed with the conditions. Identifying those categories of disease along a chronic disease continuum provides a view of disease burden and presents opportunities for effective interventions, improved health service use and development of health policy (Grant et al., 2006; Grant et al., 2009). When specifically considering osteoporosis, the chronic disease

**3.1.7 Weighting** 

**3.1.8 Ethics approval** 

• Sex; • Age;

• Country of birth; • Marital status;

• Area of residence; and • Year of survey.

doctor that you have osteoporosis? "

**3.2 North West Adelaide Health Study** 

continuum can be described as presented in Figure 1.

• Work status;

Grant et al., 2009).

Residential Population data for SA.

committee, by the University of Adelaide.

examination of prevalence changes over time.

**3.1.9 Questions related to osteoporosis prevalence** 

Questions within the SAHOS include demographic characteristics:

• Income (gross annual household income before tax in Australian dollars);

4,000 participants located in the northwest suburbs of Adelaide, SA, Australia.

Fig. 1. Chronic Disease Continuum for Osteoporosis

### **3.2.1 Stage one**

All households in the northern and western areas of Adelaide, SA, with a telephone connected and a telephone number listed in the Electronic White Pages were eligible for selection in the NWAHS. Households were randomly selected and sent an approach letter and brochure informing them about the study. The person who was last to have their birthday within each household and aged 18 years and over was selected for interview. Interviews were conducted using Computer Assisted Telephone Interview (CATI) technology.

During the telephone interview respondents were asked a range of health-related and demographic questions, and were invited to attend an assessment clinic for a 45 minute

• Sex; • Age;

• Country of birth; • Marital status;

• Work status; and • Area of residence.

questionnaire.

**3.3 Data analysis** 

**4. Results** 

asked what type of arthritis they had.

Self-Reported Prevalence of Osteoporosis in Australia 89

The question used to determine osteoporosis prevalence is "Have you ever been told by a doctor that you have osteoporosis?" This information is collected as part of the CATI in Stage 2. Other information collected as part of the CATI was the self-reported occurrence of fractures following a fall from a standing height or less in the past year and self-reported types of arthritis, including rheumatoid and osteoarthritis (that is, "Have you ever been told by a doctor that you have arthritis?"). Those who responded in the affirmative were then

Other variables that are collected as part of the NWAHS were: family history of osteoporosis (mother, father, sister, brother, grandparent, other), self-reported smoking (which is categorised as current, ex- or non-smoker) and alcohol intake. Regarding alcohol intake, participants were asked how often they drank alcohol, and if they drank, on a day when they drank alcohol, how many drinks they usually had. They were then classified according to their level of risk of harm from alcohol, as non-drinkers or no risk, low alcohol risk, and intermediate to very high alcohol risk (National Heart Foundation of Australia, 1989). Physical activity level was also determined, respondents were asked about the amount of walking, moderate and vigorous activity they had undertaken in the past two weeks. These questions were the same as those used in the Australian National Health Survey in 2001 and 2004 (ABS, 2003, 2006), and the responses were classified into four activity levels (sedentary, low, moderate and high). All of these variables were obtained from the self-completed

Height and weight were measured as part of the clinic assessment to calculate body mass index and DXA scans were provided to those aged 50 years and over who consented to the scan and respondents were classified as having osteoporosis (T score ≤ -2.5) or osteopenia (- 1.0 < T score > -2.5) using the World Health Organization (WHO) definition of osteoporosis

Analyses were conducted using SPSS Version 18 (IBM SPSS Statistics, New York, NY, USA)

The self-reported prevalence of osteoporosis has been collected every year in SAHOS between 1995 and 2010 except in 1996 and 2000. Thus there are fourteen years of data available. The aggregated sample size was n=41,487. Overall, 49% of respondents were male and 51.0% female, with a mean age of 45.0 years (SD 18.85, range 15-102). The aggregated prevalence of self-reported osteoporosis among those aged 15 years and over, between 1995

(WHO, 1994). Overall 75.7% of eligible participants undertook a DXA scan.

and STATA Version 11.2 (StataCorp, College Station, TX, USA).

**4.1 Prevalence of osteoporosis (SAHOS)** 

and 2010, was 4.8% (95% CI 4.6-5.0).

• Income (gross annual household income before tax in Australian dollars);

appointment at either of two local hospitals in Adelaide, one in the western suburbs and one in the northern suburbs. All study participants who agreed to attend the clinic were sent an information pack about the study, including a self-report questionnaire which examined other chronic conditions and health-related risk factors that were not included in the telephone interview.

During the clinic visit, the tests included: height, weight, waist and hip circumference, and blood pressure. Lung function was calculated and a fasting blood sample was taken to measure glucose, tryglycerides, total cholesterol, high density lipid (HDL), low density lipid (LDL), and glycated haemoglobin (HbA1c). The response rate for attending the clinic in Stage 1 was 49.4% with a final sample of n=4056.

#### **3.2.2 Stage two**

All participants that could be contacted, were invited to attend the clinic for Stage 2 using a telephone interview that also obtained demographic and health-related information. Of the original living cohort, over 90% provided some Stage 2 information, and 3,205 (over 81.0%) attended the clinic assessment between 2004 and 2006 for the second time. The minimum age of participants in Stage 2 was 20 years. In addition to the measurements taken at Stage 1 (which concentrated on the chronic conditions diabetes, chronic obstructive pulmonary disease and asthma), renal function and musculoskeletal conditions were also assessed. The musculoskeletal conditions included both arthritis and osteoporosis and a range of questions related to specific joint pain. Participants aged 50 years and over were offered a DXA scan to measure their bone density, and fat and lean body mass.

The longitudinal nature of the cohort study means that following Stage 2, valuable information was obtained relating to the number of people who had developed chronic conditions over the timeframe of the study and the factors that may have contributed to their risk of developing chronic disease. Stage 3 of the study has recently been completed with all respondents who could be contacted again being asked to attend the clinic for assessment and information relating to musculoskeletal conditions again included in the study. However the results in this chapter are limited to Stage 2 data only.

#### **3.2.3 Weighting**

Weighting was used to correct for the disproportionality of the original sample with respect to the population of interest. The data were weighted for age, sex, probability of selection in the household and area of residence. These weights reflect any unequal sample inclusion probabilities and compensate for differential non-response. The data were weighted using the ABS Census data so that the health estimates calculated would be representative of the adult populations of the north west area of Adelaide. Subsequently, each stage of the study is weighted with the initial sample weight as the foundation figure.

#### **3.2.4 Ethics approval**

Ethics approval for the each stage of the NWAHS has been granted by the Ethics of Human Research Committee of The Queen Elizabeth Hospital, Adelaide, SA.

#### **3.2.5 Questions related to osteoporosis prevalence**

Data collection methods for the NWAHS are a CATI, a self-complete questionnaire and a clinic assessment. Questions incorporated within the NWAHS include demographic characteristics: • Sex;

88 Osteoporosis

appointment at either of two local hospitals in Adelaide, one in the western suburbs and one in the northern suburbs. All study participants who agreed to attend the clinic were sent an information pack about the study, including a self-report questionnaire which examined other chronic conditions and health-related risk factors that were not included in the

During the clinic visit, the tests included: height, weight, waist and hip circumference, and blood pressure. Lung function was calculated and a fasting blood sample was taken to measure glucose, tryglycerides, total cholesterol, high density lipid (HDL), low density lipid (LDL), and glycated haemoglobin (HbA1c). The response rate for attending the clinic in

All participants that could be contacted, were invited to attend the clinic for Stage 2 using a telephone interview that also obtained demographic and health-related information. Of the original living cohort, over 90% provided some Stage 2 information, and 3,205 (over 81.0%) attended the clinic assessment between 2004 and 2006 for the second time. The minimum age of participants in Stage 2 was 20 years. In addition to the measurements taken at Stage 1 (which concentrated on the chronic conditions diabetes, chronic obstructive pulmonary disease and asthma), renal function and musculoskeletal conditions were also assessed. The musculoskeletal conditions included both arthritis and osteoporosis and a range of questions related to specific joint pain. Participants aged 50 years and over were offered a

The longitudinal nature of the cohort study means that following Stage 2, valuable information was obtained relating to the number of people who had developed chronic conditions over the timeframe of the study and the factors that may have contributed to their risk of developing chronic disease. Stage 3 of the study has recently been completed with all respondents who could be contacted again being asked to attend the clinic for assessment and information relating to musculoskeletal conditions again included in the

Weighting was used to correct for the disproportionality of the original sample with respect to the population of interest. The data were weighted for age, sex, probability of selection in the household and area of residence. These weights reflect any unequal sample inclusion probabilities and compensate for differential non-response. The data were weighted using the ABS Census data so that the health estimates calculated would be representative of the adult populations of the north west area of Adelaide. Subsequently, each stage of the study

Ethics approval for the each stage of the NWAHS has been granted by the Ethics of Human

Data collection methods for the NWAHS are a CATI, a self-complete questionnaire and a clinic assessment. Questions incorporated within the NWAHS include demographic characteristics:

DXA scan to measure their bone density, and fat and lean body mass.

study. However the results in this chapter are limited to Stage 2 data only.

is weighted with the initial sample weight as the foundation figure.

Research Committee of The Queen Elizabeth Hospital, Adelaide, SA.

**3.2.5 Questions related to osteoporosis prevalence** 

telephone interview.

**3.2.2 Stage two** 

**3.2.3 Weighting** 

**3.2.4 Ethics approval** 

Stage 1 was 49.4% with a final sample of n=4056.


The question used to determine osteoporosis prevalence is "Have you ever been told by a doctor that you have osteoporosis?" This information is collected as part of the CATI in Stage 2. Other information collected as part of the CATI was the self-reported occurrence of fractures following a fall from a standing height or less in the past year and self-reported types of arthritis, including rheumatoid and osteoarthritis (that is, "Have you ever been told by a doctor that you have arthritis?"). Those who responded in the affirmative were then asked what type of arthritis they had.

Other variables that are collected as part of the NWAHS were: family history of osteoporosis (mother, father, sister, brother, grandparent, other), self-reported smoking (which is categorised as current, ex- or non-smoker) and alcohol intake. Regarding alcohol intake, participants were asked how often they drank alcohol, and if they drank, on a day when they drank alcohol, how many drinks they usually had. They were then classified according to their level of risk of harm from alcohol, as non-drinkers or no risk, low alcohol risk, and intermediate to very high alcohol risk (National Heart Foundation of Australia, 1989). Physical activity level was also determined, respondents were asked about the amount of walking, moderate and vigorous activity they had undertaken in the past two weeks. These questions were the same as those used in the Australian National Health Survey in 2001 and 2004 (ABS, 2003, 2006), and the responses were classified into four activity levels (sedentary, low, moderate and high). All of these variables were obtained from the self-completed questionnaire.

Height and weight were measured as part of the clinic assessment to calculate body mass index and DXA scans were provided to those aged 50 years and over who consented to the scan and respondents were classified as having osteoporosis (T score ≤ -2.5) or osteopenia (- 1.0 < T score > -2.5) using the World Health Organization (WHO) definition of osteoporosis (WHO, 1994). Overall 75.7% of eligible participants undertook a DXA scan.

### **3.3 Data analysis**

Analyses were conducted using SPSS Version 18 (IBM SPSS Statistics, New York, NY, USA) and STATA Version 11.2 (StataCorp, College Station, TX, USA).

### **4. Results**

#### **4.1 Prevalence of osteoporosis (SAHOS)**

The self-reported prevalence of osteoporosis has been collected every year in SAHOS between 1995 and 2010 except in 1996 and 2000. Thus there are fourteen years of data available. The aggregated sample size was n=41,487. Overall, 49% of respondents were male and 51.0% female, with a mean age of 45.0 years (SD 18.85, range 15-102). The aggregated prevalence of self-reported osteoporosis among those aged 15 years and over, between 1995 and 2010, was 4.8% (95% CI 4.6-5.0).

Self-Reported Prevalence of Osteoporosis in Australia 91

Logistic regression analysis of the aggregated SAHOS data set was then undertaken in order to determine the demographic characteristics most likely to be associated with self-reporting the presence of osteoporosis. Data for these analyses were restricted to respondents aged 20 years and over to enable comparisons with the NWAHS data. The variables included in the analysis were: age, sex, country of birth, income, education, marital status and work status. Area of residence was not included as SAHOS is a state wide sample and NWAHS is a metropolitan sample. Bivariate and then multivariate logistic regression analyses were conducted to identify the best sets of explanatory variables associated with osteoporosis, with variables that were significant at p<0.25 in the bivariate analysis included in the multivariate model, as these may still be candidates for model predictors - they can continue to be a good fit when other variables are included in the model (Hosmer & Lemeshow, 2000). Then the non-significant variables at p≥0.05 were removed until all remaining variables were significant. Finally, all models were tested for "goodness of fit" using the

Analysis of the demographic variables associated with self-reported osteoporosis for the SAHOS and NWAHS produced similar factors, with increasing age, sex (female) and work status (unemployed, retired and "other") significant for both datasets (Table 1). In the SAHOS, those who reported that they undertook home duties were also significantly more likely to report that they had osteoporosis. Those earning between \$12,001 and \$50,000, were also significantly more likely to self-report osteoporosis in the SAHOS, whereas this variable

A model was then created for the SAHOS data only, to examine the impact of time. The variables associated with self-reporting osteoporosis were: increasing age, sex (female), work status (unemployed, retired and "other", home duties), income (up to \$50,000 and not stated) and year, with more recent years associated with higher self-reported prevalence of

The self-reported prevalences collected as part of the SAHOS and the NWAHS were then compared to the prevalence of osteoporosis and osteopenia as defined in the NWAHS using DXA scans. DXA scans were only undertaken on those aged 50 years and over, thus the analysis is limited to this age group. The aggregated prevalence of self-reported osteoporosis among those aged 50 years and over in SAHOS was 10.7% (95% CI 10.3-11.2) compared to 8.8% (95% CI 7.5-10.3) for self-report in NWAHS and 18.7% (95% CI 16.6-20.9) for those classified with osteoporosis and osteopenia combined as defined by DXA scans (osteoporosis 3.6% (95% CI 2.6-4.9) and osteopenia 15.1% (95% CI 13.2-17.1)). It was considered appropriate to combine the categories of osteoporosis and osteopenia as both are

Bivariate and multivariate analyses were then undertaken for all participants aged 50 years and over. This second group of models included all of the demographic characteristics collected as part of both studies and examined the variables associated with self-report and clinically defined osteoporosis (Table 2). Increasing age and female sex were significant for all three models and again for SAHOS and self-reported osteoporosis from NWAHS, work status (unemployed and retired) was significant. Income was also significantly associated with self-reporting osteoporosis in SAHOS, while marital status (never married) was

Hosmer and Lemeshow goodness of fit test (Hosmer & Lemeshow, 2000).

was not significant for those self-reporting osteoporosis in the NWAHS.

significantly associated with low bone density as defined by DXA scans.

**4.3 Logistic regression analyses** 

osteoporosis (data not shown).

indicators of abnormal bone density.

The self-reported prevalence from SAHOS was then age and sex standardised to the 2006 Australian Census (ABS, 2007) to enable prevalence comparisons between years and the results are presented in Figure 2. Data points for 1996 and 2000 are not available as these years had missing data.

As the data were aggregated, autocorrelation may occur which violates the assumptions of linear analysis. A Durbin-Watson test was undertaken to determine if first order autocorrelation of the residuals of the annual prevalence estimates had occurred. The value was 1.73, close to 2 indicating that there was not excessive autocorrelation of the data (Chatfield, 2004; Yaffee & McGee, 2000).

Fig. 2. Prevalence of self-reported osteoporosis from SAHOS and NWAHS

The data were examined to determine if a deviation from a linear trend existed. The regression coefficients were graphed and demonstrated an approximate straight line and a Box-Tidwell regression model was undertaken (Box & Tidwell, 1962), which also indicated that the nonlinear deviation was not significant (p=0.09). A chi-square test for trend was then conducted, which indicated that there had been a significant change in the selfreported osteoporosis prevalence over time (p<0.001).

#### **4.2 Prevalence of osteoporosis (NWAHS)**

Participants in Stage 2 of the NWAHS undertook one, two or all three of the data collection methods (CATI, self-complete questionnaire, clinic assessment) depending on their time constraints and desired level of participation. There were n=3500 respondents to the CATI questionnaire (49.1% male and 50.9% female; mean age 47.42, SD 17.57, range 20-93), n=3259 responded to the self-complete questionnaire (49.1% male and 50.9% female; mean age 47.59, SD 17.51, range 20-95) and n=3205 attended the clinic (49.1% male and 50.9% female; mean age 47.58, SD 17.52, range 20-95). The self-reported prevalence of osteoporosis among participants in the NWAHS aged 20 years and over during Stage 2 (2004 to 2006) was 3.8% (95% CI 3.2-4.5). The crude prevalence of osteoporosis obtained from the NWAHS is shown in Figure 2.

#### **4.3 Logistic regression analyses**

90 Osteoporosis

The self-reported prevalence from SAHOS was then age and sex standardised to the 2006 Australian Census (ABS, 2007) to enable prevalence comparisons between years and the results are presented in Figure 2. Data points for 1996 and 2000 are not available as these

As the data were aggregated, autocorrelation may occur which violates the assumptions of linear analysis. A Durbin-Watson test was undertaken to determine if first order autocorrelation of the residuals of the annual prevalence estimates had occurred. The value was 1.73, close to 2 indicating that there was not excessive autocorrelation of the data

Fig. 2. Prevalence of self-reported osteoporosis from SAHOS and NWAHS

reported osteoporosis prevalence over time (p<0.001).

**4.2 Prevalence of osteoporosis (NWAHS)** 

The data were examined to determine if a deviation from a linear trend existed. The regression coefficients were graphed and demonstrated an approximate straight line and a Box-Tidwell regression model was undertaken (Box & Tidwell, 1962), which also indicated that the nonlinear deviation was not significant (p=0.09). A chi-square test for trend was then conducted, which indicated that there had been a significant change in the self-

Participants in Stage 2 of the NWAHS undertook one, two or all three of the data collection methods (CATI, self-complete questionnaire, clinic assessment) depending on their time constraints and desired level of participation. There were n=3500 respondents to the CATI questionnaire (49.1% male and 50.9% female; mean age 47.42, SD 17.57, range 20-93), n=3259 responded to the self-complete questionnaire (49.1% male and 50.9% female; mean age 47.59, SD 17.51, range 20-95) and n=3205 attended the clinic (49.1% male and 50.9% female; mean age 47.58, SD 17.52, range 20-95). The self-reported prevalence of osteoporosis among participants in the NWAHS aged 20 years and over during Stage 2 (2004 to 2006) was 3.8% (95% CI 3.2-4.5).

The crude prevalence of osteoporosis obtained from the NWAHS is shown in Figure 2.

years had missing data.

(Chatfield, 2004; Yaffee & McGee, 2000).

Logistic regression analysis of the aggregated SAHOS data set was then undertaken in order to determine the demographic characteristics most likely to be associated with self-reporting the presence of osteoporosis. Data for these analyses were restricted to respondents aged 20 years and over to enable comparisons with the NWAHS data. The variables included in the analysis were: age, sex, country of birth, income, education, marital status and work status. Area of residence was not included as SAHOS is a state wide sample and NWAHS is a metropolitan sample. Bivariate and then multivariate logistic regression analyses were conducted to identify the best sets of explanatory variables associated with osteoporosis, with variables that were significant at p<0.25 in the bivariate analysis included in the multivariate model, as these may still be candidates for model predictors - they can continue to be a good fit when other variables are included in the model (Hosmer & Lemeshow, 2000). Then the non-significant variables at p≥0.05 were removed until all remaining variables were significant. Finally, all models were tested for "goodness of fit" using the Hosmer and Lemeshow goodness of fit test (Hosmer & Lemeshow, 2000).

Analysis of the demographic variables associated with self-reported osteoporosis for the SAHOS and NWAHS produced similar factors, with increasing age, sex (female) and work status (unemployed, retired and "other") significant for both datasets (Table 1). In the SAHOS, those who reported that they undertook home duties were also significantly more likely to report that they had osteoporosis. Those earning between \$12,001 and \$50,000, were also significantly more likely to self-report osteoporosis in the SAHOS, whereas this variable was not significant for those self-reporting osteoporosis in the NWAHS.

A model was then created for the SAHOS data only, to examine the impact of time. The variables associated with self-reporting osteoporosis were: increasing age, sex (female), work status (unemployed, retired and "other", home duties), income (up to \$50,000 and not stated) and year, with more recent years associated with higher self-reported prevalence of osteoporosis (data not shown).

The self-reported prevalences collected as part of the SAHOS and the NWAHS were then compared to the prevalence of osteoporosis and osteopenia as defined in the NWAHS using DXA scans. DXA scans were only undertaken on those aged 50 years and over, thus the analysis is limited to this age group. The aggregated prevalence of self-reported osteoporosis among those aged 50 years and over in SAHOS was 10.7% (95% CI 10.3-11.2) compared to 8.8% (95% CI 7.5-10.3) for self-report in NWAHS and 18.7% (95% CI 16.6-20.9) for those classified with osteoporosis and osteopenia combined as defined by DXA scans (osteoporosis 3.6% (95% CI 2.6-4.9) and osteopenia 15.1% (95% CI 13.2-17.1)). It was considered appropriate to combine the categories of osteoporosis and osteopenia as both are indicators of abnormal bone density.

Bivariate and multivariate analyses were then undertaken for all participants aged 50 years and over. This second group of models included all of the demographic characteristics collected as part of both studies and examined the variables associated with self-report and clinically defined osteoporosis (Table 2). Increasing age and female sex were significant for all three models and again for SAHOS and self-reported osteoporosis from NWAHS, work status (unemployed and retired) was significant. Income was also significantly associated with self-reporting osteoporosis in SAHOS, while marital status (never married) was significantly associated with low bone density as defined by DXA scans.

Self-Reported Prevalence of Osteoporosis in Australia 93

a standing height or less over the last year and self-reported rheumatoid arthritis. The

*Group two* OR p-value OR p-value OR p-value

Female 4.44 **<0.001** 5.50 **<0.001** 1.94 **<0.001** 

Male 1.00 1.00 1.00

**Age** 1.04 **<0.001** 1.03 **0.020** 1.09 **<0.001** 

SAHOS self-report NWAHS self-report NWAHS DXA

results of the multivariate analysis are in Table 3.

Full time 1.00 1.00

Part time 1.16 0.46 1.12 0.823 Home duties 1.72 **0.003** 0.93 0.934 Unemployed 2.05 **0.035** 3.04 **0.015**  Retired 1.75 **0.002** 2.67 **0.034**  Student 3.25 **0.018** - - Other 6.08 **<0.001** 2.57 0.180 Not stated - - 4.69 0.081

Married/de facto 1.00

Separated/divorced 0.80 0.345 Widowed 1.28 0.253 Never married 1.90 **0.043**  Not stated 0.86 0.903

Table 2. Logistic regression analysis of osteoporosis prevalence, SAHOS and NWAHS self-

**Sex** 

**Work status** 

**Income** 

**Martial status** 

\$80,001 and more 1.00

\$60,001 - \$80,000 1.31 0.295 \$50,001 - \$60,000 1.14 0.632 \$40,001 - \$50,000 1.87 **0.012**  \$30,001 - \$40,000 1.50 0.106 \$20,001 - \$30,000 1.55 0.051 \$12,001 - \$20,000 1.60 **0.038**  Up to \$12,000 1.28 0.272 Not stated 1.18 0.465

report and NWAHS DXA, age 50 years and over


Table 1. Logistic regression analysis of self-report osteoporosis, SAHOS and NWAHS, age 20 years and over

A model was also constructed for those aged 50 years and over using SAHOS data only, which examined the demographic characteristics associated with self-reported osteoporosis and included year within the model. Increasing age, female sex, increasing years, work status (home duties, retired, student, other) and income (up to \$50,000) were all significant and associated with self-reporting osteoporosis (data not shown).

A third group of models was then created using NWAHS data and examining other factors associated with osteoporosis. Variables examined at a bivariate level were alcohol risk, smoking, family history, body mass index, physical activity, fracture as a result of a fall from

*Group One* OR p-value OR p-value

Female 3.76 **<0.001** 5.55 **<0.001** 

Part time 1.13 0.432 1.48 0.430 Home duties 1.47 **0.009** 1.16 0.866 Unemployed 2.05 **0.024** 3.25 **0.015**  Retired 1.44 **0.015** 2.95 **0.037**  Student 1.40 0.436 - - Other 5.65 **<0.001** 4.43 **0.020**  Not stated - - 4.84 0.108

Male 1.00 1.00

**Age** 1.06 **<0.001** 1.06 **<0.001** 

Table 1. Logistic regression analysis of self-report osteoporosis, SAHOS and NWAHS, age

A model was also constructed for those aged 50 years and over using SAHOS data only, which examined the demographic characteristics associated with self-reported osteoporosis and included year within the model. Increasing age, female sex, increasing years, work status (home duties, retired, student, other) and income (up to \$50,000) were all significant

A third group of models was then created using NWAHS data and examining other factors associated with osteoporosis. Variables examined at a bivariate level were alcohol risk, smoking, family history, body mass index, physical activity, fracture as a result of a fall from

Full time 1.00 1.00

**Sex** 

**Work status** 

**Income** 

20 years and over

\$80,001 and more 1.00

\$60,001 - \$80,000 1.41 0.108 \$50,001 - \$60,000 1.23 0.362 \$40,001 - \$50,000 1.80 **0.004**  \$30,001 - \$40,000 1.61 **0.022**  \$20,001 - \$30,000 1.68 **0.006**  \$12,001 - \$20,000 1.72 **0.004**  Up to \$12,000 1.33 0.129 Not stated 1.31 0.146

and associated with self-reporting osteoporosis (data not shown).

SAHOS self-report NWAHS self-report

a standing height or less over the last year and self-reported rheumatoid arthritis. The results of the multivariate analysis are in Table 3.


Table 2. Logistic regression analysis of osteoporosis prevalence, SAHOS and NWAHS selfreport and NWAHS DXA, age 50 years and over

**Sex** 

**Work status** 

**Family history** 

**5. Discussion** 

contributed to this.

NWAHS, age 50 years and over

Self-Reported Prevalence of Osteoporosis in Australia 95

*Group four* OR p-value OR p-value

Female 4.71 **<0.001** 2.13 **<0.001** 

Male 1.00 1.00

Full time 1.00

No 1.00

First degree relative 3.24 **<0.001**  Don't know 2.17 **0.001**  Not stated 0.97 0.962

Table 4. Overall models demographic and other factors associated with osteoporosis,

The results of this analysis indicate that while determining the population prevalence of osteoporosis remains a difficult issue, there is a role for self-report to play in the monitoring of osteoporosis prevalence over time. At this time, DXA scans are not available to the general population as a screening tool (Davis et al., 2011) and other means of assessing osteoporosis in the population are required. However, it is likely, as this study has shown, that self-reported prevalence will differ from that obtained from bone density assessment. In this study, the prevalence of osteoporosis as measured by DXA among those 50 years and over was lower than the self-reported prevalence but when combined with osteopenia was higher. Sample differences and self-selection to undertake a DXA scan are likely to have

Data from the SAHOS indicate that there has been a significant increase in the self-reported prevalence of osteoporosis over time. It is however difficult to assess whether this is a true increase. Other factors such as a greater awareness of the condition due to marketing campaigns in Australia, particularly in relation to over the counter supplements such as

Part time 1.05 0.922 Home duties 0.78 0.775 Unemployed 2.85 **0.023**  Retired 2.55 **0.044**  Student - - Other 2.19 0.275 Not stated 6.22 **0.023** 

**Age** 1.03 **0.013** 1.10 **<0.001 BMI** 0.82 **<0.001** 

NWAHS self-report NWAHS DXA

For both self-report and DXA, non-smokers were more likely to have osteoporosis. Those with a low to high risk of harm from alcohol and with a first degree relative with osteoporosis were more likely to self-report that they had osteoporosis whereas those undertaking lower levels of activity were more likely to have low bone density. Those with a higher body mass index were less likely to have a low bone density (Table 3).


Table 3. Logistic regression analysis of other factors associated with osteoporosis, NWAHS self-report and DXA, age 50 years and over

Finally a fourth set of models combined both demographic and other relevant factors associated with osteoporosis, for the data obtained from the NWAHS. Increasing age and female sex remained significant for both models, while those with a higher body mass index were less likely to have a lower bone density and those with self-reported osteoporosis were more likely to have family members with the condition. The work status categories, unemployed and retired, also remained significant for self-reported osteoporosis (Table 4).

For both self-report and DXA, non-smokers were more likely to have osteoporosis. Those with a low to high risk of harm from alcohol and with a first degree relative with osteoporosis were more likely to self-report that they had osteoporosis whereas those undertaking lower levels of activity were more likely to have low bone density. Those with

*Group three* OR p-value OR p-value

Ex smoker 1.21 0.629 1.13 0.637 Non smoker 2.37 **0.026** 1.80 **0.020** 

**BMI** 0.82 **<0.001** 

NWAHS self-report NWAHS DXA

a higher body mass index were less likely to have a low bone density (Table 3).

Current smoker 1.00 1.00

No 1.00 1.00

High exercise 1.00

First degree relative 3.66 **<0.001** 1.43 0.095 Don't know 2.73 **<0.001** 1.45 **0.037**  Not stated 1.13 0.851 2.20 0.124

Moderate exercise 1.71 0.144 Low exercise 2.07 **0.042**  Sedentary 2.15 **0.034**  Not stated 2.40 **0.027** 

Table 3. Logistic regression analysis of other factors associated with osteoporosis, NWAHS

Finally a fourth set of models combined both demographic and other relevant factors associated with osteoporosis, for the data obtained from the NWAHS. Increasing age and female sex remained significant for both models, while those with a higher body mass index were less likely to have a lower bone density and those with self-reported osteoporosis were more likely to have family members with the condition. The work status categories, unemployed and retired, also remained significant for self-reported

**Alcohol risk** 

**Smoking** 

**Physical activity** 

osteoporosis (Table 4).

Non drinker/no risk 1.00

**Family history of osteoporosis**

self-report and DXA, age 50 years and over

Low to high risk 1.54 **0.025**  Not stated 1.34 0.593


Table 4. Overall models demographic and other factors associated with osteoporosis, NWAHS, age 50 years and over

### **5. Discussion**

The results of this analysis indicate that while determining the population prevalence of osteoporosis remains a difficult issue, there is a role for self-report to play in the monitoring of osteoporosis prevalence over time. At this time, DXA scans are not available to the general population as a screening tool (Davis et al., 2011) and other means of assessing osteoporosis in the population are required. However, it is likely, as this study has shown, that self-reported prevalence will differ from that obtained from bone density assessment. In this study, the prevalence of osteoporosis as measured by DXA among those 50 years and over was lower than the self-reported prevalence but when combined with osteopenia was higher. Sample differences and self-selection to undertake a DXA scan are likely to have contributed to this.

Data from the SAHOS indicate that there has been a significant increase in the self-reported prevalence of osteoporosis over time. It is however difficult to assess whether this is a true increase. Other factors such as a greater awareness of the condition due to marketing campaigns in Australia, particularly in relation to over the counter supplements such as

Self-Reported Prevalence of Osteoporosis in Australia 97

understanding of the risk of a prior fracture in relation to the occurrence of subsequent fractures (Center et al., 2007). Targeted self-management courses for osteoporosis have demonstrated an improved understanding of osteoporosis and related behaviours in the short term (Francis et al., 2009; Laslett et al., 2011) and in Australia, approximately 40% of those with osteoporosis are more likely to use complementary and alternative medicines, which includes vitamin D and calcium (Armstrong el al., 2011). But despite public campaigns promoting better nutrition and increasing the awareness of osteoporosis, Pasco et al. (2000) demonstrated that women did not achieve the required calcium intake and Czernichow et al. (2010) have shown that the vitamin D intake among postmenopausal

women with osteoporosis in France is significantly lower than recommended doses.

understanding of the condition in the population.

to play in the prevention and management of the condition.

fellow to Fellow (Australian Public Health, ID 1013552).

**6. Conclusion** 

**7. Acknowledgment** 

**8. References** 

and all of the participants in the NWAHS.

pp. 384-390, ISSN 1326-0200

res12001?OpenDocument

As highlighted in this study, similar factors were associated with osteoporosis prevalence, notwithstanding the method of data collection. Thus, surveillance can play a role in the ability to target information, identify at-risk groups and evaluate the impact of health promotion programs. It is however evident that there is a continued need to further explore means of adequately ascertaining the prevalence of osteoporosis and to improve the

While prevalence estimates of osteoporosis vary within the population according to data collection method, generally there are consistent covariates associated with osteoporosis, which are important for the targeting of health promotion campaigns. In the absence of clinical testing, the monitoring of the prevalence of osteoporosis using self-report has a role

The authors would like to acknowledge all of the SAHOS participants over the past 16 years

Tiffany Gill is currently a National Health and Medical Research Council Early Career

Armstrong, A.R., Thiébaut, S.P., Brown, L.J. & Nepal, B. (2011). Australian Adults Use

Australian Bureau of Statistics. (2003). *National Health Survey: Users Guide, 2001*. Cat no

http://www.abs.gov.au/AUSSTATS/abs@.nsf/Lookup/4363.0.55.001Main+Featu

Australian Bureau of Statistics. (2006). *National Health Survey: Users Guide, 2004-05*. Cat no

http://www.ausstats.abs.gov.au/ausstats/subscriber.nsf/0/A58E031838C37F81C

4363.0.55.001, ABS, Canberra, Australia, Retrieved from

4363.0.55.001, ABS, Canberra, Australia, Retrieved from

A257141000F1AAF/\$File/4363055001\_2004-05.pdf

Complementary and Alternative Medicine in the Treatment of Chronic Illness: A National Study. *Australian and New Zealand Journal of Public Health*, Vol. 35, No. 4,

vitamin D and calcium, may have played a role in increasing the awareness of the condition. Nevertheless, it can also be argued that this improved awareness, even if it impacts estimates of true prevalence, may still assist in the prevention or management of the condition. Nayak et al. (2010) demonstrated that belief in being susceptible to osteoporosis among older adults, those most at risk of osteoporosis, is low, and the older the respondents were, the less likely they were to believe that osteoporosis is a severe condition. Thus any information or advertising may assist patient education. It is also of interest that the results of DXA scans are not immune to errors in self-report with Cadarette et al. (2007) demonstrating that while there was minimal error in self-reporting that a DXA scan had been undertaken, the self-reporting of results was poor, again providing an underestimate of osteoporosis prevalence. The understanding of these results could however be improved by providing them in writing (Brask-Lindemann et al., 2011). This again highlights issues of patient knowledge and understanding of the condition.

Consequently, in recent years, there has been an increased focus on functional health literacy of the population, which is considered to be the ability of people to read, analyse and take action with regard to both oral and written information obtained in the health care setting (Nielsen-Bohlman et al. 2004). It has been acknowledged that those with low or limited functional health literacy are more likely to have adverse health outcomes, not undertake preventive health behaviours, have premature mortality and higher health-care costs. In addition, people with lower functional health literacy are less likely to undertake active management of their condition (Berkman et al., 2004; De Walt et al., 2005). Unpublished analysis of other data obtained using the SAHOS has indicated that 70% of those with doctor-diagnosed osteoporosis had a low health literacy, further supporting the view that despite the method used to assess osteoporosis prevalence, inaccuracies in the reporting of the condition may occur, which has implications for management of the condition.

While understanding of the condition and reporting of prevalence is variable, it is of note that there remained a general consistency in the variables that were associated with osteoporosis prevalence, and these are supported by previous work. Genetic factors have been shown to contribute to osteoporosis (Harvey & Cooper, 2003; Marini & Brandi, 2010; Recker & Deng, 2002), thus family history of osteoporosis is an important factor. Sex and age are also significant covariates (Cawthon, 2011; Keen, 2007; Werner, 2003) and these variables are strongly evident during multivariate modelling. Varenna et al. (1999) determined that higher levels of education were associated with a lower risk of osteoporosis and lower income levels and unemployment have been associated with a greater risk of hip fracture (Farahmand et al., 2000). Low body mass index, previous low trauma fracture, rheumatoid arthritis, physical activity, smoking and excessive alcohol consumption have all been identified as risk factors for osteoporosis (Keen, 2007). Despite the fact that many of these variables were self-report, the associations with osteoporosis all occurred in the expected manner, except for smoking, where non-smokers were more likely to have a lower bone density and to self-report osteoporosis. Smokers are more likely to be from lower socioeconomic groups (Scollo & Winstanley, 2008) which are also groups with a lower level of health literacy (Barber et al., 2009). Thus this group may be less likely to undergo a DXA scan and self-report osteoporosis, as they have a poorer understanding of the condition.

The consequences of osteoporosis in terms of fracture also need to be considered. The overall lack of awareness of osteoporosis within the population also extends to a lack of understanding of the risk of a prior fracture in relation to the occurrence of subsequent fractures (Center et al., 2007). Targeted self-management courses for osteoporosis have demonstrated an improved understanding of osteoporosis and related behaviours in the short term (Francis et al., 2009; Laslett et al., 2011) and in Australia, approximately 40% of those with osteoporosis are more likely to use complementary and alternative medicines, which includes vitamin D and calcium (Armstrong el al., 2011). But despite public campaigns promoting better nutrition and increasing the awareness of osteoporosis, Pasco et al. (2000) demonstrated that women did not achieve the required calcium intake and Czernichow et al. (2010) have shown that the vitamin D intake among postmenopausal women with osteoporosis in France is significantly lower than recommended doses.

As highlighted in this study, similar factors were associated with osteoporosis prevalence, notwithstanding the method of data collection. Thus, surveillance can play a role in the ability to target information, identify at-risk groups and evaluate the impact of health promotion programs. It is however evident that there is a continued need to further explore means of adequately ascertaining the prevalence of osteoporosis and to improve the understanding of the condition in the population.

### **6. Conclusion**

96 Osteoporosis

vitamin D and calcium, may have played a role in increasing the awareness of the condition. Nevertheless, it can also be argued that this improved awareness, even if it impacts estimates of true prevalence, may still assist in the prevention or management of the condition. Nayak et al. (2010) demonstrated that belief in being susceptible to osteoporosis among older adults, those most at risk of osteoporosis, is low, and the older the respondents were, the less likely they were to believe that osteoporosis is a severe condition. Thus any information or advertising may assist patient education. It is also of interest that the results of DXA scans are not immune to errors in self-report with Cadarette et al. (2007) demonstrating that while there was minimal error in self-reporting that a DXA scan had been undertaken, the self-reporting of results was poor, again providing an underestimate of osteoporosis prevalence. The understanding of these results could however be improved by providing them in writing (Brask-Lindemann et al., 2011). This again highlights issues of

Consequently, in recent years, there has been an increased focus on functional health literacy of the population, which is considered to be the ability of people to read, analyse and take action with regard to both oral and written information obtained in the health care setting (Nielsen-Bohlman et al. 2004). It has been acknowledged that those with low or limited functional health literacy are more likely to have adverse health outcomes, not undertake preventive health behaviours, have premature mortality and higher health-care costs. In addition, people with lower functional health literacy are less likely to undertake active management of their condition (Berkman et al., 2004; De Walt et al., 2005). Unpublished analysis of other data obtained using the SAHOS has indicated that 70% of those with doctor-diagnosed osteoporosis had a low health literacy, further supporting the view that despite the method used to assess osteoporosis prevalence, inaccuracies in the reporting of the condition may occur, which has implications for management of the

While understanding of the condition and reporting of prevalence is variable, it is of note that there remained a general consistency in the variables that were associated with osteoporosis prevalence, and these are supported by previous work. Genetic factors have been shown to contribute to osteoporosis (Harvey & Cooper, 2003; Marini & Brandi, 2010; Recker & Deng, 2002), thus family history of osteoporosis is an important factor. Sex and age are also significant covariates (Cawthon, 2011; Keen, 2007; Werner, 2003) and these variables are strongly evident during multivariate modelling. Varenna et al. (1999) determined that higher levels of education were associated with a lower risk of osteoporosis and lower income levels and unemployment have been associated with a greater risk of hip fracture (Farahmand et al., 2000). Low body mass index, previous low trauma fracture, rheumatoid arthritis, physical activity, smoking and excessive alcohol consumption have all been identified as risk factors for osteoporosis (Keen, 2007). Despite the fact that many of these variables were self-report, the associations with osteoporosis all occurred in the expected manner, except for smoking, where non-smokers were more likely to have a lower bone density and to self-report osteoporosis. Smokers are more likely to be from lower socioeconomic groups (Scollo & Winstanley, 2008) which are also groups with a lower level of health literacy (Barber et al., 2009). Thus this group may be less likely to undergo a DXA scan and self-report osteoporosis, as they have a poorer understanding of the condition. The consequences of osteoporosis in terms of fracture also need to be considered. The overall lack of awareness of osteoporosis within the population also extends to a lack of

patient knowledge and understanding of the condition.

condition.

While prevalence estimates of osteoporosis vary within the population according to data collection method, generally there are consistent covariates associated with osteoporosis, which are important for the targeting of health promotion campaigns. In the absence of clinical testing, the monitoring of the prevalence of osteoporosis using self-report has a role to play in the prevention and management of the condition.

### **7. Acknowledgment**

The authors would like to acknowledge all of the SAHOS participants over the past 16 years and all of the participants in the NWAHS.

Tiffany Gill is currently a National Health and Medical Research Council Early Career fellow to Fellow (Australian Public Health, ID 1013552).

### **8. References**


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**5** 

*Japan* 

**Prevalence of Back Pain in** 

**Postmenopausal Osteoporosis and** 

Naohisa Miyakoshi, Michio Hongo and Yoichi Shimada

**Associations with Multiple Spinal Factors** 

*Department of Orthopedic Surgery, Akita University Graduate School of Medicine* 

Back pain is considered to be most prevalent musculoskeletal pain, particularly in elderly populations (Woo et al., 2009). The existing literature suggests a prevalence of chronic back pain among the elderly ranging from 7% to 58% (Edmond & Felson, 2000; Jacobs et al., 2006; Lavsky-Shulan et al., 1985; March et al., 1998), with differences attributable to a lack of concordance in terms of age stratification, definition, and methodology, but with consistently much higher rates in women than men (Jabobs et al., 2006; Woo et al., 2009). The reason why back pain is common among elderly women may be related to osteoporosis. As lower bone mineral density (BMD) and the rapid decline in BMD following menopause in women result in a greater prevalence of osteoporosis and vertebral fractures compared to men, osteoporosis is likely to represent a major cause of back pain among elderly women. However, although osteoporosis may be an underlying cause of back pain, especially in postmenopausal elderly women, the prevalence of back pain in this group has not been fully

Although back pain in osteoporosis is often attributed to vertebral fractures (Nevitt et al., 1998; Ulivieri, 2007), the intensity of pain is not always influenced by fracture status (Hübscher et al., 2010). Liu-Ambrose et al. demonstrated that osteoporotic women may experience back pain without a concomitant history of vertebral compression fractures (Liu-Ambrose et al., 2002). The cause of back pain in osteoporosis thus seems likely to be related

Spinal alignment and mobility are important factors for spinal function and may be related to back pain. Loss of lumbar lordosis correlates well with the incidence of chronic low back pain in adults (Djurasovic & Glassman, 2007; Glassman et al., 2005). Patients with a less mobile spine may show more severe symptoms. In addition, we have previously demonstrated that back extensor strength is significantly associated with spinal mobility (Miyakoshi et al., 2005). However, to the best of our knowledge, simultaneous assessment of back pain and multiple spinal factors such as vertebral fractures, spinal alignment and mobility, as well as back extensor strength, has not yet been investigated in patients with

The objectives of this study were thus: 1) to determine the prevalence of back pain in patients with postmenopausal osteoporosis who visited their practitioner; and 2) to evaluate

**1. Introduction** 

investigated.

to multiple factors.

osteoporosis.


## **Prevalence of Back Pain in Postmenopausal Osteoporosis and Associations with Multiple Spinal Factors**

Naohisa Miyakoshi, Michio Hongo and Yoichi Shimada *Department of Orthopedic Surgery, Akita University Graduate School of Medicine Japan* 

### **1. Introduction**

102 Osteoporosis

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*for Postmenopausal Osteoporosis*. Technical Report Series 843, WHO, ISBN 92-4-

*Applications of SAS and SPSS*, Academic Press, ISBN 978-0-12-767870-2, San Diego,

Back pain is considered to be most prevalent musculoskeletal pain, particularly in elderly populations (Woo et al., 2009). The existing literature suggests a prevalence of chronic back pain among the elderly ranging from 7% to 58% (Edmond & Felson, 2000; Jacobs et al., 2006; Lavsky-Shulan et al., 1985; March et al., 1998), with differences attributable to a lack of concordance in terms of age stratification, definition, and methodology, but with consistently much higher rates in women than men (Jabobs et al., 2006; Woo et al., 2009). The reason why back pain is common among elderly women may be related to osteoporosis. As lower bone mineral density (BMD) and the rapid decline in BMD following menopause in women result in a greater prevalence of osteoporosis and vertebral fractures compared to men, osteoporosis is likely to represent a major cause of back pain among elderly women. However, although osteoporosis may be an underlying cause of back pain, especially in postmenopausal elderly women, the prevalence of back pain in this group has not been fully investigated.

Although back pain in osteoporosis is often attributed to vertebral fractures (Nevitt et al., 1998; Ulivieri, 2007), the intensity of pain is not always influenced by fracture status (Hübscher et al., 2010). Liu-Ambrose et al. demonstrated that osteoporotic women may experience back pain without a concomitant history of vertebral compression fractures (Liu-Ambrose et al., 2002). The cause of back pain in osteoporosis thus seems likely to be related to multiple factors.

Spinal alignment and mobility are important factors for spinal function and may be related to back pain. Loss of lumbar lordosis correlates well with the incidence of chronic low back pain in adults (Djurasovic & Glassman, 2007; Glassman et al., 2005). Patients with a less mobile spine may show more severe symptoms. In addition, we have previously demonstrated that back extensor strength is significantly associated with spinal mobility (Miyakoshi et al., 2005). However, to the best of our knowledge, simultaneous assessment of back pain and multiple spinal factors such as vertebral fractures, spinal alignment and mobility, as well as back extensor strength, has not yet been investigated in patients with osteoporosis.

The objectives of this study were thus: 1) to determine the prevalence of back pain in patients with postmenopausal osteoporosis who visited their practitioner; and 2) to evaluate

Prevalence of Back Pain in Postmenopausal Osteoporosis

long did you have it in the daytime?

last week?

back pain?

back pain?

the last week?

\*Reference from Kumamoto et al., 2010.

**2.4 Evaluation of vertebral fractures** 

(JOQOL)\*

and Associations with Multiple Spinal Factors 105

Never 4 1. 1 day per week or less 3 2. 2-3 days per week 2 3. 4-6 days per week 1 4. Every day 0

1. No pain 4 2. 1-2 hours 3 3. 3-5 hours 2 4. 6-10 hours 1 5. All day 0

1. No pain 4 2. Mild 3 3. Moderate 2 4. Severe 1 5. Unbearable 0

1. No pain 4 2. Mild 3 3. Moderate 2 4. Severe 1 5. Unbearable 0

1. Never 4 2. Once 3 3. Twice 2 4. Every other night 1 5. Almost every night 0 Total 20

Table 1. Pain domain questions of the Japanese Osteoporosis Quality of Life Questionnaire

X-rays of the thoracic and lumbar spine in lateral views with the patient in a neutral/lateral decubitus position were taken with a film-tube distance of 1 m. Thoracic films were centered

How often have you had back or low back pain in the

If you have had back pain or low back pain, for how

While you kept still, how severe was your back or low

When you moved, how severe was your back or low

Has the back or low back pain disturbed your sleep in

Question Score (points)

associations of back pain and vertebral fractures, spinal alignment, mobility, and back extensor strength in these patients.

### **2. Materials and methods**

#### **2.1 Patients**

A total of 174 consecutive women with postmenopausal osteoporosis aged 50 years and older who visited their practitioner (orthopedic clinic) were enrolled in the present study. All these patients were the same patients who enrolled in our previous study assessing back extensor strength and quality of life (QOL) (Miyakoshi et al., 2007). Osteoporosis was diagnosed according to the criteria proposed by the Japanese Society for Bone and Mineral Research (JSBMR) (Orimo et al., 2001). Briefly, patients with BMD less than 70% of the young adult mean BMD or with fragility fracture were diagnosed as having osteoporosis. All participants were asked whether they had clinically relevant back pain, and BMD, number of vertebral fractures, angle of kyphosis, range of motion (ROM) of the thoracic and lumbar spine, and back extensor strength were evaluated. These variables were compared between subjects with back pain (BP group) and those without back pain (non-BP group). In the BP group, associations between intensity of back pain and other measured variables were further evaluated.

Exclusion criteria were as follows: 1) women with a history of metabolic bone disease, malignancy, or recent antiosteoporotic treatment (with exception of calcium); 2) patients with hip fracture; 3) patients who could not lie in a prone position; 4) chronic use of glucocorticoids; 5) a concomitant illness that would substantially influence the daily living (e.g., chronic pulmonary disease, asthma, angina, chronic congestive heart failure, stroke, blindness, etc.); 6) other diseases that might cause back pain (e.g., scoliosis, lumbar spondylolisthesis, lumbar disc disease, etc.); and 7) patients with documented vertebral fracture within the last 6 months. Patients enrolled in the present study thus showed chronic back pain that was not attributable to a fresh vertebral fracture.

#### **2.2 Definition of clinically relevant back pain**

Back pain was considered clinically relevant if the participant answered that pain had been moderately to severely bothersome, or if the participant needed any medical treatment (Miyakoshi et al., 2010; Nevitt et al., 1998). In this study, the definition of back was not limited to the narrow sense of the upper and middle back, and low back was also included, as patients with osteoporosis often complain of pain affecting both definitions and differentiating between these seems difficult (Satoh et al., 1988).

#### **2.3 Evaluation of back pain intensity**

Intensity of back pain was evaluated using the pain domain score of the Japanese Osteoporosis QOL Questionnaire (JOQOL) (Table 1) (Kumamoto et al., 2010; Takahashi et al., 2000); as all questions for this score are limited to back pain, all domain scores show significant correlations on test and retest (Kendall's τ = 0.691-0.818) (Kumamoto et al., 2010) and the score can be used as a continuous variable to evaluate correlations with other measured variables. The pain domain score of JOQOL contains 5 questions. Scores for each item range from 0 to 4, for a full score of 20. Pain intensity indicated in this study was calculated as 20 – estimated pain domain score of JOQOL. The pain intensity evaluated in this study thus ranged from 0 (no pain) to 20 (worst pain).

associations of back pain and vertebral fractures, spinal alignment, mobility, and back

A total of 174 consecutive women with postmenopausal osteoporosis aged 50 years and older who visited their practitioner (orthopedic clinic) were enrolled in the present study. All these patients were the same patients who enrolled in our previous study assessing back extensor strength and quality of life (QOL) (Miyakoshi et al., 2007). Osteoporosis was diagnosed according to the criteria proposed by the Japanese Society for Bone and Mineral Research (JSBMR) (Orimo et al., 2001). Briefly, patients with BMD less than 70% of the young adult mean BMD or with fragility fracture were diagnosed as having osteoporosis. All participants were asked whether they had clinically relevant back pain, and BMD, number of vertebral fractures, angle of kyphosis, range of motion (ROM) of the thoracic and lumbar spine, and back extensor strength were evaluated. These variables were compared between subjects with back pain (BP group) and those without back pain (non-BP group). In the BP group, associations between intensity of back pain and other measured variables

Exclusion criteria were as follows: 1) women with a history of metabolic bone disease, malignancy, or recent antiosteoporotic treatment (with exception of calcium); 2) patients with hip fracture; 3) patients who could not lie in a prone position; 4) chronic use of glucocorticoids; 5) a concomitant illness that would substantially influence the daily living (e.g., chronic pulmonary disease, asthma, angina, chronic congestive heart failure, stroke, blindness, etc.); 6) other diseases that might cause back pain (e.g., scoliosis, lumbar spondylolisthesis, lumbar disc disease, etc.); and 7) patients with documented vertebral fracture within the last 6 months. Patients enrolled in the present study thus showed chronic

Back pain was considered clinically relevant if the participant answered that pain had been moderately to severely bothersome, or if the participant needed any medical treatment (Miyakoshi et al., 2010; Nevitt et al., 1998). In this study, the definition of back was not limited to the narrow sense of the upper and middle back, and low back was also included, as patients with osteoporosis often complain of pain affecting both definitions and

Intensity of back pain was evaluated using the pain domain score of the Japanese Osteoporosis QOL Questionnaire (JOQOL) (Table 1) (Kumamoto et al., 2010; Takahashi et al., 2000); as all questions for this score are limited to back pain, all domain scores show significant correlations on test and retest (Kendall's τ = 0.691-0.818) (Kumamoto et al., 2010) and the score can be used as a continuous variable to evaluate correlations with other measured variables. The pain domain score of JOQOL contains 5 questions. Scores for each item range from 0 to 4, for a full score of 20. Pain intensity indicated in this study was calculated as 20 – estimated pain domain score of JOQOL. The pain intensity evaluated in

back pain that was not attributable to a fresh vertebral fracture.

differentiating between these seems difficult (Satoh et al., 1988).

this study thus ranged from 0 (no pain) to 20 (worst pain).

**2.2 Definition of clinically relevant back pain** 

**2.3 Evaluation of back pain intensity** 

extensor strength in these patients.

**2. Materials and methods** 

were further evaluated.

**2.1 Patients** 


\*Reference from Kumamoto et al., 2010.

Table 1. Pain domain questions of the Japanese Osteoporosis Quality of Life Questionnaire (JOQOL)\*

#### **2.4 Evaluation of vertebral fractures**

X-rays of the thoracic and lumbar spine in lateral views with the patient in a neutral/lateral decubitus position were taken with a film-tube distance of 1 m. Thoracic films were centered

Prevalence of Back Pain in Postmenopausal Osteoporosis

were considered statistically significant.

**3. Results** 

(Table 3).

back pain.

pain intensity (Table 5).

bone mineral density; ROM, range of motion.

and Associations with Multiple Spinal Factors 107

differences between groups were compared using an unpaired t-test. Logistic regression analysis was used for analyzing significant risk factors for back pain. Correlations between pain intensity and other measured variables were analyzed using Pearson's correlation coefficient and simple regression analysis. Further analyses using multiple regression were conducted to determine which variables best correlated with back pain. Values of P<0.05

In this study, among 174 patients with postmenopausal osteoporosis, 159 patients (91.4%) complained of back pain. Mean values for age and measured variables in the BP and non-BP groups are listed in Table 2. No significant differences were apparent between BP and non-BP groups with regard to age, BMDs, number of vertebral fractures, angles of thoracic and lumbar kyphosis, and thoracic and lumbar ROMs. However, back extensor strength was significantly lower in the BP group than in the non-BP group. Similarly, when univariate logistic regression analysis was performed with the presence of back pain as a dependent variable and the other estimated variables as independent variables, only back extensor strength was identified as an index significantly associated with the presence of back pain

In patients with back pain, correlations between pain intensity and measured variables were evaluated. Pain intensity showed a significant positive correlation with the number of vertebral fractures, and negative correlations with lumbar spinal ROM and back extensor strength (Table 4). However, no significant correlations were observed between pain intensity and age, BMDs of all measured sites, angles of thoracic and lumbar kyphosis, or thoracic spinal ROM. Based on these results, number of vertebral fractures, lumbar spinal ROM, and back extensor strength were selected as independent variables for multiple regression modeling of pain intensity. Multiple regression analysis for pain intensity revealed lumbar spinal ROM and back extensor strength as significantly associated with

Age (years) 67.8±6.5 65.5±7.0 0.1819 Lumbar spine BMD (g/cm2) 0.696±0.111 0.687±0.103 0.7757 Femoral neck BMD (g/cm2) 0.550±0.087 0.542±0.070 0.7105 Whole-body BMD (g/cm2) 0.818±0.075 0.812±0.047 0.7556 No. of vertebral fractures 1.2±1.7 0.3±0.5 0.0637 Thoracic kyphosis angle (degrees) 44.2±14.1 42.9±12.3 0.7326 Lumbar kyphosis angle (degrees) -15.5±18.2 -23.7±16.8 0.0977 Thoracic spinal ROM (degrees) 17.5±12.8 19.7±19.7 0.5499 Lumbar spinal ROM (degrees) 51.3±17.6 57.3±14.6 0.2025 Back extensor strength (kg) 12.9±6.3 17.3±6.6 0.0130 Values represent mean ± SD. BP, patients with back pain; non-BP, patients without back pain; BMD,

Table 2. Comparison of estimated variables between osteoporotic patients with and without

BP (n=159) Non-BP (n=15) *P* 

on T8, while lumbar films were centered on L3 (Miyakoshi et al., 2003b). Anterior, central, and posterior heights of each vertebral body from T4 to L5 were measured using calipers (Miyakoshi et al., 2003b). Coefficient of variation for this measurement was 2-3% (Orimo et al., 1994). Vertebral fracture was considered present if at least one of the three height measurements (anterior, middle, or posterior) of one vertebral body had decreased by more than 20% compared with the height of the nearest uncompressed vertebral body (Orimo et al., 1994).

### **2.5 Measurement of spinal kyphosis angles and ROMs**

Angles of kyphosis and ROM of the thoracic (T1-T12) and lumbar (L1-L5) spine were measured using a device for computerized measurement of surface curvature (SpinalMouse®; Idiag, Volkerswill, Switzerland) in an upright position and at maximum flexion and extension (Kasukawa et al., 2010; Miyakoshi et al., 2005). Details regarding this device have been provided elsewhere (Post & Leferink, 2004). The device consists of a mobile unit of 2 rolling wheels interfacing with a base station through telemetry. By sliding the mobile unit along the spinal curvature, sagittal spinal alignment is calculated and displayed on the computer monitor. Repeating this process with the patient in flexion and extension of the spine allows measurement of ROM (Post & Leferink, 2004). SpinalMouse® delivers consistently reliable values for standing curvatures and ROM (Mannion et al., 2004; Post & Leferink, 2004). Post and Leferink (Post & Leferink, 2004) reported that interrater intraclass correlation coefficients (ICCs) for curvature measurement with SpinalMouse® were greater than 0.92. Mannion et al. (Mannion et al., 2004) reported that intrarater ICCs ranged from 0.82 to 0.83, while interrater ICCs ranged from 0.81 to 0.86. In addition, our previous studies have shown that thoracic and lumbar angles of kyphosis and spinal ROM measured using the SpinalMouse® correlate strongly with those measured on spinal radiography (r=0.804, r=0.863, and r=0.783, respectively; p<0.0001) (Miyakoshi et al., 2004).

#### **2.6 Measurement of BMD**

BMD was measured by dual-energy X-ray absorptiometry (QDR-4500; Hologic, Bedford, MA). Measurements were obtained from anteroposterior projections of the second to fourth lumbar vertebrae, the femoral neck, and the whole body. The coefficient of variation for these variables in 5 corresponding measurements from 5 normal volunteers was less than 1.5% (Miyakoshi et al., 2007).

#### **2.7 Measurement of back extensor strength**

Isometric back extensor strength in prone position was measured using a strain-gauge dynamometer (Digital Force Gauge DPU-1000N; IMADA, Toyohashi, Japan) as previously described (Hongo et al., 2007; Limburg et al., 1991; Miyakoshi et al., 2005). Subjects were allowed one warm-up trial, followed by three successive maximal effort trials separated by 60-s rest periods (Hongo et al., 2007). Maximal force among the three trials was selected and documented. Coefficient of variation for this measurement was 2.3% (Limburg et al., 1991).

#### **2.8 Data analysis**

All data are presented as mean and standard deviation (SD). Statistical analysis was performed using StatView version 5.0 software (Abacus Concepts, Berkeley, CA). Statistical differences between groups were compared using an unpaired t-test. Logistic regression analysis was used for analyzing significant risk factors for back pain. Correlations between pain intensity and other measured variables were analyzed using Pearson's correlation coefficient and simple regression analysis. Further analyses using multiple regression were conducted to determine which variables best correlated with back pain. Values of P<0.05 were considered statistically significant.

### **3. Results**

106 Osteoporosis

on T8, while lumbar films were centered on L3 (Miyakoshi et al., 2003b). Anterior, central, and posterior heights of each vertebral body from T4 to L5 were measured using calipers (Miyakoshi et al., 2003b). Coefficient of variation for this measurement was 2-3% (Orimo et al., 1994). Vertebral fracture was considered present if at least one of the three height measurements (anterior, middle, or posterior) of one vertebral body had decreased by more than 20% compared with the height of the nearest uncompressed vertebral body (Orimo et

Angles of kyphosis and ROM of the thoracic (T1-T12) and lumbar (L1-L5) spine were measured using a device for computerized measurement of surface curvature (SpinalMouse®; Idiag, Volkerswill, Switzerland) in an upright position and at maximum flexion and extension (Kasukawa et al., 2010; Miyakoshi et al., 2005). Details regarding this device have been provided elsewhere (Post & Leferink, 2004). The device consists of a mobile unit of 2 rolling wheels interfacing with a base station through telemetry. By sliding the mobile unit along the spinal curvature, sagittal spinal alignment is calculated and displayed on the computer monitor. Repeating this process with the patient in flexion and extension of the spine allows measurement of ROM (Post & Leferink, 2004). SpinalMouse® delivers consistently reliable values for standing curvatures and ROM (Mannion et al., 2004; Post & Leferink, 2004). Post and Leferink (Post & Leferink, 2004) reported that interrater intraclass correlation coefficients (ICCs) for curvature measurement with SpinalMouse® were greater than 0.92. Mannion et al. (Mannion et al., 2004) reported that intrarater ICCs ranged from 0.82 to 0.83, while interrater ICCs ranged from 0.81 to 0.86. In addition, our previous studies have shown that thoracic and lumbar angles of kyphosis and spinal ROM measured using the SpinalMouse® correlate strongly with those measured on spinal radiography (r=0.804, r=0.863, and r=0.783, respectively; p<0.0001) (Miyakoshi et al., 2004).

BMD was measured by dual-energy X-ray absorptiometry (QDR-4500; Hologic, Bedford, MA). Measurements were obtained from anteroposterior projections of the second to fourth lumbar vertebrae, the femoral neck, and the whole body. The coefficient of variation for these variables in 5 corresponding measurements from 5 normal volunteers was less than

Isometric back extensor strength in prone position was measured using a strain-gauge dynamometer (Digital Force Gauge DPU-1000N; IMADA, Toyohashi, Japan) as previously described (Hongo et al., 2007; Limburg et al., 1991; Miyakoshi et al., 2005). Subjects were allowed one warm-up trial, followed by three successive maximal effort trials separated by 60-s rest periods (Hongo et al., 2007). Maximal force among the three trials was selected and documented. Coefficient of variation for this measurement was 2.3% (Limburg et al., 1991).

All data are presented as mean and standard deviation (SD). Statistical analysis was performed using StatView version 5.0 software (Abacus Concepts, Berkeley, CA). Statistical

**2.5 Measurement of spinal kyphosis angles and ROMs** 

al., 1994).

**2.6 Measurement of BMD** 

1.5% (Miyakoshi et al., 2007).

**2.8 Data analysis** 

**2.7 Measurement of back extensor strength** 

In this study, among 174 patients with postmenopausal osteoporosis, 159 patients (91.4%) complained of back pain. Mean values for age and measured variables in the BP and non-BP groups are listed in Table 2. No significant differences were apparent between BP and non-BP groups with regard to age, BMDs, number of vertebral fractures, angles of thoracic and lumbar kyphosis, and thoracic and lumbar ROMs. However, back extensor strength was significantly lower in the BP group than in the non-BP group. Similarly, when univariate logistic regression analysis was performed with the presence of back pain as a dependent variable and the other estimated variables as independent variables, only back extensor strength was identified as an index significantly associated with the presence of back pain (Table 3).

In patients with back pain, correlations between pain intensity and measured variables were evaluated. Pain intensity showed a significant positive correlation with the number of vertebral fractures, and negative correlations with lumbar spinal ROM and back extensor strength (Table 4). However, no significant correlations were observed between pain intensity and age, BMDs of all measured sites, angles of thoracic and lumbar kyphosis, or thoracic spinal ROM. Based on these results, number of vertebral fractures, lumbar spinal ROM, and back extensor strength were selected as independent variables for multiple regression modeling of pain intensity. Multiple regression analysis for pain intensity revealed lumbar spinal ROM and back extensor strength as significantly associated with pain intensity (Table 5).


Values represent mean ± SD. BP, patients with back pain; non-BP, patients without back pain; BMD, bone mineral density; ROM, range of motion.

Table 2. Comparison of estimated variables between osteoporotic patients with and without back pain.

Prevalence of Back Pain in Postmenopausal Osteoporosis

**4. Discussion** 

**4.1 Prevalence of back pain** 

and Associations with Multiple Spinal Factors 109

Back pain is a major source of morbidity among patients with osteoporosis. Osteoporotic vertebral fractures usually cause acute, disabling, painful episodes at the fracture site. Such acute back pain subsides with fracture healing. However, after the fracture heals, the resulting increase in spinal kyphosis is likely to cause chronic back pain (Francis et al., 2008; Satoh et al., 1988). Increased spinal kyphosis is likely to induce abnormal stress on the supporting structures of the spinal column and may cause chronic back pain that usually develops while standing, walking, or doing other normal daily activities (Satoh et al., 1988). The back pain evaluated in the present study was considered to be chronic, because patients with documented vertebral fracture within the preceding 6 months were not included. The prevalence of back pain, particularly chronic back pain, in patients with osteoporosis has not been fully investigated. Cockerill et al. (Cockerill et al., 2000) reported that the prevalence of back pain in the current and past year for women aged 50 years and over was significantly higher in women with single lumbar vertebral deformities (51.4% and 72.6%, respectively) than in women without vertebral deformity (39% and 60.6%, respectively) (p<0.05). Jacobs et al. (Jacobs et al., 2006) undertook a longitudinal study of 277 elderly subjects, finding that the prevalence of chronic back pain increased from 44% to 58% at ages 70 and 77 years, respectively, and this pain was associated with female sex at age 70 years and osteoporosis at age 77 years. More recently, Kuroda et al. (Kuroda et al., 2009) reported that back pain was observed in 28% of 818 Japanese postmenopausal women aged over 40 years (mean, 62.1 years) who visited their practitioner, and this back pain was associated with osteoporosis and vertebral fractures. In the present study, the prevalence of clinically relevant back pain was 91.4%. This percentage is higher than previously reported prevalences of back pain in osteoporosis (28-72.6%) (Cockerill et al., 2000; Jacobs et al., 2006; Kuroda et al., 2009), probably because all patients enrolled in the present study were visitors

to an orthopedic clinic and might have had more musculoskeletal symptoms.

Previous studies have shown that vertebral fractures are associated with back pain and disability, with the strength of these associations increasing with the number and severity of fractures (Ettinger et al., 1992; Huang et al., 1996; Matthis et al., 1998). Increased spinal kyphosis caused by vertebral fractures is also known to induce back pain and disability in patients with osteoporosis (Miyakoshi et al., 2003a). In the present study, the number of vertebral fractures and angles of lumbar kyphosis tended to be higher in patients with back pain than in those without back pain, but no significant differences were identified (p=0.0637 and p=0.0977, respectively). However, in patients with back pain, the present study also showed a significant positive correlation between number of vertebral fractures

An important association between back pain and back extensor strength in patients with osteoporosis is indicated from the present study. Back extensor strength was significantly lower in patients with back pain compared to those without back pain, but other factors we evaluated showed no significant differences between groups. In addition, among patients with back pain, multiple regression analysis for pain intensity revealed back extensor strength and lumbar spinal ROM as significantly associated with pain intensity. Decreased back extensor strength may thus represent the most important factor contributing to back

**4.2 Factors associated with back pain and pain intensity** 

and pain intensity (r=0.171, p=0.0312).


OR, odds ratio; CI, confidence interval; BMD, bone mineral density; ROM, range of motion.

Table 3. Univariate logistic regression analysis for back pain in patients with osteoporosis (n=174).


\*Pain intensity ranged from 0 (no pain) to 20 (worst pain) was calculated from 20 minus estimated pain domain score of JOQOL. BMD, bone mineral density; ROM, range of motion.

Table 4. Correlations between pain intensity\* and estimated variables in patients with osteoporosis and back pain (n=159).


\*Pain intensity ranged from 0 (no pain) to 20 (worst pain), calculated as 20 minus the estimated pain domain score of JOQOL. ROM, range of motion.

Table 5. Multiple regression analysis for pain intensity\* in patients with osteoporosis and back pain (n=159).

## **4. Discussion**

108 Osteoporosis

Age (years) 1.052 0.976-1.134 0.1845 Lumbar spine BMD (g/cm2) 2.044 0.015-269.925 0.7741 Femoral neck BMD (g/cm2) 3.289 0.006-1695.221 0.7086 Whole body BMD (g/cm2) 3.275 0.002-5461.831 0.7540 No. of vertebral fractures 2.107 0.949-4.680 0.0670 Thoracic kyphosis angle (degrees) 1.007 0.969-1.046 0.7308 Lumbar kyphosis angle (degrees) 1.033 0.994-1.074 0.0958 Thoracic spinal ROM (degrees) 0.988 0.951-1.027 0.5475 Lumbar spinal ROM (degrees) 0.980 0.951-1.011 0.2033 Back extensor strength (kg) 0.906 0.835-0.982 0.0166

OR, odds ratio; CI, confidence interval; BMD, bone mineral density; ROM, range of motion.

domain score of JOQOL. BMD, bone mineral density; ROM, range of motion.

osteoporosis and back pain (n=159).

domain score of JOQOL. ROM, range of motion.

back pain (n=159).

(n=174).

Table 3. Univariate logistic regression analysis for back pain in patients with osteoporosis

Age (years) 0.118 0.1391 Lumbar spine BMD (g/cm2) -0.089 0.2643 Femoral neck BMD (g/cm2) -0.090 0.2583 Whole body BMD (g/cm2) -0.097 0.2258 No. of vertebral fractures 0.171 0.0312 Thoracic kyphosis angle (degree) -0.043 0.5892 Lumbar kyphosis angle (degree) 0.139 0.0803 Thoracic spinal ROM (degree) -0.109 0.1707 Lumbar spinal ROM (degree) -0.264 0.0007 Back extensor strength (kg) -0.268 0.0006 \*Pain intensity ranged from 0 (no pain) to 20 (worst pain) was calculated from 20 minus estimated pain

Table 4. Correlations between pain intensity\* and estimated variables in patients with

Intercept 11.238 <0.0001 No. of vertebral fractures 0.132 0.4517 Lumbar spinal ROM (degrees) -0.041 0.0179 Back extensor strength (kg) -0.116 0.0142 \*Pain intensity ranged from 0 (no pain) to 20 (worst pain), calculated as 20 minus the estimated pain

Table 5. Multiple regression analysis for pain intensity\* in patients with osteoporosis and

OR 95% CI *P* 

Correlation coefficient *(r) P* 

Coefficient *(r) P* 

### **4.1 Prevalence of back pain**

Back pain is a major source of morbidity among patients with osteoporosis. Osteoporotic vertebral fractures usually cause acute, disabling, painful episodes at the fracture site. Such acute back pain subsides with fracture healing. However, after the fracture heals, the resulting increase in spinal kyphosis is likely to cause chronic back pain (Francis et al., 2008; Satoh et al., 1988). Increased spinal kyphosis is likely to induce abnormal stress on the supporting structures of the spinal column and may cause chronic back pain that usually develops while standing, walking, or doing other normal daily activities (Satoh et al., 1988). The back pain evaluated in the present study was considered to be chronic, because patients with documented vertebral fracture within the preceding 6 months were not included.

The prevalence of back pain, particularly chronic back pain, in patients with osteoporosis has not been fully investigated. Cockerill et al. (Cockerill et al., 2000) reported that the prevalence of back pain in the current and past year for women aged 50 years and over was significantly higher in women with single lumbar vertebral deformities (51.4% and 72.6%, respectively) than in women without vertebral deformity (39% and 60.6%, respectively) (p<0.05). Jacobs et al. (Jacobs et al., 2006) undertook a longitudinal study of 277 elderly subjects, finding that the prevalence of chronic back pain increased from 44% to 58% at ages 70 and 77 years, respectively, and this pain was associated with female sex at age 70 years and osteoporosis at age 77 years. More recently, Kuroda et al. (Kuroda et al., 2009) reported that back pain was observed in 28% of 818 Japanese postmenopausal women aged over 40 years (mean, 62.1 years) who visited their practitioner, and this back pain was associated with osteoporosis and vertebral fractures. In the present study, the prevalence of clinically relevant back pain was 91.4%. This percentage is higher than previously reported prevalences of back pain in osteoporosis (28-72.6%) (Cockerill et al., 2000; Jacobs et al., 2006; Kuroda et al., 2009), probably because all patients enrolled in the present study were visitors to an orthopedic clinic and might have had more musculoskeletal symptoms.

### **4.2 Factors associated with back pain and pain intensity**

Previous studies have shown that vertebral fractures are associated with back pain and disability, with the strength of these associations increasing with the number and severity of fractures (Ettinger et al., 1992; Huang et al., 1996; Matthis et al., 1998). Increased spinal kyphosis caused by vertebral fractures is also known to induce back pain and disability in patients with osteoporosis (Miyakoshi et al., 2003a). In the present study, the number of vertebral fractures and angles of lumbar kyphosis tended to be higher in patients with back pain than in those without back pain, but no significant differences were identified (p=0.0637 and p=0.0977, respectively). However, in patients with back pain, the present study also showed a significant positive correlation between number of vertebral fractures and pain intensity (r=0.171, p=0.0312).

An important association between back pain and back extensor strength in patients with osteoporosis is indicated from the present study. Back extensor strength was significantly lower in patients with back pain compared to those without back pain, but other factors we evaluated showed no significant differences between groups. In addition, among patients with back pain, multiple regression analysis for pain intensity revealed back extensor strength and lumbar spinal ROM as significantly associated with pain intensity. Decreased back extensor strength may thus represent the most important factor contributing to back

Prevalence of Back Pain in Postmenopausal Osteoporosis

**6. Acknowledgement** 

conducting the study.

**7. References** 

decreased back extensor strength and limited lumbar spinal mobility.

(January 1997), pp.152-157, ISSN 0884-0431

Vol.7, No.4, (April 1992), pp.449-456, ISSN 0884-0431

Vol.30, No.18, (September 2005), 2024-2029, ISSN 0362-2436

pp.223-227, ISSN 1042-3680

pp.895-903, ISSN 0937-941X

(July 1996), pp.1026-1032, ISSN 0884-0431

No.3, (July 2010), pp.383-385, ISSN 0966-6362

941X

and Associations with Multiple Spinal Factors 111

was significantly lower in patients with back pain compared to those without back pain. Among subjects with back pain, intensity of back pain showed significant relationships with

We wish to thank all the staff of Joto Orthopedic Clinic for their valuable assistance in

Burger, H.; Van Daele, P.L.; Grashuis, K.; Hofman, A.; Grobbee, D.E.; Schütte, H.E.;

Cockerill, W.; Ismail, A.A.; Cooper, C.; Matthis, C.; Raspe, H.; Silman, A.J. & O'Neill, T.W.

*Rheumatic Diseases,* Vol.59, No.5, (May 2000), pp.368-371, ISSN 0003-4967 Djurasovic. M. & Glassman, S.D. (2007). Correlation of radiographic and clinical findings in

Edmond, S.L. & Felson, D.T. (2000). Prevalence of back symptoms in elders. *The Journal of Rheumatology,* Vol.27, No.1, (January 2000), pp.220-225, ISSN 0315-162X Ettinger, B.; Black, D.M.; Nevitt, M.C.; Rundle, A.C.; Cauley, J.A.; Cummings, S.R. & Genant,

Francis, R.M.; Aspray, T.J.; Hide, G.; Sutcliffe, A.M. & Wilkinson, P. (2008). Back pain in

Glassman, S.D.; Bridwell, K.; Dimar, J.R.; Horton, W.; Berven, S. & Schwab F. (2005). The

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back pain among older women. *Journal of Bone and Mineral Research,* Vol.11, No.7,

falling and physical function in women with osteoporosis. *Gait & Posture,* Vol.32,

pain and pain intensity in patients with osteoporosis. Subjects on acute back pain due to fresh vertebral fractures maybe could not perform the back extensor strength tests as good as non-acute pain subjects. However, because the back pain evaluated in the present study was considered to be chronic, all the patients could perform the strength tests without increasing the pain. Thus, we concluded that the weakness of back extensor is a very important factor for chronic back pain in patients with osteoporosis.

Back extensor strength reportedly shows a significant relation with spinal mobility (Miyakoshi et al., 2005), and decreased mobility of the spine is thought to lead to increased kyphosis and weakness of the paravertebral muscles, as well as the development of impaired physical function (Burger et al., 1997). Decreased back extensor strength may thus reduce mobility of the lumbar spine, and a less mobile lumbar spine may cause stiffness of the back muscles, resulting in back pain. As muscle strength is determined largely by muscle mass, particularly the cross-sectional area of muscle (Maughan, 2005), and because the muscle cross-sectional area of back extensor muscles (the erector spinae group) is larger at the lumbar spine level than at the thoracic spine level (Marras et al., 2001), total back extensor strength is largely influenced by lumbar extensor muscles rather than thoracic extensor muscles. The results of the present study are not inconsistent with this anatomical background. Weakness of the back extensor muscles, particularly the lumbar extensor muscles, is thought to be responsible for lumbar spinal mobility.

#### **4.3 Other possible factors contributing to back pain in osteoporosis**

The present study focused on back pain and multiple spinal factors in patients with osteoporosis. However, the etiology of back pain is more complex and more multifactorial than could be examined in this study. Prevalence of musculoskeletal pain is also known to be associated with various measures of socio-economic status, as well as comorbidities (Thomas et al., 1999; Woo et al., 2009). Severity of pain may also be influenced by psychological factors (Woo et al., 2009). In addition, elderly patients with osteoporosis sometimes show other painful spinal disorders such as spondylosis to varying extents (Miyakoshi et al., 2003b). Findings in the present study might also have been influenced, at least in part, by factors other than osteoporosis.

#### **4.4 Study limitations**

Limitations of the present study should be noted. First, the number of subjects in the present study was much smaller than in previous studies evaluating the prevalence of back pain (Cockerill et al., 2000; Jacobs et al., 2006; Kuroda et al., 2009). However, we would like to emphasize that this is the first study to simultaneously evaluate back pain and multiple spinal factors in patients with osteoporosis. Second, data could not be obtained from severely kyphotic patients with established osteoporosis who were too disabled to lie in a prone position because of increased back pain in this position. This was because the dynamometer for measuring back extensor strength in the present study needed the patient to lie in a prone position. Therefore, the results of the present study might be considered for patients with mild or moderate spinal deformity.

#### **5. Conclusions**

In conclusion, the prevalence of back pain among patients with postmenopausal osteoporosis 50 years old who visited their practitioner was 91.4%. Back extensor strength was significantly lower in patients with back pain compared to those without back pain. Among subjects with back pain, intensity of back pain showed significant relationships with decreased back extensor strength and limited lumbar spinal mobility.

### **6. Acknowledgement**

We wish to thank all the staff of Joto Orthopedic Clinic for their valuable assistance in conducting the study.

### **7. References**

110 Osteoporosis

pain and pain intensity in patients with osteoporosis. Subjects on acute back pain due to fresh vertebral fractures maybe could not perform the back extensor strength tests as good as non-acute pain subjects. However, because the back pain evaluated in the present study was considered to be chronic, all the patients could perform the strength tests without increasing the pain. Thus, we concluded that the weakness of back extensor is a very

Back extensor strength reportedly shows a significant relation with spinal mobility (Miyakoshi et al., 2005), and decreased mobility of the spine is thought to lead to increased kyphosis and weakness of the paravertebral muscles, as well as the development of impaired physical function (Burger et al., 1997). Decreased back extensor strength may thus reduce mobility of the lumbar spine, and a less mobile lumbar spine may cause stiffness of the back muscles, resulting in back pain. As muscle strength is determined largely by muscle mass, particularly the cross-sectional area of muscle (Maughan, 2005), and because the muscle cross-sectional area of back extensor muscles (the erector spinae group) is larger at the lumbar spine level than at the thoracic spine level (Marras et al., 2001), total back extensor strength is largely influenced by lumbar extensor muscles rather than thoracic extensor muscles. The results of the present study are not inconsistent with this anatomical background. Weakness of the back extensor muscles, particularly the lumbar extensor

The present study focused on back pain and multiple spinal factors in patients with osteoporosis. However, the etiology of back pain is more complex and more multifactorial than could be examined in this study. Prevalence of musculoskeletal pain is also known to be associated with various measures of socio-economic status, as well as comorbidities (Thomas et al., 1999; Woo et al., 2009). Severity of pain may also be influenced by psychological factors (Woo et al., 2009). In addition, elderly patients with osteoporosis sometimes show other painful spinal disorders such as spondylosis to varying extents (Miyakoshi et al., 2003b). Findings in the present study might also have been influenced, at

Limitations of the present study should be noted. First, the number of subjects in the present study was much smaller than in previous studies evaluating the prevalence of back pain (Cockerill et al., 2000; Jacobs et al., 2006; Kuroda et al., 2009). However, we would like to emphasize that this is the first study to simultaneously evaluate back pain and multiple spinal factors in patients with osteoporosis. Second, data could not be obtained from severely kyphotic patients with established osteoporosis who were too disabled to lie in a prone position because of increased back pain in this position. This was because the dynamometer for measuring back extensor strength in the present study needed the patient to lie in a prone position. Therefore, the results of the present study might be considered for

In conclusion, the prevalence of back pain among patients with postmenopausal osteoporosis 50 years old who visited their practitioner was 91.4%. Back extensor strength

important factor for chronic back pain in patients with osteoporosis.

muscles, is thought to be responsible for lumbar spinal mobility.

least in part, by factors other than osteoporosis.

patients with mild or moderate spinal deformity.

**4.4 Study limitations** 

**5. Conclusions** 

**4.3 Other possible factors contributing to back pain in osteoporosis** 


Prevalence of Back Pain in Postmenopausal Osteoporosis

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**Part 3** 

**The Diagnosis and Assessment** 

**of Osteoporosis and Fractures Risk** 

edition. *Journal of Japanese Society for Bone and Mineral Research,* Vol.18, No.3, (January 2001), pp.85-101, ISSN 0910-0067 (in Japanese)


## **Part 3**

**The Diagnosis and Assessment of Osteoporosis and Fractures Risk** 

114 Osteoporosis

Thomas, E.; Silman, A.J.; Croft, P.R.; Papageorgiou, A.C.; Jayson, M.I. & Macfarlane, G.J.

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fractures. *Aging Clinical and Experimental Research,* Vol.19, No.3 Suppl., (June 2007),

Chinese elderly and the impact on 4-year physical function and quality of life.

**6** 

Frank Bonura

*USA* 

**The Diagnosis and Workup of Patients for** 

*St. Catherine of Siena Medical Center, Smithtown, NY* 

**Osteoporosis or Osteopenia (Low Bone Mass)** 

The rate of screening and treatment for osteoporosis remains low. Osteoporosis affects approximately 200 million women worldwide and two thirds of women 80 or older have this disease. It causes more than 1.6 million hip fractures worldwide. (International Osteoporosis Foundation, 2006) In the United States, more than 10 million Americans have osteoporosis and 3.6 million have low bone mineral density of the hip. In 2005 in the United States, there were more than 2 million osteoporotic fractures in men and women. These fractures caused more than 432,000 hospitalist admissions, 2.5 million physician office visits and about 180,000 nursing home admissions yearly in the United States. In 2005, the cost of osteoporotic fractures was approximately 17 billion dollars. (U.S. Department of Health and Human Services, 2004) Osteoporosis is responsible for approximately 90% of all spine and

Fifty percent of women and twenty-five percent of men greater than age 50 will experience an osteoporotic fracture in their remaining lifetime. (National Osteoporosis Foundation, Feb. 2008) Less that 5 percent of patients with a clinical low trauma fragility fracture are referred for medical evaluation and treatment. (Bonura, 2009) In 2005, a population based study reported that the proportion of women screened and treated for osteoporosis after a fragility fracture was 10.2 percent and 12.9 percent respectfully. In males, studies indicate that a low proportion of men are evaluated for osteoporosis or receive anti-resorptive therapy after a fragility fracture. (Feldstein, 2005) Most patients with hip fractures receive no

Physician frequently fail to diagnose and treat osteoporosis, even in the elderly patients who have suffered a fractures. (Bonura, 2009) Less then 20 percent of women with wrist fractures are screened for osteoporosis, and only 12.9 percent are treated for osteoporosis after a facture. (Cuddihy, 2002) In a clinical study the majority of patients with clinical vertebral fractures (80 percent) did not receive osteoporosis therapy. (Lindsay, 2005) A prior osteoporotic fracture increases the risk of future fractures. A forearm fracture is associated with a two fold increased risk of fractures. Radiographic vertebral fractures are associated with a higher risk of subsequent hip and other fractures. In the year following a vertebral fracture, 26 percent of patients will fracture a hip, pelvis, vertebrae, wrist, humerus, or leg. (Klotzbuecher, 2000) Following a hip fracture in women, the mortality ranges between 20-24% within one year. 25% of patients are admitted to a long term healthcare facility and only 40% are able to obtain their pre-fracture level of independence. Worldwide, one-third of hip fractures occur

hip fractures in Caucasian females age 65-84 in the United States.

pharmacologic treatment for osteoporosis.

**1. Introduction** 

## **The Diagnosis and Workup of Patients for Osteoporosis or Osteopenia (Low Bone Mass)**

### Frank Bonura

*St. Catherine of Siena Medical Center, Smithtown, NY USA* 

### **1. Introduction**

The rate of screening and treatment for osteoporosis remains low. Osteoporosis affects approximately 200 million women worldwide and two thirds of women 80 or older have this disease. It causes more than 1.6 million hip fractures worldwide. (International Osteoporosis Foundation, 2006) In the United States, more than 10 million Americans have osteoporosis and 3.6 million have low bone mineral density of the hip. In 2005 in the United States, there were more than 2 million osteoporotic fractures in men and women. These fractures caused more than 432,000 hospitalist admissions, 2.5 million physician office visits and about 180,000 nursing home admissions yearly in the United States. In 2005, the cost of osteoporotic fractures was approximately 17 billion dollars. (U.S. Department of Health and Human Services, 2004) Osteoporosis is responsible for approximately 90% of all spine and hip fractures in Caucasian females age 65-84 in the United States.

Fifty percent of women and twenty-five percent of men greater than age 50 will experience an osteoporotic fracture in their remaining lifetime. (National Osteoporosis Foundation, Feb. 2008) Less that 5 percent of patients with a clinical low trauma fragility fracture are referred for medical evaluation and treatment. (Bonura, 2009) In 2005, a population based study reported that the proportion of women screened and treated for osteoporosis after a fragility fracture was 10.2 percent and 12.9 percent respectfully. In males, studies indicate that a low proportion of men are evaluated for osteoporosis or receive anti-resorptive therapy after a fragility fracture. (Feldstein, 2005) Most patients with hip fractures receive no pharmacologic treatment for osteoporosis.

Physician frequently fail to diagnose and treat osteoporosis, even in the elderly patients who have suffered a fractures. (Bonura, 2009) Less then 20 percent of women with wrist fractures are screened for osteoporosis, and only 12.9 percent are treated for osteoporosis after a facture. (Cuddihy, 2002) In a clinical study the majority of patients with clinical vertebral fractures (80 percent) did not receive osteoporosis therapy. (Lindsay, 2005) A prior osteoporotic fracture increases the risk of future fractures. A forearm fracture is associated with a two fold increased risk of fractures. Radiographic vertebral fractures are associated with a higher risk of subsequent hip and other fractures. In the year following a vertebral fracture, 26 percent of patients will fracture a hip, pelvis, vertebrae, wrist, humerus, or leg. (Klotzbuecher, 2000)

Following a hip fracture in women, the mortality ranges between 20-24% within one year. 25% of patients are admitted to a long term healthcare facility and only 40% are able to obtain their pre-fracture level of independence. Worldwide, one-third of hip fractures occur

The Diagnosis and Workup of Patients for Osteoporosis or Osteopenia (Low Bone Mass) 119

Low calcium intake Vitamin D insufficiency Excess vitamin A

Alcohol (3 or more drinks/d) Inadequate physical activity Immobilization Smoking (active or passive) Falling Thinness

Adrenal insufficiency Diabetes mellitus Thyrotoxicosis

Gaucher's disease Idiopathic hypercalciuria Porphyria

Leukemia and lymphomas Sickle cell diseases Thalassemia

Depression Multiple sclerosis Sarcoidosis

tacrolimus

Aromatase inhibitors Depo-medroxyprogesterone Lithium

drugs

Anticoagulants (heparin) Cancer chemotherapeutic

and Fractures (National Osteoporosis Foundation, 2008)

Anticonvulsants Cyclosporine A and

Hemochromatosis Menkes steely hair syndrome

Celiac disease Inflammatory bowel disease Pancreatic disease Gastric bypass Malabsorption Primary biliary cirrhosis

Cystic fibrosis Homocystinuria Osteogenesis imperfecta Ehlers-Danlos Hypophosphatasia Parental history of hip fracture

Glycogen storage diseases Marfan syndrome Riley-Day syndrome

Hemophilia Multiple myeloma Systemic mastocytosis

Ankylosing spondylitis Lupus Rheumatoid arthritis

Alcoholism Emphysema Muscular dystrophy Amlyloidosis End stage renal disease Parenteral nutrition

Chronic metabolic acidosis Epilepsy Post-transplant bone disease Congestive heart failure Idiopathic scoliosis Prior fracture as an adult

Table 2. Conditions, Diseases and Medications That Cause or Contribute to Osteoporosis

Cushing's syndrome Hyperparathyroidism

High caffeine intake High salt intake Aluminum (in antacids)

Androgen insensitivity Hyperprolactinemia Premature ovarian failure

Panhypopituitarism Turner's & Klinefelter's

syndromes

Glucocorticoids (≥ 5 mg/d of prednisone or equivalent for ≥

Gonadotropin releasing hormone agonists

3 mo)

**Lifestyle Factors**

**Hypogonadal States**

Anorexia nervosa and

Athletic amenorrhea **Endocrine Disorders**

**Gastrointestinal Disorders**

**Hematologic Disorders**

**Medications** 

Barbiturates

**Rheumatic and Autoimmune Diseases**

**Miscellaneous Conditions and Diseases**

bulimia

GI surgery **Genetic Factors** 

in men and more men than women die after a hip fracture with a mortality rate of about 37.5%. (Jiang, 2005) The most common of all the osteoporotic fractures are vertebral fractures. They are usually painless, but can cause back pain, height loss, deformity, reeducated respiratory function, disability, and a reduced quality of life. There is also an increase in mortality in women of about 23% over 8 years and they can cause an increase in future vertebral and non vertebral fractures. (Kado, 1999)


Table 1. Prior Fracture as a Predictor of Fracture Risk (Klotzbuecher, 2000))

### **2. Evaluation**

Postmenopausal women and men after age 50 should be evaluated for their risk factors for osteoporosis and fracture, and their risk factors of falling. This evaluation includes a history and a physical exam, including a height measurement and, if necessary diagnostic testing. Several clinical risk factors for osteoporosis have been indentified and should be evaluated. Non-modifiable risk factors include advancing age, female sex, Asian or Caucasian ethnicity, history of a fracture as an adult, family history of a fracture in a first degree relative (maternal or paternal history of a hip fracture) and rheumatoid arthritis. Modifiable risk factors comprise low body weight, hormone deficiency, long term use of medications that affect bone homeostasis (e.g., glucocorticoids), causes of secondary osteoporosis, smoking, excessive alcohol consumption, an inactive lifestyle, and a lifetime diet low in calcium and vitamin D. The more risk factor that a patient has, the greater the risk of a fracture. (Bonura, 2009)

The most important of all these risk factors are age (65 or greater in women and 70 or greater in men) and the occurrence of a low trauma fracture after age 40. Other risk factors of importance are bone mineral density, genetics, menopause, BMI, and lifestyle.

As a woman ages, their fracture risk increases. After age 50, their fracture risk doubles every 7 or 8 years. The average age of a hip fracture in women is 82 years and in men 50% of their hip fractures occur before age 80. Vertebral fractures usually occur in women and men in their seventies. (Chang, 2004) A prior osteoporotic fracture increases the risk of future osteoporotic fracture risk. If a postmenopausal female sustains an osteoporotic fracture, she has approximately a two fold increase of sustaining another osteoporotic fracture in her lifetime.

Bone mineral density also is a risk factor for future fractures. Bone mineral density affects fracture risk. The lower the bone mineral density (BMD), the higher the risk for fractures. A decrease of 1 standard deviation of bone mineral density (BMD) represents a 10-12% decrease in BMD and can increase fracture risk by 1.5 to 2.6 times. (Marshall, 1996) Genetics plays a role in osteoporosis and future fracture risk. Daughters of women who have had an osteoporotic fracture, and daughters of first degree relatives (mother or sisters) or have osteoporosis have lower bone mineral density (BMD) for their age. Also a history of an

in men and more men than women die after a hip fracture with a mortality rate of about 37.5%. (Jiang, 2005) The most common of all the osteoporotic fractures are vertebral fractures. They are usually painless, but can cause back pain, height loss, deformity, reeducated respiratory function, disability, and a reduced quality of life. There is also an increase in mortality in women of about 23% over 8 years and they can cause an increase in

Wrist 3.3 1.7 1.9 Vertebral 1.4 4.4 2.3 Hip Not Available 2.5 2.3

Postmenopausal women and men after age 50 should be evaluated for their risk factors for osteoporosis and fracture, and their risk factors of falling. This evaluation includes a history and a physical exam, including a height measurement and, if necessary diagnostic testing. Several clinical risk factors for osteoporosis have been indentified and should be evaluated. Non-modifiable risk factors include advancing age, female sex, Asian or Caucasian ethnicity, history of a fracture as an adult, family history of a fracture in a first degree relative (maternal or paternal history of a hip fracture) and rheumatoid arthritis. Modifiable risk factors comprise low body weight, hormone deficiency, long term use of medications that affect bone homeostasis (e.g., glucocorticoids), causes of secondary osteoporosis, smoking, excessive alcohol consumption, an inactive lifestyle, and a lifetime diet low in calcium and vitamin D. The more risk factor that a patient has, the greater the risk of a

The most important of all these risk factors are age (65 or greater in women and 70 or greater in men) and the occurrence of a low trauma fracture after age 40. Other risk factors

As a woman ages, their fracture risk increases. After age 50, their fracture risk doubles every 7 or 8 years. The average age of a hip fracture in women is 82 years and in men 50% of their hip fractures occur before age 80. Vertebral fractures usually occur in women and men in their seventies. (Chang, 2004) A prior osteoporotic fracture increases the risk of future osteoporotic fracture risk. If a postmenopausal female sustains an osteoporotic fracture, she has approximately a two fold increase of sustaining another osteoporotic fracture in her

Bone mineral density also is a risk factor for future fractures. Bone mineral density affects fracture risk. The lower the bone mineral density (BMD), the higher the risk for fractures. A decrease of 1 standard deviation of bone mineral density (BMD) represents a 10-12% decrease in BMD and can increase fracture risk by 1.5 to 2.6 times. (Marshall, 1996) Genetics plays a role in osteoporosis and future fracture risk. Daughters of women who have had an osteoporotic fracture, and daughters of first degree relatives (mother or sisters) or have osteoporosis have lower bone mineral density (BMD) for their age. Also a history of an

of importance are bone mineral density, genetics, menopause, BMI, and lifestyle.

Table 1. Prior Fracture as a Predictor of Fracture Risk (Klotzbuecher, 2000))

**Relative Risk of Future Fractures**  Wrist Vertebral Hip

future vertebral and non vertebral fractures. (Kado, 1999)

Prior Fracture

**2. Evaluation** 

fracture. (Bonura, 2009)

lifetime.


Table 2. Conditions, Diseases and Medications That Cause or Contribute to Osteoporosis and Fractures (National Osteoporosis Foundation, 2008)

The Diagnosis and Workup of Patients for Osteoporosis or Osteopenia (Low Bone Mass) 121

During a patient's examination, height measurement may be useful to indicate occult vertebral compression fractures, which are indicative of osteoporosis. They are the most common osteoporotic fractures in postmenopausal women, and two-thirds of these fractures are not clinically recognized. (Cauley, 2007) The loss of height, kyphosis, and back pain may be signs of vertebral fractures. Normally after achieving maximal height, women can lose up to 1.0 – 1.5 inches (2.0 – 3.8 cm) of height as part of the normal aging process, due to degenerative arthritis and shrinkage of intervertebral disks. Height loss of greater than 1.5 inches (3.8 cm) increases the risk of a vertebral fracture. One must suspect a vertebral fracture in postmenopausal women with a historical height loss greater than 4 cm (1.6 in.) or a prospective height loss greater than 2 cm (0.8 in.). In men, a historical height loss greater than 6 cm (2.4 in.) or a prospective height loss greater than 3 cm (1.2 in.). Vertebral fractures are associated with an increase of vertebral and nonvertebral fractures in the future. Nineteen percent of patients who have a vertebral fracture will sustain another fracture within one year. (Laster, 2007) Across a range of BMD, prevalent vertebral fractures increase fracture risk by up to 12 times. Risk assessments based only on BMD may overestimate the risk of future fractures in patients without vertebral fractures and under estimate the risk of future fractures in patients with vertebral fractures. (Siris, 2007) When measuring height annually, it should be performed with a stadiometer or a wall mounted ruler. If there is a historical height loss of more than 1.5 inches (3.8 cm) in menopausal women or than 2.4 inches (6 cm) in men, an evaluation to rule out vertebral fractures should be performed. This can be accomplished by a vertebral fracture assessment (VFA) or by a lateral thoracolumbar radiograph. It is also important in patients who have acute or chronic back pain or kyphosis

The diagnosis of osteoporosis is made by BMD. The decision to assess bone density should be based on the skeletal health and risk profile of the individualized patient. Table 4 and 5 summarizes the Internal Society of Clinical Densitometry and the North American

Women aged 65 and older Adults with a disease or condition associated

Men aged 70 and older Anyone being treated, to monitor treatment effect

Adults with a fragility fracture Women discontinuing estrogen should be

Table 4. Indications for Bone Mineral Density (BMD) Testing - ISCD (Baim, 2008))

therapy

with low bone mass or bone loss

low bone mass or bone loss

Adults taking medications associated with

Anyone being considered for pharmacologic

Anyone not receiving therapy in whom evidence of bone loss would lead to treatment

to the indications listed above

considered for bone density testing according

(to rule out vertebral fractures).

**3. Bone mineral density assessment** 

Postmenopausal women under age 65 with

Women during the menopausal transition with clinical risk factors for fracture, such as low body weight, prior fracture or high-risk

Men under age 70 with clinical risk factors

risk factors for fracture

medication use

for fracture

Menopausal Society indications for Bone Mineral Density (BMD). **Indications for Bone Mineral Density (BMD) Testing – ISCD**

osteoporotic fracture in a first degree relative increases an individual's risk of osteoporotic fractures. (Seaman, 1989) During the late menopausal transition (2-3 years before menopause) and during menopause, there is an increase in bone resorption due to a decrease in estrogen production. Women lose approximately 2% of BMD annually for about 5 years during menopause. After which they lose 1-2% per year. They can lose 10.5% in their spine and 5.3% in their hip over this 5-7 year period in this time. (Recker, 2000) In men bone loss increases after age 70 and it is more common in men who are deficient in testosterone or estradiol. (Fink, 2006)

If a woman is thin, a weight of less than 127 pounds, it is a risk factor for a low BMD and a high risk for fracture, A high BMI may be protective. In older women, low BMI is associated with a higher fracture risk. (Van Der Voort, 2001)

The lifestyle factors that are associated with low bone mass and fracture risk are cigarette smoking, alcoholism, poor nutrition, and lack of physical activity, There are also secondary causes of low bone mineral density, including medications, genetic disorders, and various disease states.

Also, in all menopausal women and men after age 50, their risk for falls should be evaluated. About one-third of men and women age 65 years of age or older fall each year. They should be questioned about their history of falls, muscle weakness, dizziness, difficulty walking, impaired vision, balance problems, or medications that affect balance (e.g., sedatives, narcotics, anti-hypertensives). Some of the medications that have the highest association with falls are the serotonin-reuptake inhibitors, antiarrhythmic drugs, tricyclic antidepressants, neuroeleptic agents, benzodiazepines, and the anticonvulsants. (Leipzig, 1999) Ten percent of these falls result in hip fractures and 90% of hip fractures are due to falls. An excellent screening test is the "Get Up and Go" test. Have a senior patient get up from a chair, without using their arms, and then have them walk and observe for unsteadiness. (Mathias, 1986) The more number of risk factors of falling, the greater risk of falls.


Table 3. Risk Factors for Falls (National Osteoporosis Foundation, 2008)

During a patient's examination, height measurement may be useful to indicate occult vertebral compression fractures, which are indicative of osteoporosis. They are the most common osteoporotic fractures in postmenopausal women, and two-thirds of these fractures are not clinically recognized. (Cauley, 2007) The loss of height, kyphosis, and back pain may be signs of vertebral fractures. Normally after achieving maximal height, women can lose up to 1.0 – 1.5 inches (2.0 – 3.8 cm) of height as part of the normal aging process, due to degenerative arthritis and shrinkage of intervertebral disks. Height loss of greater than 1.5 inches (3.8 cm) increases the risk of a vertebral fracture. One must suspect a vertebral fracture in postmenopausal women with a historical height loss greater than 4 cm (1.6 in.) or a prospective height loss greater than 2 cm (0.8 in.). In men, a historical height loss greater than 6 cm (2.4 in.) or a prospective height loss greater than 3 cm (1.2 in.). Vertebral fractures are associated with an increase of vertebral and nonvertebral fractures in the future. Nineteen percent of patients who have a vertebral fracture will sustain another fracture within one year. (Laster, 2007) Across a range of BMD, prevalent vertebral fractures increase fracture risk by up to 12 times. Risk assessments based only on BMD may overestimate the risk of future fractures in patients without vertebral fractures and under estimate the risk of future fractures in patients with vertebral fractures. (Siris, 2007) When measuring height annually, it should be performed with a stadiometer or a wall mounted ruler. If there is a historical height loss of more than 1.5 inches (3.8 cm) in menopausal women or than 2.4 inches (6 cm) in men, an evaluation to rule out vertebral fractures should be performed. This can be accomplished by a vertebral fracture assessment (VFA) or by a lateral thoracolumbar radiograph. It is also important in patients who have acute or chronic back pain or kyphosis (to rule out vertebral fractures).

### **3. Bone mineral density assessment**

120 Osteoporosis

osteoporotic fracture in a first degree relative increases an individual's risk of osteoporotic fractures. (Seaman, 1989) During the late menopausal transition (2-3 years before menopause) and during menopause, there is an increase in bone resorption due to a decrease in estrogen production. Women lose approximately 2% of BMD annually for about 5 years during menopause. After which they lose 1-2% per year. They can lose 10.5% in their spine and 5.3% in their hip over this 5-7 year period in this time. (Recker, 2000) In men bone loss increases after age 70 and it is more common in men who are deficient in testosterone or

If a woman is thin, a weight of less than 127 pounds, it is a risk factor for a low BMD and a high risk for fracture, A high BMI may be protective. In older women, low BMI is associated

The lifestyle factors that are associated with low bone mass and fracture risk are cigarette smoking, alcoholism, poor nutrition, and lack of physical activity, There are also secondary causes of low bone mineral density, including medications, genetic disorders, and various

Also, in all menopausal women and men after age 50, their risk for falls should be evaluated. About one-third of men and women age 65 years of age or older fall each year. They should be questioned about their history of falls, muscle weakness, dizziness, difficulty walking, impaired vision, balance problems, or medications that affect balance (e.g., sedatives, narcotics, anti-hypertensives). Some of the medications that have the highest association with falls are the serotonin-reuptake inhibitors, antiarrhythmic drugs, tricyclic antidepressants, neuroeleptic agents, benzodiazepines, and the anticonvulsants. (Leipzig, 1999) Ten percent of these falls result in hip fractures and 90% of hip fractures are due to falls. An excellent screening test is the "Get Up and Go" test. Have a senior patient get up from a chair, without using their arms, and then have them walk and observe for unsteadiness. (Mathias, 1986) The more number of

Age Medications causing over-sedation (narcotic analgesics, anticonvulsants, psychotropics)

diminished cognitive skills

(25(OH)D) < 30 ng/ml (75 nmol/L)]

Kyphosis Fear of falling

**Other Risk Factors** 

Impaired transfer and mobility Vitamin D insufficiency [serum 25-hydroxyvitamin D

Depression Reduced problem solving and mental acuity and

estradiol. (Fink, 2006)

disease states.

**Medical Risk Factors**

Malnutrition

bathrooms

Lack of assistive devices in

Slippery outdoor conditions

with a higher fracture risk. (Van Der Voort, 2001)

risk factors of falling, the greater risk of falls.

Dehydration Previous fall

Loose throw rugs Poor balance

Obstacles in the walking path Weak muscles

Low level lighting Reduced proprioception

Anxiety and agitation Orthostatic hypotension Arrhythmias Poor vision and use of bifocals

Female gender Urgent urinary incontinence

**Environmental Risk Factors Neuro and Musculoskeletal Risk Factors**

Table 3. Risk Factors for Falls (National Osteoporosis Foundation, 2008)

The diagnosis of osteoporosis is made by BMD. The decision to assess bone density should be based on the skeletal health and risk profile of the individualized patient. Table 4 and 5 summarizes the Internal Society of Clinical Densitometry and the North American Menopausal Society indications for Bone Mineral Density (BMD).


Table 4. Indications for Bone Mineral Density (BMD) Testing - ISCD (Baim, 2008))

The Diagnosis and Workup of Patients for Osteoporosis or Osteopenia (Low Bone Mass) 123

Peripheral Dual Energy X-Ray Absorptiometry (pDXA) measures areal bone density of the forearm, finger, or heel. It can indentify individuals at risk for fracture but this modality cannot be used for the diagnosis of osteoporosis or for follow up of patients. The measurement of peripheral sites are useful only in screening patients for the need of a central DXA, they are not useful for follow up in patients or in patients taking medications for osteoporosis. (Recker, 2000) Quantitative Computed Tomography (QCT) can measure spinal BMD and can predict vertebral fractures in women, but there is a lack of evidence of a prediction of vertebral fractures in men. There is no evidence that spine QCT can predict hip fractures in women or men. Peripheral Quantitative Computed Tomography (pQCT) of the ultra distal radius can predict hip fracture risk, but not spine fracture risk in postmenopausal women. Quantitative Ultrasound (QUS) can predict fragility fractures in postmenopausal women (hip and

According to the World Health Organization (WHO) only the measurement of BMD by central DXA can be used for the diagnosis of osteoporosis, the follow up of individuals and

The WHO has defined low bone mass (Osteopenia) as a BMD between -1.0 and 2.5 SD below the normal for young healthy adults of the same sex (T-score < 1.0 and > -2.5), osteoporosis by a BMD of -2.5 SD or below (T-score ≤ -2.5) and severe osteoporosis with a T-score of ≤ -

> BMD is 2.5 SD or more below that of a "young normal" adult (T-score at or below -2.5). Patients in this group who have already experienced one or more fracture are deemed to have severe or "established" osteoporosis."

**The World Health Organization has established the following definitions based on** 

**Note:** Although these definitions are necessary to establish the presence of osteoporosis, they should

In postmenopausal women and men age 50 and older, T-scores are preferred, using the WHO criteria. In women prior to menopause and in males younger than age 50, Z-scores, not T-scores are preferred. The WHO diagnostic criteria may be applied to women in the

At the time of a central DXA, a vertebral fracture assessment (VFA) can be performed. It is a densitometric spine imaging than can detect vertebral fractures. (Schousboe, 2008) Most vertebral fractures are asymptomatic and if present can increase an individual's future risk of fracture. A Vertebral Fracture Assessment (VFA) is a diagnostic method in which low intensity or dual x-ray absorptiometry is used to examine the lateral spine (T4-L4), thereby identifying vertebral fractures. (Leipzig, 1999) There is much less radiation with a VFA in

According to the International Society of Clinical Densitometry a vertebral fracture

comparison to a lateral spine x-ray (3µSV for VFA versus 600µSV for a radiograph).

vertebral) and men over age 65 (hip and nonvertebral fractures). (Baim, 2008)

2.5 and a fragility fracture. (World Health Organization, 2003)

BMD is within 1 SD

of a "young normal" adult (Tscore at -1.0 and

above.

**BMD measurement at the spine, hip, or forearm by DXA devices: Normal Low Bone Mass (Osteopenia) Osteoporosis** 

> below that of a "young normal" adult (T-score between -1.0 and -2.5).

not be used as the sole determinant of treatment decisions. Table 6. Defining Osteoporosis by BMD (Kanis, 1994)

menopausal transition with risk factors for osteoporosis.

assessment should be performed in the following circumstances:

BMD is between 1.0 and 2.5 SD

the monitoring of treatment efficacy. (National Osteoporosis Foundation, 2008)


Table 5. Indications for Bone Mineral Density (BMD) Testing of the North American Menopause Society (NAMS) (North American Menopause Society, 2010)

There are many techniques that measure BMD. The gold standard in diagnosis of osteoporosis is made by central DXA using dual energy absorptiometry. Using two different x-ray energies, a DXA device can record attenuation profiles at two different photon energies. At low energy (30-50 keV) bone attenuation is greater than soft tissue attenuation; where as high energy (greater than 70 keV) bone attenuation is similar to soft tissues attenuation. Thus, two types of tissue are distinguished: bone (hydroxyapatite) and soft tissue (everything else). (International Society of Clinical Densitometry, 2010) DXA measures areal BMD. The results are reported as grams of mineral per square centimeter (g/cm2).

The skeletal sites that are measured with central DXA are both the PA spine (L1 – L4) and the hip (femoral neck or total proximal femur of either hip). In certain circumstances when a hip or a spine cannot be measured then a forearm (33% radius or one third radius of the non dominant arm) should be measured (e.g., patients who are obese and whose weight is above the limit of the DXA table). Results of DXA are reported as a comparison of two norms. A Tscore uses a Caucasian female 20-29 NHANES III database, for women of all ethnic groups. In men, a Caucasian male 20-29 NHANES III database is used in all ethnic groups. The difference between the patient's score is expressed in standard deviation above or below the norm. Also, a Z-score will be generated. The patient's BMD is compared to individuals of the same age, sex, and ethnicity. Z-scores should be population specific where adequate reference data exists (International Society for Clinical Densitometry, 2009).

The lower the BMD (T-score) the higher the fracture risk. A decrease of 1 standard deviation represents a 10 - 12% decrease in BMD and an increase in fracture risk by a factor of 1.5 to 2.6, depending on fracture type. The risks of spine and hip fracture increase 2.3 fold and 2.6 fold respectively, for each decrease of 1 standard deviation at the spine and hip. A Z-score of -2.0 or lower is defined as below expected range for age. A Z-score above -2.0 is within the expected range for age.

Table 5. Indications for Bone Mineral Density (BMD) Testing of the North American

There are many techniques that measure BMD. The gold standard in diagnosis of osteoporosis is made by central DXA using dual energy absorptiometry. Using two different x-ray energies, a DXA device can record attenuation profiles at two different photon energies. At low energy (30-50 keV) bone attenuation is greater than soft tissue attenuation; where as high energy (greater than 70 keV) bone attenuation is similar to soft tissues attenuation. Thus, two types of tissue are distinguished: bone (hydroxyapatite) and soft tissue (everything else). (International Society of Clinical Densitometry, 2010) DXA measures areal BMD. The results are reported as grams of mineral per square centimeter

The skeletal sites that are measured with central DXA are both the PA spine (L1 – L4) and the hip (femoral neck or total proximal femur of either hip). In certain circumstances when a hip or a spine cannot be measured then a forearm (33% radius or one third radius of the non dominant arm) should be measured (e.g., patients who are obese and whose weight is above the limit of the DXA table). Results of DXA are reported as a comparison of two norms. A Tscore uses a Caucasian female 20-29 NHANES III database, for women of all ethnic groups. In men, a Caucasian male 20-29 NHANES III database is used in all ethnic groups. The difference between the patient's score is expressed in standard deviation above or below the norm. Also, a Z-score will be generated. The patient's BMD is compared to individuals of the same age, sex, and ethnicity. Z-scores should be population specific where adequate

The lower the BMD (T-score) the higher the fracture risk. A decrease of 1 standard deviation represents a 10 - 12% decrease in BMD and an increase in fracture risk by a factor of 1.5 to 2.6, depending on fracture type. The risks of spine and hip fracture increase 2.3 fold and 2.6 fold respectively, for each decrease of 1 standard deviation at the spine and hip. A Z-score of -2.0 or lower is defined as below expected range for age. A Z-score above -2.0 is within

Menopause Society (NAMS) (North American Menopause Society, 2010)

reference data exists (International Society for Clinical Densitometry, 2009).

Testing should be considered for

or BMI < 21 kg/m2)

wine, or 1 oz. of liquor)

 Current smoker Rheumatoid arthritis

postmenopausal women age 50 and over when one or more of the following risk factors for fracture have been identified

 Fracture (other than skull, facial bone, ankle, finger, and toe) after menopause

History of hip fracture in a parent

Thinness (body weight < 127 lbs. [57.7 kg]

 Alcohol intake of more than two units per day (one unit is 12 oz. of beer, 4 oz. of

**Indications for Bone Mineral Density (BMD) Testing - NAMS** 

BMD Should Be Measured in the Following

All women age 65 and over regardless of

 Postmenopausal women with medical causes of bone loss (eg, steroid use, hyperparathyroidism), regardless of age

 Post menopausal women age 50 and over with additional risk factors (see below)

 Postmenopausal women with a fragility fracture (eg, fracture from a fall from

Populations:

clinical risk factors

standing height)

(g/cm2).

the expected range for age.

Peripheral Dual Energy X-Ray Absorptiometry (pDXA) measures areal bone density of the forearm, finger, or heel. It can indentify individuals at risk for fracture but this modality cannot be used for the diagnosis of osteoporosis or for follow up of patients. The measurement of peripheral sites are useful only in screening patients for the need of a central DXA, they are not useful for follow up in patients or in patients taking medications for osteoporosis. (Recker, 2000) Quantitative Computed Tomography (QCT) can measure spinal BMD and can predict vertebral fractures in women, but there is a lack of evidence of a prediction of vertebral fractures in men. There is no evidence that spine QCT can predict hip fractures in women or men. Peripheral Quantitative Computed Tomography (pQCT) of the ultra distal radius can predict hip fracture risk, but not spine fracture risk in postmenopausal women. Quantitative Ultrasound (QUS) can predict fragility fractures in postmenopausal women (hip and vertebral) and men over age 65 (hip and nonvertebral fractures). (Baim, 2008)

According to the World Health Organization (WHO) only the measurement of BMD by central DXA can be used for the diagnosis of osteoporosis, the follow up of individuals and the monitoring of treatment efficacy. (National Osteoporosis Foundation, 2008)

The WHO has defined low bone mass (Osteopenia) as a BMD between -1.0 and 2.5 SD below the normal for young healthy adults of the same sex (T-score < 1.0 and > -2.5), osteoporosis by a BMD of -2.5 SD or below (T-score ≤ -2.5) and severe osteoporosis with a T-score of ≤ - 2.5 and a fragility fracture. (World Health Organization, 2003)


**Note:** Although these definitions are necessary to establish the presence of osteoporosis, they should not be used as the sole determinant of treatment decisions.

severe or "established" osteoporosis."

Table 6. Defining Osteoporosis by BMD (Kanis, 1994)

In postmenopausal women and men age 50 and older, T-scores are preferred, using the WHO criteria. In women prior to menopause and in males younger than age 50, Z-scores, not T-scores are preferred. The WHO diagnostic criteria may be applied to women in the menopausal transition with risk factors for osteoporosis.

At the time of a central DXA, a vertebral fracture assessment (VFA) can be performed. It is a densitometric spine imaging than can detect vertebral fractures. (Schousboe, 2008) Most vertebral fractures are asymptomatic and if present can increase an individual's future risk of fracture. A Vertebral Fracture Assessment (VFA) is a diagnostic method in which low intensity or dual x-ray absorptiometry is used to examine the lateral spine (T4-L4), thereby identifying vertebral fractures. (Leipzig, 1999) There is much less radiation with a VFA in comparison to a lateral spine x-ray (3µSV for VFA versus 600µSV for a radiograph).

According to the International Society of Clinical Densitometry a vertebral fracture assessment should be performed in the following circumstances:

The Diagnosis and Workup of Patients for Osteoporosis or Osteopenia (Low Bone Mass) 125

In a study comparing VFA to spine radiographs, VFA had a sensitivity of 95% to detect vertebral fractures indentified by spine radiographs and a specificity of 82% to exclude

Fig. 1. Genant's Semiquantitative Analysis Grading of Fracture Deformity (Genant, 1993)

Follow up DXA testing by central DXA should be performed every 2-5 years in untreated menopausal women and in men age 70 or older. In patients who are receiving osteoporosis therapy, BMD testing should be performed every 1-2 years. (Van Der Voort, 2001) In order to determine if the change in BMD over time is a real biological change and not to due to chance, a precision study must be performed. Each DXA facility should determine its precision error and calculate the least significant change (LSC), within a 95% statistical confidence. The precision error that is supplied by the manufacturer should not be used. To perform a precision analysis, the technologist measures 15 patients 3 times or 30 patients 2 times, repositioning the patient after each scan. They then calculate the root mean square stand deviation and obtain the LSC at 95% confidence. This is a real biological change over time and is not due to chance. The minimum acceptable precision for an individual technologist is: lumbar spine 1.9% (LSC = 5.3%), total hip 1.8% (LSC = 5.0%), and femoral

Within one year of a hip fracture 10-20% of patients die, 20% are placed in nursing homes, and only 40% regain independent functioning. (U.S. Department of Health and Human

neck 2.5% (LSC = 6.9%). (International Society for Clinical Densitometry, 2007)

fractures not visualized in a radiograph. (Vokes, 2003)

**4. Follow up bone mineral density testing** 

**5. Evaluation for treatment** 


Table 7. Indications for VFA (Schousboe, 2008)

The VFA is interpreted using a semi-quantitative visual inspection with assignment of fracture grade by the radiologist or the clinician. Using Genant's method, the clinician determines if a vertebra is fractured or normal. The thoracic and lumbar spine is scanned for deformities and height loss exceeding twenty percent in the anterior, middle, or posterior dimensions. What the clinician determines visually using the semiquantitative method of Genant are morphological changes in the vertebrae. Clinicians should look for end plate deformities (horizontal edges), lack of parallelism of the end plates, buckling of the cortices (vertical edges) and loss of vertical continuity with the adjacent vertebrae. Clinicians then grade the fracture deformity. If a fracture is suspected, it is compared to a standard:


Depending on where deformities are present in the vertebra, fractures are classified as wedge (loss of anterior height), crush (loss of posterior height) and biconcave (loss of middle height). (Genant, 1993)

**following:** 

(2.4 in.)

(1.2 in.)

**Men with low bone bass (Osteopenia) by BMD criteria, PLUS any one of the** 

Historical height loss greater than 6 cm

Prospective height loss greater than 3 cm

Self-reported prior non-vertebral

On pharmacologic androgen deprivation therapy or following orchiectomy

**documentation of one or more vertebral fractures will alter clinical management.** 

**Postmenopausal women or men with osteoporosis by BMD criteria, if** 

 Chronic systemic diseases associated with increased risk of vertebral fractures (e.g., moderate to several COPD or COAD, seropositive rheumatoid arthritis, Crohn's disease

Self-reported vertebral fracture (not

previously documented)

fracture

**Consider VFA when results may influence management.** 

Age greater than or equal to 70 years Age 80 years or older

 Two or more of the following: Two or more of the following: Age 60 to 69 years Age 70 to 79 years

Historical height loss of 2 to 4 cm Historical height loss of 3 to 6 cm

The VFA is interpreted using a semi-quantitative visual inspection with assignment of fracture grade by the radiologist or the clinician. Using Genant's method, the clinician determines if a vertebra is fractured or normal. The thoracic and lumbar spine is scanned for deformities and height loss exceeding twenty percent in the anterior, middle, or posterior dimensions. What the clinician determines visually using the semiquantitative method of Genant are morphological changes in the vertebrae. Clinicians should look for end plate deformities (horizontal edges), lack of parallelism of the end plates, buckling of the cortices (vertical edges) and loss of vertical continuity with the adjacent vertebrae. Clinicians then

grade the fracture deformity. If a fracture is suspected, it is compared to a standard:

Depending on where deformities are present in the vertebra, fractures are classified as wedge (loss of anterior height), crush (loss of posterior height) and biconcave (loss of middle

**Postmenopausal women with low bone mass (Osteopenia) by BMD criteria PLUS** 

Historical height loss greater than 4 cm

Prospective height loss greater than 2 cm

Self-reported prior non-vertebral

 Chronic systemic diseases associated with increased risk of vertebral fractures (e.g., moderate to severe COPD or COAD, seropositive

rheumatoid arthritis, Crohn's disease)

**Women or men on Chronic Glucocorticoid therapy (equivalent to 5 mg or more of prednisone daily for three (3) months or** 

Table 7. Indications for VFA (Schousboe, 2008)

 Grade 1 (mild fracture) height loss 20-25% Grade 2 (moderate) height loss of 25-40% Grade 3 (severe) height loss of > 40%

height). (Genant, 1993)

Self-reported vertebral fracture (not

previously documented)

fracture

**any one of the following:** 

(1.6 in.)

(0.8 in.)

**longer).** 

In a study comparing VFA to spine radiographs, VFA had a sensitivity of 95% to detect vertebral fractures indentified by spine radiographs and a specificity of 82% to exclude fractures not visualized in a radiograph. (Vokes, 2003)

Fig. 1. Genant's Semiquantitative Analysis Grading of Fracture Deformity (Genant, 1993)

## **4. Follow up bone mineral density testing**

Follow up DXA testing by central DXA should be performed every 2-5 years in untreated menopausal women and in men age 70 or older. In patients who are receiving osteoporosis therapy, BMD testing should be performed every 1-2 years. (Van Der Voort, 2001) In order to determine if the change in BMD over time is a real biological change and not to due to chance, a precision study must be performed. Each DXA facility should determine its precision error and calculate the least significant change (LSC), within a 95% statistical confidence. The precision error that is supplied by the manufacturer should not be used.

To perform a precision analysis, the technologist measures 15 patients 3 times or 30 patients 2 times, repositioning the patient after each scan. They then calculate the root mean square stand deviation and obtain the LSC at 95% confidence. This is a real biological change over time and is not due to chance. The minimum acceptable precision for an individual technologist is: lumbar spine 1.9% (LSC = 5.3%), total hip 1.8% (LSC = 5.0%), and femoral neck 2.5% (LSC = 6.9%). (International Society for Clinical Densitometry, 2007)

## **5. Evaluation for treatment**

Within one year of a hip fracture 10-20% of patients die, 20% are placed in nursing homes, and only 40% regain independent functioning. (U.S. Department of Health and Human

The Diagnosis and Workup of Patients for Osteoporosis or Osteopenia (Low Bone Mass) 127

Height Continuous Expressed in centimeters. The modal calculates

variable.

age 40 or 90.

range, the model computes fracture risks as of

body mass index and uses it as a continuous

spontaneously or with low trauma (e.g., osteoporosis-related fractures), including morphometric vertebral fractures.

observed but is not reflected in the model.

5 mg/d prednisolone for ≥ 3 months. Dosedependence of fracture risk has been observed

of conditions including, but not limited to, insulin-dependent diabetes, adult osteogenesis imperfecta, uncontrolled hyperthyroidism, menopause at 45 years, hypogonadism, chronic malnutrition/malabsorption, or

aperitif, or 30 mL distilled spirits. Dosedependence of fracture risk has been observed

model used to obtain it, or enter T-score. Risk estimates can also be produced without BMD. If only total hip BMD is available, that can be used. Spinal or peripheral BMD are not to be

but is not reflected in the model.

but is not reflected in the model.

arthritis should be scored.

chronic liver disease.

Age Continuous 40-90 years. For ages below or above this

Sex Male/female Model validated for men and women.

Previous fracture Yes/no Includes adult fractures occurring

Parental hip fracture Yes/no Any hip fracture affecting either parent. Current smoking Yes/no Dose-dependence of fracture risk has been

Oral glucocorticoid use Yes/no Present or past exposure to doses equivalent to

Rheumatoid arthritis Yes/no Only a confirmed diagnosis of rheumatoid

Alcohol ≥ 3 units daily Yes/no 1 unit is 285 mL beer, 120 mL wine, 60 mL

Femoral neck BMD Continuous Enter BMD value and select DXA machine

risk beyond what the model calculates; clinical judgment should be used.

Table 8. Risk Factors Included in the FRAX Algorithm (Siris, 2010)

accounts for, and clinical judgment should be used.

osteoporosis button becomes inactivated.

used. Clinical vertebral fractures and multiple osteoporosis-related fractures confer additional

For a "yes" answer to smoking, alcohol, or glucocorticoid use, the model assumes average levels of exposure. With high exposures, facture risk may increase more than the model

When a femoral neck T-score is entered into the online FRAX model, the secondary

Secondary osteoporosis Yes/no Secondary osteoporosis occurs in the presence

Weight Continuous Expressed in kilograms.

**Risk Factor Type of Variable Description**

Services, 2004) There are more low-trauma fractures in patients with low bone density (Osteopenia) than in those with a DXA diagnosis of osteoporosis. This occurs because there are more individuals with Osteopenia than osteoporosis. (Khosla, 2007) In the study of osteoporotic fractures (SOF), 54% of women with hip fractures did not have osteoporosis according to their BMD results. (Wainwright, 2005) Therefore, it is important to identify and treat individuals who have Osteopenia (low bone density) who have the highest chance of a fracture. Not all patients with low bone mass will fracture.

### **6. FRAX assessment tool**

The WHO sponsored the development of the FRAX assessment tool to indentify which individuals with low bone mineral density have the greatest chance of fracture and which patients need to be treated. (Kanis, 2008) It identifies which patients, who have Osteopenia (low bone lass) who have a higher fracture risk and need to be treated. (Internal Society for Bone Densitometry Course) FRAX is based on an analysis of approximately 60,000 patients that were studied in Europe, North American, Asia, and Australia. The FRAX tool is for untreated individuals with low bone density and indentifies which individuals are at the highest risk of fracture. The NOF recommends the FRAX tool for untreated postmenopausal and men 50 or more years of age with a T-score in the osteopenic range (low bone mass). FRAX predicts the 10 year probability for hip fracture and for major osteoporotic fractures (hip, proximal humerus, distal forearm, and clinical vertebral fractures). FRAX uses clinical risk factors with or without femoral neck BMD. Economic modeling was performed to indentify the 10 year hip fracture risks above which is cost effective, from the societal perspective, to treat with pharmacological agents.

NOF criteria for using FRAX to assist with treatment decisions are:


Examples of "untreated" patients include:


This model uses femoral neck BMD but, in women, if femoral neck BMD is unavailable, total hip BMD may be used. In men, only femoral neck BMD can be used in FRAX. (World Health Organization, 2003) Spine of peripheral BMD measurements should not be used in FRAX. (Kanis) There are multiple limitations of FRAX. It does not consider the other risk factors for fracture. These include a history of falls, patients with clinical vertebral fractures, doses of glucocorticoids, exposure dose of alcohol, nicotine, drugs which lower BMD (anticonvulsants, anticoagulants, antineoplastics, antiestrogenic or antiandrogenic agents), parental history of non hip fractures and lumbar spine BMD. This tool only recognizes a hip fracture of a parent. Spinal fractures of a parent due to osteoporosis also may increase fractures risk in the offspring. The therapeutic thresholds that are proposed in the FRAX tool are for clinical guidance and are not rules. They do not preclude clinicians from considering intervention strategies in patients who do not have osteoporosis, nor should they mandate treatment in patients with osteopenia. The decision to treat a patient must be made on a case by case basis.

Services, 2004) There are more low-trauma fractures in patients with low bone density (Osteopenia) than in those with a DXA diagnosis of osteoporosis. This occurs because there are more individuals with Osteopenia than osteoporosis. (Khosla, 2007) In the study of osteoporotic fractures (SOF), 54% of women with hip fractures did not have osteoporosis according to their BMD results. (Wainwright, 2005) Therefore, it is important to identify and treat individuals who have Osteopenia (low bone density) who have the highest chance

The WHO sponsored the development of the FRAX assessment tool to indentify which individuals with low bone mineral density have the greatest chance of fracture and which patients need to be treated. (Kanis, 2008) It identifies which patients, who have Osteopenia (low bone lass) who have a higher fracture risk and need to be treated. (Internal Society for Bone Densitometry Course) FRAX is based on an analysis of approximately 60,000 patients that were studied in Europe, North American, Asia, and Australia. The FRAX tool is for untreated individuals with low bone density and indentifies which individuals are at the highest risk of fracture. The NOF recommends the FRAX tool for untreated postmenopausal and men 50 or more years of age with a T-score in the osteopenic range (low bone mass). FRAX predicts the 10 year probability for hip fracture and for major osteoporotic fractures (hip, proximal humerus, distal forearm, and clinical vertebral fractures). FRAX uses clinical risk factors with or without femoral neck BMD. Economic modeling was performed to indentify the 10 year hip fracture risks above which is cost effective, from the societal

of a fracture. Not all patients with low bone mass will fracture.

perspective, to treat with pharmacological agents.

d. An evaluable hip for DXA study Examples of "untreated" patients include:

b. No calcitonin for the past one year c. No PTH for the past one year d. No denosumab for the past one year

b. With low bone mass (T-score between -1.0 and -2.5)

NOF criteria for using FRAX to assist with treatment decisions are: a. An untreated postmenopausal women or a man age 50 or older

c. With no prior hip or vertebral fracture (clinical or morphometric)

a. No ET/HT or estrogen agonist/antagonist (SERM) for the past one year

e. No bisphosphonate for the past two years (unless it is an oral taken for < 2 months) This model uses femoral neck BMD but, in women, if femoral neck BMD is unavailable, total hip BMD may be used. In men, only femoral neck BMD can be used in FRAX. (World Health Organization, 2003) Spine of peripheral BMD measurements should not be used in FRAX. (Kanis) There are multiple limitations of FRAX. It does not consider the other risk factors for fracture. These include a history of falls, patients with clinical vertebral fractures, doses of glucocorticoids, exposure dose of alcohol, nicotine, drugs which lower BMD (anticonvulsants, anticoagulants, antineoplastics, antiestrogenic or antiandrogenic agents), parental history of non hip fractures and lumbar spine BMD. This tool only recognizes a hip fracture of a parent. Spinal fractures of a parent due to osteoporosis also may increase fractures risk in the offspring. The therapeutic thresholds that are proposed in the FRAX tool are for clinical guidance and are not rules. They do not preclude clinicians from considering intervention strategies in patients who do not have osteoporosis, nor should they mandate treatment in patients with osteopenia. The decision to treat a patient must be made on a case by case basis.

**6. FRAX assessment tool** 


For a "yes" answer to smoking, alcohol, or glucocorticoid use, the model assumes average levels of exposure. With high exposures, facture risk may increase more than the model accounts for, and clinical judgment should be used.

When a femoral neck T-score is entered into the online FRAX model, the secondary osteoporosis button becomes inactivated.

Table 8. Risk Factors Included in the FRAX Algorithm (Siris, 2010)

The Diagnosis and Workup of Patients for Osteoporosis or Osteopenia (Low Bone Mass) 129

Low Vitamin D deficiency,

Gastrointestinal (GI) malabsorption

malabsorption,

involving bone, hyperparathyroidism, hyperthyroidism

bone turnover)

contraindication to bisphosphonates

D deficiency

Low GI malabsorption, inadequate

Low Hyperthyroidism (causes excess

Elevated Predictive of celiac disease

malabsorption, celiac disease

hyperparathyroidism, Paget's disease, liver/biliary disease

myeloma, metastatic cancer

intake of calcium and vitamin D

**Test Diagnostic Result Possible Secondary Cause** 

Completed blood cell count Anemia Multiple myeloma Serum calcium Elevated Hyperparathyroidism

 Low Hyperparathyroidism Serum 25-hydroxyvitamin D Low Undersupplemenataion, GI

calcium, nutritional

Serum alkaline phosphatase Elevated Vitamin D deficiency, GI

Urinary calcium excretion Elevated Renal calcium leak, multiple

Creatinine Elevated Renal osteodystrophy, possible

PTH Elevated Hyperparathyroidism, vitamin

Table 9. Laboratory Tests for Osteoporosis Evaluation (North American Menopause Society,

Bone turnover markers are proteins that are produced by the activity of osteoclasts and by osteoblasts. The resorption markers of osteoclastic activity are the breakdown products of type I collagen (N-telopeptides, C-telopeptides, deoxypyridinolone). There are markers of osteoblastic synthesis of bone matrix (bone-specific alkaline phosphatates, osteocalcin,

deficiencies

 High Hypothyroidism Serum protein electrophoresis Monoclonal band Multiple myeloma

Serum phosphate Elevated Renal failure

Serum albumin Used to interpret serum

Thyroid-stimulating hormone

**8. Bone turnover markers** 

procollagen type I N-terminal propetide).

Tissue transglutaminase antibody (gluten enteropathy)

(TSH)

2010)


Fig. 2. FRAX Calculation Tool

### **7. Whom should we treat: NOF guidelines**

Consider FDA approved medical therapies for patients with:


Physicians should use clinical judgment to treat patients at lower FRAX risk levels if additional risk factors for fracture are present.

Before developing a management plan, the clinician should rule out secondary causes of osteoporosis or bone loss. About 20% of postmenopausal women with osteoporosis and 40% of men with osteoporosis have a secondary cause that can be indentified and treated. (Fitzpatrick, 2002) Secondary osteoporosis can result from a variety of medical conditions including endocrine, hematopoietic or nutritional disorders, and vitamin D deficiency. Diseases such as celiac (malabsorption), liver and renal diseases, the use of glucocorticoids, aromatase inhibitors, antiandrogen therapy (GNRH) and chemotherapy can cause bone loss. These secondary causes must be ruled out before staring pharmacological therapy.

Some of the routine tests would be a complete blood count, serum levels of calcium and phosphate, 25-hydroxyvitamin D, bone specific alkaline phosphatase, creatinine and a 24-hour urine for calcium. Some of the specialized tests may include a thyroid stimulating hormone (TSH), serum levels of parathyroid hormone (PTH) to screen for hyperparathyroidism, a serum protein electrophoresis to indentify abnormal protein produced by multiple myeloma and antitissue transglutaminase antibodies for celiac disease. (Hodgson, 2003)


Table 9. Laboratory Tests for Osteoporosis Evaluation (North American Menopause Society, 2010)

### **8. Bone turnover markers**

128 Osteoporosis

Osteoporosis diagnosed by a BMD T-score ≤ -2.5 (femoral neck or spine) after

 Low bone density (a BMD score between -1 and -2.5 at the femoral neck or spine) and a FRAX 10 year probability of hip fracture ≥ 3% or a major osteoporotic fracture (hip,

Physicians should use clinical judgment to treat patients at lower FRAX risk levels if

Before developing a management plan, the clinician should rule out secondary causes of osteoporosis or bone loss. About 20% of postmenopausal women with osteoporosis and 40% of men with osteoporosis have a secondary cause that can be indentified and treated. (Fitzpatrick, 2002) Secondary osteoporosis can result from a variety of medical conditions including endocrine, hematopoietic or nutritional disorders, and vitamin D deficiency. Diseases such as celiac (malabsorption), liver and renal diseases, the use of glucocorticoids, aromatase inhibitors, antiandrogen therapy (GNRH) and chemotherapy can cause bone loss.

Some of the routine tests would be a complete blood count, serum levels of calcium and phosphate, 25-hydroxyvitamin D, bone specific alkaline phosphatase, creatinine and a 24-hour urine for calcium. Some of the specialized tests may include a thyroid stimulating hormone (TSH), serum levels of parathyroid hormone (PTH) to screen for hyperparathyroidism, a serum protein electrophoresis to indentify abnormal protein produced by multiple myeloma

These secondary causes must be ruled out before staring pharmacological therapy.

and antitissue transglutaminase antibodies for celiac disease. (Hodgson, 2003)

appropriate evaluation to exclude secondary causes of osteoporosis

wrist, proximal humerus, clinical vertebral fracture) of ≥ 20%

Fig. 2. FRAX Calculation Tool

**7. Whom should we treat: NOF guidelines** 

additional risk factors for fracture are present.

Consider FDA approved medical therapies for patients with: A hip or vertebral (clinical or morphometric) fracture

> Bone turnover markers are proteins that are produced by the activity of osteoclasts and by osteoblasts. The resorption markers of osteoclastic activity are the breakdown products of type I collagen (N-telopeptides, C-telopeptides, deoxypyridinolone). There are markers of osteoblastic synthesis of bone matrix (bone-specific alkaline phosphatates, osteocalcin, procollagen type I N-terminal propetide).

The Diagnosis and Workup of Patients for Osteoporosis or Osteopenia (Low Bone Mass) 131

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Jiang, H, et Al. (2005). Development and Initial Validation of a Risk Score for Predicting In-

Kado, D, et Al. (1999). Vertebral Fractures and Mortality in Older Women. Study of

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Kanis, J, et Al. (2008). FRAX and the Assessment of Fracture Probability in Men and Women from the UK. *Osteoporosis International*, 19, 4, (April 2008), pp. 385-397 Khosla, S, et Al. (2005). Study of Osteoporosis Fractures Group. *Journal of Clinical* 

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The changes of bone turnover markers occur more rapidly than changes in BMD and they can also predict patient compliance or poor response to antiresorptive therapy. There is a high degree of biological and analytical variability in the measurement of biochemical markers. This variability can be reduced by obtaining samples in the early morning after an overnight fast. (National Osteoporosis Foundation, 2008)

### **9. Conclusion**

In all senior men and in all postmenopausal women a history should be obtained to evaluate a patient's risk factors for osteoporosis and for fractures. As part of a patient's physical exam, a height measurement should be performed. This can indentify when there is a significant height loss or an asymptomatic vertebral fracture. When necessary, a central DXA and sometimes a Vertebral Fracture Assessment (VFA) may be performed. Clinicians should estimate a patient's 10-year probability of a hip or a major osteoporotic related fracture using FRAX. We should use the WHO criteria to determine who we should treat and which individuals whom we should not treat. Clinicians also must perform a laboratory workup on patients, to rule our secondary causes of osteoporosis, before starting a pharmacological treatment regimen.

### **10. References**


Suppression of biochemical markers of bone turnover occur 3-6 months of specific antiresorptive therapies and they increase after 1-3 months of anabolic therapies. The NOF recommends a baseline and a repeat bone resorption marker after initiation of therapy as a

The changes of bone turnover markers occur more rapidly than changes in BMD and they can also predict patient compliance or poor response to antiresorptive therapy. There is a high degree of biological and analytical variability in the measurement of biochemical markers. This variability can be reduced by obtaining samples in the early morning after an

In all senior men and in all postmenopausal women a history should be obtained to evaluate a patient's risk factors for osteoporosis and for fractures. As part of a patient's physical exam, a height measurement should be performed. This can indentify when there is a significant height loss or an asymptomatic vertebral fracture. When necessary, a central DXA and sometimes a Vertebral Fracture Assessment (VFA) may be performed. Clinicians should estimate a patient's 10-year probability of a hip or a major osteoporotic related fracture using FRAX. We should use the WHO criteria to determine who we should treat and which individuals whom we should not treat. Clinicians also must perform a laboratory workup on patients, to rule our secondary causes of osteoporosis, before starting a

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**9. Conclusion** 

**10. References** 

426

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pharmacological treatment regimen.


**1. Introduction** 

and mineralization (NIH Consensus, 2001).

The aims of this chapter are stated in table 1.

(DEXA or DXA) scanning.

bone density measurement.

Table 1. Statement of objectives

metabolism.

1994).

**7** 

*Spain* 

**Evolutionary Pathways of** 

Antonio Bazarra-Fernández *A Coruña University Hospital Trust* 

**Diagnosis in Osteoporosis** 

Osteoporosis was formally identified as a disease by a group of World Health Organization (WHO) experts in 1994 resulting in publication of "Assessment of Fracture Risk and its Application to Screening for Postmenopausal Osteoporosis" (WHO Technical Report Series,

Osteoporosis is defined as a skeletal disorder characterized by compromised bone strength predisposing to an increased risk of fracture. Bone strength reflects the integration of two main features: bone density and bone quality. Bone density is expressed as grams of mineral per area or volume and in any given individual is determined by peak bone mass and amount of bone loss. Bone quality refers to architecture, turnover, damage accumulation

Osteoporosis occurs in all populations and at all ages and is a devastating disorder with significant physical, psychosocial and financial consequences. The WHO operationally defines osteoporosis as a bone density at least 2.5 standard deviations below the mean peak bone mass for healthy young adult white women, also referred to as a *T-score* of –2.5. Because of the difficulty in accurate measurement and standardization between instruments and sites, controversy exists among experts regarding the continued use of this diagnostic criterion. So different instruments have not the same performance in regard to a accurate

In the evolutionary pathways of diagnostics in bone loss the osteoporosis diagnosis is often performed by measuring bone mineral density (BMD) that measures the amount of calcium

1. Identify the technique, safety and limitations of dual energy X-ray absorptiometry

2. Explain the value of utilizing bone densitometry to assess and monitor fracture risk.

4. Explain the value of identifying the different components that make up the bone

in different regions of the skeleton as femur neck or/and 1-4 lumbar vertebrae .

3. Incorporate clinical risk factors that predict future fracture.

5. Open new tracks for diagnosis of osteoporosis


## **Evolutionary Pathways of Diagnosis in Osteoporosis**

Antonio Bazarra-Fernández *A Coruña University Hospital Trust Spain* 

### **1. Introduction**

132 Osteoporosis

North American Menopause Society. 2010. Management of Osteopororsis in

Recker, R, et Al. (2000). Characterization of Perimenopausal Bone Loss: A Prospective Study.

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Siris, E, et Al. (2007). Enhanced Predication of Fracture Risk Combining Fracture Status and

Siris, E, et Al. (2010), Primary Care Use of FRAX: Absolute Fracture Risk Assessment in

U.S. Department of Health and Human Services. (2004). *Bone Health and Osteoporosis: A* 

Van Der Voort, D, et Al. (2001). Risk Factors for Osteoporosis Related to Their Outcomes.

Vokes, T, et Al. (2003). Clinical Utility of Dual Energy Vertebral Assessment (DVA).

World Health Organization. (2003). Prevention and Management of Osteoporosis*.* World

Postmenopausal Women and Older Men. *Postgraduate Medicine*, 122, 1, (January

*Report of the Surgeon General*, Department of Health and Human Services, Office of

Menopause Society. *Menopause*, 17, 1, (January 2010), pp. 23-54

*Journal Bone Mineral Research*, 15, 10, (October 2000), pp. 1965-1973

*New England Journal of Medicine*, 320, 9, (March 1989), pp. 554-558

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BMD. *Osteoporosis International*, 18, 6, (June 2007), pp. 761-770

*Osteoporosis International*, 12, 8, (September 2001), pp. 630-638

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Health Organization Technical Report Series, 921, (2003), pp. 1-64

2010), pp. 82-90

the Surgeon General, Rockville, MD

Postmenopausal Women: 2010 Position Statement of the North American

Osteoporosis was formally identified as a disease by a group of World Health Organization (WHO) experts in 1994 resulting in publication of "Assessment of Fracture Risk and its Application to Screening for Postmenopausal Osteoporosis" (WHO Technical Report Series, 1994).

Osteoporosis is defined as a skeletal disorder characterized by compromised bone strength predisposing to an increased risk of fracture. Bone strength reflects the integration of two main features: bone density and bone quality. Bone density is expressed as grams of mineral per area or volume and in any given individual is determined by peak bone mass and amount of bone loss. Bone quality refers to architecture, turnover, damage accumulation and mineralization (NIH Consensus, 2001).

Osteoporosis occurs in all populations and at all ages and is a devastating disorder with significant physical, psychosocial and financial consequences. The WHO operationally defines osteoporosis as a bone density at least 2.5 standard deviations below the mean peak bone mass for healthy young adult white women, also referred to as a *T-score* of –2.5. Because of the difficulty in accurate measurement and standardization between instruments and sites, controversy exists among experts regarding the continued use of this diagnostic criterion. So different instruments have not the same performance in regard to a accurate bone density measurement.

The aims of this chapter are stated in table 1.


Table 1. Statement of objectives

In the evolutionary pathways of diagnostics in bone loss the osteoporosis diagnosis is often performed by measuring bone mineral density (BMD) that measures the amount of calcium in different regions of the skeleton as femur neck or/and 1-4 lumbar vertebrae .

Evolutionary Pathways of Diagnosis in Osteoporosis 135

subjects and underestimate the bone mineral density of smaller subjects. This error is due to the way in which DXA calculates BMD. In DXA, bone mineral content, measured as the attenuation of the X-ray by the bones being scanned, is divided by the area, also measured

Because of DXA calculates BMD using area (aBMD: areal Bone Mineral Density), it is not an accurate measurement of true bone mineral density, which is mass divided by a volume. In order to distinguish DXA BMD from volumetric bone-mineral density, researchers

The National Osteoporosis Foundation's guidelines state that women over 65, younger post menopausal women who have any of the osteoporosis risk factors, as well as those with specific fractures should have this test. However, men are also at risk for osteoporosis as

The bone density test is performed using various methods. Some of these BMD tests are

Quantitative Ultrasound (QUS) is the most basic bone density test performed. It can be the first step in order to diagnose any primary bone related problem. If the ultrasound test finds any defect in the bone density, then the DEXA test is recommended. QUS can be used to predict fracture risk, but it cannot be used for the diagnosis of osteoporosis or for monitoring the effects of treatment. Ultrasounds measure the BMD in the heel and uses sound waves of different frequencies through water or air, to perform the task. Bone density test is painless, fast and without harmful radiations. Ultrasounds are unable to detect complicated bone problems and hence there are other methods that are capable of detecting

Ultrasound axial transmission, a technique using propagation of ultrasound waves along the cortex of cortical bones, has been proposed as a diagnostic technique for the evaluation of fracture healing. Quantitative ultrasound parameters have been reported to be sensitive to callus changes during the regeneration process. The results suggest that the time of flight measured in axial transmission is affected by local changes of speed of sound induced by

Quantitative Computer Tomography Scan (QCT) is done to find true volumetric bone mineral content by measuring separately trabecular and three-dimensional cortical bone. Image quality degradation due to subject motion is a common artefact affecting *in vivo* highresolution peripheral quantitative computed tomography (HR-pQCT) of bones. These artefacts confound the accuracy and reproducibility of bone density, geometry, and cortical and trabecular structure measurements. Observer-based systems for grading image quality and criteria for deciding when to repeat an acquisition and post hoc data quality control

The QCT scan is a not so famous form of bone density test because it is expensive, utilizes a

they age especially if they have some of the causes of osteopenia or osteoporosis

by the machine, in the site being scanned.

sometimes refer to DXA BMD as aBMD.

explained here briefly.

the more complicated ones.

changes in local mineralization.

**2.2.2 Quantitative computer tomography scan** 

remain highly subjective and non-standardized (Sodeab et al, 2011).

high amount of radiation and its accuracy is minimum.

**2.2 Other methods of osteoporosis diagnosis** 

**2.2.1 Quantitative ultrasound parameters** 

In establishing diagnosis of osteoporosis three parameters should be considered as stated in table 2.


Table 2. Statement of objectives

### **2. Osteoporosis and fracture risk: Monitoring and assessment**

Several methods are available to measure BMD. In general, the lower bone density the greater osteoporotic fracture risk. Unfortunately osteoporosis frequently remains undiagnosed until a fracture occurs. BMD methods involve DEXA or quantitative computer tomography scans (Osteo CT or QCT) of bones in the spine or femur. The most widely used technique is DXA.

### **2.1 Technique, safety and limitations of DXA scanning**

Bone densitometry is the *gold standard method* for measuring BMD. Bone densitometry is the method used to determine the drug efficacy in recent large clinical trials and to characterize fracture risk in large epidemiological studies. DXA, previously DEXA, is a method of measuring BMD. A DXA scan uses low energy X-rays. A machine sends X-rays from two different sources through the bone being tested. Bone blocks a certain amount of the X-rays. The more dense the bone is, the fewer X-rays get through to the detector. By using two different X-ray sources rather than one it greatly improves the accuracy in measuring the bone density. The amount of X-rays that comes through the bone from each of the two X-ray sources is measured by a detector. This information is sent to a computer which calculates a score of the average density of the bone. A low score indicates that the bone is less dense than it should be, some material of the bone has been lost, and is more prone to fracture.

Older methods such as single photon absorptiometry(SPA) do not predict hip fractures as well as DXA.

But currently there is no accurate measure of overall bone strength. Osteoporosis is related to decreased bone strength, which encompasses both BMD and bone quality. Notwithstanding BMD assessed by DXA remains the *gold standard* for the diagnosis of osteoporosis.

DEXA is the most widely available method of bone densitometry. The measurement of BMD by DEXA has served as a fit surrogate for the measurement of bone strength and accounts for approximately 70 percent of bone strength, it was said. DEXA measures the BMD in the spine, hip or total body.

Based on the 1994 WHO report, osteoporosis is defined as a BMD value from at least -2.5 SD below the mean value of a young healthy population (T-score≤-2.5). Any bone can be affected, but of special concern are the fractures of the hip and spine.

Diagnosis of osteoporosis is generally on the basis of BMD assessment at the spine and proximal femur by DXA. Two X-ray beams with differing energy levels are targeted at the patient's bones. But, there are other variables in addition to age which are suggested to confound the interpretation of BMD as measured by DXA. One important confounding variable is bone size. DXA has been shown to overestimate the bone mineral density of taller

In establishing diagnosis of osteoporosis three parameters should be considered as stated in

Several methods are available to measure BMD. In general, the lower bone density the greater osteoporotic fracture risk. Unfortunately osteoporosis frequently remains undiagnosed until a fracture occurs. BMD methods involve DEXA or quantitative computer tomography scans (Osteo CT or QCT) of bones in the spine or femur. The most widely used

Bone densitometry is the *gold standard method* for measuring BMD. Bone densitometry is the method used to determine the drug efficacy in recent large clinical trials and to characterize fracture risk in large epidemiological studies. DXA, previously DEXA, is a method of measuring BMD. A DXA scan uses low energy X-rays. A machine sends X-rays from two different sources through the bone being tested. Bone blocks a certain amount of the X-rays. The more dense the bone is, the fewer X-rays get through to the detector. By using two different X-ray sources rather than one it greatly improves the accuracy in measuring the bone density. The amount of X-rays that comes through the bone from each of the two X-ray sources is measured by a detector. This information is sent to a computer which calculates a score of the average density of the bone. A low score indicates that the bone is less dense than it should be, some material of the bone has been lost, and is more prone to fracture. Older methods such as single photon absorptiometry(SPA) do not predict hip fractures as

But currently there is no accurate measure of overall bone strength. Osteoporosis is related to decreased bone strength, which encompasses both BMD and bone quality. Notwithstanding BMD assessed by DXA remains the *gold standard* for the diagnosis of

DEXA is the most widely available method of bone densitometry. The measurement of BMD by DEXA has served as a fit surrogate for the measurement of bone strength and accounts for approximately 70 percent of bone strength, it was said. DEXA measures the BMD in the

Based on the 1994 WHO report, osteoporosis is defined as a BMD value from at least -2.5 SD below the mean value of a young healthy population (T-score≤-2.5). Any bone can be

Diagnosis of osteoporosis is generally on the basis of BMD assessment at the spine and proximal femur by DXA. Two X-ray beams with differing energy levels are targeted at the patient's bones. But, there are other variables in addition to age which are suggested to confound the interpretation of BMD as measured by DXA. One important confounding variable is bone size. DXA has been shown to overestimate the bone mineral density of taller

affected, but of special concern are the fractures of the hip and spine.

**2. Osteoporosis and fracture risk: Monitoring and assessment** 

**2.1 Technique, safety and limitations of DXA scanning** 

2. The diagnosis of bone metabolism components.

table 2.

Table 2. Statement of objectives

1. The diagnosis of osteoporosis.

technique is DXA.

well as DXA.

osteoporosis.

spine, hip or total body.

subjects and underestimate the bone mineral density of smaller subjects. This error is due to the way in which DXA calculates BMD. In DXA, bone mineral content, measured as the attenuation of the X-ray by the bones being scanned, is divided by the area, also measured by the machine, in the site being scanned.

Because of DXA calculates BMD using area (aBMD: areal Bone Mineral Density), it is not an accurate measurement of true bone mineral density, which is mass divided by a volume. In order to distinguish DXA BMD from volumetric bone-mineral density, researchers sometimes refer to DXA BMD as aBMD.

The National Osteoporosis Foundation's guidelines state that women over 65, younger post menopausal women who have any of the osteoporosis risk factors, as well as those with specific fractures should have this test. However, men are also at risk for osteoporosis as they age especially if they have some of the causes of osteopenia or osteoporosis

### **2.2 Other methods of osteoporosis diagnosis**

The bone density test is performed using various methods. Some of these BMD tests are explained here briefly.

#### **2.2.1 Quantitative ultrasound parameters**

Quantitative Ultrasound (QUS) is the most basic bone density test performed. It can be the first step in order to diagnose any primary bone related problem. If the ultrasound test finds any defect in the bone density, then the DEXA test is recommended. QUS can be used to predict fracture risk, but it cannot be used for the diagnosis of osteoporosis or for monitoring the effects of treatment. Ultrasounds measure the BMD in the heel and uses sound waves of different frequencies through water or air, to perform the task. Bone density test is painless, fast and without harmful radiations. Ultrasounds are unable to detect complicated bone problems and hence there are other methods that are capable of detecting the more complicated ones.

Ultrasound axial transmission, a technique using propagation of ultrasound waves along the cortex of cortical bones, has been proposed as a diagnostic technique for the evaluation of fracture healing. Quantitative ultrasound parameters have been reported to be sensitive to callus changes during the regeneration process. The results suggest that the time of flight measured in axial transmission is affected by local changes of speed of sound induced by changes in local mineralization.

#### **2.2.2 Quantitative computer tomography scan**

Quantitative Computer Tomography Scan (QCT) is done to find true volumetric bone mineral content by measuring separately trabecular and three-dimensional cortical bone.

Image quality degradation due to subject motion is a common artefact affecting *in vivo* highresolution peripheral quantitative computed tomography (HR-pQCT) of bones. These artefacts confound the accuracy and reproducibility of bone density, geometry, and cortical and trabecular structure measurements. Observer-based systems for grading image quality and criteria for deciding when to repeat an acquisition and post hoc data quality control remain highly subjective and non-standardized (Sodeab et al, 2011).

The QCT scan is a not so famous form of bone density test because it is expensive, utilizes a high amount of radiation and its accuracy is minimum.

Evolutionary Pathways of Diagnosis in Osteoporosis 137

patient and not one year probability. On the other hand "the FRAX® assessment does not tell you who to treat which remains a matter of clinical judgement. In many countries, guidelines are provided that are based on expert opinion and/or on health economic grounds", what the question remain to be wonder what to do with?. That supposes one first principles answer. Level D evidence-based medicine according to the standards of the UK

Bayes' theorem deals with the role of new information in revising probability estimates. The theorem assumes that the probability of a hypothesis (the posterior probability) is a function

Specific chart reminders to physicians combined with mailed patient education substantially increased the levels of bone density testing and could potentially be used to improve osteoporosis screening in primary care. Bayesian hierarchical analysis makes it possible to assess practice-level interventions when few practices are randomized (Levy BT et al. 2009). In probability theory and applications, Bayes' theorem shows how to determine inverse probabilities: knowing the conditional probability of B given A, what is the conditional probability of A given B? This can be done, but also involves the so-called prior or

This theorem is named for Thomas Bayes and often called Bayes' law or Bayes' rule. Bayes' theorem expresses the conditional probability, or "posterior probability", of a hypothesis H (its probability after evidence E is observed) in terms of the "prior probability" of H, the prior probability of E, and the conditional probability of E given H. It implies that evidence has a confirming effect if it is more likely given H than given not-H. Bayes' theorem is valid in all common interpretations of probability, and it is commonly applied in science and engineering. However, there is disagreement among statisticians regarding the question whether it can be used to reduce all statistical questions to problems of inverse probability.

The key idea is that the probability of an event A given an event B depends not only on the relationship between events A and B but also on the marginal probability of occurrence of

As a formal theorem, Bayes' theorem is valid in all common interpretations of probability. However, frequentist and Bayesian interpretations disagree on how (and to what) probabilities are assigned. In the Bayesian interpretation, probabilities are rationally coherent degrees of belief, or a degree of belief in a proposition given a body of well-specified information. Bayes' theorem can then be understood as specifying how an ideally rational person responds to evidence. In the frequentist interpretation, probabilities are the frequencies of occurrence of random events as proportions of a whole. Though his name has become associated with

Bayes' theorem is often more easy to apply, and to generalize, when expressed in terms of odds. It is then usually referred to as Bayes' rule, which is expressed in words as posterior odds equals prior odds times likelihood ratio. The term Bayes factor is often used instead of

In statistics, the use of Bayes factors is a Bayesian alternative to classical hypothesis testing.

The adoption of Bayes' theorem has led to the development of Bayesian methods for data analysis. Bayesian methods have been defined as "the explicit use of external evidence in the

subjective probability, Bayes himself interpreted the theorem in an objective sense.

Bayesian model comparison is a method of model selection based on Bayes factors.

National Health Service or lower level if any existed in the evidence-based medicine.

of new evidence (the likelihood) and previous knowledge (prior probability).

Can competing scientific hypotheses be assigned prior probabilities?

**2.2.3.1 The Bayes' theorem** 

unconditional probabilities of A and B.

each event.

likelihood ratio.

The QCT measures BMD at spine or hip. Bone architecture, measured by CT, is a BMDindependent determinant of bone strength (Bauer & Link, 2009).

Because bone density can vary from one location in the body to another, a measurement taken at the heel usually is not as accurate a predictor of fracture risk as is a measurement taken at the spine or hip. That is why, if the test on a peripheral device is positive, DXA scan should be performed at the spine or hip to confirm the diagnosis. But what happen at the spine or hip is not what happen at the heel or wrist. So, the problem endures.

#### **2.2.3 Bone fracture risk calculators**

The fracture risk assessment tool (FRAX®) case finding algorithm has been developed to predict the 10-year risk of major and hip fractures based on clinical risk factors, with and without BMD. The Garvan fracture risk calculator is another tool that is available online to calculate the risk of fracture. The FORE Fracture Risk Calculator™ uses risk factors established by the W HO, such as alcohol use, family history of hip fractures, and certain chronic diseases.

FRAX and Garvan fracture risk calculators estimate the absolute risk of osteoporotic fractures. Garvan estimated higher absolute fracture risk than FRAX. None of the calculators provide better discrimination than models based on age and BMD, and their discriminative ability is only moderate, which may limit their clinical utility (Bolland et al., 2011).

The Framingham Osteoporosis Study, an ancillary study of the Framingham Heart Study, has contributed substantially to the understanding of risk factors for age-related bone loss and fractures in men and women. For the past fifteen years, this research program has been investigating a variety of risk factors for bone loss and fractures by assessing BMD using SPA, dual photon absorptiometry (DPA), DXA, QUS, and by ascertaining fracture incidence in the Framingham Study

The FRAX® tool has been developed by WHO to evaluate fracture risk of patients that integrate the risks associated with clinical risk factors as well as with or without BMD at the femoral neck. The FRAX® algorithms give the 10-year probability of fracture (Kanis et al., 2000).

The prediction of hip fracture and other osteoporotic fractures based on the assessment algorithms (FRAX™) which includes clinical risk factors alone, or the combination of clinical risk factors plus BMD is prediction, but Medicine is Medicine and future prediction is not Medicine and the important is not the statistics but if the human ill being who must be treated or not. In the evaluation of the FRAX and Garvan fracture risk calculators in older women it was found that Garvan calculator was well calibrated for osteoporotic fractures but overestimated hip fractures. FRAX with BMD underestimated osteoporotic and hip fractures. FRAX without BMD underestimated osteoporotic and overestimated hip fractures. In summary, none of the calculators provided better discrimination than models based on age and BMD, and their discriminative ability was only moderate, which may limit their clinical utility. The calibration varied, suggesting that the calculators should be validated in local cohorts before clinical use.

The probability is not certainty of fracture. It is statistics. That is science that deals with the collection, classification, analysis, and interpretation of numerical facts or data, and that, by use of mathematical theories of probability, imposes order and regularity on aggregates of more or less disparate elements. Is that the matter?. May be, but it is not medicine. And osteoporosis is a medical condition. And risk factors do not mean disease. The patient is the patient and not one year probability. On the other hand "the FRAX® assessment does not tell you who to treat which remains a matter of clinical judgement. In many countries, guidelines are provided that are based on expert opinion and/or on health economic grounds", what the question remain to be wonder what to do with?. That supposes one first principles answer. Level D evidence-based medicine according to the standards of the UK National Health Service or lower level if any existed in the evidence-based medicine.

### **2.2.3.1 The Bayes' theorem**

136 Osteoporosis

The QCT measures BMD at spine or hip. Bone architecture, measured by CT, is a BMD-

Because bone density can vary from one location in the body to another, a measurement taken at the heel usually is not as accurate a predictor of fracture risk as is a measurement taken at the spine or hip. That is why, if the test on a peripheral device is positive, DXA scan should be performed at the spine or hip to confirm the diagnosis. But what happen at the

The fracture risk assessment tool (FRAX®) case finding algorithm has been developed to predict the 10-year risk of major and hip fractures based on clinical risk factors, with and without BMD. The Garvan fracture risk calculator is another tool that is available online to calculate the risk of fracture. The FORE Fracture Risk Calculator™ uses risk factors established by the W HO, such as alcohol use, family history of hip fractures, and certain

FRAX and Garvan fracture risk calculators estimate the absolute risk of osteoporotic fractures. Garvan estimated higher absolute fracture risk than FRAX. None of the calculators provide better discrimination than models based on age and BMD, and their discriminative

The Framingham Osteoporosis Study, an ancillary study of the Framingham Heart Study, has contributed substantially to the understanding of risk factors for age-related bone loss and fractures in men and women. For the past fifteen years, this research program has been investigating a variety of risk factors for bone loss and fractures by assessing BMD using SPA, dual photon absorptiometry (DPA), DXA, QUS, and by ascertaining fracture incidence

The FRAX® tool has been developed by WHO to evaluate fracture risk of patients that integrate the risks associated with clinical risk factors as well as with or without BMD at the femoral neck. The FRAX® algorithms give the 10-year probability of fracture (Kanis et al.,

The prediction of hip fracture and other osteoporotic fractures based on the assessment algorithms (FRAX™) which includes clinical risk factors alone, or the combination of clinical risk factors plus BMD is prediction, but Medicine is Medicine and future prediction is not Medicine and the important is not the statistics but if the human ill being who must be treated or not. In the evaluation of the FRAX and Garvan fracture risk calculators in older women it was found that Garvan calculator was well calibrated for osteoporotic fractures but overestimated hip fractures. FRAX with BMD underestimated osteoporotic and hip fractures. FRAX without BMD underestimated osteoporotic and overestimated hip fractures. In summary, none of the calculators provided better discrimination than models based on age and BMD, and their discriminative ability was only moderate, which may limit their clinical utility. The calibration varied, suggesting that the calculators should be

The probability is not certainty of fracture. It is statistics. That is science that deals with the collection, classification, analysis, and interpretation of numerical facts or data, and that, by use of mathematical theories of probability, imposes order and regularity on aggregates of more or less disparate elements. Is that the matter?. May be, but it is not medicine. And osteoporosis is a medical condition. And risk factors do not mean disease. The patient is the

ability is only moderate, which may limit their clinical utility (Bolland et al., 2011).

independent determinant of bone strength (Bauer & Link, 2009).

**2.2.3 Bone fracture risk calculators** 

chronic diseases.

in the Framingham Study

validated in local cohorts before clinical use.

2000).

spine or hip is not what happen at the heel or wrist. So, the problem endures.

Bayes' theorem deals with the role of new information in revising probability estimates. The theorem assumes that the probability of a hypothesis (the posterior probability) is a function of new evidence (the likelihood) and previous knowledge (prior probability).

Specific chart reminders to physicians combined with mailed patient education substantially increased the levels of bone density testing and could potentially be used to improve osteoporosis screening in primary care. Bayesian hierarchical analysis makes it possible to assess practice-level interventions when few practices are randomized (Levy BT et al. 2009).

In probability theory and applications, Bayes' theorem shows how to determine inverse probabilities: knowing the conditional probability of B given A, what is the conditional probability of A given B? This can be done, but also involves the so-called prior or unconditional probabilities of A and B.

This theorem is named for Thomas Bayes and often called Bayes' law or Bayes' rule. Bayes' theorem expresses the conditional probability, or "posterior probability", of a hypothesis H (its probability after evidence E is observed) in terms of the "prior probability" of H, the prior probability of E, and the conditional probability of E given H. It implies that evidence has a confirming effect if it is more likely given H than given not-H. Bayes' theorem is valid in all common interpretations of probability, and it is commonly applied in science and engineering. However, there is disagreement among statisticians regarding the question whether it can be used to reduce all statistical questions to problems of inverse probability. Can competing scientific hypotheses be assigned prior probabilities?

The key idea is that the probability of an event A given an event B depends not only on the relationship between events A and B but also on the marginal probability of occurrence of each event.

As a formal theorem, Bayes' theorem is valid in all common interpretations of probability. However, frequentist and Bayesian interpretations disagree on how (and to what) probabilities are assigned. In the Bayesian interpretation, probabilities are rationally coherent degrees of belief, or a degree of belief in a proposition given a body of well-specified information. Bayes' theorem can then be understood as specifying how an ideally rational person responds to evidence. In the frequentist interpretation, probabilities are the frequencies of occurrence of random events as proportions of a whole. Though his name has become associated with subjective probability, Bayes himself interpreted the theorem in an objective sense.

Bayes' theorem is often more easy to apply, and to generalize, when expressed in terms of odds. It is then usually referred to as Bayes' rule, which is expressed in words as posterior odds equals prior odds times likelihood ratio. The term Bayes factor is often used instead of likelihood ratio.

In statistics, the use of Bayes factors is a Bayesian alternative to classical hypothesis testing. Bayesian model comparison is a method of model selection based on Bayes factors.

The adoption of Bayes' theorem has led to the development of Bayesian methods for data analysis. Bayesian methods have been defined as "the explicit use of external evidence in the

Evolutionary Pathways of Diagnosis in Osteoporosis 139

3. Peripheral dual energy X-ray absorptiometry (PDEXA) is a type of DEXA test that measures the density of bones in the arms or legs, such as the wrist or a finger. It cannot measure the density of the bones most likely to break, such as the hip and spine. PDEXA is not as useful as DEXA for finding out how well medicine used to treat

4. SPA is a method that uses a single-energy photon beam that is passed through bone and soft tissue to a detector. The amount of mineral in the path is then quantified. 5. Dual-photon absorptiometry (DPA) uses a photon beam that has two distinct energy peaks. One energy peak is absorbed more by the soft tissue. The other energy peak is absorbed more by bone. The soft-tissue component is subtracted to determine the BMD. 6. Radiographic absorptiometry (RA) uses an X-ray of the hand and a small metal wedge to calculate bone density. This is an approach that include different methods to significantly increase the proportion of eligible patients tested for low BMD, using a low-cost peripheral BMD system in the primary care physician's office or satellite facility to identify those patients who could receive further BMD assessment by central DXA.

Bone metabolism control is performed inside and outside the bone. Through lab tests which may be carried out in blood and urine samples, bone metabolism becomes known. The results of these tests can help identify conditions that may be contributing to bone loss. The most common blood tests evaluate: blood calcium levels, blood vitamin D levels, liver function, kidney function tests: both creatinine and BUN are included on the common chemical profiles, thyroid function: TSH, T4, T3 tests , parathyroid hormone levels, estradiol levels in women, follicle stimulating hormone test to establish menopause status,

A 24-hour urine collection can show if there is a problem with intestinal absorption of calcium (Ca) or leakage of calcium through the kidneys. Blood tests are done to check things such as blood chemistries, blood count, proteins, vitamin D level, thyroid function, and antibodies for celiac disease, a condition that may cause poor intestinal absorption of important nutrients. A simple urine specimen shows the bone metabolism or an important factor in determining bone density and bone strength. With this test, natural bone protein

Dairy products constitute one of the most important types of functional food. And dairy products-calcium intake and its good intestinal absorption is basic. Renal Ca clearance is

Essential hypertensive (EH) patients have a higher rate of urinary calcium excretion and, according to some reports, somewhat lower levels of serum ionized calcium. The mean renal calcium clearance is somewhat higher, but the difference from controls did not reach statistical

testosterone levels in men, osteocalcin levels to measure bone formation.

wrist, used SXA to assess bone mineral density.

**2.3 The diagnosis of bone metabolism control** 

products such as N-telopeptide (NTX) are tested.

other parameter to be measured.

osteoporosis is working.

Quantitative methods such as morphometry or MRI have been developed over the past years and can be used to assess more precisely the features of vertebral fractures. 2. Single-energy X-ray absorptiometry (SXA) is a method of assessing bone mineral density using a single energy X-ray beam. This may be used to measure the wrist or heel bone density, but SXA is not used as often as DEXA. It is now widely considered inferior to dual-energy X-ray absorptiometry which uses a second energy beam to correct for absorption of X-ray energy by non-calcium containing tissues. Many previous studies of peripheral bone mineral density measurement for instance at the

design, monitoring, analysis, interpretation and reporting" of studies (Spiegelhalter, 1999). The Bayesian approach to data analysis allows consideration of all possible sources of evidence in the determination of the posterior probability of an event. It is argued that this approach has more relevance to decision making than classical statistical inference, as it focuses on the transformation from initial knowledge to final opinion rather than on providing the "correct" inference.

In addition to its practical use in probability analysis, Bayes' theorem can be used as a normative model to assess how well people use empirical information to update the probability that a hypothesis is true.

The odds in favor of an event or a proposition are expressed as the ratio of a pair of integers, which is the ratio of the probability that an event will happen to the probability that it will not happen.

Frequency probability is the interpretation of probability that defines an event's probability as the limit of its relative frequency in a large number of trials. The development of the frequentist account was motivated by the problems and paradoxes of the previously dominant viewpoint, the classical interpretation. The shift from the classical view to the frequentist view represents a paradigm shift in the progression of statistical thought.

Frequentists talk about probabilities only when dealing with well-defined random experiments.The set of all possible outcomes of a random experiment is called the sample space of the experiment.

A paradigm is what members of a scientific community, and they alone, share. A paradigm shift (or revolutionary science) is, according to Thomas Kuhn in his influential book The Structure of Scientific Revolutions (1962), a change in the basic assumptions, or paradigms, within the ruling theory of science. It is in contrast to his idea of normal science. A proposition is true if it works. Thus, older occupants in motor-vehicle crashes are more likely to experience injury than younger occupants. Crash-injury data were used with Bayes' Theorem to estimate the conditional probability of AIS 3+ skeletal injury given that an occupant is osteoporotic for the injury to the head, spine, thorax, lower extremities, and upper extremities. It suggests that the increase in AIS 3+ injury risk with age for non-spine injuries is likely influenced by factors other than osteoporosis (Rupp et al., 2010).

#### **2.2.4 The radiological assessment of vertebral osteoporosis**

Vertebral fracture assessment (VFA) is recognized as the standard in fracture risk assessment. High definition instant vertebral assessment allows identifying spine fractures with one rapid, low dose, single energy image at double the resolution of previously available techniques. VFA differs from radiological detection of fractures, because VFA uses a lower radiation exposure and can detect only fractures, while traditional x-ray images can detect other bone and soft tissue abnormalities in addition to spinal fractures.

#### **2.2.5 Some other methods**

1. Morphometry. VFA may be referred to as DEXA or DXA or morphometric x-ray absorptiometry. Magnetic resonance imaging (MRI) is a new method of measuring bone density. MRI has made significant contributions to the diagnosis of acute hip joint disease in adults by enabling early differentiation between such conditions as idiopathic avascular femoral head necrosis, septic coxitis, degenerative disease, and tumors. MRI may provide information pertaining to bone density and structure as well as to occult fracture detection.

design, monitoring, analysis, interpretation and reporting" of studies (Spiegelhalter, 1999). The Bayesian approach to data analysis allows consideration of all possible sources of evidence in the determination of the posterior probability of an event. It is argued that this approach has more relevance to decision making than classical statistical inference, as it focuses on the transformation from initial knowledge to final opinion rather than on

In addition to its practical use in probability analysis, Bayes' theorem can be used as a normative model to assess how well people use empirical information to update the

The odds in favor of an event or a proposition are expressed as the ratio of a pair of integers, which is the ratio of the probability that an event will happen to the probability that it will

Frequency probability is the interpretation of probability that defines an event's probability as the limit of its relative frequency in a large number of trials. The development of the frequentist account was motivated by the problems and paradoxes of the previously dominant viewpoint, the classical interpretation. The shift from the classical view to the

Frequentists talk about probabilities only when dealing with well-defined random experiments.The set of all possible outcomes of a random experiment is called the sample

A paradigm is what members of a scientific community, and they alone, share. A paradigm shift (or revolutionary science) is, according to Thomas Kuhn in his influential book The Structure of Scientific Revolutions (1962), a change in the basic assumptions, or paradigms, within the ruling theory of science. It is in contrast to his idea of normal science. A proposition is true if it works. Thus, older occupants in motor-vehicle crashes are more likely to experience injury than younger occupants. Crash-injury data were used with Bayes' Theorem to estimate the conditional probability of AIS 3+ skeletal injury given that an occupant is osteoporotic for the injury to the head, spine, thorax, lower extremities, and upper extremities. It suggests that the increase in AIS 3+ injury risk with age for non-spine

Vertebral fracture assessment (VFA) is recognized as the standard in fracture risk assessment. High definition instant vertebral assessment allows identifying spine fractures with one rapid, low dose, single energy image at double the resolution of previously available techniques. VFA differs from radiological detection of fractures, because VFA uses a lower radiation exposure and can detect only fractures, while traditional x-ray images can

1. Morphometry. VFA may be referred to as DEXA or DXA or morphometric x-ray absorptiometry. Magnetic resonance imaging (MRI) is a new method of measuring bone density. MRI has made significant contributions to the diagnosis of acute hip joint disease in adults by enabling early differentiation between such conditions as idiopathic avascular femoral head necrosis, septic coxitis, degenerative disease, and tumors. MRI may provide information pertaining to bone density and structure as well as to occult

frequentist view represents a paradigm shift in the progression of statistical thought.

injuries is likely influenced by factors other than osteoporosis (Rupp et al., 2010).

detect other bone and soft tissue abnormalities in addition to spinal fractures.

**2.2.4 The radiological assessment of vertebral osteoporosis** 

providing the "correct" inference.

probability that a hypothesis is true.

not happen.

space of the experiment.

**2.2.5 Some other methods** 

fracture detection.

Quantitative methods such as morphometry or MRI have been developed over the past years and can be used to assess more precisely the features of vertebral fractures.


### **2.3 The diagnosis of bone metabolism control**

Bone metabolism control is performed inside and outside the bone. Through lab tests which may be carried out in blood and urine samples, bone metabolism becomes known. The results of these tests can help identify conditions that may be contributing to bone loss. The most common blood tests evaluate: blood calcium levels, blood vitamin D levels, liver function, kidney function tests: both creatinine and BUN are included on the common chemical profiles, thyroid function: TSH, T4, T3 tests , parathyroid hormone levels, estradiol levels in women, follicle stimulating hormone test to establish menopause status, testosterone levels in men, osteocalcin levels to measure bone formation.

A 24-hour urine collection can show if there is a problem with intestinal absorption of calcium (Ca) or leakage of calcium through the kidneys. Blood tests are done to check things such as blood chemistries, blood count, proteins, vitamin D level, thyroid function, and antibodies for celiac disease, a condition that may cause poor intestinal absorption of important nutrients. A simple urine specimen shows the bone metabolism or an important factor in determining bone density and bone strength. With this test, natural bone protein products such as N-telopeptide (NTX) are tested.

Dairy products constitute one of the most important types of functional food. And dairy products-calcium intake and its good intestinal absorption is basic. Renal Ca clearance is other parameter to be measured.

Essential hypertensive (EH) patients have a higher rate of urinary calcium excretion and, according to some reports, somewhat lower levels of serum ionized calcium. The mean renal calcium clearance is somewhat higher, but the difference from controls did not reach statistical

Evolutionary Pathways of Diagnosis in Osteoporosis 141

densitometry to diagnose and monitor osteoporosis, such as beta-crosslap, a biochemical bone marker of bone resorption. Biochemical bone markers, such as the bone isoenzyme form of alkaline phosphatase, have been used to assess the bone formation phase of bone turnover in health and disease. Markers of biochemical bone remodeling can be used in

Chronic uremia is characterized by decreased levels of plasma 1,25-dihydroxyvitamin D3(1,25-(OH)2D3), a hormone with immunomodulatory properties, due to decreased renal 1-hydroxylase activity and by decreased renal phosphate excretion. The consequence is an increased synthesis and secretion of parathyroid hormone--secondary hyperparathyroidism- -due to the low levels of plasma calcium, low levels of plasma 1,25(OH)2D3 and high levels of phosphate. The association between renal bone disease and chronic renal failure is well described. An association also exists between secondary hyperparathyroidism and increased

Calcium carbonate and calcium acetate were used as phosphate binders. Until recently, the most commonly used active vitamin D drug was either the natural 1,25(OH)2D3, or the 1 alpha-hydroxylated analog, 1alpha(OH)D3 which after 25-hydroxylation in the liver is converted to 1,25(OH)2D3. This increases the intestinal absorption of calcium and improves skeletal abnormalities. The combined treatment with calcium containing phosphate binders and active vitamin D induces an increase in plasma Ca and hypercalcemia became a clinical problem. It was demonstrated a direct suppressive effect of intravenous 1,25(OH)2D3 on

The use of 1 alpha-hydroxyvitamin D3 (1 alpha(OH)D3) derivatives in a uremic patient is justified only in the treatment of hyperparathyroidism. The following prerequisites have however to be satisfied: a good vitamin D3 repletion should be secured by plasma 25-OH-D3 levels of 20-30 ng/ml, and phosphate retention and the consequent possible hyperphosphatemia should be prevented or corrected by the oral administration of alkaline salts of calcium given before the meals as phosphate binders without inducing hypercalcemia. In X-linked hypophosphatemia, phosphate wasting results from increased circulating levels of fibroblast growth factor 23 (FGF-23). Administration of calcitonin causes a drop in serum levels of FGF-23. Calcitonin might have the same effect in patients with X-linked hypophosphatemia. Serum levels of 1,25-dihydroxyvitamin D rose similarly in untreated patients with X-linked hypophosphatemia and in controls after a single subcutaneous injection of 200 IU of salmon calcitonin in both groups for 21 hours but diverged thereafter (P=0.008). The rise in serum levels of 1,25-dihydroxyvitamin D is probably due to the direct stimulatory effect of calcitonin on renal 1α-hydroxylase. Both groups had slight and similar changes in serum levels of calcium and PTH. Serum phosphate levels rose after treatment. Recently, it was reported that osteocytes express the calcitonin receptor and respond to calcitonin with an increase in sclerostin production. Sclerostin has an inhibitory effect on the

lifetime of the osteoblast. Sclerostin production by osteocytes is inhibited by PTH.

PTH is the most important endocrine regulator of Ca and phosphorus concentration in extracellular fluid. It enhances the release of Ca from the large reservoir contained in the bones. Bone resorption is the normal destruction of bone by osteoclasts, which are indirectly

**2.3.3 The PTH, serum Ca, insulin and vitamin D** 

assessing and managing osteoporis in conjunction with DEXA.

mortality and cardiovascular calcifications in chronic uremic patients.

**2.3.2 The active vitamin D** 

plasma PTH.

significance. These data indicate an abnormal handling of a calcium load by patients with EH and raise the possibility that such abnormality may not be due simply to a renal defect but perhaps to an altered calcium distribution among different compartments in the body.

Altered regulation of serum calcium level was proposed to be associated with arterial hypertension and to be dependent on a renal Ca leak or altered Ca binding to plasma proteins and cell membrane described in human and experimental hypertension. Hypertensive patients have an altered regulation of serum Ca concentrations, probably due to a different body distribution of Ca, rather than to altered Ca binding to plasma proteins.

It has been reported that changes in salt loading influence parameters of calcium metabolism in hypertensive subjects. It was also reported that response of blood pressure to salt intake is related to salt-induced increase in intracellular calcium and decrease in intracellular magnesium concentrations. Several authors showed that salt-sensitive hypertensive subjects significantly decreased blood pressure after calcium intake which was emphasized by high salt intake.

It has been showed that during high salt intake regimen increase in blood pressure was followed with decrease in serum calcium level, this was explained by the fact that high salt intake stimulates the Ca uptake by cells. They also reported the following characteristics of hypertensive patients with additionally lower blood pressure as a response to Ca intake: salt-sensitive, low serum ionized Ca and plasma renin activity (PRA) values and high parathyroid hormonE (PTH) values and 1,25-(OH)2-D3 values.

A number of abnormalities in the extracellular and intracellular handling of Ca in arterial hypertension, namely an increased urinary Ca excretion, a reduced serum ionized Ca level and an enhanced intracellular free calcium concentration, have previously been reported. The total body Ca clearance, calculated from the area under the curve of the serum Ca concentrations, was enhanced in hypertensive patients (P less than 0.03). Although the renal Ca excretion is higher in hypertension, the renal calcium clearance account for only a minor fraction of the total body clearance, suggesting that the reduced serum Ca levels achieved by the hypertensive patients are not explained by the renal Ca leak. The enhanced total body Ca clearance found in hypertensive subjects is therefore due to an increased tissue Ca uptake. This finding provides indirect evidence of altered cell Ca handling in hypertension.

Ca metabolism has been investigated in patients with essential hypertension and normal renal function to evaluate the renal calcium handling and the reported increase in renal Ca loss. The results support the hypothesis of primary renal Ca leak in essential hypertension. Enhanced urinary calcium excretion rate may cause compensatory PTH overactivity.

Increased gut Ca absorption or reduced renal tubular Ca reabsorption have been alternatively reported in idiopathic hypercalciuria with kidney calculi. Although renal Ca excretion is higher in hypercalciurics, renal Ca clearance account for only a minor fraction of the total body clearance, suggesting that the reduced serum Ca levels found in the hypercalciurics could not be explained by the renal Ca leak. The enhanced total body Ca clearance found in hypercalciuric subjects is therefore due to an increased tissue Ca uptake. This finding provides indirect evidence of altered cell Ca handling in idiopathic hypercalciura with no difference between the so-called absorptives and renals in terms of the pathophysiologic mechanism.

#### **2.3.1 Testing collagen in urine or blood**

Laboratory tests that measure the amount of collagen in urine or blood samples can indicate bone loss. Lab tests may also be used in conjunction with DEXA or other methods of bone densitometry to diagnose and monitor osteoporosis, such as beta-crosslap, a biochemical bone marker of bone resorption. Biochemical bone markers, such as the bone isoenzyme form of alkaline phosphatase, have been used to assess the bone formation phase of bone turnover in health and disease. Markers of biochemical bone remodeling can be used in assessing and managing osteoporis in conjunction with DEXA.

### **2.3.2 The active vitamin D**

140 Osteoporosis

significance. These data indicate an abnormal handling of a calcium load by patients with EH and raise the possibility that such abnormality may not be due simply to a renal defect but

Altered regulation of serum calcium level was proposed to be associated with arterial hypertension and to be dependent on a renal Ca leak or altered Ca binding to plasma proteins and cell membrane described in human and experimental hypertension. Hypertensive patients have an altered regulation of serum Ca concentrations, probably due to a different body distribution of Ca, rather than to altered Ca binding to plasma proteins. It has been reported that changes in salt loading influence parameters of calcium metabolism in hypertensive subjects. It was also reported that response of blood pressure to salt intake is related to salt-induced increase in intracellular calcium and decrease in intracellular magnesium concentrations. Several authors showed that salt-sensitive hypertensive subjects significantly decreased blood pressure after calcium intake which was

It has been showed that during high salt intake regimen increase in blood pressure was followed with decrease in serum calcium level, this was explained by the fact that high salt intake stimulates the Ca uptake by cells. They also reported the following characteristics of hypertensive patients with additionally lower blood pressure as a response to Ca intake: salt-sensitive, low serum ionized Ca and plasma renin activity (PRA) values and high

A number of abnormalities in the extracellular and intracellular handling of Ca in arterial hypertension, namely an increased urinary Ca excretion, a reduced serum ionized Ca level and an enhanced intracellular free calcium concentration, have previously been reported. The total body Ca clearance, calculated from the area under the curve of the serum Ca concentrations, was enhanced in hypertensive patients (P less than 0.03). Although the renal Ca excretion is higher in hypertension, the renal calcium clearance account for only a minor fraction of the total body clearance, suggesting that the reduced serum Ca levels achieved by the hypertensive patients are not explained by the renal Ca leak. The enhanced total body Ca clearance found in hypertensive subjects is therefore due to an increased tissue Ca uptake. This finding provides indirect evidence of altered cell Ca handling in hypertension. Ca metabolism has been investigated in patients with essential hypertension and normal renal function to evaluate the renal calcium handling and the reported increase in renal Ca loss. The results support the hypothesis of primary renal Ca leak in essential hypertension.

Enhanced urinary calcium excretion rate may cause compensatory PTH overactivity.

Increased gut Ca absorption or reduced renal tubular Ca reabsorption have been alternatively reported in idiopathic hypercalciuria with kidney calculi. Although renal Ca excretion is higher in hypercalciurics, renal Ca clearance account for only a minor fraction of the total body clearance, suggesting that the reduced serum Ca levels found in the hypercalciurics could not be explained by the renal Ca leak. The enhanced total body Ca clearance found in hypercalciuric subjects is therefore due to an increased tissue Ca uptake. This finding provides indirect evidence of altered cell Ca handling in idiopathic hypercalciura with no difference between the so-called absorptives and renals in terms of the pathophysiologic mechanism.

Laboratory tests that measure the amount of collagen in urine or blood samples can indicate bone loss. Lab tests may also be used in conjunction with DEXA or other methods of bone

parathyroid hormonE (PTH) values and 1,25-(OH)2-D3 values.

perhaps to an altered calcium distribution among different compartments in the body.

emphasized by high salt intake.

**2.3.1 Testing collagen in urine or blood** 

Chronic uremia is characterized by decreased levels of plasma 1,25-dihydroxyvitamin D3(1,25-(OH)2D3), a hormone with immunomodulatory properties, due to decreased renal 1-hydroxylase activity and by decreased renal phosphate excretion. The consequence is an increased synthesis and secretion of parathyroid hormone--secondary hyperparathyroidism- -due to the low levels of plasma calcium, low levels of plasma 1,25(OH)2D3 and high levels of phosphate. The association between renal bone disease and chronic renal failure is well described. An association also exists between secondary hyperparathyroidism and increased mortality and cardiovascular calcifications in chronic uremic patients.

Calcium carbonate and calcium acetate were used as phosphate binders. Until recently, the most commonly used active vitamin D drug was either the natural 1,25(OH)2D3, or the 1 alpha-hydroxylated analog, 1alpha(OH)D3 which after 25-hydroxylation in the liver is converted to 1,25(OH)2D3. This increases the intestinal absorption of calcium and improves skeletal abnormalities. The combined treatment with calcium containing phosphate binders and active vitamin D induces an increase in plasma Ca and hypercalcemia became a clinical problem. It was demonstrated a direct suppressive effect of intravenous 1,25(OH)2D3 on plasma PTH.

The use of 1 alpha-hydroxyvitamin D3 (1 alpha(OH)D3) derivatives in a uremic patient is justified only in the treatment of hyperparathyroidism. The following prerequisites have however to be satisfied: a good vitamin D3 repletion should be secured by plasma 25-OH-D3 levels of 20-30 ng/ml, and phosphate retention and the consequent possible hyperphosphatemia should be prevented or corrected by the oral administration of alkaline salts of calcium given before the meals as phosphate binders without inducing hypercalcemia.

In X-linked hypophosphatemia, phosphate wasting results from increased circulating levels of fibroblast growth factor 23 (FGF-23). Administration of calcitonin causes a drop in serum levels of FGF-23. Calcitonin might have the same effect in patients with X-linked hypophosphatemia. Serum levels of 1,25-dihydroxyvitamin D rose similarly in untreated patients with X-linked hypophosphatemia and in controls after a single subcutaneous injection of 200 IU of salmon calcitonin in both groups for 21 hours but diverged thereafter (P=0.008). The rise in serum levels of 1,25-dihydroxyvitamin D is probably due to the direct stimulatory effect of calcitonin on renal 1α-hydroxylase. Both groups had slight and similar changes in serum levels of calcium and PTH. Serum phosphate levels rose after treatment.

Recently, it was reported that osteocytes express the calcitonin receptor and respond to calcitonin with an increase in sclerostin production. Sclerostin has an inhibitory effect on the lifetime of the osteoblast. Sclerostin production by osteocytes is inhibited by PTH.

### **2.3.3 The PTH, serum Ca, insulin and vitamin D**

PTH is the most important endocrine regulator of Ca and phosphorus concentration in extracellular fluid. It enhances the release of Ca from the large reservoir contained in the bones. Bone resorption is the normal destruction of bone by osteoclasts, which are indirectly

Evolutionary Pathways of Diagnosis in Osteoporosis 143

Calcitonin is a 32-amino acid linear polypeptide hormone that is produced in humans primarily by the parafollicular cells (also known as C-cells) of the thyroid, and in many other animals in the ultimobranchial body. It acts to reduce blood Ca, opposing the effects of PTH. The hormone participates in calcium Ca and phosphorus metabolism. In many ways,

Polybrominated diphenyl ethers (PBDEs) are flame retardants that have been widely used in manufacturing. They are major household and environmental contaminants that bioaccumulate. Humans are exposed primarily through dust inhalation and dietary ingestion of animal products. PBDEs increase rodent circulating T3 and T4 concentrations and gonadal osteopontin mRNA, and activate the osteopontin gene promoter. These changes may have clinical implications as others have shown associations between human exposure to PBDEs

Vitamin K2 (menaquinone), is itself a category of vitamin K that includes many types of vitamin K2. The two subtypes of vitamin K2 that have been most studied are menaquinone-4 (MK4) and menaquinone-7 (MK7). MK4 is produced via conversion of vitamin K1 in the body, in the testes, pancreas and arterial walls. Studies demonstrate that the conversion of

In contrast to MK4, MK7 is not produced by humans but is converted from phylloquinone in the intestines by gut bacteria. However, bacteria-derived menaquinones appear to contribute minimally to overall vitamin K status. MK4 has been approved for the prevention and treatment of osteoporosis, and it has been shown to decrease fractures up to 87%. MK4 has also been shown to prevent bone loss and/or fractures caused by corticosteroids, anorexia nervosa, cirrhosis of the liver and postmenopausal osteoporosis. MK7 has never been shown in any clinical trials to reduce fractures and is not approved by any government for the prevention or treatment of any disease. MK7 has been approved in the purpose of

BMD is only bone mineral density, risk factors for osteoporosis are only risk factors and the mixing of both parameters does not make quite more sense. It is not better than each one separately. BMD is a subrogate parameter for diagnosing bone strength that is good but it is not enough, because with a suitable BMD caused by sodium fluoride bone fragility is increased and some individuals with decreased BMD undergo quantitatively and objectively bone fractures and another different person does not suffer this bone condition. Bone risk factors are good for diagnosis but they do not mean necessarily one disease and nor are they sufficient to osteoporosis. With and without them there are persons with and without suitable bone strength and with and without fractures. It is important to understand

The confounding effect of differences in bone size is due to the missing depth value in the calculation of BMD. It should be noted that despite DXA technology's problems in

that bone is not a hard and lifeless structure; it is, in fact, a complex, living tissue.

estimating volume, it is still a fairly accurate measure of BMD.

**2.3.5 Calcitonin and PTH** 

calcitonin counteracts PTH.

**2.3.6 Environmental contaminants** 

**2.3.7 Vitamin K2 (menaquinone)** 

increasing bone mineral density.

**3. Overture** 

and subclinical hyperthyroidism (Blake et al., 2011).

vitamin K1 to MK4, is not dependent on gut bacteria .

stimulated by PTH. Stimulation is indirect since osteoclasts do not have a receptor for PTH; rather, PTH binds to osteoblasts, the cells responsible for creating bone. In the kidney it enhances active reabsorption of Ca and magnesium from distal tubules and the thick ascending limb. It enhances the absorption of calcium in the intestine by increasing the production of activated vitamin D.

Patients with primary hyperparathyroidism have impaired glucose tolerance more often than do controls, and parathyroid resection sometimes improves this derangement. However, it is unclear whether serum Ca or PTH is more strongly related to impaired glucose metabolism in subjects without primary hyperparathyroidism. Multiple regression analyses showed that the significant and positive correlations between serum Ca vs fasting plasma glucose and homeostasis model assessment insulin resistance in men still remained after adjustment for intact PTH as well as age, body weight, height, creatinine, albumin, phosphate, bone metabolic markers, and estradiol (P < .05). Serum Ca level is positively associated with impaired glucose metabolism, independent of PTH or bone metabolism, in men with type 2 DM.

In the relationship between biochemical parameters, parathyroid adenoma volume, and bone mineral density with respect to intact parathyroid hormone (iPTH) levels in patients with primary hyperparathyroidism, it was found there was no correlation between iPTH, serum calcium levels and total T scores at the femur and lumbar spine. After excluding patients with 25-(OH)D3 insufficiency, there was still no correlation between serum iPTH and calcium levels. Parathyroid adenoma volume, serum iPTH and calcium levels were also not different between patients with and without 25-(OH)D3 insufficiency.

Primary hyperparathyroidism (PHPT) and vitamin D insufficiency are two very frequent conditions. Vitamin D treatment is recommended and may decrease PTH levels in PHPT. However, there is no randomized controlled trial to prove any beneficial effect. For safety reasons, it is recommended to monitor plasma and urinary Ca during treatment. Furthermore, the effect of vitamin D repletion on other outcomes like quality of life, muscle function and central nervous system symptoms should be assessed.

#### **2.3.4 Ghrelin and bone mass density**

Serum ghrelin is positively correlated with trabecular BMD in a cohort of elderly healthy Italian women. The fact that trabecular is more metabolically active than cortical bone and the larger number of females might explain this selective association.

Previously undetected contributors to secondary osteoporosis and metabolic bone diseases (SECOB) are frequently found in patients with osteoporosis, but the prevalence in patients at the time they present with a clinical fracture is unknown (Napoli et al. 2011). At presentation with a fracture, 26.5% of patients have previously unknown contributors to SECOB, as monoclonal proteinemia, renal insufficiency grade III or greater, primary and secondary hyperparathyroidism, hyperthyroidism, and hypogonadism in men. Newly diagnosed SECOBs, serum 25-hydroxyvitamin D less than 50 nmol/liter (in 63.9%), and dietary calcium intake less than 1200 mg/d were found at any age, in both sexes, after any fracture (except SECOB in men with finger and toe fractures) and at any level of bone mineral density, which are treatable or need follow-up, and more than 90% of patients have an inadequate vitamin D status and/or calcium intake. Systematic screening of patients with a recent fracture identifies those in whom potentially reversible contributors to SECOB and calcium and vitamin D deficiency are present ( Bours et al., 2011).

### **2.3.5 Calcitonin and PTH**

142 Osteoporosis

stimulated by PTH. Stimulation is indirect since osteoclasts do not have a receptor for PTH; rather, PTH binds to osteoblasts, the cells responsible for creating bone. In the kidney it enhances active reabsorption of Ca and magnesium from distal tubules and the thick ascending limb. It enhances the absorption of calcium in the intestine by increasing the

Patients with primary hyperparathyroidism have impaired glucose tolerance more often than do controls, and parathyroid resection sometimes improves this derangement. However, it is unclear whether serum Ca or PTH is more strongly related to impaired glucose metabolism in subjects without primary hyperparathyroidism. Multiple regression analyses showed that the significant and positive correlations between serum Ca vs fasting plasma glucose and homeostasis model assessment insulin resistance in men still remained after adjustment for intact PTH as well as age, body weight, height, creatinine, albumin, phosphate, bone metabolic markers, and estradiol (P < .05). Serum Ca level is positively associated with impaired glucose metabolism, independent of PTH or bone metabolism, in

In the relationship between biochemical parameters, parathyroid adenoma volume, and bone mineral density with respect to intact parathyroid hormone (iPTH) levels in patients with primary hyperparathyroidism, it was found there was no correlation between iPTH, serum calcium levels and total T scores at the femur and lumbar spine. After excluding patients with 25-(OH)D3 insufficiency, there was still no correlation between serum iPTH and calcium levels. Parathyroid adenoma volume, serum iPTH and calcium levels were also

Primary hyperparathyroidism (PHPT) and vitamin D insufficiency are two very frequent conditions. Vitamin D treatment is recommended and may decrease PTH levels in PHPT. However, there is no randomized controlled trial to prove any beneficial effect. For safety reasons, it is recommended to monitor plasma and urinary Ca during treatment. Furthermore, the effect of vitamin D repletion on other outcomes like quality of life, muscle

Serum ghrelin is positively correlated with trabecular BMD in a cohort of elderly healthy Italian women. The fact that trabecular is more metabolically active than cortical bone and

Previously undetected contributors to secondary osteoporosis and metabolic bone diseases (SECOB) are frequently found in patients with osteoporosis, but the prevalence in patients at the time they present with a clinical fracture is unknown (Napoli et al. 2011). At presentation with a fracture, 26.5% of patients have previously unknown contributors to SECOB, as monoclonal proteinemia, renal insufficiency grade III or greater, primary and secondary hyperparathyroidism, hyperthyroidism, and hypogonadism in men. Newly diagnosed SECOBs, serum 25-hydroxyvitamin D less than 50 nmol/liter (in 63.9%), and dietary calcium intake less than 1200 mg/d were found at any age, in both sexes, after any fracture (except SECOB in men with finger and toe fractures) and at any level of bone mineral density, which are treatable or need follow-up, and more than 90% of patients have an inadequate vitamin D status and/or calcium intake. Systematic screening of patients with a recent fracture identifies those in whom potentially reversible contributors to SECOB and

not different between patients with and without 25-(OH)D3 insufficiency.

function and central nervous system symptoms should be assessed.

the larger number of females might explain this selective association.

calcium and vitamin D deficiency are present ( Bours et al., 2011).

**2.3.4 Ghrelin and bone mass density** 

production of activated vitamin D.

men with type 2 DM.

Calcitonin is a 32-amino acid linear polypeptide hormone that is produced in humans primarily by the parafollicular cells (also known as C-cells) of the thyroid, and in many other animals in the ultimobranchial body. It acts to reduce blood Ca, opposing the effects of PTH. The hormone participates in calcium Ca and phosphorus metabolism. In many ways, calcitonin counteracts PTH.

### **2.3.6 Environmental contaminants**

Polybrominated diphenyl ethers (PBDEs) are flame retardants that have been widely used in manufacturing. They are major household and environmental contaminants that bioaccumulate. Humans are exposed primarily through dust inhalation and dietary ingestion of animal products. PBDEs increase rodent circulating T3 and T4 concentrations and gonadal osteopontin mRNA, and activate the osteopontin gene promoter. These changes may have clinical implications as others have shown associations between human exposure to PBDEs and subclinical hyperthyroidism (Blake et al., 2011).

### **2.3.7 Vitamin K2 (menaquinone)**

Vitamin K2 (menaquinone), is itself a category of vitamin K that includes many types of vitamin K2. The two subtypes of vitamin K2 that have been most studied are menaquinone-4 (MK4) and menaquinone-7 (MK7). MK4 is produced via conversion of vitamin K1 in the body, in the testes, pancreas and arterial walls. Studies demonstrate that the conversion of vitamin K1 to MK4, is not dependent on gut bacteria .

In contrast to MK4, MK7 is not produced by humans but is converted from phylloquinone in the intestines by gut bacteria. However, bacteria-derived menaquinones appear to contribute minimally to overall vitamin K status. MK4 has been approved for the prevention and treatment of osteoporosis, and it has been shown to decrease fractures up to 87%. MK4 has also been shown to prevent bone loss and/or fractures caused by corticosteroids, anorexia nervosa, cirrhosis of the liver and postmenopausal osteoporosis. MK7 has never been shown in any clinical trials to reduce fractures and is not approved by any government for the prevention or treatment of any disease. MK7 has been approved in the purpose of increasing bone mineral density.

### **3. Overture**

BMD is only bone mineral density, risk factors for osteoporosis are only risk factors and the mixing of both parameters does not make quite more sense. It is not better than each one separately. BMD is a subrogate parameter for diagnosing bone strength that is good but it is not enough, because with a suitable BMD caused by sodium fluoride bone fragility is increased and some individuals with decreased BMD undergo quantitatively and objectively bone fractures and another different person does not suffer this bone condition. Bone risk factors are good for diagnosis but they do not mean necessarily one disease and nor are they sufficient to osteoporosis. With and without them there are persons with and without suitable bone strength and with and without fractures. It is important to understand that bone is not a hard and lifeless structure; it is, in fact, a complex, living tissue.

The confounding effect of differences in bone size is due to the missing depth value in the calculation of BMD. It should be noted that despite DXA technology's problems in estimating volume, it is still a fairly accurate measure of BMD.

Evolutionary Pathways of Diagnosis in Osteoporosis 145

regions included in one ROI (the variation is not caused by noise or the imaging process),

The error of method one is directly proportional to the noise of the system used and becomes highest when data is measured nearest the asymptote of the curve fit used to calibrate the data. Most data unfortunately have some natural density variation and some

We are facing a big concern: Osteoporosis is a major public health threat. How can we treat

An expert technical assessment of the many factors that influence the risk of osteoporotic fracture in postmenopausal women need to be considered when planning the most effective public health interventions. In view of growing awareness of the need to prevent and treat postmenopausal osteoporosis, it is good to resolve several controversies concerning the usefulness of screening programmes, the appropriate target populations, the most effective methods for predicting fracture risk, techniques for assessment, and the comparative effectiveness of currently available preventive and therapeutic interventions. There are advantages and limitations of the methods for predicting future fracture risk: assessment of bone mass, assessment of bone loss, and clinical assessment of risk factors. It is needed information on non-invasive physical techniques for bone mass assessment. The aims and

By reason of the two-dimensional nature of DXA, assumptions must be made regarding the tridimensional nature of the bones involving a great deal to cope with. Therefore it is deduced, that this method seems to be very sensitive to error, and it is necessary to know how to deal with these errors, especially with the systematic errors introduced by using a parameterized model. Even though a high concordance between the densitometers was observed on a single measurement occasion, a significant discordance in longitudinal

Bone strength is comprised of many components, which include architecture, geometry, cortical porosity, and tissue mineralization density. These components are contained within

Bone strength is comprised of many components including, but not limited to bone

The exceptional mechanical properties of bones are not only the result of the amount and type of the micro-constituents, but also of their morphological organization at the different

Mechanical properties of bone are determined not only by BMD, but also by tissue trabecular structure and organic composition. Direct measurement of these components of bone strength may result in improved fracture risk prediction or therapeutic monitoring

In addition to loading in axial compression, long bones are also and, in fact, primarily loaded in bending. In linear coupled bending and extension of an unbalanced bonded repair the tensile forces are exerted on the bending-created convex surface, whereas compressive forces are exerted on the concave surface. This bending increases the stress intensity in the underlying crack and causes adhesive peel stresses and bending of the repair which can, relative to a repair that is restrained against bending, lead to early failure and certain assumptions must be made about the symmetry of the bone in cross-section at the different ROIs, which are not entirely accurate. Additionally, cortical thickness must be assumed to

the measurement of BMD but cannot be individually distinguished.

than is currently possible using the surrogate measure of BMD.

architecture, geometry, cortical porosity and tissue mineralization density.

then the method one produces a better estimation of mean.

variation caused by the imaging process (noise).

it if we have not the adequate diagnosis tool?.

design of screening programmes are not clear.

changes in BMD was observed.

lower scales.

Methods to correct for this shortcoming include the calculation of a volume which is approximated from the projected area measure by DXA. DXA BMD results adjusted in this manner are referred to as the bone mineral apparent density (BMAD) and are a ratio of the bone mineral content versus a cuboidal estimation of the volume of bone. As aBMD, BMAD results do not accurately represent true bone mineral density, since they use approximations of the bone's volume.

It is important to get repeated BMD measurements done on the same machine each time, or at least a machine from the same manufacturer. Error between machines, or trying to convert measurements from one manufacturer's standard to another can introduce errors large enough to wipe out the sensitivity of the measurements.

It is possible to use a scaling system for pixels which has a one to one correspondence to the concentration of what you are studying. Sample concentrations can be determined using optical, electronic, and most importantly for our purposes, a computer based imaging technique. Densitometric science was described originally by Bouguer and Lambert who described loss of radiation (or light) in passing through a medium. Later, Beer found that the radiation loss in a media was a function of the substance's molarity or concentration.

According to Beer's law, concentration is proportional to optical density (OD). The logarithmic optical density scale, and net integral of density values for an object in an image is the proper measure for use in quantitation. By Beer's law, the density of a point is the log ratio of incident light upon it and transmitted light through it.

OD = Log10(Io / I)

When dealing with noisy data if there is a region of interest (ROI) or image area that is calibrated, such as is done during concentration calibrations, which method for calculation of a the calibrated mean is preferable?


Calibrated mean = cvalue(sum(P[i,j]) / N) where P[i,j] is each pixel intensity in the ROI, and N is the total number of pixels in the ROI. In an ideal world, it would not make any difference. Both methods would yield the same value. However in the real world, measurement and other types of error enter in, and we should think of the problem in a statistical context. If the errors (i.e. the standard deviation) are small, the method used does not matter much. But how small is small? What really matters is the relationship of the standard deviation to the curvature of the calibration curve.

If the calibration curve were truly linear, the order of operations would not matter (a property of linear functions). However, in the current context, the calibration curve is always nonlinear, at least in some regions.

The key question then becomes which of the two methods is appropriate on the data? The answer is: it depends. Some cases are clear cut others are in-between. It is safe to assume that, if there is a fairly uniform grey level region of interest, where the only variation is caused by the noise of the imaging process (all noises), method two produces a better estimation of the mean. In cases where the region contains two highly differing density

Methods to correct for this shortcoming include the calculation of a volume which is approximated from the projected area measure by DXA. DXA BMD results adjusted in this manner are referred to as the bone mineral apparent density (BMAD) and are a ratio of the bone mineral content versus a cuboidal estimation of the volume of bone. As aBMD, BMAD results do not accurately represent true bone mineral density, since they use approximations

It is important to get repeated BMD measurements done on the same machine each time, or at least a machine from the same manufacturer. Error between machines, or trying to convert measurements from one manufacturer's standard to another can introduce errors

It is possible to use a scaling system for pixels which has a one to one correspondence to the concentration of what you are studying. Sample concentrations can be determined using optical, electronic, and most importantly for our purposes, a computer based imaging technique. Densitometric science was described originally by Bouguer and Lambert who described loss of radiation (or light) in passing through a medium. Later, Beer found that the radiation loss in a media was a function of the substance's molarity or concentration. According to Beer's law, concentration is proportional to optical density (OD). The logarithmic optical density scale, and net integral of density values for an object in an image is the proper measure for use in quantitation. By Beer's law, the density of a point is the

When dealing with noisy data if there is a region of interest (ROI) or image area that is calibrated, such as is done during concentration calibrations, which method for calculation

1. Adding up a calibrated value for each pixel in terms of the calibrated unit, then finding

2. Adding up all the pixel values in pixel intensity units, finding the mean pixel intensity value, finally finding the one calibrated value for the mean pixel intensity and calling

Calibrated mean = cvalue(sum(P[i,j]) / N) where P[i,j] is each pixel intensity in the ROI, and N is the total number of pixels in the ROI. In an ideal world, it would not make any difference. Both methods would yield the same value. However in the real world, measurement and other types of error enter in, and we should think of the problem in a statistical context. If the errors (i.e. the standard deviation) are small, the method used does not matter much. But how small is small? What really matters is the relationship of the

If the calibration curve were truly linear, the order of operations would not matter (a property of linear functions). However, in the current context, the calibration curve is

The key question then becomes which of the two methods is appropriate on the data? The answer is: it depends. Some cases are clear cut others are in-between. It is safe to assume that, if there is a fairly uniform grey level region of interest, where the only variation is caused by the noise of the imaging process (all noises), method two produces a better estimation of the mean. In cases where the region contains two highly differing density

Calibrated mean = (sum(cvalue(P[i,j])) / N where cvalue(P[i,j]) is the calibrated value

the average calibrated unit value and calling this the calibrated mean.

for each pixel in your ROI, and N is the total number of pixels in the ROI

large enough to wipe out the sensitivity of the measurements.

log ratio of incident light upon it and transmitted light through it.

standard deviation to the curvature of the calibration curve.

of the bone's volume.

OD = Log10(Io / I)

of a the calibrated mean is preferable?

this the calibrated mean.

always nonlinear, at least in some regions.

regions included in one ROI (the variation is not caused by noise or the imaging process), then the method one produces a better estimation of mean.

The error of method one is directly proportional to the noise of the system used and becomes highest when data is measured nearest the asymptote of the curve fit used to calibrate the data. Most data unfortunately have some natural density variation and some variation caused by the imaging process (noise).

We are facing a big concern: Osteoporosis is a major public health threat. How can we treat it if we have not the adequate diagnosis tool?.

An expert technical assessment of the many factors that influence the risk of osteoporotic fracture in postmenopausal women need to be considered when planning the most effective public health interventions. In view of growing awareness of the need to prevent and treat postmenopausal osteoporosis, it is good to resolve several controversies concerning the usefulness of screening programmes, the appropriate target populations, the most effective methods for predicting fracture risk, techniques for assessment, and the comparative effectiveness of currently available preventive and therapeutic interventions. There are advantages and limitations of the methods for predicting future fracture risk: assessment of bone mass, assessment of bone loss, and clinical assessment of risk factors. It is needed information on non-invasive physical techniques for bone mass assessment. The aims and design of screening programmes are not clear.

By reason of the two-dimensional nature of DXA, assumptions must be made regarding the tridimensional nature of the bones involving a great deal to cope with. Therefore it is deduced, that this method seems to be very sensitive to error, and it is necessary to know how to deal with these errors, especially with the systematic errors introduced by using a parameterized model. Even though a high concordance between the densitometers was observed on a single measurement occasion, a significant discordance in longitudinal changes in BMD was observed.

Bone strength is comprised of many components, which include architecture, geometry, cortical porosity, and tissue mineralization density. These components are contained within the measurement of BMD but cannot be individually distinguished.

Bone strength is comprised of many components including, but not limited to bone architecture, geometry, cortical porosity and tissue mineralization density.

The exceptional mechanical properties of bones are not only the result of the amount and type of the micro-constituents, but also of their morphological organization at the different lower scales.

Mechanical properties of bone are determined not only by BMD, but also by tissue trabecular structure and organic composition. Direct measurement of these components of bone strength may result in improved fracture risk prediction or therapeutic monitoring than is currently possible using the surrogate measure of BMD.

In addition to loading in axial compression, long bones are also and, in fact, primarily loaded in bending. In linear coupled bending and extension of an unbalanced bonded repair the tensile forces are exerted on the bending-created convex surface, whereas compressive forces are exerted on the concave surface. This bending increases the stress intensity in the underlying crack and causes adhesive peel stresses and bending of the repair which can, relative to a repair that is restrained against bending, lead to early failure and certain assumptions must be made about the symmetry of the bone in cross-section at the different ROIs, which are not entirely accurate. Additionally, cortical thickness must be assumed to

Evolutionary Pathways of Diagnosis in Osteoporosis 147

There is concern that the additional 3d information which is gained in this inference process comes entirely from the model, which then would increase the systematic uncertainties

And there is an anisotropic problem, and therefore different inferences must be done making measurements from different directions. But we wonder should the anisotropies are

It should be very easy to test the reliability of this method, by making inferences from datasets taken from different sides, and see to what degree they agree, this would give a simple estimate about some of the systematic errors introduced in the inference method, and how reliable the entire method is. If the reliability is sufficiently high for purposes to study then it would be say there is no use in making a more complicated model. A much deeper investigation of these effects can be carried out in the framework of Bayesian statistics,

But if the reliability is not within the desired range, then of course the only way to tackle this problem is to introduce more complexity to the model to also pick up effects coming from the anisotropies. Which would also means more data might be needed. Treating anisotropies in data inference is in general a very hard business, and a lot of work is going

In this case we have good chances of attacking this problem, because the anisotropies which might occur are not so nasty, so it might be feasible to build a slightly more general model by allowing elliptic shapes, which introduces two parameters a(x) and b(x) for semi and major axis at each point x along the bone axis, or use other Kernel functions which can

The finite element method (FEM), its practical application often known as finite element analysis (FEA), is a numerical technique for finding approximate solutions of partial differential equations (PDE) as well as of integral equations. FEA was first developed in 1943 by R. Courant, who utilized the Ritz method of numerical analysis and minimization of variational calculus to obtain approximate solutions to vibration systems. FEA has been developed to an incredible precision. It consists of a computer model of a material or design that is stressed and analyzed for specific results. It is used in new product design, and existing product refinement. Modifying an existing product or structure is utilized to qualify the product or structure for a new service condition. In case of structural failure, FEA may

FEA is a widely-used technique for the computer modelling of structures under mechanical loading. A finite element is an individual regular shape thathas a known stiffness so that any applied load will give a predictable corresponding displacement. Elements are joined together at nodes and along edges. Complex designs are created as an assembly of elements to which restraints and loads may be applied. During the computer analysis of the model, a series of simultaneous equations are established that represent the overall stiffness of the structure. The equations are then solved giving the nodal displacements resulting from the applied loads. For the analysis of bone structures, finite element analysis would therefore be dependent upon the density of each element, the arrangement of elements (eg trabecular structure), the composition (eg cortical shell or cancellous) and the external shape (eg length,

be used to help determine the design modifications to meet the new condition.

about the quantities that are inferred from the data.

which is very well suited for problems like this.

on at the moment to tackle this problems.

describe the shape more precisely.

**3.1 The finite element method** 

angle and width of femoral neck).

really that bad problem.

be uniform about the circumference of the cross-section. Many of these assumptions are necessitated by the 2-dimensional nature of DXA and may be addressed with 3-dimensional imaging.

The geometric parameters are predictive of fracture risk although they do not seem to be better predictors of risk than a conventional measurement of BMD. DXA measured *in vivo*  "BMD" methodology shows to be an intrinsically flawed and misleading indicator of bone mineral status and an erroneous gauge of relative fracture risk.

DXA methodology to provide accurate, quantitative, and meaningful *in vivo* (not in cadaver) area bone mineral density ("aBMD") determinations have been proven to be unwarranted and misplaced. The underlying systematic of sizable, inherently unavoidable and uncorrectable inaccuracies in the DXA output values of *in vivo* "BMD" have been shown to be quantitatively consistent with being the root cause of unreliable, misdirected, and misinterpreted aspects of consensual knowledge of bone fragility, osteoporotic diagnostics/prognostics, and remodelling therapies.

So, as said above, BMD is only BMD, risk factors to osteoporosis are only risk factors and mixing of both parameters does not make quite more sense. It is not best than each of them alone. Although spatial information is currently recorded in the form of a DXA image, this information is not utilised clinically. It should be noted that BMD assessment provides an areal density measure, where the cross-sectional scan area is known but not the tissue thickness, providing units of g/cm2.

Precise in vivo measurement of the trabecular bone mechanical properties is very important, being essential a method for quantitatively and objectively assessing bone mass and anisotropy and not only in a qualitative manner and with risks which sometimes are not. The cortical bone properties constitute another system with microsystems, isotropy and anisotropy and variety of cross-section of the long bone. But the mechanical properties of bones are not only the result of the amount and type of the micro-constituents, but also of their morphological organization at the different lower scales. Measurement of BMD has served as a fit surrogate for the measurement of bone strength. DXA is one osteoporosis imaging diagnosis testing. By reason of the two-dimensional nature of DXA, assumptions must be made regarding the tridimensional nature of the bones, dealing with an inference problem from a set of measurements. It is needed to make inference about certain parameters which help to make predictions of a certain fracture risk. The main limitation for a proper inference is that only 2d information is got from detectors, and therefore all 3d information is lost, as it is integrated out due to the nature of detector. It is necessary to be very careful when using models for data inference, because we obviously will never know the underlying truth contained in the data. Therefore, it is tried to regain some information about the third dimension by building a model of the bone, which assumes axial symmetry.

By using a model, to be arranged the parameter of this model in such a way that they best fit the data, so it is only gained information about how good the model can explain the data, but it is not gotten any information of how good this model actually is, and maybe there is a much better model, which we do not know it yet. It is very difficult to make good inference of the bone strength due to the noisy character of the data, and dealing with the errors of the apparatus is crucial for making inference.

Therefore it is deduced, that this method seems to be very sensitive to error, and it is necessary to know how to deal with these errors, especially with the systematic errors introduced by using a parameterized model.

be uniform about the circumference of the cross-section. Many of these assumptions are necessitated by the 2-dimensional nature of DXA and may be addressed with 3-dimensional

The geometric parameters are predictive of fracture risk although they do not seem to be better predictors of risk than a conventional measurement of BMD. DXA measured *in vivo*  "BMD" methodology shows to be an intrinsically flawed and misleading indicator of bone

DXA methodology to provide accurate, quantitative, and meaningful *in vivo* (not in cadaver) area bone mineral density ("aBMD") determinations have been proven to be unwarranted and misplaced. The underlying systematic of sizable, inherently unavoidable and uncorrectable inaccuracies in the DXA output values of *in vivo* "BMD" have been shown to be quantitatively consistent with being the root cause of unreliable, misdirected, and misinterpreted aspects of consensual knowledge of bone fragility, osteoporotic

So, as said above, BMD is only BMD, risk factors to osteoporosis are only risk factors and mixing of both parameters does not make quite more sense. It is not best than each of them alone. Although spatial information is currently recorded in the form of a DXA image, this information is not utilised clinically. It should be noted that BMD assessment provides an areal density measure, where the cross-sectional scan area is known but not the tissue

Precise in vivo measurement of the trabecular bone mechanical properties is very important, being essential a method for quantitatively and objectively assessing bone mass and anisotropy and not only in a qualitative manner and with risks which sometimes are not. The cortical bone properties constitute another system with microsystems, isotropy and anisotropy and variety of cross-section of the long bone. But the mechanical properties of bones are not only the result of the amount and type of the micro-constituents, but also of their morphological organization at the different lower scales. Measurement of BMD has served as a fit surrogate for the measurement of bone strength. DXA is one osteoporosis imaging diagnosis testing. By reason of the two-dimensional nature of DXA, assumptions must be made regarding the tridimensional nature of the bones, dealing with an inference problem from a set of measurements. It is needed to make inference about certain parameters which help to make predictions of a certain fracture risk. The main limitation for a proper inference is that only 2d information is got from detectors, and therefore all 3d information is lost, as it is integrated out due to the nature of detector. It is necessary to be very careful when using models for data inference, because we obviously will never know the underlying truth contained in the data. Therefore, it is tried to regain some information about the third dimension by building a model of the bone, which assumes axial symmetry. By using a model, to be arranged the parameter of this model in such a way that they best fit the data, so it is only gained information about how good the model can explain the data, but it is not gotten any information of how good this model actually is, and maybe there is a much better model, which we do not know it yet. It is very difficult to make good inference of the bone strength due to the noisy character of the data, and dealing with the errors of the

Therefore it is deduced, that this method seems to be very sensitive to error, and it is necessary to know how to deal with these errors, especially with the systematic errors

mineral status and an erroneous gauge of relative fracture risk.

diagnostics/prognostics, and remodelling therapies.

thickness, providing units of g/cm2.

apparatus is crucial for making inference.

introduced by using a parameterized model.

imaging.

There is concern that the additional 3d information which is gained in this inference process comes entirely from the model, which then would increase the systematic uncertainties about the quantities that are inferred from the data.

And there is an anisotropic problem, and therefore different inferences must be done making measurements from different directions. But we wonder should the anisotropies are really that bad problem.

It should be very easy to test the reliability of this method, by making inferences from datasets taken from different sides, and see to what degree they agree, this would give a simple estimate about some of the systematic errors introduced in the inference method, and how reliable the entire method is. If the reliability is sufficiently high for purposes to study then it would be say there is no use in making a more complicated model. A much deeper investigation of these effects can be carried out in the framework of Bayesian statistics, which is very well suited for problems like this.

But if the reliability is not within the desired range, then of course the only way to tackle this problem is to introduce more complexity to the model to also pick up effects coming from the anisotropies. Which would also means more data might be needed. Treating anisotropies in data inference is in general a very hard business, and a lot of work is going on at the moment to tackle this problems.

In this case we have good chances of attacking this problem, because the anisotropies which might occur are not so nasty, so it might be feasible to build a slightly more general model by allowing elliptic shapes, which introduces two parameters a(x) and b(x) for semi and major axis at each point x along the bone axis, or use other Kernel functions which can describe the shape more precisely.

#### **3.1 The finite element method**

The finite element method (FEM), its practical application often known as finite element analysis (FEA), is a numerical technique for finding approximate solutions of partial differential equations (PDE) as well as of integral equations. FEA was first developed in 1943 by R. Courant, who utilized the Ritz method of numerical analysis and minimization of variational calculus to obtain approximate solutions to vibration systems. FEA has been developed to an incredible precision. It consists of a computer model of a material or design that is stressed and analyzed for specific results. It is used in new product design, and existing product refinement. Modifying an existing product or structure is utilized to qualify the product or structure for a new service condition. In case of structural failure, FEA may be used to help determine the design modifications to meet the new condition.

FEA is a widely-used technique for the computer modelling of structures under mechanical loading. A finite element is an individual regular shape thathas a known stiffness so that any applied load will give a predictable corresponding displacement. Elements are joined together at nodes and along edges. Complex designs are created as an assembly of elements to which restraints and loads may be applied. During the computer analysis of the model, a series of simultaneous equations are established that represent the overall stiffness of the structure. The equations are then solved giving the nodal displacements resulting from the applied loads. For the analysis of bone structures, finite element analysis would therefore be dependent upon the density of each element, the arrangement of elements (eg trabecular structure), the composition (eg cortical shell or cancellous) and the external shape (eg length, angle and width of femoral neck).

Evolutionary Pathways of Diagnosis in Osteoporosis 149

osteoporosis. There is not any disease but one ill person and so must be considered irrespective of other philosophies including economic resources. These facts are essential in

Report of a WHO Study Group (1994). *Assessment of fracture risk and its application to* 

NIH Consensus Panel Addresses Osteoporosis Prevention, Diagnosis, and Therapy on osteoporosis prevention, diagnosis, and therapy (2001). *JAMA*;14;285(6):785-95. Kanis, J.A.; Johnell, O.; Oden, A.; Jonsson, B,; Dawson, A.; Dere, W. (2000). Risk of hip

Sodeab, M.; Burghardtb, A. J.; Pialatbcd, J.B.; Linkb, T. M.; Majumdarab, S. (2011) .

Bauer, J.S.; & Link T.M. (2009). Advances in osteoporosis imaging. *Eur J Radiol.,* 71(3):440-

Bolland, M.J.; Siu, A.T.; Mason, B.H.; Horne, A.M.; Ames, R.W.; Grey, A,B.; Gamble, G.D.;

Levy, B.T; Hartz, A; Woodworth, G; Xu, Y; Sinift, S. Interventions to improving osteoporosis

Napoli, N.; Pedone; C.; Pozzilli, P.; Lauretani, F.; Bandinelli, S.; Ferrucci, L.; Incalzi, R.A.

Bours, S.P.; van Geel T.A.; Geusens, P.P.; Janssen, M.J.; Janzing, H.M.; Hoffland, G.A.;

Rupp, J.D; Flannagan, C.A; Hoff, C.N; Cunningham, R.M.; Effects of osteoporosis on AIS 3+ injury risk in motor-vehicle crashes. (2010). *Accid Anal Prev.*; 42(6):2140-3. Vilayphiou N, Boutroy S, Szulc P, van Rietbergen B, Munoz F, Delmas PD, Chapurlat R.

*Exp Biol Med (Maywood);* 236(4):445-55. Epub 2011 Mar 2.26(5):965-73. Christiansen, B.A.; Kopperdahl, D.L.; Kiel, D.P.; Keaveny, T.M.; Bouxsein, M.L. Mechanical

QCT-based finite element analysis. (2011). *J Bone Miner Res.*; 26(5):974-83.

*screening for postmenopausal osteoporosis,* World Health Organ Tech Rep Ser.;843:1-

fracture derived from relative risks: an analysis applied to the population of

Quantitative characterization of subject motion in HR-pQCT images of the distal

Reid, I.R. (2011). Evaluation of the FRAX and Garvan fracture risk calculators in

screening: an Iowa Research Network (IRENE) study. (2009) *J Am Board Fam Med.*

Effect of ghrelin on bone mass density: The InChianti study (2011). *Bone.*; Apr 9.

Willems, P.C.; van den Bergh, J.P.(2011). Contributors to Secondary Osteoporosis and Metabolic Bone Diseases in Patients Presenting with a Clinical Fracture. *J Clin* 

Finite element analysis performed on radius and tibia HR-pQCT images and fragility fractures at all sites in men. J Bone Miner Res. (2011). *J Bone Miner Res.*; Blake, C.A.; McCoy G.L.; Hui, Y.Y.; Lavoie, H.A. (2011). Perinatal exposure to low-dose DE-

71 increases serum thyroid hormones and gonadal osteopontin gene expression.

contributions of the cortical and trabecular compartments contribute to differences in age-related changes in vertebral body strength in men and women assessed by

drawing up any test for diagnosis in osteoporosis.

Sweden. *Osteoporosis International;* 11: 120-127.

radius and tibia. *Bone,* 48: 1291-1297.

older women. *J Bone Miner Res,* 26:420-7.

*Endocrinol Metab,* Mar 16. [Epub ahead of print].

**5. References** 

129.

9.

;22(4):360-7.

[Epub ahead of print].

FEA has previously been applied to computer modelling of several bioengineering situations incorporating bone including cellular remodelling, prosthetic loosening, fracture progression and fracture healing. Studies related to osteoporosis have tended to utilise the full 3D potential of FEA via incorporation of computed tomography data.

FEA predicts the mechanical behaviour (displacement or stress) of a structure under loading rather than the exact yield point (fracture); but since osteoporosis fracture risk assessment requires only a proportional, rather than exact, measure of fracture load, FEA derived stiffness (load / displacement) should have significant clinical potential. FEXI (finite element analysis of x-ray images) provides a thin plate computer simulation of a bone being mechanically tested.

Finite element analysis inherently offers dependence upon the external shape and internal structure of a bone and should, therefore, have the potential to provide a superior prediction of mechanical integrity than simple areal density (BMD). The novel feature of the FEXI approach is that a conventional mechanical compression test is simulated. An important aspect of the technique is that, being based upon conventional 2D DXA images or radiographs, it could be readily utilised into routine clinical practice.

Thus, bone microarchitecture and biomechanical properties in men have been investigated (Vilayphiou et al. 2011). Patient-specific finite element (PSFE) models based on QCT are generally used to predict the biomechanical response of human bones with the future goal to be applied in clinical decision-making (Trabelsi & Yosibash, 2011). The biomechanical mechanisms underlying sex-specific differences in age-related vertebral fracture rates are ill defined. To gain insight into this issue, we used finite element analysis of clinical CT scans of the vertebral bodies (Christiansen et al., 2011).

### **4. Conclusion**

Therefore it is necessary to carry out more research and to open new tracks to have any further reliable tool in the diagnosis of osteoporosis. Precise *in vivo* measurement of the bone mechanical properties is very important, being essential a method for assessing quantitatively and objectively bone mass and anisotropy and not only in a qualitative way and with risks which sometimes are not. Thus, a mathematical, physical and physiological 5-dimensional model must be developed in order to gauge bone properties including geometry(2-dimensional DXA), space, time, motion and stress with some portablecomputer-devices that uses the body space of the user as an interface with equipment and programs designed to communicate information from one system of computing devices and programs to anothers. Because the person is not one body died, and is more than one statistic sampling; he is not a 10-year probability of hip fracture; he is alive and not one lifeless inert element; and bones are not quite as strong as one compact material object without life; it is somewhat more flexible and this is useful in bones that are jointed performing its necessary task. Probability is good after the event but not before. It is unknown what is going to happen to one person as the justification is wholly independent of sense experience in *a priori* knowledge. The person to study can be the case who is no concluded from the probability. The probability is not the reality and the patient, to a greater or lesser extent, is not a probability that is to say it is one sophism: a plausible but fallacious argument or deceptive argumentation. This is one poor approach to diagnosis in osteoporosis. There is not any disease but one ill person and so must be considered irrespective of other philosophies including economic resources. These facts are essential in drawing up any test for diagnosis in osteoporosis.

### **5. References**

148 Osteoporosis

FEA has previously been applied to computer modelling of several bioengineering situations incorporating bone including cellular remodelling, prosthetic loosening, fracture progression and fracture healing. Studies related to osteoporosis have tended to utilise the

FEA predicts the mechanical behaviour (displacement or stress) of a structure under loading rather than the exact yield point (fracture); but since osteoporosis fracture risk assessment requires only a proportional, rather than exact, measure of fracture load, FEA derived stiffness (load / displacement) should have significant clinical potential. FEXI (finite element analysis of x-ray images) provides a thin plate computer simulation of a bone being

Finite element analysis inherently offers dependence upon the external shape and internal structure of a bone and should, therefore, have the potential to provide a superior prediction of mechanical integrity than simple areal density (BMD). The novel feature of the FEXI approach is that a conventional mechanical compression test is simulated. An important aspect of the technique is that, being based upon conventional 2D DXA images or

Thus, bone microarchitecture and biomechanical properties in men have been investigated (Vilayphiou et al. 2011). Patient-specific finite element (PSFE) models based on QCT are generally used to predict the biomechanical response of human bones with the future goal to be applied in clinical decision-making (Trabelsi & Yosibash, 2011). The biomechanical mechanisms underlying sex-specific differences in age-related vertebral fracture rates are ill defined. To gain insight into this issue, we used finite element analysis of clinical CT scans

Therefore it is necessary to carry out more research and to open new tracks to have any further reliable tool in the diagnosis of osteoporosis. Precise *in vivo* measurement of the bone mechanical properties is very important, being essential a method for assessing quantitatively and objectively bone mass and anisotropy and not only in a qualitative way and with risks which sometimes are not. Thus, a mathematical, physical and physiological 5-dimensional model must be developed in order to gauge bone properties including geometry(2-dimensional DXA), space, time, motion and stress with some portablecomputer-devices that uses the body space of the user as an interface with equipment and programs designed to communicate information from one system of computing devices and programs to anothers. Because the person is not one body died, and is more than one statistic sampling; he is not a 10-year probability of hip fracture; he is alive and not one lifeless inert element; and bones are not quite as strong as one compact material object without life; it is somewhat more flexible and this is useful in bones that are jointed performing its necessary task. Probability is good after the event but not before. It is unknown what is going to happen to one person as the justification is wholly independent of sense experience in *a priori* knowledge. The person to study can be the case who is no concluded from the probability. The probability is not the reality and the patient, to a greater or lesser extent, is not a probability that is to say it is one sophism: a plausible but fallacious argument or deceptive argumentation. This is one poor approach to diagnosis in

full 3D potential of FEA via incorporation of computed tomography data.

radiographs, it could be readily utilised into routine clinical practice.

of the vertebral bodies (Christiansen et al., 2011).

mechanically tested.

**4. Conclusion** 


**1. Introduction** 

prevention or overtreatment (Geusens, 2009).

**2. Screening of osteoporosis** 

high risk of fracture and early diagnosis are important.

**8** 

H.J. Choi

*South Korea* 

*Department of Family Medicine, Eulji University School of Medicine* 

**Approach to the Screening** 

**and Diagnosis of Osteoporosis** 

The goal of treatment of osteoporosis is to decrease the risk of fractures in patients with high risk for a first or subsequent fracture. The efficacy of treatment will depend on the efficacy and level of accomplishment of case finding to select patients at risk, the results of additional investigations, the efficacy, tolerance, and safety of medical intervention, and the adherence to treatment during follow-up. Each of these steps is critical in treatment in daily clinical practice. Failure to consider one or other step can result in suboptimal fracture

On the other hand, measurement of bone mineral density (BMD), assessment of the fracture risk, and making decisions regarding to appropriate therapeutic intervention are the ultimate goal when evaluating patients for osteoporosis (NIH Consensus Development Panel on Osteoporosis Prevention, Diagnosis, and Therapy, 2001). Since many fractures among postmenopausal women occur in those with T-scores better than in the osteoporotic range (Siris et al, 2004; Schuit et al, 2004; Cranney et al, 2007), screening of the patients at

The aim of screening is obviously to direct interventions to those most in need, and to avoid treatment of healthy individuals who will never fracture. Bone mass is used conventionally as a proxy of overall bone strength and low bone mass is a major risk factor for osteoporotic fractures. Although BMD measurement is the standard test for the diagnosis of osteoporosis before fracture, ongoing research indicates that BMD measurement alone may not be adequate for detection of individuals at high risk of fracture (Kanis, 1994). Epidemiological studies have shown that a substantial proportion of osteoporotic fractures occur in postmenopausal women who do not meet BMD criteria for osteoporosis defined according to the WHO definition as a T-score of -2.5 or below (Siris et al, 2004; Schuit et al, 2004; Cranney et al, 2007). This suggests that factors other than BMD contribute to a patient's risk of fracture. Central dual-energy x-ray absorptiometry (DXA) is not available everywhere. Furthermore, although BMD measurement is specific, it lacks sensitivity when used alone, so that a number of high-risk patients escape identification (Kanis, 1994). Thus, the potential

Trabelsi, N.; Yosibash, Z. Patient-specific finite-element analyses of the proximal femur with orthotropic material properties validated by experiments. *J Biomech Eng*. 2011 Jun;133(6):061001.

## **Approach to the Screening and Diagnosis of Osteoporosis**

### H.J. Choi

*Department of Family Medicine, Eulji University School of Medicine South Korea* 

### **1. Introduction**

150 Osteoporosis

Trabelsi, N.; Yosibash, Z. Patient-specific finite-element analyses of the proximal femur with

Jun;133(6):061001.

orthotropic material properties validated by experiments. *J Biomech Eng*. 2011

The goal of treatment of osteoporosis is to decrease the risk of fractures in patients with high risk for a first or subsequent fracture. The efficacy of treatment will depend on the efficacy and level of accomplishment of case finding to select patients at risk, the results of additional investigations, the efficacy, tolerance, and safety of medical intervention, and the adherence to treatment during follow-up. Each of these steps is critical in treatment in daily clinical practice. Failure to consider one or other step can result in suboptimal fracture prevention or overtreatment (Geusens, 2009).

On the other hand, measurement of bone mineral density (BMD), assessment of the fracture risk, and making decisions regarding to appropriate therapeutic intervention are the ultimate goal when evaluating patients for osteoporosis (NIH Consensus Development Panel on Osteoporosis Prevention, Diagnosis, and Therapy, 2001). Since many fractures among postmenopausal women occur in those with T-scores better than in the osteoporotic range (Siris et al, 2004; Schuit et al, 2004; Cranney et al, 2007), screening of the patients at high risk of fracture and early diagnosis are important.

### **2. Screening of osteoporosis**

The aim of screening is obviously to direct interventions to those most in need, and to avoid treatment of healthy individuals who will never fracture. Bone mass is used conventionally as a proxy of overall bone strength and low bone mass is a major risk factor for osteoporotic fractures. Although BMD measurement is the standard test for the diagnosis of osteoporosis before fracture, ongoing research indicates that BMD measurement alone may not be adequate for detection of individuals at high risk of fracture (Kanis, 1994). Epidemiological studies have shown that a substantial proportion of osteoporotic fractures occur in postmenopausal women who do not meet BMD criteria for osteoporosis defined according to the WHO definition as a T-score of -2.5 or below (Siris et al, 2004; Schuit et al, 2004; Cranney et al, 2007). This suggests that factors other than BMD contribute to a patient's risk of fracture. Central dual-energy x-ray absorptiometry (DXA) is not available everywhere. Furthermore, although BMD measurement is specific, it lacks sensitivity when used alone, so that a number of high-risk patients escape identification (Kanis, 1994). Thus, the potential

Approach to the Screening and Diagnosis of Osteoporosis 153

The T-score represent the number of SDs from the mean bone density values in normal gender-matched young adults. T-score is used to make a diagnosis of normal bone density, osteoporosis or osteopenia in postmenopausal women and in men age 50 years and older (Leib et al, 2004). Z-scores represent the number of SDs from the normal mean value for ageand gender-matched control subjects. A Z-score of -2.0 or lower may suggest the presence of a secondary cause of osteoporosis, although no definitive data support this hypothesis. Zscores are used preferentially to assess bone loss in premenopausal women and men younger than age 50 years. A Z-score of -2.0 or lower is defined as "below the expected range for age"; a Z-score above -2.0 is "within the expected range for age." (Leib et al, 2004). Originally, the definition of osteoporosis was developed for the estimation of the prevalence of osteoporosis across populations. It was not for the assessment of osteoporosis in individual patient. In other words, diagnostic thresholds differ from intervention thresholds. The fracture risk varies at different ages, even with the same T-score. Other factors that determine intervention thresholds include the presence of clinical risk factors

In the past decade, a great deal of research has taken place to identify factors other than BMD that contribute to fracture risk. The consideration of well-validated CRFs, with or without BMD, is likely to improve fracture risk prediction and the selection of individuals at high risk for treatment. Some of these risk factors act independently of BMD to increase fracture risk whereas others increase fracture risk through their association with reduced BMD (e.g., some of the secondary causes of osteoporosis) (Table 2) (Compston et al, 2009). Several models have been proposed to stratify osteoporotic fracture risk. These include strategies to identify patients with a high risk of low BMD (e.g., the OST index (Gensens et al, 2002), and the FRAX algorithm (Kanis, et al, 2008a, 2008b)) or with a high absolute risk of fractures based on CRFs, with or without BMD (e.g., FRAX algorithm (Kanis, et al, 2008a, 2008b)), Fracture Risk in Glucocorticoid Users (FIGS) (van Staa et al, 2005), the Garvan

Among these models, FRAX®, developed by WHO is an algorithm for individualized fracture risk prediction which is depend on population-based cohort from Europe, North

FRAX® is a clinical tool for case finding for identifying patients at high risk for fractures, for selecting patients to measure BMD, and for treatment decisions. FRAX® should not be considered a gold standard but rather provides an aid to enhance patient assessment. The aim of FRAX® is to provide an assessment tool for the fracture prediction with use of CRFs with or without femoral neck BMD (Kanis et al, 2008a). These CRFs include age, sex, race, height, weight, body mass index (BMI), a history of fragility fracture, a parental history of hip fracture, use of oral glucocorticoid, rheumatoid arthritis, and other secondary causes of osteoporosis, current smoking, and alcohol intake of three or more units daily. These risk factors were identified and validated based on an analysis of 12 prospective studies, yielding a total of 250,000 person-years in 60,000 men and women with more than 5,000 osteoporotic fractures (Kanis, 1994). Because fracture probability also varies markedly among different regions of the

**)** 

(CRFs), costs and and benefits of treatment.

algorithm (Nguyen et al, 2008)), and simplified questionnaires.

**4.1 Use of WHO Fracture Risk Assessment Tool (FRAX®**

**4. Determination of fracture risk** 

America, Asia, and Australia.

impact of extensive population-based screening with BMD in women at the time of menopause on the burden of fractures is less than optimal; screening the general population with BMD would not be cost-effective and is considered inadvisable in many countries (World Health Organization [WHO], 2004). In practice, most guidelines recommend using risk factor assessment tools such as Fracture Risk Assessment Tool FRAX® to help select patients for BMD measurement and/or treatment.

The National Osteoporosis Foundation (NOF), US Preventive Services Task Force (USPSTF), and the American Association of Clinical Endocrinologists (AACE) recommend that BMD testing should be performed to guide treatment decisions, based on the patient's risk profile (National Osteoporosis Foundation [NOF], 2003; US Preventive Services Task Force [USPSTF], 2002; Hodgson et al, 2001). Also, the NOF recommends that all postmenopausal women and men age 50 and older should be evaluated clinically for osteoporosis risk in order to determine the need for BMD measurement and considered the possibility of osteoporosis and fracture risk in men and women, based on the presence of the risk factors and conditions (NOF, 2010).

The National Osteoporosis Guideline Group (NOGG) recommends that patients are identified opportunistically using a case-finding strategy on the finding of a previous fragility fracture or the presence of significant clinical risk factors because, at present, there is no universally accepted policy for population screening in the UK to identify individuals with osteoporosis or those at high risk of fracture (Compston et al, 2009).

### **3. Diagnosis of osteoporosis**

Osteoporosis is diagnosed on the basis of either a low-impact or fragility fracture or a low BMD. A low-impact fracture is one that occurs after a fall from standing height or less; a fragility fracture occurs spontaneously or with no trauma (cough, sneezing, sudden movement) (Mauck & Clarke, 2006).

Until recent years, diagnosis of non-fractured patients was based on the quantitative assessment of BMD, usually by central DXA. In 1994, the World Health Organization (WHO) developed a definition of osteoporosis on the basis of studies of women of various ages (Table 1) (Kanis et al, 1994). The BMD, measured with DXA, results are reported as a density measurement in gm/cm2, in addition to T- and Z-scores.


Table 1. Definition of osteoporosis by the WHO

impact of extensive population-based screening with BMD in women at the time of menopause on the burden of fractures is less than optimal; screening the general population with BMD would not be cost-effective and is considered inadvisable in many countries (World Health Organization [WHO], 2004). In practice, most guidelines recommend using risk factor assessment tools such as Fracture Risk Assessment Tool FRAX® to help select

The National Osteoporosis Foundation (NOF), US Preventive Services Task Force (USPSTF), and the American Association of Clinical Endocrinologists (AACE) recommend that BMD testing should be performed to guide treatment decisions, based on the patient's risk profile (National Osteoporosis Foundation [NOF], 2003; US Preventive Services Task Force [USPSTF], 2002; Hodgson et al, 2001). Also, the NOF recommends that all postmenopausal women and men age 50 and older should be evaluated clinically for osteoporosis risk in order to determine the need for BMD measurement and considered the possibility of osteoporosis and fracture risk in men and women, based on the presence of the risk factors

The National Osteoporosis Guideline Group (NOGG) recommends that patients are identified opportunistically using a case-finding strategy on the finding of a previous fragility fracture or the presence of significant clinical risk factors because, at present, there is no universally accepted policy for population screening in the UK to identify individuals

Osteoporosis is diagnosed on the basis of either a low-impact or fragility fracture or a low BMD. A low-impact fracture is one that occurs after a fall from standing height or less; a fragility fracture occurs spontaneously or with no trauma (cough, sneezing, sudden

Until recent years, diagnosis of non-fractured patients was based on the quantitative assessment of BMD, usually by central DXA. In 1994, the World Health Organization (WHO) developed a definition of osteoporosis on the basis of studies of women of various ages (Table 1) (Kanis et al, 1994). The BMD, measured with DXA, results are reported as a

Below average Be watchful for clinical triggers

High Exclude secondary causes

patients

patients

Above average Consider prevention in peri- or post-MPW Be watchful for clinical triggers

Exclude secondary causes

Possibly repeat investigations in 2-3 years

Therapeutic intervention indicated in most

Therapeutic intervention indicated in most

Category Fracture Risk Action

with osteoporosis or those at high risk of fracture (Compston et al, 2009).

density measurement in gm/cm2, in addition to T- and Z-scores.

Established osteoporosis

patients for BMD measurement and/or treatment.

and conditions (NOF, 2010).

**3. Diagnosis of osteoporosis** 

movement) (Mauck & Clarke, 2006).

Normal

Osteopenia T-score between -1.0 and -2.5

Osteoporosis

more fractures

T-score at -1.0 or above

T-score at -2.5 or below

T-score at -2.5 or below and already experienced one or

Table 1. Definition of osteoporosis by the WHO

Severe Osteoporosis

The T-score represent the number of SDs from the mean bone density values in normal gender-matched young adults. T-score is used to make a diagnosis of normal bone density, osteoporosis or osteopenia in postmenopausal women and in men age 50 years and older (Leib et al, 2004). Z-scores represent the number of SDs from the normal mean value for ageand gender-matched control subjects. A Z-score of -2.0 or lower may suggest the presence of a secondary cause of osteoporosis, although no definitive data support this hypothesis. Zscores are used preferentially to assess bone loss in premenopausal women and men younger than age 50 years. A Z-score of -2.0 or lower is defined as "below the expected range for age"; a Z-score above -2.0 is "within the expected range for age." (Leib et al, 2004). Originally, the definition of osteoporosis was developed for the estimation of the prevalence of osteoporosis across populations. It was not for the assessment of osteoporosis in individual patient. In other words, diagnostic thresholds differ from intervention thresholds. The fracture risk varies at different ages, even with the same T-score. Other factors that determine intervention thresholds include the presence of clinical risk factors (CRFs), costs and and benefits of treatment.

### **4. Determination of fracture risk**

In the past decade, a great deal of research has taken place to identify factors other than BMD that contribute to fracture risk. The consideration of well-validated CRFs, with or without BMD, is likely to improve fracture risk prediction and the selection of individuals at high risk for treatment. Some of these risk factors act independently of BMD to increase fracture risk whereas others increase fracture risk through their association with reduced BMD (e.g., some of the secondary causes of osteoporosis) (Table 2) (Compston et al, 2009).

Several models have been proposed to stratify osteoporotic fracture risk. These include strategies to identify patients with a high risk of low BMD (e.g., the OST index (Gensens et al, 2002), and the FRAX algorithm (Kanis, et al, 2008a, 2008b)) or with a high absolute risk of fractures based on CRFs, with or without BMD (e.g., FRAX algorithm (Kanis, et al, 2008a, 2008b)), Fracture Risk in Glucocorticoid Users (FIGS) (van Staa et al, 2005), the Garvan algorithm (Nguyen et al, 2008)), and simplified questionnaires.

Among these models, FRAX®, developed by WHO is an algorithm for individualized fracture risk prediction which is depend on population-based cohort from Europe, North America, Asia, and Australia.

#### **4.1 Use of WHO Fracture Risk Assessment Tool (FRAX® )**

FRAX® is a clinical tool for case finding for identifying patients at high risk for fractures, for selecting patients to measure BMD, and for treatment decisions. FRAX® should not be considered a gold standard but rather provides an aid to enhance patient assessment. The aim of FRAX® is to provide an assessment tool for the fracture prediction with use of CRFs with or without femoral neck BMD (Kanis et al, 2008a). These CRFs include age, sex, race, height, weight, body mass index (BMI), a history of fragility fracture, a parental history of hip fracture, use of oral glucocorticoid, rheumatoid arthritis, and other secondary causes of osteoporosis, current smoking, and alcohol intake of three or more units daily. These risk factors were identified and validated based on an analysis of 12 prospective studies, yielding a total of 250,000 person-years in 60,000 men and women with more than 5,000 osteoporotic fractures (Kanis, 1994). Because fracture probability also varies markedly among different regions of the

Approach to the Screening and Diagnosis of Osteoporosis 155

The National Osteoporosis Society (NOS) starts case finding with CRFs of FRAX® in all postmenopausal women (Compston et al, 2009). Treatment is advocated in high-risk patients based on CRFs of FRAX without DXA and in patients with intermediate risk when

It should also be acknowledged that there are many other risk factors for fracture that are not incorporated into assessment algorithms. FRAX® does not include fall-related risk factors and other risk factors for fractures: dose and duration of some risk factors like glucocorticoid use; characteristics of previous fractures (location, number, and severity); vitamin D deficiency; and levels of biochemical markers of bone turnover (van Geel et al, 2010). Moreover, no randomized clinical trials focusing on prevention of fractures in patients who are included based on FRAX® are available (van Geel et al, 2010). Further studies will be needed on the ability to treatment to reduce fracture risk in subjects at high risk for fractures based on FRAX®. Another drawback is that FRAX® is only applicable in

Comprehensive approach to the clinical evaluation of osteoporosis is recommended. A detailed history and physical examination together with BMD assessment and the 10-year estimated fracture probability are utilized to establish the individual patient's risk. The range of tests will depend on the severity of the disease, age at presentation, and the presence or absence of fractures. The aims of patient evaluation are to exclude diseases that mimic osteoporosis (e.g. osteomalacia, myeloma), identify the cause of osteoporosis and contributory factors, assess the risk of subsequent fractures and select the most appropriate

Many metabolic bone diseases are associated with low BMD, therefore a complete and thorough history taking and physical examination are essential to establishing a correct diagnosis of osteoporosis. A complete history should be obtained, with specific attention given to the risk factors, including lifestyle, medical, family, and medication histories (Table 3) (NOF, 2010). Physical examination should include height and weight for BMI and determining any loss of height (historical height loss >4 cm). A thorough physical examination may detect kyphosis, a protruding abdomen, rib-iliac crest distance of less than 2 cm, height loss (prospective height loss >2 cm), acute or chronic back pain and/or tenderness, reduced gait speed or grip strength, and poor visual acuity. Certain other findings, such as nodular thyroid, hepatic enlargement, jaundice, or cushingoid features

Since the majority of osteoporosis-related fractures result from falls, it is also important to evaluate risk factors for falling. The most important of these seem to be a personal history of falling, along with muscle weakness and gait, balance and visual deficits (Anonymous, 2001). All elderly should be asked annually about the occurrence of falls. Any patient who reports a single fall should undergo basic evaluation of gait/balance (e.g., "Get Up and Go test")(Anonymous, 2001). Items that should be included as a part of a fall risk assessment

BMD results integrated in FRAX® indicate a high risk.

treatment naïve patients (Saag, 2009).

form of treatment (Compston et al, 2009).

**5.1 History and physical examination** 

are summarized in Table 4 (NOF, 2010).

may reveal secondary causes of osteoporosis (Lane, 2006).

**5. Clinical investigations** 

world, FRAX® allows fracture risk to be calculated for countries where the incidences of both fractures and mortality are known (Unnanuntana et al, 2010).

FRAX® has been developed for calculating the 10-year absolute fracture risk in individual patients in primary care settings for a major osteoporotic fracture (in the proximal humerus, the wrist, or the hip or a clinical vertebral fracture) and for a hip fracture calibrated to the fracture and death hazards. The relative risks are difficult to apply in clinical practice since their clinical significance depends on the prevalence of fractures in the general population. As a result, the concept of the absolute risk of fractures has emerged and refers to the individual's risk for fracture over a certain time period, e.g., over the next 5 or 10 years which is the usual duration of the effects of osteoporosis medications during and after use (van Geel et al, 2010).

The FRAX® algorithm is available at www.nof.org and at www.shef.ac.uk/FRAX. FRAX® is intended for postmenopausal women and men age 50 and older who have not been treated for osteoporosis; it is not intended for use in younger adults or children.

NOF starts case finding with age as a criterion (NOF, 2011). Below 65 years, NOF advocates clinical attention for the presence of CRFs (those included in FRAX, with the addition of other risks), and a DXA in the presence of CRFs. In all women older than 65 years, NOF advocates BMD. Treatment is advocated in women with osteoporosis or osteoporotic fracture and in women with osteopenia if FRAX® calculation with BMD indicates a high risk of fracture or when specific high risks (total immobilization and glucocorticoid use) are present.


\* Not presently accommodated in the FRAX® algorithm

Table 2. Clinical risk factors used for the assessment of fracture probability

The National Osteoporosis Society (NOS) starts case finding with CRFs of FRAX® in all postmenopausal women (Compston et al, 2009). Treatment is advocated in high-risk patients based on CRFs of FRAX without DXA and in patients with intermediate risk when BMD results integrated in FRAX® indicate a high risk.

It should also be acknowledged that there are many other risk factors for fracture that are not incorporated into assessment algorithms. FRAX® does not include fall-related risk factors and other risk factors for fractures: dose and duration of some risk factors like glucocorticoid use; characteristics of previous fractures (location, number, and severity); vitamin D deficiency; and levels of biochemical markers of bone turnover (van Geel et al, 2010). Moreover, no randomized clinical trials focusing on prevention of fractures in patients who are included based on FRAX® are available (van Geel et al, 2010). Further studies will be needed on the ability to treatment to reduce fracture risk in subjects at high risk for fractures based on FRAX®. Another drawback is that FRAX® is only applicable in treatment naïve patients (Saag, 2009).

### **5. Clinical investigations**

154 Osteoporosis

world, FRAX® allows fracture risk to be calculated for countries where the incidences of both

FRAX® has been developed for calculating the 10-year absolute fracture risk in individual patients in primary care settings for a major osteoporotic fracture (in the proximal humerus, the wrist, or the hip or a clinical vertebral fracture) and for a hip fracture calibrated to the fracture and death hazards. The relative risks are difficult to apply in clinical practice since their clinical significance depends on the prevalence of fractures in the general population. As a result, the concept of the absolute risk of fractures has emerged and refers to the individual's risk for fracture over a certain time period, e.g., over the next 5 or 10 years which is the usual duration of the effects of osteoporosis medications during and after use

The FRAX® algorithm is available at www.nof.org and at www.shef.ac.uk/FRAX. FRAX® is intended for postmenopausal women and men age 50 and older who have not been treated

NOF starts case finding with age as a criterion (NOF, 2011). Below 65 years, NOF advocates clinical attention for the presence of CRFs (those included in FRAX, with the addition of other risks), and a DXA in the presence of CRFs. In all women older than 65 years, NOF advocates BMD. Treatment is advocated in women with osteoporosis or osteoporotic fracture and in women with osteopenia if FRAX® calculation with BMD indicates a high risk of fracture or

for osteoporosis; it is not intended for use in younger adults or children.

\* Not presently accommodated in the FRAX® algorithm

Table 2. Clinical risk factors used for the assessment of fracture probability

when specific high risks (total immobilization and glucocorticoid use) are present.

fractures and mortality are known (Unnanuntana et al, 2010).

(van Geel et al, 2010).

Comprehensive approach to the clinical evaluation of osteoporosis is recommended. A detailed history and physical examination together with BMD assessment and the 10-year estimated fracture probability are utilized to establish the individual patient's risk. The range of tests will depend on the severity of the disease, age at presentation, and the presence or absence of fractures. The aims of patient evaluation are to exclude diseases that mimic osteoporosis (e.g. osteomalacia, myeloma), identify the cause of osteoporosis and contributory factors, assess the risk of subsequent fractures and select the most appropriate form of treatment (Compston et al, 2009).

### **5.1 History and physical examination**

Many metabolic bone diseases are associated with low BMD, therefore a complete and thorough history taking and physical examination are essential to establishing a correct diagnosis of osteoporosis. A complete history should be obtained, with specific attention given to the risk factors, including lifestyle, medical, family, and medication histories (Table 3) (NOF, 2010). Physical examination should include height and weight for BMI and determining any loss of height (historical height loss >4 cm). A thorough physical examination may detect kyphosis, a protruding abdomen, rib-iliac crest distance of less than 2 cm, height loss (prospective height loss >2 cm), acute or chronic back pain and/or tenderness, reduced gait speed or grip strength, and poor visual acuity. Certain other findings, such as nodular thyroid, hepatic enlargement, jaundice, or cushingoid features may reveal secondary causes of osteoporosis (Lane, 2006).

Since the majority of osteoporosis-related fractures result from falls, it is also important to evaluate risk factors for falling. The most important of these seem to be a personal history of falling, along with muscle weakness and gait, balance and visual deficits (Anonymous, 2001). All elderly should be asked annually about the occurrence of falls. Any patient who reports a single fall should undergo basic evaluation of gait/balance (e.g., "Get Up and Go test")(Anonymous, 2001). Items that should be included as a part of a fall risk assessment are summarized in Table 4 (NOF, 2010).

Approach to the Screening and Diagnosis of Osteoporosis 157

Although central DXA of the hip (femoral neck or total hip) is the gold standard for diagnosing osteoporosis, many experts including the International Society for Clinical Densitometry (ISCD), recommend using the lowest central DXA T-score of posteroanterior lumbar spine (L1-L4), femoral neck, or total hip (or the 33% distal radius of the nondominant forearm, if measured) to make the diagnosis (Leib et al, 2004). DXA measurement of BMD at other sites (including the trochanter, Ward triangle, lateral lumbar spine, other forearm regions, heel, or total body) or with other technologies (calcaneal ultrasonography, peripheral DXA, quantitative computed tomography, single- or dual-photon radionuclide absorptiometry, or magnetic resonance imaging) are not recommended for use in

As a spine region of interest, posteroanterior L1-L4 for spine BMD measurement and only exclude vertebrae that are affected by local structural change (e.g., degenerative change or compression fracture) or artifact should be used (Baim et al, 2008). However, BMD based diagnostic classification should not be made using a single vertebra. If only one evaluable vertebra remains after excluding other vertebrae, diagnosis should be based on different

Table 4. Risk factors for falls

valid skeletal site.

**5.2 Bone mineral density measurement** 

diagnosing osteoporosis (Leib et al, 2004; Marshall et al, 1996).


Table 3. Conditions, diseases, and medications that cause or contribute to osteoporosis and fractures

Table 3. Conditions, diseases, and medications that cause or contribute to osteoporosis and

fractures


Table 4. Risk factors for falls

#### **5.2 Bone mineral density measurement**

Although central DXA of the hip (femoral neck or total hip) is the gold standard for diagnosing osteoporosis, many experts including the International Society for Clinical Densitometry (ISCD), recommend using the lowest central DXA T-score of posteroanterior lumbar spine (L1-L4), femoral neck, or total hip (or the 33% distal radius of the nondominant forearm, if measured) to make the diagnosis (Leib et al, 2004). DXA measurement of BMD at other sites (including the trochanter, Ward triangle, lateral lumbar spine, other forearm regions, heel, or total body) or with other technologies (calcaneal ultrasonography, peripheral DXA, quantitative computed tomography, single- or dual-photon radionuclide absorptiometry, or magnetic resonance imaging) are not recommended for use in diagnosing osteoporosis (Leib et al, 2004; Marshall et al, 1996).

As a spine region of interest, posteroanterior L1-L4 for spine BMD measurement and only exclude vertebrae that are affected by local structural change (e.g., degenerative change or compression fracture) or artifact should be used (Baim et al, 2008). However, BMD based diagnostic classification should not be made using a single vertebra. If only one evaluable vertebra remains after excluding other vertebrae, diagnosis should be based on different valid skeletal site.

Approach to the Screening and Diagnosis of Osteoporosis 159

Table 5. Indications for vertebral fracture assessment using x-ray absorptiometry

Bone turnover is the principal factor that controls both the quality and the quantity of bone in adult skeleton and it can be assessed by measuring biochemical markers in blood and urine samples. Bone turnover markers (BTMs) represent the products of bone formation and

**5.4 Biochemical markers of bone turnover** 

Table 6. Markers of bone turnover

resorption that are released into the circulation (Table 6).

As a hip region of interest, femoral neck or total proximal femur, whichever is lowest should be used (Baim et al, 2008). Forearm BMD should be measured under the following circumstances: hip and/or spine cannot be measured or interpreted; hyperparathyroidism; and very obese patients (over the weight limit for DXA table) (Baim et al, 2008).

Peripheral DXA (pDXA), quantitative computed tomography (QCT), and quantitative ultrasound densitometry (QUS) are also capable of predicting both site-specific and overall fracture risk (NOF, 2010). When performed according to accepted standards, these densitometry techniques are accurate and highly reproducible (USPSTF, 2002). However, Tscores from these technologies cannot be used according to the WHO diagnostic classification because they are not equivalent to T-scores derived from DXA (NOF, 2010). Moreover, these measurements are less useful in predicting the risk of fractures of the spine and proximal femur than central DXA (Lane, 2006).

The accuracy of QCT of the spine in predicting spinal fracture is comparable to that of DXA but has the advantage of measuring true volumetric or 3-dementional BMD, in contrast to the areal BMD obtained from DXA (Miller, 1999). QCT can distinguish between cortical and trabecular bone and thus is more sensitive to changes in BMD caused by the higher bone turnover rate of trabecular bone (Brunader & Shelton, 2002). It is also precise enough to detect BMD changes over time, and it can be used to follow the disease state or to monitor the response of osteoporosis therapy (Brunader & Shelton, 2002). For this reason, QCT are not the gold standard at the moment, but are also recommended (if applicable) to evaluate osteoporosis.

#### **5.3 Vertebral fracture assessment**

Morphometric vertebral fractures are the most frequent fractures in women and men older than 50 years (Sambrook & Cooper, 2006). Independent of BMD, age, and other CRFs, radiographically confirmed vertebral fracture is a strong predictor of future vertebral, nonvertebral, and hip fracture risk (Lems, 2007). The presence of a vertebral fracture increases the relative risk of future vertebral fractures by 4.4-fold and increases the risk of fragility fractures at other skeletal sites as well (Klotzbuecher et al, 2000). The higher the grade (severity) of the existing vertebral fracture, or the more vertebral fractures present (one, two, or three), the greater the risk for future fractures (Gallagher et al, 2005; Black et al, 1999).

Clinical vertebral fractures represent one out of three to four morphometric vertebral fractures (van Helden et al, 2008). Because most morphometric vertebral fractures are not diagnosed until clinically suspected and imaging by x-ray is performed, vertebral fractures are often missed.

Imaging techniques to detect and evaluate vertebral fractures in clinical practice include plain radiography (x-ray), computed tomography (CT), magnetic resonance imaging (MRI) nuclear bone scanning, and vertebral fracture assessment (VFA). There are differences in each of these in terms of imaging resolution, radiation exposure, availability, cost, and patient convenience.

Vertebral Fracture Assessment (VFA) is a new method to evaluate the presence of morphometric vertebral fractures and deformities using central DXA. VFA reliably and accurately identified patients with vertebral fractures that have not been recognized, with greater patient convenience, lower cost, and less radiation than standard x-ray. VFA is indicated when there is a probability that a prevalent vertebral fracture will influence clinical management of the patient (Lewiecki & Laster, 2006). The use of VFA contributes to better define the fracture risk in women with osteopenia and contributes to treatment decisions identifies patients at high risk of fractures in the absence of BMD-based osteoporosis. Indications for VFA according to the ISCD are presented in Table 5 (Baim et al, 2008).

As a hip region of interest, femoral neck or total proximal femur, whichever is lowest should be used (Baim et al, 2008). Forearm BMD should be measured under the following circumstances: hip and/or spine cannot be measured or interpreted; hyperparathyroidism;

Peripheral DXA (pDXA), quantitative computed tomography (QCT), and quantitative ultrasound densitometry (QUS) are also capable of predicting both site-specific and overall fracture risk (NOF, 2010). When performed according to accepted standards, these densitometry techniques are accurate and highly reproducible (USPSTF, 2002). However, Tscores from these technologies cannot be used according to the WHO diagnostic classification because they are not equivalent to T-scores derived from DXA (NOF, 2010). Moreover, these measurements are less useful in predicting the risk of fractures of the spine

The accuracy of QCT of the spine in predicting spinal fracture is comparable to that of DXA but has the advantage of measuring true volumetric or 3-dementional BMD, in contrast to the areal BMD obtained from DXA (Miller, 1999). QCT can distinguish between cortical and trabecular bone and thus is more sensitive to changes in BMD caused by the higher bone turnover rate of trabecular bone (Brunader & Shelton, 2002). It is also precise enough to detect BMD changes over time, and it can be used to follow the disease state or to monitor the response of osteoporosis therapy (Brunader & Shelton, 2002). For this reason, QCT are not the gold standard at the moment, but are also recommended (if applicable) to evaluate

Morphometric vertebral fractures are the most frequent fractures in women and men older than 50 years (Sambrook & Cooper, 2006). Independent of BMD, age, and other CRFs, radiographically confirmed vertebral fracture is a strong predictor of future vertebral, nonvertebral, and hip fracture risk (Lems, 2007). The presence of a vertebral fracture increases the relative risk of future vertebral fractures by 4.4-fold and increases the risk of fragility fractures at other skeletal sites as well (Klotzbuecher et al, 2000). The higher the grade (severity) of the existing vertebral fracture, or the more vertebral fractures present (one, two, or three), the greater the risk for future fractures (Gallagher et al, 2005; Black et al, 1999). Clinical vertebral fractures represent one out of three to four morphometric vertebral fractures (van Helden et al, 2008). Because most morphometric vertebral fractures are not diagnosed until clinically suspected and imaging by x-ray is performed, vertebral fractures

Imaging techniques to detect and evaluate vertebral fractures in clinical practice include plain radiography (x-ray), computed tomography (CT), magnetic resonance imaging (MRI) nuclear bone scanning, and vertebral fracture assessment (VFA). There are differences in each of these in terms of imaging resolution, radiation exposure, availability, cost, and patient convenience. Vertebral Fracture Assessment (VFA) is a new method to evaluate the presence of morphometric vertebral fractures and deformities using central DXA. VFA reliably and accurately identified patients with vertebral fractures that have not been recognized, with greater patient convenience, lower cost, and less radiation than standard x-ray. VFA is indicated when there is a probability that a prevalent vertebral fracture will influence clinical management of the patient (Lewiecki & Laster, 2006). The use of VFA contributes to better define the fracture risk in women with osteopenia and contributes to treatment decisions identifies patients at high risk of fractures in the absence of BMD-based osteoporosis.

Indications for VFA according to the ISCD are presented in Table 5 (Baim et al, 2008).

and very obese patients (over the weight limit for DXA table) (Baim et al, 2008).

and proximal femur than central DXA (Lane, 2006).

osteoporosis.

are often missed.

**5.3 Vertebral fracture assessment** 


Table 5. Indications for vertebral fracture assessment using x-ray absorptiometry

#### **5.4 Biochemical markers of bone turnover**

Bone turnover is the principal factor that controls both the quality and the quantity of bone in adult skeleton and it can be assessed by measuring biochemical markers in blood and urine samples. Bone turnover markers (BTMs) represent the products of bone formation and resorption that are released into the circulation (Table 6).


Table 6. Markers of bone turnover

Approach to the Screening and Diagnosis of Osteoporosis 161

Among men, 30% to 60% of osteoporosis cases are associated with secondary cause. Among perimenopausal women, more than 50% of cases are associated with secondary causes (NIH Consensus Development Panel on Osteoporosis Prevention, Diagnosis, and Therapy, 2001). In patients referred for DXA in the clinical context of an osteoporosis clinic, contributors to secondary osteoporosis were already documented in one out of three postmenopausal women, previously undiagnosed contributors were found in an additional 30% of women

General consensus exists among experts that a minimum screening laboratory tests should be considered for all patients who are diagnosed as having osteoporosis prior to treatment. Many experts have also suggested that patients who have osteoporosis and a Z-score of less than -2.0 should have more extensive laboratory tests for secondary cause of osteoporosis. A diagnosis of osteoporosis in men should also prompt a through work-up for secondary

The range of laboratory tests will depend on the severity of the disease, age at presentation, and the presence or absence of fractures. In patients with BMD-based osteoporosis or presenting with a clinical fracture or both, diagnostic evaluation is necessary and should include blood cell count, sedimentation rate or C-reactive protein, serum calcium, phosphate, alkaline phosphatase, liver transaminase, albumin, creatinine, thyroid stimulating hormone (TSH) and 25(OH)D3. According to the clinical features and suspicion, other measurements such as parathyroid hormone (PTH), protein immunolelectrophoresis and urinary Bence-Jones proteins, serum testosterone, sex-hormone binding globulin (SHBG), follicle stimulating hormone (FSH), and luteinizing hormone (LH) in men, serum prolactin, 24-hour urinary cortisol/dexamethasone suppression test, endomysial and/or tissue transglutaminase antibodies, 24-hour urinary calcium and creatinine looking for secondary causes are indicated (Compston et al, 2009).If a specific secondary cause of osteoporosis is suspected on the basis of

Many factors are associated with osteoporosis and fracture, including low peak bone mass, hormonal factors, the use of certain medications, cigarette smoking, low physical activity, low calcium and vitamin D intake, race, small body size, and a personal or family history of fracture. All these factors should be taken into account when assessing the risk of fracture to determine which patients require further assessment and/or treatment. Clinical guidelines help guide practice but should not replace clinical judgment and patient preferences. The final decision about screening, assessment, and/or treatment is ultimately at the discretion

Anonymous. (2001). Guideline for the prevention of falls in older persons. *Journal of American Geriatric Society*, Vol.49, No.5, pp. 664-672, ISSN 0002-8614 Baim, S ; Binkley, N. Bilezikian, J.P. Kendler, D.L. Hans, D.B. Lewiecki, E.M. & Silverman, S.

*Clinical Densitometry*, Vol.11, No.1, pp. 75-91, ISSN 1094-6950

(2008). Official Positions of the International Society for Clinical Densitometry and executive summary of the 2007 ISCD Position Development Conference. *Journal of* 

the history and physical examination findings, further direct testing is indicated.

**5.5 Laboratory tests** 

(Tannenbaum et al, 2002).

**6. Conclusion** 

**7. References** 

of the physician and the patient.

causes regardless of their Z-score (Mauck & Clarke, 2006).

Quantitative changes in BTMs reflect the dynamic process of bone metabolism. BTMs have been associated with increased osteoporotic fractures independently of BMD in large prospective studies. They also may predict bone loss and, when repeated after 3 to 6 months of treatment with FDA approved antiresorptive drugs, may be predictive of fracture risk reduction. However, BTMs are not a substitute for DXA in women at risk. The value of BTMs in the assessment of fracture risk is likely to be in combination with risk factors, including BMD (Delmas et al, 2000). Generally, their use in the diagnosis of osteoporosis is not recommended (Lash et al, 2009).

There are multiple factors that may cause variations in the levels of BTMs (Table 7). Therefore it is necessary to review certain factors that affect bone marker levels. The main source of variability is pre-analytical; mostly sample conservation and biological variability (Unnanuntana et al, 2010). Pyridinoline crosslinks are light sensitive and degraded under the influence of intense UV irradiation (Body et al, 2009). Osteocalcin concentrations are decreased by freeze-thaw cycles and hemolysis. Assays detecting only intact osteocalcin are particularly affected by in vitro degradation, so it may be advantageous to use assays recognizing both the intact molecule and the large N-terminal fragment (N-MID, 1–43 amino acid), which appear to be more stable, sensitive and reproducible. (Delmas et al, 1985) Some osteocalcin fragments are also released during bone resorption (Delmas et al, 1990). In adults, the main source of undesirable biological variability is the circadian rhythm, with higher values in the early morning hours (peak in 4:00 A.M. and 8:00 A.M.), then a steep decrease in the morning, to attain a nadir at the end of the afternoon (through in 1:00 P.M. and 11:00 P.M.) (Seibel et al, 2005). Most BTMs follow the same pattern, with the exception of alkaline phosphatase because of its longer half-life. Practically, it implies that the measurement of BTMs must be performed in the same lab using standard procedures; samples should be taken while fasting and always at the same time of day. For the urinary BTMs, it is best to obtain either a 24-hour urine collection or morning second voided urine sample. Creatinine excretion also contributes to the overall variability in the levels of urinary BTMs (Unnanuntana et al, 2010).


Table 7. Factors affecting levels of bone turnover markers

### **5.5 Laboratory tests**

160 Osteoporosis

Quantitative changes in BTMs reflect the dynamic process of bone metabolism. BTMs have been associated with increased osteoporotic fractures independently of BMD in large prospective studies. They also may predict bone loss and, when repeated after 3 to 6 months of treatment with FDA approved antiresorptive drugs, may be predictive of fracture risk reduction. However, BTMs are not a substitute for DXA in women at risk. The value of BTMs in the assessment of fracture risk is likely to be in combination with risk factors, including BMD (Delmas et al, 2000). Generally, their use in the diagnosis of osteoporosis is

There are multiple factors that may cause variations in the levels of BTMs (Table 7). Therefore it is necessary to review certain factors that affect bone marker levels. The main source of variability is pre-analytical; mostly sample conservation and biological variability (Unnanuntana et al, 2010). Pyridinoline crosslinks are light sensitive and degraded under the influence of intense UV irradiation (Body et al, 2009). Osteocalcin concentrations are decreased by freeze-thaw cycles and hemolysis. Assays detecting only intact osteocalcin are particularly affected by in vitro degradation, so it may be advantageous to use assays recognizing both the intact molecule and the large N-terminal fragment (N-MID, 1–43 amino acid), which appear to be more stable, sensitive and reproducible. (Delmas et al, 1985) Some osteocalcin fragments are also released during bone resorption (Delmas et al, 1990). In adults, the main source of undesirable biological variability is the circadian rhythm, with higher values in the early morning hours (peak in 4:00 A.M. and 8:00 A.M.), then a steep decrease in the morning, to attain a nadir at the end of the afternoon (through in 1:00 P.M. and 11:00 P.M.) (Seibel et al, 2005). Most BTMs follow the same pattern, with the exception of alkaline phosphatase because of its longer half-life. Practically, it implies that the measurement of BTMs must be performed in the same lab using standard procedures; samples should be taken while fasting and always at the same time of day. For the urinary BTMs, it is best to obtain either a 24-hour urine collection or morning second voided urine sample. Creatinine excretion also contributes to the overall variability in the levels of

not recommended (Lash et al, 2009).

urinary BTMs (Unnanuntana et al, 2010).

Table 7. Factors affecting levels of bone turnover markers

Among men, 30% to 60% of osteoporosis cases are associated with secondary cause. Among perimenopausal women, more than 50% of cases are associated with secondary causes (NIH Consensus Development Panel on Osteoporosis Prevention, Diagnosis, and Therapy, 2001). In patients referred for DXA in the clinical context of an osteoporosis clinic, contributors to secondary osteoporosis were already documented in one out of three postmenopausal women, previously undiagnosed contributors were found in an additional 30% of women (Tannenbaum et al, 2002).

General consensus exists among experts that a minimum screening laboratory tests should be considered for all patients who are diagnosed as having osteoporosis prior to treatment. Many experts have also suggested that patients who have osteoporosis and a Z-score of less than -2.0 should have more extensive laboratory tests for secondary cause of osteoporosis. A diagnosis of osteoporosis in men should also prompt a through work-up for secondary causes regardless of their Z-score (Mauck & Clarke, 2006).

The range of laboratory tests will depend on the severity of the disease, age at presentation, and the presence or absence of fractures. In patients with BMD-based osteoporosis or presenting with a clinical fracture or both, diagnostic evaluation is necessary and should include blood cell count, sedimentation rate or C-reactive protein, serum calcium, phosphate, alkaline phosphatase, liver transaminase, albumin, creatinine, thyroid stimulating hormone (TSH) and 25(OH)D3. According to the clinical features and suspicion, other measurements such as parathyroid hormone (PTH), protein immunolelectrophoresis and urinary Bence-Jones proteins, serum testosterone, sex-hormone binding globulin (SHBG), follicle stimulating hormone (FSH), and luteinizing hormone (LH) in men, serum prolactin, 24-hour urinary cortisol/dexamethasone suppression test, endomysial and/or tissue transglutaminase antibodies, 24-hour urinary calcium and creatinine looking for secondary causes are indicated (Compston et al, 2009).If a specific secondary cause of osteoporosis is suspected on the basis of the history and physical examination findings, further direct testing is indicated.

### **6. Conclusion**

Many factors are associated with osteoporosis and fracture, including low peak bone mass, hormonal factors, the use of certain medications, cigarette smoking, low physical activity, low calcium and vitamin D intake, race, small body size, and a personal or family history of fracture. All these factors should be taken into account when assessing the risk of fracture to determine which patients require further assessment and/or treatment. Clinical guidelines help guide practice but should not replace clinical judgment and patient preferences. The final decision about screening, assessment, and/or treatment is ultimately at the discretion of the physician and the patient.

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**9** 

**Early Detection Techniques for Osteoporosis** 

Osteoporosis (OP) is a serious disease and its early diagnosis is very important at the right time. These days, there are some conventional techniques of the diagnosis of this disease but these techniques have their limitations and reliable information is not obtained at the initial stage of the disease. Therefore, a new technique for the detection of OP at an early stage is required to be developed. In the present chapter, a new technique, based on Micro Electro Mechanical System (MEMS) technology, will be discussed to overcome the limitations of

In the present chapter, main emphasis is placed on the early detection of OP. New types of OP detection techniques, based on the biomechanical, optical and electrochemical principles, will be explained and compared to achieve an improved detection methodology for OP. A new amperometric immunosensor using gold nanoparticles and a novel microfluidics BioMEMS chip as a point of care testing (POCT) technique will be introduced for design,

The chapter covers the study which has been mainly divided into three parts: basic measurements on physical, biomechanical, optical and chemical properties of normal and OP bones and serum; and design and development of amperometric immunosensor and BioMEMS chip. (Ahn C.H et al., 2004, Arnaud C.D at al., 1996 Atkinson, P.J. 1964, Auroux, P.A et al., 2002, Bakker, E., 2006, Berthonnaud L, F., 2002, Bianchi, 2005, Ban C, 2004, Bal

An overview of OP research trends with the objectives of the research, and scope and significance of the study, is also presented. Causes and diagnostic techniques for OP will be

Since OP is most common among elder people, the overall costs to maintain the healthy body will most likely escalate in the near future. Hence to reduce the sufferings, the best solution is early detection (Bianchi, M.L., 2000, Blair, 2000). The early detection of disease states results in improved treatment outcomes, possibility of living longer a healthy life

Early detection is possible by biomarkers or the "intervening phenotypes" in the biofluids like saliva, serum and urine which can be (a) surrogate measures of any malignancy in the bone;

**1. Introduction** 

earlier techniques.

S.K, 2002)

fabrication and characterization.

reviewed in the beginning of the chapter.

(Arnaud et al., 1996; Singh, 2006).

**2. OP detection & early detection of osteoporosis (EDO)** 

Kanika Singh1,2 and Kyung Chun Kim2

*1KHAN Co, Ltd, Aju-dong, Geoje-do, 2Pusan National University, Busan,* 

*Republic of Korea* 


## **Early Detection Techniques for Osteoporosis**

Kanika Singh1,2 and Kyung Chun Kim2

*1KHAN Co, Ltd, Aju-dong, Geoje-do, 2Pusan National University, Busan, Republic of Korea* 

### **1. Introduction**

164 Osteoporosis

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Summary meeting report, July,2011, Available from:

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postmenopausal women. *Arthrotis Research & Therapy*, Vol.11, No.5, pp.251, ISSN

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variability. *The Clinical biochemist. Reviews,* Vol.26, No.4, pp. 97-122, ISSN 0159-8090

(2004). Bone mineral density thresholds for pharmacological interventions to prevent fractures. *Archives of internal medicine,* Vol.164, No.10, pp. 1108-1112, ISSN 0003-9926 Tannenbaum, C.; Clark, J. Schwartzman, K. Wallenstein, S. Lapinski, R. Meier, D. & Luckey,

M. (2002). Yield of laboratory testing to identify secondary contributors to osteoporosis in otherwise healthy women. *The Journal of Clinical Endocrinology and* 

women: recommendations and rationale. Annals of Internal Medicine, Vol.137,

Brink, P.R. (2008). Bone and fall-related fracture risks in women and men with a recent clinical fracture. *The Journal of bone and joint surgery. American volume.* Vol.90,

simple score for estimating the long–term risk of fracture in patients using oral glucocorticoids. *Monthly journal of the Association of Physicians.* Vol.98, No.3, pp.191Osteoporosis (OP) is a serious disease and its early diagnosis is very important at the right time. These days, there are some conventional techniques of the diagnosis of this disease but these techniques have their limitations and reliable information is not obtained at the initial stage of the disease. Therefore, a new technique for the detection of OP at an early stage is required to be developed. In the present chapter, a new technique, based on Micro Electro Mechanical System (MEMS) technology, will be discussed to overcome the limitations of earlier techniques.

In the present chapter, main emphasis is placed on the early detection of OP. New types of OP detection techniques, based on the biomechanical, optical and electrochemical principles, will be explained and compared to achieve an improved detection methodology for OP. A new amperometric immunosensor using gold nanoparticles and a novel microfluidics BioMEMS chip as a point of care testing (POCT) technique will be introduced for design, fabrication and characterization.

The chapter covers the study which has been mainly divided into three parts: basic measurements on physical, biomechanical, optical and chemical properties of normal and OP bones and serum; and design and development of amperometric immunosensor and BioMEMS chip. (Ahn C.H et al., 2004, Arnaud C.D at al., 1996 Atkinson, P.J. 1964, Auroux, P.A et al., 2002, Bakker, E., 2006, Berthonnaud L, F., 2002, Bianchi, 2005, Ban C, 2004, Bal S.K, 2002)

An overview of OP research trends with the objectives of the research, and scope and significance of the study, is also presented. Causes and diagnostic techniques for OP will be reviewed in the beginning of the chapter.

### **2. OP detection & early detection of osteoporosis (EDO)**

Since OP is most common among elder people, the overall costs to maintain the healthy body will most likely escalate in the near future. Hence to reduce the sufferings, the best solution is early detection (Bianchi, M.L., 2000, Blair, 2000). The early detection of disease states results in improved treatment outcomes, possibility of living longer a healthy life (Arnaud et al., 1996; Singh, 2006).

Early detection is possible by biomarkers or the "intervening phenotypes" in the biofluids like saliva, serum and urine which can be (a) surrogate measures of any malignancy in the bone;

Early Detection Techniques for Osteoporosis 167

1 Early detection Screening for large number of population 2 Minimal invasive Uses only micro amounts of biofluids 3 Site-specific Bone turnover specific bonemarkers

5 User-friendly Self testing is possible, easy to use

Osteoprotegerin, also known as osteoclastogenesis inhibitory factor (OCIF), is a cytokine and a member of the tumor necrosis factor (TNF) receptor superfamily. It is a basic glycoprotein comprising 401 amino acid residues arranged into 7 structural domains. It is

It is a combination of a Micro-electromechanical system (MEMS) with the biological systems, like protein, DNA or cell. It includes micro- and nanosystems for genomics, proteomics, and drug delivery analysis; molecular assembly, tissue engineering, biosensor development, and nanoscale imaging (Singh et al., 2007, 2009, Vijayendran et al., 2003).

Microfluidics is a multidisciplinary field comprising physics, chemistry, engineering and biotechnology that studies the behavior of fluids at the microscale and mesoscale, that is, fluids at volumes thousands of times smaller than a common droplet. It also concerns the design of systems in which such small volumes of fluids are used (Singh, 2007; Vijayendran et al., 2003).

The biosensor in which a biological process is harnessed to an electrical sensor system, such as an enzyme electrode. Other types couple a biological event to an electrical one via a range of mechanisms, such as those based on oxygen and pH (Heineman, 2001, Singh et al, 2008, 2009).

Immunosensor uses the immuno-compounds (antibodies or antigens) as biological receptors configures the so-called immunosensors, which are usually the result of the integration in one device of an immunoassay and a directly associated transducer. The antigen-antibody complex formation can be detected either directly (without using any labeled compound) by certain physical (potential, capacitance, conductivity compound) measurements or indirect approaches in which one immuno-compound is conjugated with an indicator molecule

It is a non-invasive analytical technique with an infinitely broad range of applications, especially in medical field. This gives a non-destructive analysis. It helps in identification of

**S.No Specification Consequences**

4 Diagnostics levels OP-specific

found as either a 60 kDa monomer or 120 kDa dimer linked by disulfide bonds.

Table 1. Importance of EDO(Singh, 2006)

**3. Technical terminologies** 

**3.2 Biological MEMS (BioMEMS)** 

**3.1 Osteoproteogerin** 

**3.3 Microfluidics** 

**3.5 Immunosensor** 

(Bakker and Quin, 2006).

**3.6 Spectroscopy** 

**3.4 Electrochemical sensor** 

6 Simple, low cost Portable, home care

(b) identifiers of inherited variations associated with disease susceptibility; or (c) "pre-disease" lesions that are highly predictive of subsequent disease(Becerra-Rojas & Jupari, 2001).

Diagnosis of OP at the right time can save from compressive treatments and immobility. Generally, in medical practice, identification of disease is based on recognition of symptoms and also testing specific features to confirm the presence of a particular disease. But for OP, it is hard to predict the disease as it silently creeps into the body with minimal symptoms of back pain, toothache and some hunch-over, etc. These initial symptoms point to the old age also and hence the unaware patient realizes this only after having a fracture in the bone. The unaware human when realizes about the disease due to some bone-fractures. In the hospital, anteroposterior and lateral X-rays of the special bone site are obtained to assess the presence of fractures, using the BMD measurements. Finally, they realize the presence of OP then the treatment becomes unaffordable and the patient becomes bed-ridden as shown in Fig. 2. Hence early detection of OP (EDO) is extremely necessary (see Table 1) with new devices like POCT (point of care technology) device using BioMEMS technology. Micro-fluidic chips are also playing key role to deliver new devices for better health care. The sensitivity and specificity of the POCT device would give earliest possible detection. Several promising directions for detection of bonemarker for OP have been interrogated (Arnaud, 1996; Singh, 2006, Singh, 2007, Singh, 2008, Singh, 2009).

Various researchers have studied OP disease for biological, chemically, physiological and engineering aspects in the past, by using different types of measurement techniques and methodologies (Arnaud, 1996; Korkia, 2002; Raiz, 1997; Singh, 2006). However, newer and newer techniques with new advances in technology, like micro/ nano technology, are being developed.

Fig. 1. Early Detection of OP (EDO)


Table 1. Importance of EDO(Singh, 2006)

### **3. Technical terminologies**

### **3.1 Osteoproteogerin**

166 Osteoporosis

(b) identifiers of inherited variations associated with disease susceptibility; or (c) "pre-disease"

Diagnosis of OP at the right time can save from compressive treatments and immobility. Generally, in medical practice, identification of disease is based on recognition of symptoms and also testing specific features to confirm the presence of a particular disease. But for OP, it is hard to predict the disease as it silently creeps into the body with minimal symptoms of back pain, toothache and some hunch-over, etc. These initial symptoms point to the old age also and hence the unaware patient realizes this only after having a fracture in the bone. The unaware human when realizes about the disease due to some bone-fractures. In the hospital, anteroposterior and lateral X-rays of the special bone site are obtained to assess the presence of fractures, using the BMD measurements. Finally, they realize the presence of OP then the treatment becomes unaffordable and the patient becomes bed-ridden as shown in Fig. 2. Hence early detection of OP (EDO) is extremely necessary (see Table 1) with new devices like POCT (point of care technology) device using BioMEMS technology. Micro-fluidic chips are also playing key role to deliver new devices for better health care. The sensitivity and specificity of the POCT device would give earliest possible detection. Several promising directions for detection of bonemarker for OP have been interrogated (Arnaud, 1996; Singh,

Various researchers have studied OP disease for biological, chemically, physiological and engineering aspects in the past, by using different types of measurement techniques and methodologies (Arnaud, 1996; Korkia, 2002; Raiz, 1997; Singh, 2006). However, newer and newer techniques with new advances in technology, like micro/ nano technology, are being

lesions that are highly predictive of subsequent disease(Becerra-Rojas & Jupari, 2001).

2006, Singh, 2007, Singh, 2008, Singh, 2009).

Fig. 1. Early Detection of OP (EDO)

developed.

Osteoprotegerin, also known as osteoclastogenesis inhibitory factor (OCIF), is a cytokine and a member of the tumor necrosis factor (TNF) receptor superfamily. It is a basic glycoprotein comprising 401 amino acid residues arranged into 7 structural domains. It is found as either a 60 kDa monomer or 120 kDa dimer linked by disulfide bonds.

### **3.2 Biological MEMS (BioMEMS)**

It is a combination of a Micro-electromechanical system (MEMS) with the biological systems, like protein, DNA or cell. It includes micro- and nanosystems for genomics, proteomics, and drug delivery analysis; molecular assembly, tissue engineering, biosensor development, and nanoscale imaging (Singh et al., 2007, 2009, Vijayendran et al., 2003).

### **3.3 Microfluidics**

Microfluidics is a multidisciplinary field comprising physics, chemistry, engineering and biotechnology that studies the behavior of fluids at the microscale and mesoscale, that is, fluids at volumes thousands of times smaller than a common droplet. It also concerns the design of systems in which such small volumes of fluids are used (Singh, 2007; Vijayendran et al., 2003).

### **3.4 Electrochemical sensor**

The biosensor in which a biological process is harnessed to an electrical sensor system, such as an enzyme electrode. Other types couple a biological event to an electrical one via a range of mechanisms, such as those based on oxygen and pH (Heineman, 2001, Singh et al, 2008, 2009).

#### **3.5 Immunosensor**

Immunosensor uses the immuno-compounds (antibodies or antigens) as biological receptors configures the so-called immunosensors, which are usually the result of the integration in one device of an immunoassay and a directly associated transducer. The antigen-antibody complex formation can be detected either directly (without using any labeled compound) by certain physical (potential, capacitance, conductivity compound) measurements or indirect approaches in which one immuno-compound is conjugated with an indicator molecule (Bakker and Quin, 2006).

#### **3.6 Spectroscopy**

It is a non-invasive analytical technique with an infinitely broad range of applications, especially in medical field. This gives a non-destructive analysis. It helps in identification of

Early Detection Techniques for Osteoporosis 169

Radiogrammetry, a technique that has been in use for more than 30 years, relies on the measurement of the cortical thickness of bones in the hand (metacarpals) to estimate bone mass. This technique suffers from relatively poor accuracy and reliability and has largely

The following diagnostic techniques are generally used for the detection of osteoporosis

Bone Mineral Density Technique (BMD) is an effective approach for detection of osteoporosis. A decrease in the amount of bone, resulting in thin, weakened bones that are susceptible to fractures. Several techniques are available for BMD testing. For example; dual-energy X-RAY absorptiometry (DXA) remains the standard for testing the BMD. Dual energy absorptiometry measures the bone density within a given area of bone (g/cm2). This technique offers the advantages of higher precision, minimal ionizing radiation exposure, rapid scanning time and the ability to access cortical and trabecular bone mass at appendicular and axial sites. Limitation, include equipment expense, the need for certified X-Ray technician and non-portability. In addition, DXA scans of the spine may show a false increase in spinal BMD in patients with osteophyes, aortic calcifications and degenerative

The conception of osteoporosis relates bone health to bone strength, rather than mass. A bone's health implies that it should have enough strength to keep voluntary loads from causing spontaneous fractures. Thus, the diagnosis of osteoporosis would be a biomechanical matter concerning both bone strength and muscle strength (Martin et al., 1998). This supposes two kinds of problems, namely: (a) to properly assess bone material properties, structural design and strength; and (b) to correlate the respective indicators with suitable indicators of muscle strength. As a standard densitometry is unsuitable to assess muscle strength or bone strength, it should use of other, preferably cross-sectional analyses of bone structure as those provided by quantitative computed tomography (QCT), peripheral quantitative computed tomography (pQCT), MRI, or similar procedures. The value of pQCT lies in the ability of the software to account for all the `mass', material and architectural factors in whose-bone strength and to provide data on muscle cross-sections

This provides the evaluation of trabecular bone density of the lumbar spine based on bone volume. Quantitative computed tomography (QCT) may be less practical than DXA because of the lower precision, higher cost and increased radiation exposure (Singh et al, 2006).

These devices used for many devices single-energy X-ray absorptiometry, peripheral DXA and peripheral CT. these device have the advantages of less expense, portable equipment, reasonable precision, and low radiation exposure. The use of quantitative ultrasonography for screening of osteoporosis and assessing fracture risk has increased. Using the speed of sound and broadband ultrasonic attenuation measurements, ultrasonic densitometry provides on bone elasticity and structure in peripheral sites. Advantages of this method, is

low cost and lack of ionization radiation (Singh et al, 1997, 1998, 1999, 2006).

**4.1 Radiographic diagnosis** 

arthritic changes.

**4.2 Quantitative CT** 

been supplanted with new techniques(Bianchi, 2000)

(Arnaud, 1996; Sartoris, 1996, Bianchi, 2005)

(Burr, 1997, Boyle et al, 2003, Singh et al, 2006).

**4.3 Peripheral bone densitometry** 

the elements and the elucidation of atomic and molecular structure by measurement of the radiant energy absorbed or emitted by a substance in any of the wavelengths of the electromagnetic spectrum in response to excitation by an external energy source (Chittur, 1998; Clark and Hester. 1996).

#### **3.7 Lab-on-a-chip (LOC)**

LOC is to integrate multiple functions on a single chip of only millimeters to a square centimeters in size and that are capable of handling extremely small fluid volumes down less than pico liters, LOC device is a sub-set of MEMS device (Chittur, 1998; Clark and Hester, 1996). The term "Lab-on-a-Chip" was introduced later on when it turned out that µTAS (Micro Total Analysis System) technologies were more widely applicable than only for analysis purposes.

(http://en.wikipedia.org/wiki/Lab-on-a-chip).

### **4. Classification of OP detection techniques**

There are several methods for detection of OP as shown in Fig. 2 (Singh, 2006).

Fig. 2. Classification of Detection Techniques for OP (Singh, 2006)

#### **4.1 Radiographic diagnosis**

168 Osteoporosis

the elements and the elucidation of atomic and molecular structure by measurement of the radiant energy absorbed or emitted by a substance in any of the wavelengths of the electromagnetic spectrum in response to excitation by an external energy source (Chittur,

LOC is to integrate multiple functions on a single chip of only millimeters to a square centimeters in size and that are capable of handling extremely small fluid volumes down less than pico liters, LOC device is a sub-set of MEMS device (Chittur, 1998; Clark and Hester, 1996). The term "Lab-on-a-Chip" was introduced later on when it turned out that µTAS (Micro Total Analysis System) technologies were more widely applicable than only

There are several methods for detection of OP as shown in Fig. 2 (Singh, 2006).

**OSTEOPOROSIS DETECTION SYSTEMS**

BONE MARKER TECHNIQUES

N-Peptide

C-Peptide

Deoxypyridinoline

**BIOCHEMICAL DETECTION**

INVASIVE TECHNIQUE

**IN-VIVO**

**DETECTION**

Surgical

Needle Bone Biopsy

Alkaline Phosphatase

Biomarker Laboratory techniques

Fig. 2. Classification of Detection Techniques for OP (Singh, 2006)

1998; Clark and Hester. 1996).

**3.7 Lab-on-a-chip (LOC)** 

for analysis purposes.

(http://en.wikipedia.org/wiki/Lab-on-a-chip).

Single X-ray absorptiometry

Single energy absorptiometry Dual-Energy absorptiometry

**BONE DENSITY DETCETION**

Photo-densitometry

Peripheral Quantitative CT

Quantitative Ultrasound

Digital X-Ray Radiogrammetry

Quantitative CT

RADIOGRAPHIC TECHNIQUES

**4. Classification of OP detection techniques** 

Radiogrammetry, a technique that has been in use for more than 30 years, relies on the measurement of the cortical thickness of bones in the hand (metacarpals) to estimate bone mass. This technique suffers from relatively poor accuracy and reliability and has largely been supplanted with new techniques(Bianchi, 2000)

The following diagnostic techniques are generally used for the detection of osteoporosis (Arnaud, 1996; Sartoris, 1996, Bianchi, 2005)

Bone Mineral Density Technique (BMD) is an effective approach for detection of osteoporosis. A decrease in the amount of bone, resulting in thin, weakened bones that are susceptible to fractures. Several techniques are available for BMD testing. For example; dual-energy X-RAY absorptiometry (DXA) remains the standard for testing the BMD. Dual energy absorptiometry measures the bone density within a given area of bone (g/cm2). This technique offers the advantages of higher precision, minimal ionizing radiation exposure, rapid scanning time and the ability to access cortical and trabecular bone mass at appendicular and axial sites. Limitation, include equipment expense, the need for certified X-Ray technician and non-portability. In addition, DXA scans of the spine may show a false increase in spinal BMD in patients with osteophyes, aortic calcifications and degenerative arthritic changes.

The conception of osteoporosis relates bone health to bone strength, rather than mass. A bone's health implies that it should have enough strength to keep voluntary loads from causing spontaneous fractures. Thus, the diagnosis of osteoporosis would be a biomechanical matter concerning both bone strength and muscle strength (Martin et al., 1998). This supposes two kinds of problems, namely: (a) to properly assess bone material properties, structural design and strength; and (b) to correlate the respective indicators with suitable indicators of muscle strength. As a standard densitometry is unsuitable to assess muscle strength or bone strength, it should use of other, preferably cross-sectional analyses of bone structure as those provided by quantitative computed tomography (QCT), peripheral quantitative computed tomography (pQCT), MRI, or similar procedures. The value of pQCT lies in the ability of the software to account for all the `mass', material and architectural factors in whose-bone strength and to provide data on muscle cross-sections (Burr, 1997, Boyle et al, 2003, Singh et al, 2006).

#### **4.2 Quantitative CT**

Microchip

BioMEMS

**MEMS DETECTION**

Bone Rupture micro-sensors

> This provides the evaluation of trabecular bone density of the lumbar spine based on bone volume. Quantitative computed tomography (QCT) may be less practical than DXA because of the lower precision, higher cost and increased radiation exposure (Singh et al, 2006).

#### **4.3 Peripheral bone densitometry**

These devices used for many devices single-energy X-ray absorptiometry, peripheral DXA and peripheral CT. these device have the advantages of less expense, portable equipment, reasonable precision, and low radiation exposure. The use of quantitative ultrasonography for screening of osteoporosis and assessing fracture risk has increased. Using the speed of sound and broadband ultrasonic attenuation measurements, ultrasonic densitometry provides on bone elasticity and structure in peripheral sites. Advantages of this method, is low cost and lack of ionization radiation (Singh et al, 1997, 1998, 1999, 2006).

Early Detection Techniques for Osteoporosis 171

the hand and wrist is captured by a video camera and the levels of grey seen on the hand image are quantified and compared with the grey levels of the reference standard, resulting in an estimate of bone mineral density (BMD). The cortical thickness of the bones can also be measured. Radiographic photo densitometry comprises of comparing the optical density of bone X-ray with standard calibrative, aluminium-step-wedge. Although inexpensive and easily accessible, this method had poor reproducibility. Computer-assisted methods have reduced these errors and several commercial systems have been developed in recent years. Although RA is generally less precise than DEXA, radiographic absorptiometry holds promise as a cost-effective method to screen cases of osteoporosis. Further research is needed to evaluate its effectiveness in predicting fracture and monitoring therapy (Sartoris,

The principle of dual photon absorptiometry (DPA) is the use of a photon beam that has two distinct energy peaks. One energy peak will be more absorbed by soft tissue and the other by bone. The soft tissue component then can be mathematically subtracted and the BMD

A limb is bombarded by slow neutron from a generator. This is taken up by the soft tissue to convert it into thermal neutron. This thermal neutron is captured by the nucleus of calcium ion. The nucleus becomes radioactive. Decay of the nuclei emits photon which can be measured by a Geiger counter, giving an idea of bone mass. This is reduced in

Biomarkers are substances found in an increased amount in the blood, other body fluids, or tissues and which can be used to indicate the presence the presence of osteoporosis. Biomarkers of bone remodeling (formation and breakdown), such as alkaline phosphatase and osteocalcin (serum markers) and pyridinolines and deoxypyridinolines (urinary markers), help in evaluating risk for osteoporosis. The research studies show that biomarkers correlate with changes in indices of bone remodeling and may provide insights into the mechanisms of bone loss which may give a basic detection method. The method may not be precise or accurate but it is quick, early, cheap and non-invasive way of

There is a need for the development a non-invasive and repeated measurement of bone turnover which demands precision, accuracy and specificity. These kind of independent measurements of bone formation and resorption are done at organ or tissue level. The

The two main biochemical markers for bone formation are serum alkaline phosphatase and serum osteocalcin. Markers for bone resorbtion include urinary calcium and urinary hydroxyproline: Alkaline phosphatase, which reflects osteoclast activity in bone, is measured in serum, but it lacks sensitivity and specificity for osteoporosis, because it can be

detection. This method gives an indication of the onset of the disease (Sia, 2003).

validated biochemical markers are urine and serum (see Table 2).

1996, Singh et al, 2006, Blair et al, 2006, Bouxsien and Mary, 2005).

(source: www.iupac.org/publications/pac/1995/pdf/6711x1929.pdf).

**4.10 Double photon absorptiometry** 

thus determined (Sartoris, 1996).

**4.11 Neutron activation analysis** 

**4.12 Biochemical techniques** 

osteoporosis.

**4.13 Bone markers** 

#### **4.4 Single-energy absorptiometry**

Single-energy absorptiometry measures bone mineral at peripheral sites such as the wrist and heel. Single photon absorptiometry (SPA) used a radioactive energy source, usually iodine125 to estimate the amount of bone mineral at peripheral measurement sites. In recent years, Single-energy X-ray absorptiometry (SXA) has supplanted SPA for measurements of the peripheral skeleton (heel and wrist) because of its better reproducibility and ease of use. SXA avoids the necessity of obtaining and disposing of radioactive energy sources. It requires immersion of the part in water bath and hence can measure bone mass in peripheral bones like bones of forearm and legs (Singh et al, 2006, Blair et al, 2003).

### **4.5 Dual-energy absorptiometry**

Bone density tests are painless, non-invasive and safe. Dual-energy absorptiometry was developed to measure bone in parts of the skeleton (lumbar spine, hip, and total body) that could not be measured with single-energy devices. Currently dual-energy X-ray absorptiometry (DXA) is the most widely used technique for measuring bone at these sites. DXA devices also are capable of measuring bone at the heel and wrist with high accuracy and precision, with very low exposure to radiation (Singh et al, 2006).

#### **4.6 Peripheral quantitative CT (pQCT)**

Quantitative computed tomography (QCT) measures the density of vertebral trabecular bone, the spongy bone in the center of the vertebra. pQCT devices are QCT instruments that have been adapted for measurements at peripheral sites such as the wrist (Singh et al, 2006).

#### **4.7 Quantitative ultrasound (QUS)**

Quantitative ultrasound devices measure bone at several skeletal sites, including the heel, hand, finger, and lower leg. The heel measurement it is composed of primarily trabecular bone, similar to the composition of the spine. Ultrasound devices based on the changes in the speed of sound (SOS), as well as specific changes in sound waves (broadband attenuation or BUA) as they pass through bone. QUS measurements provide information on fracture risk by providing an indication of bone density and possibly also information on the quality of the bone. Ultrasound devices do not expose the patient to ionizing radiation. Ultrasound devices do not expose the patient to ionizing radiation (Singh, 2006, Sartris, 1996)

#### **4.8 Digital X-ray radiogrammetry (DXR)**

Recently, the computer technology has renewed interest in this old technique. The Pronosco X-posure system estimates forearm bone mass from measurements of the cortical width of bones in the hand using computerized digital x-ray radiogrammetry from a single plain radiograph of the hand and wrist. The BMD estimate, referred to as DXR-BMD, is corrected for cortical porosity and striation. The results indicate that this technique is highly reproducible and appears to be at least as good as other peripheral bone assessment techniques in its ability to discriminate among patients with low bone mass at the spine and/or hip and osteoporotic fractures (Sartoris, 1996).

#### **4.9 Photodensitometry**

Previously, radiographic absorptiometry (RA) uses standard X-ray images of the hand and distal forearm are taken with a graduated aluminum reference. The radiographic image of

Single-energy absorptiometry measures bone mineral at peripheral sites such as the wrist and heel. Single photon absorptiometry (SPA) used a radioactive energy source, usually iodine125 to estimate the amount of bone mineral at peripheral measurement sites. In recent years, Single-energy X-ray absorptiometry (SXA) has supplanted SPA for measurements of the peripheral skeleton (heel and wrist) because of its better reproducibility and ease of use. SXA avoids the necessity of obtaining and disposing of radioactive energy sources. It requires immersion of the part in water bath and hence can measure bone mass in

Bone density tests are painless, non-invasive and safe. Dual-energy absorptiometry was developed to measure bone in parts of the skeleton (lumbar spine, hip, and total body) that could not be measured with single-energy devices. Currently dual-energy X-ray absorptiometry (DXA) is the most widely used technique for measuring bone at these sites. DXA devices also are capable of measuring bone at the heel and wrist with high accuracy

Quantitative computed tomography (QCT) measures the density of vertebral trabecular bone, the spongy bone in the center of the vertebra. pQCT devices are QCT instruments that have been adapted for measurements at peripheral sites such as the wrist (Singh et al, 2006).

Quantitative ultrasound devices measure bone at several skeletal sites, including the heel, hand, finger, and lower leg. The heel measurement it is composed of primarily trabecular bone, similar to the composition of the spine. Ultrasound devices based on the changes in the speed of sound (SOS), as well as specific changes in sound waves (broadband attenuation or BUA) as they pass through bone. QUS measurements provide information on fracture risk by providing an indication of bone density and possibly also information on the quality of the bone. Ultrasound devices do not expose the patient to ionizing radiation. Ultrasound devices

Recently, the computer technology has renewed interest in this old technique. The Pronosco X-posure system estimates forearm bone mass from measurements of the cortical width of bones in the hand using computerized digital x-ray radiogrammetry from a single plain radiograph of the hand and wrist. The BMD estimate, referred to as DXR-BMD, is corrected for cortical porosity and striation. The results indicate that this technique is highly reproducible and appears to be at least as good as other peripheral bone assessment techniques in its ability to discriminate among patients with low bone mass at the spine

Previously, radiographic absorptiometry (RA) uses standard X-ray images of the hand and distal forearm are taken with a graduated aluminum reference. The radiographic image of

peripheral bones like bones of forearm and legs (Singh et al, 2006, Blair et al, 2003).

and precision, with very low exposure to radiation (Singh et al, 2006).

do not expose the patient to ionizing radiation (Singh, 2006, Sartris, 1996)

**4.4 Single-energy absorptiometry** 

**4.5 Dual-energy absorptiometry** 

**4.6 Peripheral quantitative CT (pQCT)** 

**4.7 Quantitative ultrasound (QUS)** 

**4.8 Digital X-ray radiogrammetry (DXR)** 

**4.9 Photodensitometry** 

and/or hip and osteoporotic fractures (Sartoris, 1996).

the hand and wrist is captured by a video camera and the levels of grey seen on the hand image are quantified and compared with the grey levels of the reference standard, resulting in an estimate of bone mineral density (BMD). The cortical thickness of the bones can also be measured. Radiographic photo densitometry comprises of comparing the optical density of bone X-ray with standard calibrative, aluminium-step-wedge. Although inexpensive and easily accessible, this method had poor reproducibility. Computer-assisted methods have reduced these errors and several commercial systems have been developed in recent years. Although RA is generally less precise than DEXA, radiographic absorptiometry holds promise as a cost-effective method to screen cases of osteoporosis. Further research is needed to evaluate its effectiveness in predicting fracture and monitoring therapy (Sartoris, 1996, Singh et al, 2006, Blair et al, 2006, Bouxsien and Mary, 2005).

#### **4.10 Double photon absorptiometry**

The principle of dual photon absorptiometry (DPA) is the use of a photon beam that has two distinct energy peaks. One energy peak will be more absorbed by soft tissue and the other by bone. The soft tissue component then can be mathematically subtracted and the BMD thus determined (Sartoris, 1996).

#### **4.11 Neutron activation analysis**

A limb is bombarded by slow neutron from a generator. This is taken up by the soft tissue to convert it into thermal neutron. This thermal neutron is captured by the nucleus of calcium ion. The nucleus becomes radioactive. Decay of the nuclei emits photon which can be measured by a Geiger counter, giving an idea of bone mass. This is reduced in osteoporosis.

(source: www.iupac.org/publications/pac/1995/pdf/6711x1929.pdf).

#### **4.12 Biochemical techniques**

Biomarkers are substances found in an increased amount in the blood, other body fluids, or tissues and which can be used to indicate the presence the presence of osteoporosis. Biomarkers of bone remodeling (formation and breakdown), such as alkaline phosphatase and osteocalcin (serum markers) and pyridinolines and deoxypyridinolines (urinary markers), help in evaluating risk for osteoporosis. The research studies show that biomarkers correlate with changes in indices of bone remodeling and may provide insights into the mechanisms of bone loss which may give a basic detection method. The method may not be precise or accurate but it is quick, early, cheap and non-invasive way of detection. This method gives an indication of the onset of the disease (Sia, 2003).

#### **4.13 Bone markers**

There is a need for the development a non-invasive and repeated measurement of bone turnover which demands precision, accuracy and specificity. These kind of independent measurements of bone formation and resorption are done at organ or tissue level. The validated biochemical markers are urine and serum (see Table 2).

The two main biochemical markers for bone formation are serum alkaline phosphatase and serum osteocalcin. Markers for bone resorbtion include urinary calcium and urinary hydroxyproline: Alkaline phosphatase, which reflects osteoclast activity in bone, is measured in serum, but it lacks sensitivity and specificity for osteoporosis, because it can be

Early Detection Techniques for Osteoporosis 173

Osteoporosis is the disease which creeps into one's body silently without showing a significant symptom. The nature of the disease asymptotic until a gross deformity occurs in one's body. This is can be very serious and deadly for the patient. The time the patient realizes structural support of the body has totally deteriorated. The diagnosis and treatment is sometimes unaffordable for a common man. The patient has the control over prevention of this disease or is reliable, easy and cheap way is available for such deadly disease than proper care can be taken. There are several researches going on in order to achieve some cheap, easy early detection of osteoporosis (Singh et al, 2006). The latest trend is in miniaturizing the device which make it portable, useful for homecare, user-friendly, cheap, Non-invasive and provides a kind early indication for OP. This technique is based on MEMS

The method for detection or investigation of osteoporosis is with the help of a micropump (Yung et al, 2004). The micropump has been designed using the electromagnetic principle to actuate the piston in two directions. A closed loop system is used for circulating the fluid with the pumping device. This is kind of pump is useful for blood sampling or drug delivery. Here the oscillating micropump is used to study the mechanosensitivity of bone cell for better investigation of osteoporosis. There is another research which has proposed an implantable, telemetry-based MEMS bone sensor (Singh et al, 2003, 2009) with the capability of determination of bone stress via wireless RF interface. The bone stress is detected using the embedded piezoresistive strain gauges with polysilicon layer and a CMOS chip (Singh,

Another design of micro-fabricated strain gauge array is used to monitor bone deformation *in vitro* and *in vivo* for detection of osteoporosis. These kinds of microsensor provide a map of distributed strain data over the area of interest on the surfaces of bone to monitor the structural integrity of bone. This type of strain membranes are wireless and implantable embedded in flexible membrane. A simulation experiment was conducted to develop such

A bone sensor has been used for the piezoelectric BioMEMS. An attempt has been made to develop bone-based piezoelectric sensors to detect the stress in bone (Singh, 2003). Another micro-scale sensor for bone surface strain measurement is discussed. This kind of sensor is used for studying the structural effects of osteoporosis. Designs and simulation using ANSYS finite element modeling tool of thin-film metal strain gauge. Metal films for electrical interconnection encapsulated in PDMS have been studied. The PDMS membrane was characterized to facilitate encapsulation designs. The basic fabrication steps like silanization, PDMS preparation, photolithography, PDMS metallization, wire bonding and finally device separation. With experiments were performed for optimizing and characterizing the device like mechanical testing, electrochemical testing and adhesion testing (Yang et al, 2004), and there is a new design which has been discussed

Another latest technology is detecting osteoporosis with the study of the brittleness of the bone. The bone mass and bone density play an important role in bone strength. It is

micro-strain gauge for study of osteoporotic bone (Yang et al, 2004).

**5. Recent novel techniques** 

**5.1 Bone fracture detection micro-sensor** 

based technique.

1997).

here.

elevated or decreased with many diseases. It is increased with aging (see Table 2). Urinary calcium can give some estimate of resorbtion (loss of) bone, but there are many variables that affect this measurement. Urinary hydroxyproline is derived from degradation of collagen, which forms extracellular bone matrix. However, hydroxyproline measurement is not specific for bone, because half of the body's collagen is outside the bony skeleton. It is also influenced by many diseases, as well as diet. Several ELISA kits are developed by Osteomark Company for detection of Osteoporosis (www.osteomark.org).


Table 2. Urine and serum markers (Sartoris, 1996)

### **4.14 Laboratory methods**

There are several preliminary tests to identify the loss of bone mass. A number of laboratory tests may be performed on blood and urine samples (Singh et al, 2006).

The most common blood tests evaluate:


### **4.15 Needle bone biopsy**

Needle bone biopsy is not a very common assessment technique of bone density. This test has limited availability, and is best utilized as a research technique for analysis of treatment regimens for bone diseases. The best clinical use of bone biopsy combines double tetracycline labeling to determine appositional bone growth and rule out osteomalacia. Doses of tetracycline are given weeks apart, and the bone biopsy is embedded in a plastic compound, sliced thinly, and examined under fluorescent light, where the lines of tetracycline (which auto fluoresce) will appear and appositional growth assessed (Singh et al, 2006).

### **5. Recent novel techniques**

172 Osteoporosis

elevated or decreased with many diseases. It is increased with aging (see Table 2). Urinary calcium can give some estimate of resorbtion (loss of) bone, but there are many variables that affect this measurement. Urinary hydroxyproline is derived from degradation of collagen, which forms extracellular bone matrix. However, hydroxyproline measurement is not specific for bone, because half of the body's collagen is outside the bony skeleton. It is also influenced by many diseases, as well as diet. Several ELISA kits are developed by

There are several preliminary tests to identify the loss of bone mass. A number of laboratory

Needle bone biopsy is not a very common assessment technique of bone density. This test has limited availability, and is best utilized as a research technique for analysis of treatment regimens for bone diseases. The best clinical use of bone biopsy combines double tetracycline labeling to determine appositional bone growth and rule out osteomalacia. Doses of tetracycline are given weeks apart, and the bone biopsy is embedded in a plastic compound, sliced thinly, and examined under fluorescent light, where the lines of tetracycline (which auto fluoresce) will appear and appositional growth assessed (Singh et

U-Hydroxyproline(U-OHPr)

S-C Terminal pyridine crosslinked telopeptide domain of type I


collagen (S-ICTP) S-Tartrate-resistant acid phosphatase(S-TRAP)

Osteomark Company for detection of Osteoporosis (www.osteomark.org).

2 S-osteocalcin(S-BGP) U-collagen crosslinks

tests may be performed on blood and urine samples (Singh et al, 2006).

follicle stimulating hormone (FSH) test to establish menopause status

1 S-alkaline phosphatase

type I collagen(S-PICP)

The most common blood tests evaluate:

**4.14 Laboratory methods** 

 blood calcium levels blood vitamin D levels thyroid function

parathyroid hormone levels

testosterone levels (in men)

**4.15 Needle bone biopsy** 

al, 2006).


3 S-carboxyterminal propeptide of human

Table 2. Urine and serum markers (Sartoris, 1996)

estradiol levels to measure estrogen (in women)

osteocalcin levels to measure bone formation.

**S.No Osteoblastic Activity Osteoclastic Activity** 

Osteoporosis is the disease which creeps into one's body silently without showing a significant symptom. The nature of the disease asymptotic until a gross deformity occurs in one's body. This is can be very serious and deadly for the patient. The time the patient realizes structural support of the body has totally deteriorated. The diagnosis and treatment is sometimes unaffordable for a common man. The patient has the control over prevention of this disease or is reliable, easy and cheap way is available for such deadly disease than proper care can be taken. There are several researches going on in order to achieve some cheap, easy early detection of osteoporosis (Singh et al, 2006). The latest trend is in miniaturizing the device which make it portable, useful for homecare, user-friendly, cheap, Non-invasive and provides a kind early indication for OP. This technique is based on MEMS based technique.

#### **5.1 Bone fracture detection micro-sensor**

The method for detection or investigation of osteoporosis is with the help of a micropump (Yung et al, 2004). The micropump has been designed using the electromagnetic principle to actuate the piston in two directions. A closed loop system is used for circulating the fluid with the pumping device. This is kind of pump is useful for blood sampling or drug delivery. Here the oscillating micropump is used to study the mechanosensitivity of bone cell for better investigation of osteoporosis. There is another research which has proposed an implantable, telemetry-based MEMS bone sensor (Singh et al, 2003, 2009) with the capability of determination of bone stress via wireless RF interface. The bone stress is detected using the embedded piezoresistive strain gauges with polysilicon layer and a CMOS chip (Singh, 1997).

Another design of micro-fabricated strain gauge array is used to monitor bone deformation *in vitro* and *in vivo* for detection of osteoporosis. These kinds of microsensor provide a map of distributed strain data over the area of interest on the surfaces of bone to monitor the structural integrity of bone. This type of strain membranes are wireless and implantable embedded in flexible membrane. A simulation experiment was conducted to develop such micro-strain gauge for study of osteoporotic bone (Yang et al, 2004).

A bone sensor has been used for the piezoelectric BioMEMS. An attempt has been made to develop bone-based piezoelectric sensors to detect the stress in bone (Singh, 2003). Another micro-scale sensor for bone surface strain measurement is discussed. This kind of sensor is used for studying the structural effects of osteoporosis. Designs and simulation using ANSYS finite element modeling tool of thin-film metal strain gauge. Metal films for electrical interconnection encapsulated in PDMS have been studied. The PDMS membrane was characterized to facilitate encapsulation designs. The basic fabrication steps like silanization, PDMS preparation, photolithography, PDMS metallization, wire bonding and finally device separation. With experiments were performed for optimizing and characterizing the device like mechanical testing, electrochemical testing and adhesion testing (Yang et al, 2004), and there is a new design which has been discussed here.

Another latest technology is detecting osteoporosis with the study of the brittleness of the bone. The bone mass and bone density play an important role in bone strength. It is

Early Detection Techniques for Osteoporosis 175

Pyridinoline (Pyr)

I collagen (NTx)

I collagen (CTx)

Deoxypyridinoline (dPyr)

Amino terminal telopeptide of type

Carboxy terminal telopeptide of type

Fig. 3. Microfluidic technique for early detection of OP(Singh et al., 2007 & 2009)

Osteocalcin (OC)

I collagen (PINP)

I collagen (PICP)

**5.4 BioMEMS-based sensors** 

(BAP)

Bone-specific alkaline phosphatase

Amino terminal propeptide of type

Carboxy terminal propeptide of type

Table 3. Biochemical Indices (Singh et al., 2006)

(http://www.scielo.br/img/revistas/abem/v50n4/31869t2.gif)

**Bone Formation Bone Resorption** 

BioMEMS using electrochemical immunoassay with microfluidic system (Heineman et al, 2001) help in blood sample analysis using the heterogeneous immunoassay. Two concepts of immunoassay are studied in this research. First is based on analogous microcapillary

important to measure the brittleness or fragility or the bone mechanics. Certain walking studies are done and it is found that as the heel strikes the ground it creates force pulse, energy that passes up through the body and it is absorbed by bone. The osteoporosis reduces the quality of the bone so by attaching the skin-mounted sensors for measuring the electrical pulses of the muscles which is an active part of the skeletal system. If the person has osteoporosis the energy which passes up to the body is disrupted due to porous nature of the bone (http://www.uc.edu/news/NR.asp?id=3280).

#### **5.2 Microfluidic channels – Detection by biomarkers**

The total Alkaline phosphatase (AP) is the mostly widely used bone marker in the clinics and hospitals. AP have physiological substrates which splits the inorganic phosphatase with organic phosphatase, increasing the calcium-phosphatase product and enabling mineralization. AP is essential for normal mineralization of the bone. Bone AP (bAP) constitutes approximately 50% serum AP and the serum has the half-life of 24-48hrs. Though the half-life is relatively large but it may differ on cardiac rhythm, with peak levels in afternoon and night. The exact metabolic pathway is unknown. AP is measured with the help of spectrophotometer using p-nitrophenylphosphate as substrate. The bone and liver AP may be separated by electrophoresis but this method is time consuming and gives semi-quatitaive results. The concentration of bAP concentration may be measured using two antibodies with small differences in affinity toward the isoforms (Singh et al, 2006).

MEMS based detection with alkaline phosphatase has been attempted by Kang and Park (2005). A microfluidic device has been used for enzyme assay. The measurement of enzymesubstrate reaction will to do the substrate consumed. A lab-on-a-chip (LOC) device is developed for controlling the flow containing small volumes of liquids in microchannel which can speeed up and simplifies sample preparation steps in LOC which offers high throughput, low version of traditional research. The microfluidic device is fabricated by the casting process with PDMS. It consists of three parts part I is the injection system, part II is the reaction chamber and part III is the microchannel. This particular microchannel measures the ALP activity using a micro-plate reader. Microfluidic mixing for single enzyme assay was applied and with mathematical prediction the enzymatic (Singh et al, 2006).

#### **5.3 Biochemical based BioMEMS chip**

A novel BioMEMS chip, based on gold nanoparticles, for the detection of osteoproteogerin (OPG). This biochip is used to evaluate the bone conditioning which is directly related to the diagnosis and prognosis of the osteoporosis, in an effective manner. The flow visualization of the mixing capabilities are characterized using micro-scale laser-induced fluorescence (LIF). The BioMEMS chip detection is based on competitive immunoassay. The monoclonal OPG antibody (anti-OPG) is immobilized onto the AuNPs deposited conducting polymer, using covalent bonding with a carboxylic acid group. The catalytic reduction is monitored amperometrically at - 0.4 V versus Ag/AgCl. The linear dynamic range is between 2 to 24 ng/ml with the detection limit of 2 ng/ml (Singh et al., 2007). Fig. 3 depicts schematic of the microfluidic chip.

important to measure the brittleness or fragility or the bone mechanics. Certain walking studies are done and it is found that as the heel strikes the ground it creates force pulse, energy that passes up through the body and it is absorbed by bone. The osteoporosis reduces the quality of the bone so by attaching the skin-mounted sensors for measuring the electrical pulses of the muscles which is an active part of the skeletal system. If the person has osteoporosis the energy which passes up to the body is disrupted due to porous nature

The total Alkaline phosphatase (AP) is the mostly widely used bone marker in the clinics and hospitals. AP have physiological substrates which splits the inorganic phosphatase with organic phosphatase, increasing the calcium-phosphatase product and enabling mineralization. AP is essential for normal mineralization of the bone. Bone AP (bAP) constitutes approximately 50% serum AP and the serum has the half-life of 24-48hrs. Though the half-life is relatively large but it may differ on cardiac rhythm, with peak levels in afternoon and night. The exact metabolic pathway is unknown. AP is measured with the help of spectrophotometer using p-nitrophenylphosphate as substrate. The bone and liver AP may be separated by electrophoresis but this method is time consuming and gives semi-quatitaive results. The concentration of bAP concentration may be measured using two antibodies with small differences in affinity toward the isoforms (Singh et al,

MEMS based detection with alkaline phosphatase has been attempted by Kang and Park (2005). A microfluidic device has been used for enzyme assay. The measurement of enzymesubstrate reaction will to do the substrate consumed. A lab-on-a-chip (LOC) device is developed for controlling the flow containing small volumes of liquids in microchannel which can speeed up and simplifies sample preparation steps in LOC which offers high throughput, low version of traditional research. The microfluidic device is fabricated by the casting process with PDMS. It consists of three parts part I is the injection system, part II is the reaction chamber and part III is the microchannel. This particular microchannel measures the ALP activity using a micro-plate reader. Microfluidic mixing for single enzyme assay was applied and with mathematical prediction the enzymatic (Singh et al,

A novel BioMEMS chip, based on gold nanoparticles, for the detection of osteoproteogerin (OPG). This biochip is used to evaluate the bone conditioning which is directly related to the diagnosis and prognosis of the osteoporosis, in an effective manner. The flow visualization of the mixing capabilities are characterized using micro-scale laser-induced fluorescence (LIF). The BioMEMS chip detection is based on competitive immunoassay. The monoclonal OPG antibody (anti-OPG) is immobilized onto the AuNPs deposited conducting polymer, using covalent bonding with a carboxylic acid group. The catalytic reduction is monitored amperometrically at - 0.4 V versus Ag/AgCl. The linear dynamic range is between 2 to 24 ng/ml with the detection limit of 2 ng/ml (Singh et al., 2007). Fig. 3 depicts schematic of the

of the bone (http://www.uc.edu/news/NR.asp?id=3280).

**5.2 Microfluidic channels – Detection by biomarkers** 

2006).

2006).

microfluidic chip.

**5.3 Biochemical based BioMEMS chip** 

Fig. 3. Microfluidic technique for early detection of OP(Singh et al., 2007 & 2009)


Table 3. Biochemical Indices (Singh et al., 2006) (http://www.scielo.br/img/revistas/abem/v50n4/31869t2.gif)

### **5.4 BioMEMS-based sensors**

BioMEMS using electrochemical immunoassay with microfluidic system (Heineman et al, 2001) help in blood sample analysis using the heterogeneous immunoassay. Two concepts of immunoassay are studied in this research. First is based on analogous microcapillary

Early Detection Techniques for Osteoporosis 177

There is several bone density measurement testing techniques which have been discussed with their working principles. The recent developments in the instruments for BMD measurement have also been discussed. But there are several limitations in these devices. The testing with these devices is very expensive, early detection is not easy, these are invasive measurement, errors in magnification may occur, accuracy is not achievable, scan time is high, harmful

Fig. 5. UV-visible spectroscopy for EDO (Singh et al.,2010)

Fig. 6. Cluster analysis(Singh, 2010)

**6. Discussions** 

**6.1 Bone density testing** 

immunoreactor and other combines the reaction and detection chamber within the area of electromagnet. Both are MEMS based system for alkaline phosphatase study.

Another MEMS microvalve with PDMS diaphragm and two chambers with thermopneumatic actuator for integrated blood test system with silicon have been suggested for point of care device. The blood test system can be reduced to reasonable cost with MEMS technology (Singh, 2006). The microvalve with long stroke has been fabricated with two chamber thermo-pneumatic actuator.

#### **5.5 Spectroscopic techniques for early detection of OP**

Optical techniques such as Fourier Transform Infrared Spectroscopy (FTIR) and Ultra Violet Visible Spectroscopy (UV-Vis) are employed to find the bone markers with an emphasis on the noninvasive modalities for early detection of osteoporosis. Blood plasma samples procured from two groups, patients and healthy persons were tested. Both of the optical techniques revealed obvious differences in the spectra; between two groups, for example, increase in intensity for OP persons. New peaks were found at 1588, 1456 and 1033 cm-1 in FTIR spectra, as shown in Fig. 4. On the other hand, in UV-Visible spectroscopy results, a new peak appeared in the OP patients' spectra at the wavelength of 420 nm, as shown in Fig. 5. These differences in the spectra of the two types of samples, allow rapid and costeffective discrimination of the potential patients with the optical techniques which were verified by the bone densitometer in the hospitals. The new technique used here is quick, reliable and effective.

A hierarchical algorithm is used to investigate and quantify the mutual relevance between successive clusters in terms of heterogeneity values as shown in the Fig.6.

Fig. 6 represents the classification with the spectra at 1539-1542 cm-1. This gives clear distinction between the patients and healthy groups for the amide II group.

Fig. 4. FTIR results for EDO (Singh et al., 2010)

immunoreactor and other combines the reaction and detection chamber within the area of

Another MEMS microvalve with PDMS diaphragm and two chambers with thermopneumatic actuator for integrated blood test system with silicon have been suggested for point of care device. The blood test system can be reduced to reasonable cost with MEMS technology (Singh, 2006). The microvalve with long stroke has been fabricated with two

Optical techniques such as Fourier Transform Infrared Spectroscopy (FTIR) and Ultra Violet Visible Spectroscopy (UV-Vis) are employed to find the bone markers with an emphasis on the noninvasive modalities for early detection of osteoporosis. Blood plasma samples procured from two groups, patients and healthy persons were tested. Both of the optical techniques revealed obvious differences in the spectra; between two groups, for example, increase in intensity for OP persons. New peaks were found at 1588, 1456 and 1033 cm-1 in FTIR spectra, as shown in Fig. 4. On the other hand, in UV-Visible spectroscopy results, a new peak appeared in the OP patients' spectra at the wavelength of 420 nm, as shown in Fig. 5. These differences in the spectra of the two types of samples, allow rapid and costeffective discrimination of the potential patients with the optical techniques which were verified by the bone densitometer in the hospitals. The new technique used here is quick,

A hierarchical algorithm is used to investigate and quantify the mutual relevance between

Fig. 6 represents the classification with the spectra at 1539-1542 cm-1. This gives clear

Healthy persons

1033

Patients

1800 1600 1400 1200 1000 800

1456

Wavenumber (cm-1)

successive clusters in terms of heterogeneity values as shown in the Fig.6.

distinction between the patients and healthy groups for the amide II group.

1588

electromagnet. Both are MEMS based system for alkaline phosphatase study.

chamber thermo-pneumatic actuator.

reliable and effective.

0

Fig. 4. FTIR results for EDO (Singh et al., 2010)

0.05

0.1

0.15

0.2

Absorbance (A.U)

0.25

0.3

0.35

0.4

**5.5 Spectroscopic techniques for early detection of OP** 

Fig. 5. UV-visible spectroscopy for EDO (Singh et al.,2010)

Fig. 6. Cluster analysis(Singh, 2010)

#### **6. Discussions**

#### **6.1 Bone density testing**

There is several bone density measurement testing techniques which have been discussed with their working principles. The recent developments in the instruments for BMD measurement have also been discussed. But there are several limitations in these devices. The testing with these devices is very expensive, early detection is not easy, these are invasive measurement, errors in magnification may occur, accuracy is not achievable, scan time is high, harmful

Early Detection Techniques for Osteoporosis 179

Bal, S.K., McCloskey, E.V., (2002). Menopause and bones. *Current Obst & Gynaec.* Vol.12, 354-357.

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Berthonnaud L, F., Chotel , J., Dimnet, I., (2002).The anatomic patterns of the lower limb

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Bianchi, M..L., Cimaz, R., Bardare, M., et al, (2000). Efficacy and safety of alendronate for the

Blair, J.M, Zhou, H., Seibel, M.J., Dunstan, C.R., (2006). *Nat. Clin. Pract. Oncol.* Vol.3, 41 – 49. Bouxsien, Mary L, (2005). Determinants of skeletal fragility: best practice and research.

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Clark, R.J.H., Hester, R.E., (1996). Biomedical applications of spectroscopy. New York: 1st

Heineman, W.R, Thomas, J.H, Wijayawardhana, A, Brian Halsall et.al, (2001). BioMEMS:

Korkia, P., (2002). Osteoporosis: process, prevention and treatment. J. Bodywork and

Sia, K.S. and Whitesides, G.M., (2003). Microfluidic devices fabricated in polydimethylsiloxane) for biological studies. *Electrophoresis,* Vol.24, 3563-3576. Sartoris, David, J.,Osteoporosis Diagnosis and treatment. 28/06/1996. Publisher Marcel

Singh, K.,(2007) Study of Biomechanical, Optical Spectroscopy & Electrochemical techniques

Singh, K., (2000). Development of MEMs using ASE, *National Symposium on Instrumentation* 

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Singh, K., (1998). Portable battery operated bone fracture evaluator *Proc IEEE- EMBS Int.* 

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applications *Proc First Joint BMES-EMBS Conf Sewing Humanity, Advancing* 

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Dekker Inc. ISBN 9780824795078

*(NSI),* Goa, India, Feb 2-4.

Oct 29 to Nov 3.

radiation may cause problems in the body, home care is not possible and the instruments are not portable. Specially trained persons are required to operate such sophisticated equipments. Though BMD measurement is the most accurate method for detection of Osteoporosis but it is unable to help in early detection and is very expensive. Early detection of such a silent and deadly disease is important for the mankind. Hence there is a need for new, novel, portable, cheap detection systems to be developed for point of care testing.

#### **6.2 Invasive technique**

The invasive technique has several risks involved like skin is punctured. There is a slight chance that the needle may cause fracture the bone being sampled or injure one of the nerves, blood vessels, or organs near the biopsy site. If complications occur, another surgery may be needed to treat the problem. After a bone biopsy, there is a slight chance that the bone may become infected, osteomyelitis or not heal properly. In rare instances, the bone from which the biopsy sample was taken may become weak and break, fracture at a later time. This type detection is only good for extreme severe cases.

#### **6.3 Biochemical measurement**

There are several bone markers or the biomarkers available for the early detection of the osteoporosis which control the osteoblastic and osteoclastic activity. The biochemical detection is not accurate detection but it gives the indication for onset of osteoporosis detection.

#### **6.4 MEMS-based techniques**

The MEMS-based techniques are portable, handheld, easy to use, can be used for home care and point-of-care testing. But the accuracy of the detection may be achieved by using bone mineral density testing (BMD) (Singh et al., 2009, 2010).

#### **7. Conclusions**

The radiographic techniques are needed for the accurate detection of osteoporosis as they give precise data for detection of the deadly disease. Generally, the patients are just unaware of the disease as osteoporosis creeps silently within a human body. Osteoporosis is a silent killer and is a very progressive disease. The time the person realizes the detection and treatment becomes unaffordable for patient. This research paper focuses on the urgent need for the development on early, non-invasive, cheap, and handheld POCT device for such a dangerous disease. These characteristics can be achieved by using a micro-size (MEMS/ Nano based techniques). There have been several attempts in this direction as mentioned in the paper above. But this area needs more of research and deep studies.

### **8. References**


radiation may cause problems in the body, home care is not possible and the instruments are not portable. Specially trained persons are required to operate such sophisticated equipments. Though BMD measurement is the most accurate method for detection of Osteoporosis but it is unable to help in early detection and is very expensive. Early detection of such a silent and deadly disease is important for the mankind. Hence there is a need for new, novel, portable,

The invasive technique has several risks involved like skin is punctured. There is a slight chance that the needle may cause fracture the bone being sampled or injure one of the nerves, blood vessels, or organs near the biopsy site. If complications occur, another surgery may be needed to treat the problem. After a bone biopsy, there is a slight chance that the bone may become infected, osteomyelitis or not heal properly. In rare instances, the bone from which the biopsy sample was taken may become weak and break, fracture at a later

There are several bone markers or the biomarkers available for the early detection of the osteoporosis which control the osteoblastic and osteoclastic activity. The biochemical detection

The MEMS-based techniques are portable, handheld, easy to use, can be used for home care and point-of-care testing. But the accuracy of the detection may be achieved by using bone

The radiographic techniques are needed for the accurate detection of osteoporosis as they give precise data for detection of the deadly disease. Generally, the patients are just unaware of the disease as osteoporosis creeps silently within a human body. Osteoporosis is a silent killer and is a very progressive disease. The time the person realizes the detection and treatment becomes unaffordable for patient. This research paper focuses on the urgent need for the development on early, non-invasive, cheap, and handheld POCT device for such a dangerous disease. These characteristics can be achieved by using a micro-size (MEMS/ Nano based techniques). There have been several attempts in this direction as mentioned in

Ahn C.H; Choi JW, Beaucage G, Nevin JH, Lee JB, Puntambaker A, Lee J., (2004). Disposable smart lab on a chip for point-of-care clinical diagnostics. *Proc. IEEE* 92: pp.154-173. Arnaud, C.D.; (1996). Osteoporosis: using bone markers for diagnosis and monitoring.

Atkinson, P.J. ; (1964). Age-related structural changes in trabecular and cortical bone: Cellular mechanisms and biomechanical consequences *Nature,* Vol. 201, 373 – 375. Auroux, P.A., Iossifidis, D., Reyes, D.R and Manz, A.,( 2002). Micro total analysis systems. 2. Analytical standard operations and applications. *Anal. Chem.*,Vol. 74, 2637-52.

is not accurate detection but it gives the indication for onset of osteoporosis detection.

cheap detection systems to be developed for point of care testing.

time. This type detection is only good for extreme severe cases.

mineral density testing (BMD) (Singh et al., 2009, 2010).

the paper above. But this area needs more of research and deep studies.

**6.2 Invasive technique** 

**6.3 Biochemical measurement** 

**6.4 MEMS-based techniques** 

**7. Conclusions** 

**8. References** 

*Geriatrics,* Vol. 51, 24-30.


**10** 

*Japan* 

**Sophisticated Imaging Technology** 

Huayue Chen1, Tatsuro Hayashi2, Xiangrong Zhou2, Hiroshi Fujita2, Minoru Onozuka3 and Kin-ya Kubo4

*4Seijoh University Graduate School of Health Care Studies,* 

*2Department of Intelligent Image Information, Gifu University Graduate School of Medicine* 

**in the Assessment of Osteoporosis Risk** 

*1Department of Anatomy, Gifu University Graduate School of Medicine* 

*3Department of Physiology and Neuroscience, Kanagawa Dental College* 

Osteoporosis is a common disease characterized by low bone mass and microstructural deterioration of bone tissue, with an increased fracture risk. With an aging population, osteoporosis and its related fractures have become an increasingly important health and socioeconomic issue. The aim of osteoporosis screening and treatment is to prevent bone fracture. A fracture occurs when the external force applied to a bone exceeds its strength. The ability of a bone to resist fracture depends on its amount, spatial distribution, and intrinsic properties. Sophisticated bone imaging techniques, as new modalities, improve the potential for non-invasive study of bone anatomy, physiology and pathophysiology. The objective of bone imaging in osteoporosis is to minimize fracture occurrence by identifying the osteoporotic process at an early stage, differentiate distinctive patterns of bone loss, predict fracture risk accurately and monitor treatment response precisely. Non-invasive imaging techniques, such as computed tomography (CT) and magnetic resonance imaging (MRI), provide structural information, beyond bone mineral density (BMD). Non-invasive or non-destructive imaging techniques can provide important structural information about the local and systemic skeletal status and about the propensity to fracture. These advanced imaging techniques provide information about bone beyond standard bone mineral densitometry. In this chapter, we will discuss recent progress in bone imaging in a range from the macro- to micro-structures in order to investigate the structural basis of the skeletal

In bone fragility assessment, BMD is the main parameter to quantify because of its relationship to bone strength and prediction fracture risk. In the past two decades bone densitometry has been performed with direct methods such as dual X-ray absorptiometry (DXA) and quantitative computed tomography (QCT), which also evaluates bone structural

**1. Introduction** 

fragility underlying osteoporosis.

**2. Bone mineral density measurement** 


## **Sophisticated Imaging Technology in the Assessment of Osteoporosis Risk**

Huayue Chen1, Tatsuro Hayashi2, Xiangrong Zhou2, Hiroshi Fujita2, Minoru Onozuka3 and Kin-ya Kubo4 *1Department of Anatomy, Gifu University Graduate School of Medicine 2Department of Intelligent Image Information, Gifu University Graduate School of Medicine 3Department of Physiology and Neuroscience, Kanagawa Dental College 4Seijoh University Graduate School of Health Care Studies, Japan* 

### **1. Introduction**

180 Osteoporosis

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*Biosensors and Bioelectronics,* Vol 23, Issue 11, 15 June Pages 1595-1601, 2008 Singh. K. & Kim, K.C., (2009). BioMEMS for Early detection of bone diseases" *The 5th* 

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Yang, G.Y, Vasudev, J.B., et al., (2004) Design of microfabricated strain gauge array to

*Biomedical Engineering & technology*, Vol. 2, Number 3, 279-291.

of biofluid for early disease detection, *8rth Cross Straits Symposium on Material*,

*&Biology (WFUMB) Am Institute of Ultr in Medicine(AIUM),* June 1-4, , Montreal, Canada.

and abnormal biofluids by FTIR. *The Korean Society of Visualization*, Workshop at

for osteoproteogerin based on gold nanoparticles deposited conducting polymer,

*International Conference on Microtechnologies in Medicine and Biology*, *MMB 2009*

osteoporosis, Int. J. of biomedical engineering and technology, IJBET. *Int. J.* 

for early detection of OP, *Journal of Mechanical Science and Technology* Vol.24 ,Issue

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Engineers, *KSME Int. conference*, 30th April, Bexco, Busan, Korea..

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*Mech Eng Sci Technol,* Vol.20, Issue no.12, 2265-2283.

Conference, Quebec City, Canada, April 1-9

Bioinformatics and Bioengineering (BIBE'04).

*Letters,* Vol 7, No.6, 1013-1024.

no.8, 1661~1668

1824-1828.

*Medicine &Biology (WFUMB)* hosted by American Institute of Ultrasound in

*Biomedical Engineering,* Hangzhou, China, Sept 26-28.

Medicine(AIUM), June 1-4, 2003, Montreal, Canada.

*energy and Environmental Sciences*, CSS7, 35-36.

*Mech. Eng. Sci. Technol*. 20, 2265-2283.

Dongnae University, Busan, 1st Dec.

*USA,* 1-5th Sept.

Busan, Korea.

Osteoporosis is a common disease characterized by low bone mass and microstructural deterioration of bone tissue, with an increased fracture risk. With an aging population, osteoporosis and its related fractures have become an increasingly important health and socioeconomic issue. The aim of osteoporosis screening and treatment is to prevent bone fracture. A fracture occurs when the external force applied to a bone exceeds its strength. The ability of a bone to resist fracture depends on its amount, spatial distribution, and intrinsic properties. Sophisticated bone imaging techniques, as new modalities, improve the potential for non-invasive study of bone anatomy, physiology and pathophysiology. The objective of bone imaging in osteoporosis is to minimize fracture occurrence by identifying the osteoporotic process at an early stage, differentiate distinctive patterns of bone loss, predict fracture risk accurately and monitor treatment response precisely. Non-invasive imaging techniques, such as computed tomography (CT) and magnetic resonance imaging (MRI), provide structural information, beyond bone mineral density (BMD). Non-invasive or non-destructive imaging techniques can provide important structural information about the local and systemic skeletal status and about the propensity to fracture. These advanced imaging techniques provide information about bone beyond standard bone mineral densitometry. In this chapter, we will discuss recent progress in bone imaging in a range from the macro- to micro-structures in order to investigate the structural basis of the skeletal fragility underlying osteoporosis.

### **2. Bone mineral density measurement**

In bone fragility assessment, BMD is the main parameter to quantify because of its relationship to bone strength and prediction fracture risk. In the past two decades bone densitometry has been performed with direct methods such as dual X-ray absorptiometry (DXA) and quantitative computed tomography (QCT), which also evaluates bone structural

Sophisticated Imaging Technology in the Assessment of Osteoporosis Risk 183

CT scanners are calibrated to the X-ray attenuation to the water, resulting in CT numbers, measured in Hounsfield Units (HU). To transform HU into bone mineral equivalents (mg/cm3) an appropriate bone mineral phantom is included in the scan field. QCT is the unique modality that measures the real bone density in a determinate volume (mg/cm³) without the overlapping of others tissues. QCT differs from DXA as it can allow a selective assessment of both trabecular and cortical bone. Trabecular BMD obtained by QCT shows a more rapid age dependent decrement than that measured by DXA. Single Energy QCT is normally used for clinical setting, though BMD estimation can be altered by quantity of fat tissue, which substitutes the red marrow in elderly people. This effect produces an increasing error of evaluation with the increase of elderly patients. Even if Dual Energy QCT improves the accuracy, nevertheless it uses higher radiation dose and longer scanning times without increasing QCT sensibility in discriminating between healthy and osteoporotic subjects. Over the last decade, technical developments in CT, including multi-detector CT (MDCT) have resulted in images of volumes of tissue being acquired very rapidly, and this has had an impact on QCT in that 3D volume images can be acquired rapidly. Such 3D volumetric QCT enables analysis of the hip, the important site of osteoporotic fracture,

The trabecular BMD, particularly in the vertebra, is metabolically more active and may therefore serve as an early indicator of osteoporosis treatment effect. Vertebral trabecular BMD was demonstrated to have a significant correlation with vertebral fracture. Worldwide, the number of subjects in thoracic and abdominal CT examinations has increased dramatically over the last two decades (McCollough et al., 2009). Several recent studies have shown how it is possible to obtain meaningful QCT BMD values from subjects undergoing thoraco-abdominal CT examinations without the use of a calibration phantom. Such BMD values have a high correlation with BMD values obtained from QCT. These studies demonstrate that it is technically feasible to obtain reasonably accurate BMD values in subjects undergoing thoracic or abdominal CT examinations for other reasons. It is very useful for subjects as it will allow predictions of vertebral fractures without additional radiation exposure (Lenchik et al., 2004). The analysis of BMD at different vertebral levels is necessary because most osteoporotic vertebral fractures are located in the thoracolumbar spine between T4 and L1, with the segments between T7 and L1 most affected (Wasnich, 1996). Osteoporotic fractures of the cervical spine are considered uncommon. The etiology of the striking segmental differences for osteoporotic vertebral fractures is not well explained. Recently we measured the trabecular BMD of thoracic and lumbar vertebrae from 1,031 subjects who had undergone MDCT examination (Hayashi et al., 2011). The vertebral trabecular BMD of both men and women tended to gradually decrease from Th1 to L3 in all age categories (Fig. 1). In relation to vertebral level, L3 had the lowest trabecular BMD among the thoracic and lumbar vertebrae. The correlation of the trabecular BMD among thoracic and lumbar vertebrae was also studied. On the whole, we found that the further the vertebrae were from each other, the weaker were their correlations of the trabecular BMD, and vice versa. This finding indicates that estimating the BMD of distant vertebrae existing beyond the scope of CT images is difficult. For example, if the BMDs of T7 and T12 are estimated using L3 BMD in CT images from abdominal organ examinations, the estimated accuracy of T12 (r=0.92) would be better than that of T7 (r=0.79) because T12 is nearer to L3

which was not feasible with 2D single slices.

**2.2.2 Vertebral trabecular QCT assessment** 

characteristics. The most commonly used quantitative imaging measure in osteoporosis is the areal BMD assessed by DXA. The assessment of bone macro- and micro-architecture by using more sensitive three-dimensional (3D) methods is important to determine certain aspects of bone structure and quality. Research has especially focused on the assessment of compartmental BMD and bone microstructure, since it has become technologically possible to obtain relatively high resolution volumetric images of bone in vivo.

#### **2.1 Dual X-ray absorptiometry**

Bone mineral density (BMD) measurement by dual X-ray absorptiometry (DXA) has been available for clinical use since 1987. It provides a quantitative assessment of mineralized bone mass at the axial and appendicular skeleton in vivo. This technique is currently the most readily available surrogate marker of bone strength and fracture risk. DXA measures the attenuation of photons of two different energies during radiation transmission. Bone mineral content (BMC, g) and areal BMD (g/cm2) of a region of interest are obtained. As low areal BMD is a strong risk factor for fractures, this technique provides the basis for the World Health Organization (WHO)'s guidelines for diagnosis of osteoporosis. DXA is limited in that it measures only areal BMD two-dimensionally. DXA is also limited in that it does not distinguish cortical and trabecular bone. Furthermore, measurements are subject to artefacts due to degenerative changes such as osteophytes and aortic calcification. Recommendations from the International Society for Clinical Densitometry regarding DXA examination for all ages have been updated. Although DXA is the gold standard for clinical assessment of fracture risk, its shortcomings are increasingly being recognized. Individual fracture risk has recently been standardized using the WHO Fracture Risk Assessment tool (FRAX), which was released in 2009 (Kanis et al., 2009). FRAX combines BMD from DXA with other well-known major risk factors for osteoporosis, such as age, sex and a parental history of hip fracture, to provide a 10-year risk of hip and other major fractures. Although it is not an ideal system, FRAX represents an important initiative in allowing clinicians to individualize fracture risk based on DXA examination and other factors.

#### **2.2 Quantitative computed tomography (QCT)**

In quantitative computed tomography (QCT), the X-ray source and detector rotate in synchronised fashion around the subject. Algorithms are used to reconstruct the attenuation data into 3D images. Use of a bone mineral or hydroxyapatite phantom allows calibration of the data, providing a measurement of bone density that is independent of bone size. Compared with DXA, one advantage of QCT is the capacity for separate analysis of the cortical and trabecular BMD. QCT also provides real bone density per bone volume (mg/cm3). Recently, 3D volume data from the scanning of an entire bone, such as a vertebral body or proximal femur, can be reconstructed to adjust the exact selected region for several serial images in a longitudinal study, which enables monitoring of successive changes with very good precision. QCT-based bone measurements have been used to evaluate age-, sexand ethnic-related differences in vertebral and femoral geometry and density, providing insights into the development of skeletal fragility.

#### **2.2.1 Volumetric BMD assessment by QCT**

CT image is a two step process of initial scan acquisition and then tomographic image reconstruction by a mathematical process of calculating from acquired raw data. All clinical

characteristics. The most commonly used quantitative imaging measure in osteoporosis is the areal BMD assessed by DXA. The assessment of bone macro- and micro-architecture by using more sensitive three-dimensional (3D) methods is important to determine certain aspects of bone structure and quality. Research has especially focused on the assessment of compartmental BMD and bone microstructure, since it has become technologically possible

Bone mineral density (BMD) measurement by dual X-ray absorptiometry (DXA) has been available for clinical use since 1987. It provides a quantitative assessment of mineralized bone mass at the axial and appendicular skeleton in vivo. This technique is currently the most readily available surrogate marker of bone strength and fracture risk. DXA measures the attenuation of photons of two different energies during radiation transmission. Bone mineral content (BMC, g) and areal BMD (g/cm2) of a region of interest are obtained. As low areal BMD is a strong risk factor for fractures, this technique provides the basis for the World Health Organization (WHO)'s guidelines for diagnosis of osteoporosis. DXA is limited in that it measures only areal BMD two-dimensionally. DXA is also limited in that it does not distinguish cortical and trabecular bone. Furthermore, measurements are subject to artefacts due to degenerative changes such as osteophytes and aortic calcification. Recommendations from the International Society for Clinical Densitometry regarding DXA examination for all ages have been updated. Although DXA is the gold standard for clinical assessment of fracture risk, its shortcomings are increasingly being recognized. Individual fracture risk has recently been standardized using the WHO Fracture Risk Assessment tool (FRAX), which was released in 2009 (Kanis et al., 2009). FRAX combines BMD from DXA with other well-known major risk factors for osteoporosis, such as age, sex and a parental history of hip fracture, to provide a 10-year risk of hip and other major fractures. Although it is not an ideal system, FRAX represents an important initiative in allowing clinicians to

to obtain relatively high resolution volumetric images of bone in vivo.

individualize fracture risk based on DXA examination and other factors.

In quantitative computed tomography (QCT), the X-ray source and detector rotate in synchronised fashion around the subject. Algorithms are used to reconstruct the attenuation data into 3D images. Use of a bone mineral or hydroxyapatite phantom allows calibration of the data, providing a measurement of bone density that is independent of bone size. Compared with DXA, one advantage of QCT is the capacity for separate analysis of the cortical and trabecular BMD. QCT also provides real bone density per bone volume (mg/cm3). Recently, 3D volume data from the scanning of an entire bone, such as a vertebral body or proximal femur, can be reconstructed to adjust the exact selected region for several serial images in a longitudinal study, which enables monitoring of successive changes with very good precision. QCT-based bone measurements have been used to evaluate age-, sexand ethnic-related differences in vertebral and femoral geometry and density, providing

CT image is a two step process of initial scan acquisition and then tomographic image reconstruction by a mathematical process of calculating from acquired raw data. All clinical

**2.2 Quantitative computed tomography (QCT)** 

insights into the development of skeletal fragility.

**2.2.1 Volumetric BMD assessment by QCT** 

**2.1 Dual X-ray absorptiometry** 

CT scanners are calibrated to the X-ray attenuation to the water, resulting in CT numbers, measured in Hounsfield Units (HU). To transform HU into bone mineral equivalents (mg/cm3) an appropriate bone mineral phantom is included in the scan field. QCT is the unique modality that measures the real bone density in a determinate volume (mg/cm³) without the overlapping of others tissues. QCT differs from DXA as it can allow a selective assessment of both trabecular and cortical bone. Trabecular BMD obtained by QCT shows a more rapid age dependent decrement than that measured by DXA. Single Energy QCT is normally used for clinical setting, though BMD estimation can be altered by quantity of fat tissue, which substitutes the red marrow in elderly people. This effect produces an increasing error of evaluation with the increase of elderly patients. Even if Dual Energy QCT improves the accuracy, nevertheless it uses higher radiation dose and longer scanning times without increasing QCT sensibility in discriminating between healthy and osteoporotic subjects. Over the last decade, technical developments in CT, including multi-detector CT (MDCT) have resulted in images of volumes of tissue being acquired very rapidly, and this has had an impact on QCT in that 3D volume images can be acquired rapidly. Such 3D volumetric QCT enables analysis of the hip, the important site of osteoporotic fracture, which was not feasible with 2D single slices.

#### **2.2.2 Vertebral trabecular QCT assessment**

The trabecular BMD, particularly in the vertebra, is metabolically more active and may therefore serve as an early indicator of osteoporosis treatment effect. Vertebral trabecular BMD was demonstrated to have a significant correlation with vertebral fracture. Worldwide, the number of subjects in thoracic and abdominal CT examinations has increased dramatically over the last two decades (McCollough et al., 2009). Several recent studies have shown how it is possible to obtain meaningful QCT BMD values from subjects undergoing thoraco-abdominal CT examinations without the use of a calibration phantom. Such BMD values have a high correlation with BMD values obtained from QCT. These studies demonstrate that it is technically feasible to obtain reasonably accurate BMD values in subjects undergoing thoracic or abdominal CT examinations for other reasons. It is very useful for subjects as it will allow predictions of vertebral fractures without additional radiation exposure (Lenchik et al., 2004). The analysis of BMD at different vertebral levels is necessary because most osteoporotic vertebral fractures are located in the thoracolumbar spine between T4 and L1, with the segments between T7 and L1 most affected (Wasnich, 1996). Osteoporotic fractures of the cervical spine are considered uncommon. The etiology of the striking segmental differences for osteoporotic vertebral fractures is not well explained. Recently we measured the trabecular BMD of thoracic and lumbar vertebrae from 1,031 subjects who had undergone MDCT examination (Hayashi et al., 2011). The vertebral trabecular BMD of both men and women tended to gradually decrease from Th1 to L3 in all age categories (Fig. 1). In relation to vertebral level, L3 had the lowest trabecular BMD among the thoracic and lumbar vertebrae. The correlation of the trabecular BMD among thoracic and lumbar vertebrae was also studied. On the whole, we found that the further the vertebrae were from each other, the weaker were their correlations of the trabecular BMD, and vice versa. This finding indicates that estimating the BMD of distant vertebrae existing beyond the scope of CT images is difficult. For example, if the BMDs of T7 and T12 are estimated using L3 BMD in CT images from abdominal organ examinations, the estimated accuracy of T12 (r=0.92) would be better than that of T7 (r=0.79) because T12 is nearer to L3

Sophisticated Imaging Technology in the Assessment of Osteoporosis Risk 185

A more accurate evaluation of lateral chest radiographs routinely executed could lead to the detection of a major number of vertebral fractures and earlier diagnosis of osteoporosis. Although it is ideally suited for use in large population studies, the limitation of radiography is that as a projection imaging technique, it cannot consistently visualize individual trabecula and it depends heavily on the depth of tissues under investigation. Despite these limitations, the trabecular bone properties could be described by texture analysis. Good correlations were found between direct, 3D measures of trabecular architecture and a multiple parameter model, based on 2D texture parameters, such as fractal, statistical and anisotropy measures (Guggenbuhl et al., 2006). With increasing sophistication of structural analysis techniques and an improving ability to acquire high-resolution radiographic detail, interest remains in

developing radiography to more precisely evaluate trabecular bone microstructure.

Computed tomography (CT) is a 3D X-ray imaging technique, which provides positive contrast of mineralized tissues. The image formation process begins with the acquisition of serial radiographic projections over a range of angular positions around the object of interest. The cross-sectional field of view is then reconstructed using established computational techniques. Similar to simple radiography, the reconstructed image intensity values represent the local X-ray attenuation. A material property related to the electron density. Several classes of CT devices are presently used for high-resolution imaging of trabecular and cortical bone microstructure. The multi-detector CT (MDCT) is a clinical CT technique, which is available in most diagnostic imaging departments and thus a dedicated scanner is not required. Since its inception, the number of detector rows on clinical CT units has increased from 4 to the current clinical standard of 64 rows, although 320-row MDCT systems are also commercially available. As expected, MDCT fared less well with trabecular thickness and number because the spatial resolution of all MDCT systems (250–300μm) remains larger than the trabecular thickness of 50 to 200μm (Issever et al., 2010). Nevertheless, structural parameters by MDCT provide a better discriminator of change than DXA. It has been shown that trabecular bone parameters obtained with MDCT correlate with those determined in contact radiographs from histological bone sections and micro-CT (Link et al., 2003). The advantage of MDCT technique is that more central regions of the skeleton such as the spine and proximal femur can be visualized. However, in order to achieve adequate spatial resolution and image quality the required radiation exposure is substantial, which offsets the technique's applicability in clinical routine and scientific studies. High-resolution CT scanning is associated with considerably higher radiation dose compared with standard techniques for measuring BMD. Using clinical imaging in more central regions of the skeleton such as spine and femur, it is still noted that the trabecular bone architecture visualized with MDCT is more a texture of the trabecular bone than a true

**3.2 Multi-detector computed tomography (MDCT)** 

visualization of the individual trabecular structure.

**3.3 Peripheral quantitative CT and high-resolution peripheral quantitative CT** 

The peripheral QCT (pQCT) with a resolution comparable to that of MDCT has been available since 1990 to examine the peripheral skeleton. pQCT confers a smaller effective radiation dose and is particularly useful for studying cortical bone changes in metabolic bone disorders because the distal radius contains more cortical bone than the vertebral body. As pQCT units use low-power X-ray tubes, these examinations are slow, with a

than T7 (Hayashi et al., 2011). That is to say, it may be appropriate to use an arbitrary vertebra as a first approximation for assessing vertebrae which are in the area of predilection for the fracture. If the BMD of one vertebra is known, the BMD of other vertebrae may be estimated using our knowledge of BMD correlations.

Fig. 1. The trabecular BMD of the thoracic and lumbar vertebrae. The BMD tends to decrease from the first thoracic to third lumbar vertebra (Hayashi et al., 2011)

#### **3. Bone quality assessment**

As BMD explains only part of the variation seen in bone strength and only some of the observed reduction in fracture risk that occurs with treatment, recent developments have focused more on measuring bone structure and quality of both cortical and trabecular bone rather than bone mass alone. This is done with the knowledge that a measure encompassing bone quality and structure along with bone mass will provide a better prediction of fracture risk than bone mass alone.

#### **3.1 Conventional X-rays**

Conventional radiography is a low-cost, readily available technique with high spatial resolution capable of providing fine bone detail, especially for appendicular skeleton such as the distal forearm and phalanges. It is widely available method, provides a good tissue contrast and has the potential to reflect bone microstructure. Conventional radiography is the first and most important method to identify fractures. The distal radius fractures are almost always identified by standard radiographs, while hip and especially spine fractures may have a difficult detection with important significance in their management, prognosis and therapy.

than T7 (Hayashi et al., 2011). That is to say, it may be appropriate to use an arbitrary vertebra as a first approximation for assessing vertebrae which are in the area of predilection for the fracture. If the BMD of one vertebra is known, the BMD of other

Fig. 1. The trabecular BMD of the thoracic and lumbar vertebrae. The BMD tends to decrease

**T1 T2 T3 T4 T5 T6 T7 T9 T10 T11T12 L2 L3 L4 L5** 

**T8 L1**

As BMD explains only part of the variation seen in bone strength and only some of the observed reduction in fracture risk that occurs with treatment, recent developments have focused more on measuring bone structure and quality of both cortical and trabecular bone rather than bone mass alone. This is done with the knowledge that a measure encompassing bone quality and structure along with bone mass will provide a better prediction of fracture

Conventional radiography is a low-cost, readily available technique with high spatial resolution capable of providing fine bone detail, especially for appendicular skeleton such as the distal forearm and phalanges. It is widely available method, provides a good tissue contrast and has the potential to reflect bone microstructure. Conventional radiography is the first and most important method to identify fractures. The distal radius fractures are almost always identified by standard radiographs, while hip and especially spine fractures may have a difficult detection with important significance in their management, prognosis and therapy.

from the first thoracic to third lumbar vertebra (Hayashi et al., 2011)

**3. Bone quality assessment** 

**0**

**50**

**100**

**150**

**200**

**250**

**(mg/cm3)**

risk than bone mass alone.

**3.1 Conventional X-rays** 

vertebrae may be estimated using our knowledge of BMD correlations.

A more accurate evaluation of lateral chest radiographs routinely executed could lead to the detection of a major number of vertebral fractures and earlier diagnosis of osteoporosis. Although it is ideally suited for use in large population studies, the limitation of radiography is that as a projection imaging technique, it cannot consistently visualize individual trabecula and it depends heavily on the depth of tissues under investigation. Despite these limitations, the trabecular bone properties could be described by texture analysis. Good correlations were found between direct, 3D measures of trabecular architecture and a multiple parameter model, based on 2D texture parameters, such as fractal, statistical and anisotropy measures (Guggenbuhl et al., 2006). With increasing sophistication of structural analysis techniques and an improving ability to acquire high-resolution radiographic detail, interest remains in developing radiography to more precisely evaluate trabecular bone microstructure.

### **3.2 Multi-detector computed tomography (MDCT)**

Computed tomography (CT) is a 3D X-ray imaging technique, which provides positive contrast of mineralized tissues. The image formation process begins with the acquisition of serial radiographic projections over a range of angular positions around the object of interest. The cross-sectional field of view is then reconstructed using established computational techniques. Similar to simple radiography, the reconstructed image intensity values represent the local X-ray attenuation. A material property related to the electron density. Several classes of CT devices are presently used for high-resolution imaging of trabecular and cortical bone microstructure. The multi-detector CT (MDCT) is a clinical CT technique, which is available in most diagnostic imaging departments and thus a dedicated scanner is not required. Since its inception, the number of detector rows on clinical CT units has increased from 4 to the current clinical standard of 64 rows, although 320-row MDCT systems are also commercially available. As expected, MDCT fared less well with trabecular thickness and number because the spatial resolution of all MDCT systems (250–300μm) remains larger than the trabecular thickness of 50 to 200μm (Issever et al., 2010). Nevertheless, structural parameters by MDCT provide a better discriminator of change than DXA. It has been shown that trabecular bone parameters obtained with MDCT correlate with those determined in contact radiographs from histological bone sections and micro-CT (Link et al., 2003). The advantage of MDCT technique is that more central regions of the skeleton such as the spine and proximal femur can be visualized. However, in order to achieve adequate spatial resolution and image quality the required radiation exposure is substantial, which offsets the technique's applicability in clinical routine and scientific studies. High-resolution CT scanning is associated with considerably higher radiation dose compared with standard techniques for measuring BMD. Using clinical imaging in more central regions of the skeleton such as spine and femur, it is still noted that the trabecular bone architecture visualized with MDCT is more a texture of the trabecular bone than a true visualization of the individual trabecular structure.

### **3.3 Peripheral quantitative CT and high-resolution peripheral quantitative CT**

The peripheral QCT (pQCT) with a resolution comparable to that of MDCT has been available since 1990 to examine the peripheral skeleton. pQCT confers a smaller effective radiation dose and is particularly useful for studying cortical bone changes in metabolic bone disorders because the distal radius contains more cortical bone than the vertebral body. As pQCT units use low-power X-ray tubes, these examinations are slow, with a

Sophisticated Imaging Technology in the Assessment of Osteoporosis Risk 187

bone microstructure in aging hamsters from 3 to 24 months of age using μCT (Chen et al., 2008a). In the proximal tibia and distal femur, the trabecular BV/TV, Tb.N, Tb.Th and BMD increased to a maximum at 6 or 12 months and then declined progressively from 12 to 24 months of age (Fig. 2). Tb.Sp, trabecular bone pattern factor (TBPf) and SMI increased with age. As compared with male hamsters, BV/TV and Tb.N were significantly lower in females at 18 and 24 months of age. Age-related decrease of BV/TV in the vertebral body was less than that of the femoral and tibial metaphyses. In the mid-femoral diaphysis, cortical bone area remained constant from 3 to 24 months of age. Cortical thickness decreased from 12 to 24 months and cortical BMD declined significantly from 18 to 24 months of age. These findings indicate that skeletal site and sex differences exist in hamster bone structure. Agerelated bone changes in hamsters resemble those in humans. Hamsters may be a useful

animal model to study at least some aspects of bone loss during human aging.

and declined at 18 and 24 months of age. Scale bar=1.0mm (Chen et al., 2008a)

**3.4.2 Osteoporosis model mouse (SAMP6) bone** μ**CT assessment** 

further validate the relevance of SAMP6 as a model of senile osteoporosis.

**3.4.3 Human vertebral trabecular bone** μ**CT assessment** 

Fig. 2. Three-dimensional images of the proximal tibial metaphysic in female hamsters at 3, 6, 12, 18 and 24 months of age. Trabecular bone volume is highest at 6 and 12 months of age,

The senescence-accelerated mouse P6 (SAMP6) is a model of senile osteoporosis, which possesses many features of senile osteoporosis in humans. So far, little is known about the systemic bone microstructural changes that occur at multiple skeletal sites. Recently, we investigated site dependence of bone microstructure and BMD in SAMP6 and the normal control mouse (SAMR1) using quantitative μCT and imaging analysis software (Chen et al., 2009). As compared with SAMR1, the most prominent change in SAMP6 was the reduction of vertebral trabecular BV/TV (Fig. 3) and BMD. Moderate decrease of trabecular bone loss was observed in the proximal tibia and distal femur. Increased bone marrow area and periosteal perimeter were investigated, although the cortical area and cortical thickness had no marked changes in the mid-tibial and mid-femoral cortical bones. These results indicate that bone microstructural properties in SAMP6 are remarkably heterogeneous throughout the skeleton, which is analogous to changes that occur in human bones. These findings

The vertebral trabecular bone has a complex 3D microstructure, with inhomogeneous morphology. A thorough understanding of regional variations in the microstructural properties is crucial for evaluating age- and gender-related bone loss of the vertebra, and may help to gain more insight into the mechanism of the vertebral osteoporosis and the related fracture risks. Fifty-six fourth lumbar vertebral bodies from 28 women and men (57- 98 years of age) cadaver donors were studied. Both women and men were divided into 3 age groups, middle-aged, old age and elderly groups. Five cubic specimens were prepared from

tendency toward motion artifact. With this limitation in mind, the feasibility of using clinical CT scanners with a dedicated forearm phantom as an alternative to pQCT has been investigated. The cortical and trabecular BMD, and bone geometrical parameters, such as marrow and cortical cross-sectional area, cortical thickness, periosteal and endosteal circumference, biomechanical parameters can be obtained, like cross-sectional moment of inertia, which is a measure of bending strength, polar moment of inertia, indicating bone strength in torsion and stress strain index (SSI). A non-invasive bone strength marker as SSI measured by pQCT, could be significantly correlated with a biomechanical bone strength index, as maximum load at bone failure, assessed by three-point bending test. pQCT can non-invasively determine bone mechanical properties by assessing parameters with accepted prognostic value on bone strength (Kokoroghiannis, et al., 2009). Bridging the clinical need for an imaging modality with lower radiation dose and better spatial resolution is the high-resolution pQCT (HR-pQCT). This can measure trabecular and cortical bone density and bone microstructure with an isotropic voxel of about 80μm. This technique has excellent precision for both density and structure measurements (Dalzell et al., 2009). In 2005, the first published clinical study assessing HR-pQCT found that postmenopausal women had lower BMD, trabecular number and cortical thickness compared with premenopausal women at the distal radius and tibia, although spine and hip BMD was similar. HR-pQCT is a useful modality for assessing changes in cortical and trabecular bone, with a precision of about 2% to 5% (Boutroy et al., 2005). The main limitation of HR-pQCT is that it requires a dedicated scanner, is confined to examination of distal forearm and leg, has some difficultly with registration in the Z plane and should take into consideration the expected difference among individuals of short or long radial or tibial length.

#### **3.4 Micro-CT (**μ**CT)**

The earlier conventional tool for assessing trabecular bone architecture was histomorphometry from bone biopsies, which produces a two-dimensional representation of tissue structure, while bone structure is three-dimensional. In recent years, it has progressively been imposed the direct 3D analysis of biopsy specimens imaged by micro-CT (μCT). The most common application of this technology has been the in vitro quantitation of osteoporotic change in trabecular bone architecture. The μCT system has been demonstrated to be the first device able to non-destructively reveal the "real" trabecular architecture and is an X-ray-based technique that provides 3D images of very high spatial resolution below 8 μm. Since μCT allows the depiction of individual trabecula and enables the full characterization of the trabecular network, many investigators have used it to study the trabecular network at different skeletal sites, in direct relation to biomechanical properties or as a "gold standard" for evaluating other techniques, although most of the μCT are limited to ex vivo investigations. Microarchitectural 3D data elaborated by specific software consents to evaluate many metric and non-metric bone structural parameters, such as the bone volume (BV), tissue volume (TV), bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp), structure model index (SMI), connectivity degree (Conn.D) and degree of anisotropy (DA).

#### **3.4.1 Hamster bone** μ**CT assessment**

Age-related bone loss, which is poorly characterized, is a major underlying cause of osteoporotic fractures in the elderly. In order to identify the morphological feature of agerelated bone loss, we investigated sex and site (tibia, femur and vertebra) dependence of

tendency toward motion artifact. With this limitation in mind, the feasibility of using clinical CT scanners with a dedicated forearm phantom as an alternative to pQCT has been investigated. The cortical and trabecular BMD, and bone geometrical parameters, such as marrow and cortical cross-sectional area, cortical thickness, periosteal and endosteal circumference, biomechanical parameters can be obtained, like cross-sectional moment of inertia, which is a measure of bending strength, polar moment of inertia, indicating bone strength in torsion and stress strain index (SSI). A non-invasive bone strength marker as SSI measured by pQCT, could be significantly correlated with a biomechanical bone strength index, as maximum load at bone failure, assessed by three-point bending test. pQCT can non-invasively determine bone mechanical properties by assessing parameters with accepted prognostic value on bone strength (Kokoroghiannis, et al., 2009). Bridging the clinical need for an imaging modality with lower radiation dose and better spatial resolution is the high-resolution pQCT (HR-pQCT). This can measure trabecular and cortical bone density and bone microstructure with an isotropic voxel of about 80μm. This technique has excellent precision for both density and structure measurements (Dalzell et al., 2009). In 2005, the first published clinical study assessing HR-pQCT found that postmenopausal women had lower BMD, trabecular number and cortical thickness compared with premenopausal women at the distal radius and tibia, although spine and hip BMD was similar. HR-pQCT is a useful modality for assessing changes in cortical and trabecular bone, with a precision of about 2% to 5% (Boutroy et al., 2005). The main limitation of HR-pQCT is that it requires a dedicated scanner, is confined to examination of distal forearm and leg, has some difficultly with registration in the Z plane and should take into consideration the

expected difference among individuals of short or long radial or tibial length.

(SMI), connectivity degree (Conn.D) and degree of anisotropy (DA).

**3.4.1 Hamster bone** μ**CT assessment** 

The earlier conventional tool for assessing trabecular bone architecture was histomorphometry from bone biopsies, which produces a two-dimensional representation of tissue structure, while bone structure is three-dimensional. In recent years, it has progressively been imposed the direct 3D analysis of biopsy specimens imaged by micro-CT (μCT). The most common application of this technology has been the in vitro quantitation of osteoporotic change in trabecular bone architecture. The μCT system has been demonstrated to be the first device able to non-destructively reveal the "real" trabecular architecture and is an X-ray-based technique that provides 3D images of very high spatial resolution below 8 μm. Since μCT allows the depiction of individual trabecula and enables the full characterization of the trabecular network, many investigators have used it to study the trabecular network at different skeletal sites, in direct relation to biomechanical properties or as a "gold standard" for evaluating other techniques, although most of the μCT are limited to ex vivo investigations. Microarchitectural 3D data elaborated by specific software consents to evaluate many metric and non-metric bone structural parameters, such as the bone volume (BV), tissue volume (TV), bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp), structure model index

Age-related bone loss, which is poorly characterized, is a major underlying cause of osteoporotic fractures in the elderly. In order to identify the morphological feature of agerelated bone loss, we investigated sex and site (tibia, femur and vertebra) dependence of

**3.4 Micro-CT (**μ**CT)** 

bone microstructure in aging hamsters from 3 to 24 months of age using μCT (Chen et al., 2008a). In the proximal tibia and distal femur, the trabecular BV/TV, Tb.N, Tb.Th and BMD increased to a maximum at 6 or 12 months and then declined progressively from 12 to 24 months of age (Fig. 2). Tb.Sp, trabecular bone pattern factor (TBPf) and SMI increased with age. As compared with male hamsters, BV/TV and Tb.N were significantly lower in females at 18 and 24 months of age. Age-related decrease of BV/TV in the vertebral body was less than that of the femoral and tibial metaphyses. In the mid-femoral diaphysis, cortical bone area remained constant from 3 to 24 months of age. Cortical thickness decreased from 12 to 24 months and cortical BMD declined significantly from 18 to 24 months of age. These findings indicate that skeletal site and sex differences exist in hamster bone structure. Agerelated bone changes in hamsters resemble those in humans. Hamsters may be a useful animal model to study at least some aspects of bone loss during human aging.

Fig. 2. Three-dimensional images of the proximal tibial metaphysic in female hamsters at 3, 6, 12, 18 and 24 months of age. Trabecular bone volume is highest at 6 and 12 months of age, and declined at 18 and 24 months of age. Scale bar=1.0mm (Chen et al., 2008a)

### **3.4.2 Osteoporosis model mouse (SAMP6) bone** μ**CT assessment**

The senescence-accelerated mouse P6 (SAMP6) is a model of senile osteoporosis, which possesses many features of senile osteoporosis in humans. So far, little is known about the systemic bone microstructural changes that occur at multiple skeletal sites. Recently, we investigated site dependence of bone microstructure and BMD in SAMP6 and the normal control mouse (SAMR1) using quantitative μCT and imaging analysis software (Chen et al., 2009). As compared with SAMR1, the most prominent change in SAMP6 was the reduction of vertebral trabecular BV/TV (Fig. 3) and BMD. Moderate decrease of trabecular bone loss was observed in the proximal tibia and distal femur. Increased bone marrow area and periosteal perimeter were investigated, although the cortical area and cortical thickness had no marked changes in the mid-tibial and mid-femoral cortical bones. These results indicate that bone microstructural properties in SAMP6 are remarkably heterogeneous throughout the skeleton, which is analogous to changes that occur in human bones. These findings further validate the relevance of SAMP6 as a model of senile osteoporosis.

### **3.4.3 Human vertebral trabecular bone** μ**CT assessment**

The vertebral trabecular bone has a complex 3D microstructure, with inhomogeneous morphology. A thorough understanding of regional variations in the microstructural properties is crucial for evaluating age- and gender-related bone loss of the vertebra, and may help to gain more insight into the mechanism of the vertebral osteoporosis and the related fracture risks. Fifty-six fourth lumbar vertebral bodies from 28 women and men (57- 98 years of age) cadaver donors were studied. Both women and men were divided into 3 age groups, middle-aged, old age and elderly groups. Five cubic specimens were prepared from

Sophisticated Imaging Technology in the Assessment of Osteoporosis Risk 189

Fig. 4. Three-dimensional micro-CT image in different regions of the vertebral body from a woman aged 78 years: anterosuperior (a), anteroinferior (b), central (c), posterosuperior (d) and posteroinferior (e) regions. The trabecular bone is higher in the posterosuperior and posteroinferior regions than that of the central and anterosuperior regions (Chen et al.,

Femoral neck fracture, which is one of the most common outcomes of age-related and postmenopausal osteoporosis, is a significant cause of morbidity and mortality worldwide. Femoral neck fracture is attributed to both cortical and trabecular bone loss. The relative contribution of femoral neck cortical and trabecular bone to whole bone strength is unclear. We identified 3D microstructural changes of both cortical and trabecular bone simultaneously in human femoral neck from 57 to 98 years of age (Chen et al., 2010). The findings demonstrate that cortical thickness (Ct.Th) decreased by 10-15%, cortical porosity

The trabecular BV/TV declined by around 20% between the middle-aged and elderly groups. The most obvious age-related change in the femoral neck is the increase of Ca.V/TV. The decrease of BV/TV with age is more noticeable than that of Ct.Th. There was a significant inverse correlation between Ca.V/TV and BV/TV for both women and men. As compared with women, men had higher Ct.Th and BV/TV and lower Ca.V/TV. These findings may serve as reference for ethnic comparison with age and gender and may help to

(Ca.V/TV) almost doubled between the middle-aged and elderly groups (Fig. 5).

2008b)

**3.4.4 Human femoral neck** μ**CT assessment** 

gain more insight into femoral neck fracture risk.

anterosuperior, anteroinferior, central, posterosuperior and posteroinferior regions at sagittal section (Chen et al., 2008b). Bone specimens were examined by μCT and scanning electron microscope. The results showed that BV/TV, Tb.N and Conn.D decreased, while SMI increased significantly between middle-aged and old age groups, and between old age and elderly groups. As compared with women, men had higher Tb.N in the old age group, and higher Conn.D in the middle-aged and old age groups. The central and anterosuperior regions had lower BV/TV and Conn.D than their corresponding posteroinferior region (Fig. 4). Increased resorbing surfaces, perforated or disconnected trabeculae and microcallus formations were found with aging. Vertebral trabeculae are microstructurally heterogeneous. Decreases in BV/TV and Conn.D with age are similar in women and men. Significant differences between women and men are observed at some microstructural paramenters. Age-related vertebral trabecular bone loss may be caused by increased activity of resorption. These findings illustrate potential mechanisms underlying vertebral fractures.

Fig. 3. Micro-CT images representative the fourth lumbar vertebral body in SAMP6 and SAMR1 mice at 5 and 12 months of age. Compared with SAMR1, the trabecular bone is reduced in SAMP6 both at 5 and 12 months of age. Scale bar=0.5mm (Chen et al., 2009)

anterosuperior, anteroinferior, central, posterosuperior and posteroinferior regions at sagittal section (Chen et al., 2008b). Bone specimens were examined by μCT and scanning electron microscope. The results showed that BV/TV, Tb.N and Conn.D decreased, while SMI increased significantly between middle-aged and old age groups, and between old age and elderly groups. As compared with women, men had higher Tb.N in the old age group, and higher Conn.D in the middle-aged and old age groups. The central and anterosuperior regions had lower BV/TV and Conn.D than their corresponding posteroinferior region (Fig. 4). Increased resorbing surfaces, perforated or disconnected trabeculae and microcallus formations were found with aging. Vertebral trabeculae are microstructurally heterogeneous. Decreases in BV/TV and Conn.D with age are similar in women and men. Significant differences between women and men are observed at some microstructural paramenters. Age-related vertebral trabecular bone loss may be caused by increased activity of resorption. These findings illustrate potential mechanisms underlying vertebral fractures.

Fig. 3. Micro-CT images representative the fourth lumbar vertebral body in SAMP6 and SAMR1 mice at 5 and 12 months of age. Compared with SAMR1, the trabecular bone is reduced in SAMP6 both at 5 and 12 months of age. Scale bar=0.5mm (Chen et al., 2009)

Fig. 4. Three-dimensional micro-CT image in different regions of the vertebral body from a woman aged 78 years: anterosuperior (a), anteroinferior (b), central (c), posterosuperior (d) and posteroinferior (e) regions. The trabecular bone is higher in the posterosuperior and posteroinferior regions than that of the central and anterosuperior regions (Chen et al., 2008b)

#### **3.4.4 Human femoral neck** μ**CT assessment**

Femoral neck fracture, which is one of the most common outcomes of age-related and postmenopausal osteoporosis, is a significant cause of morbidity and mortality worldwide. Femoral neck fracture is attributed to both cortical and trabecular bone loss. The relative contribution of femoral neck cortical and trabecular bone to whole bone strength is unclear. We identified 3D microstructural changes of both cortical and trabecular bone simultaneously in human femoral neck from 57 to 98 years of age (Chen et al., 2010). The findings demonstrate that cortical thickness (Ct.Th) decreased by 10-15%, cortical porosity (Ca.V/TV) almost doubled between the middle-aged and elderly groups (Fig. 5).

The trabecular BV/TV declined by around 20% between the middle-aged and elderly groups. The most obvious age-related change in the femoral neck is the increase of Ca.V/TV. The decrease of BV/TV with age is more noticeable than that of Ct.Th. There was a significant inverse correlation between Ca.V/TV and BV/TV for both women and men. As compared with women, men had higher Ct.Th and BV/TV and lower Ca.V/TV. These findings may serve as reference for ethnic comparison with age and gender and may help to gain more insight into femoral neck fracture risk.

Sophisticated Imaging Technology in the Assessment of Osteoporosis Risk 191

compartment of the proximal tibial metaphyses were examined with μCT and scanning electron microscopy (Chen et al., 2011). It was shown that from 57 to 98 years of age, the trabecular BV/TV decreased by 6-7% and the trabecular BMD declined around 4% per decade at the proximal tibia. Figure 6 shows the typical 3D reconstructions of trabecular bone of the middle-aged and elderly groups for both women and men. The trabecular Tb.Th decreased between the middle-aged and elderly groups similarly in women and men. However, Tb.N decreased by 13% between the middle-aged and elderly groups in women and nearly doubled that in men. As compared with women, men had higher BV/TV and lower Tb.Sp in the old age and elderly groups, and higher Tb.N and Conn.D in the elderly group. Increased trabecular resorbing surfaces, perforated or disconnected trabeculae and microcallus formations were observed with age. These findings indicate that both BMD and BV/TV decreased at the proximal tibia with age similarly for women and men, but significant differences between women and men were observed for some microstructural parameters.

Fig. 6. Three-dimensional reconstructed images of trabecular microstructure at proximal tibia from a man aged 62 years (a), a man aged 92 years (b), a woman aged 62 years (c) and a woman aged 92 years (d). The trabecular bone volume fraction is highest in man aged 62

years and lowest in woman aged 92 years (Chen et al., 2011)

Fig. 5. Three-dimensional reconstructed images of the canal networks in the inferior femoral neck cortex from a man aged 62 years (a), a man aged 92 years (b), a woman aged 62 years (c) and a woman aged 92 years (d). There are more enlarged canals in the 92-year-old woman than that of the 62-year-old man. Representative two-dimensional micro-CT image of the femoral neck cortex from a woman aged 92 years (e) is shown. Periosteal surface faces right for all specimens (Chen et al., 2010)

#### **3.4.5 Human proximal tibia** μ**CT assessment**

The analyses of local trabecular microstructure have been mainly performed in regions most susceptible to fractures, such as spine, proximal femur and radius. Studies of the proximal tibia also have an important clinical significance, as it is fractured in aging patients, specifically those suffering from osteoporosis. The proximal tibia, with its rich trabecular network, can be used as a donor site for bone grafting and it is the most easily accessible site for quantification of BMD and bone microstructure. The trabecular bone specimens from the medial

Fig. 5. Three-dimensional reconstructed images of the canal networks in the inferior femoral neck cortex from a man aged 62 years (a), a man aged 92 years (b), a woman aged 62 years (c) and a woman aged 92 years (d). There are more enlarged canals in the 92-year-old woman than that of the 62-year-old man. Representative two-dimensional micro-CT image of the femoral neck cortex from a woman aged 92 years (e) is shown. Periosteal surface faces

The analyses of local trabecular microstructure have been mainly performed in regions most susceptible to fractures, such as spine, proximal femur and radius. Studies of the proximal tibia also have an important clinical significance, as it is fractured in aging patients, specifically those suffering from osteoporosis. The proximal tibia, with its rich trabecular network, can be used as a donor site for bone grafting and it is the most easily accessible site for quantification of BMD and bone microstructure. The trabecular bone specimens from the medial

right for all specimens (Chen et al., 2010)

**3.4.5 Human proximal tibia** μ**CT assessment** 

compartment of the proximal tibial metaphyses were examined with μCT and scanning electron microscopy (Chen et al., 2011). It was shown that from 57 to 98 years of age, the trabecular BV/TV decreased by 6-7% and the trabecular BMD declined around 4% per decade at the proximal tibia. Figure 6 shows the typical 3D reconstructions of trabecular bone of the middle-aged and elderly groups for both women and men. The trabecular Tb.Th decreased between the middle-aged and elderly groups similarly in women and men. However, Tb.N decreased by 13% between the middle-aged and elderly groups in women and nearly doubled that in men. As compared with women, men had higher BV/TV and lower Tb.Sp in the old age and elderly groups, and higher Tb.N and Conn.D in the elderly group. Increased trabecular resorbing surfaces, perforated or disconnected trabeculae and microcallus formations were observed with age. These findings indicate that both BMD and BV/TV decreased at the proximal tibia with age similarly for women and men, but significant differences between women and men were observed for some microstructural parameters.

Fig. 6. Three-dimensional reconstructed images of trabecular microstructure at proximal tibia from a man aged 62 years (a), a man aged 92 years (b), a woman aged 62 years (c) and a woman aged 92 years (d). The trabecular bone volume fraction is highest in man aged 62 years and lowest in woman aged 92 years (Chen et al., 2011)

Sophisticated Imaging Technology in the Assessment of Osteoporosis Risk 193

Boutroy, S.; Bouxsein, ML.; Munoz, F. & Delmas, PD. (2005) In vivo assessment of trabecular

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accelerated mouse (SAMP6): a murine model for senile osteoporosis. *Experimental* 

changes in three-dimensional microstructure of cortical and trabecular bone at the human femoral neck. *Osteoporosis International*, Vol.21, No.4, (April 2010), pp. 627-

dimensional microstructure of trabecular bone at the human proximal tibia with aging. *Histology and Histopathology*, Vol.26, No.5, (April 2011), pp. 563-570, ISSN

Reeve, J. (2009) Bone micro-architecture and determinants of strength in the radius and tibia: age-related changes in a population-based study of normal adults measured with high-resolution pQCT. *Osteoporosis International*, Vol.20, No.10,

X-ray radiographs of iliac bone is correlated with bone micro-CT. *Osteoporosis International,* Vol.17, No.3, (January 2006), pp. 447–454, ISSN 1433-2965 (Print);

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S. & Diederichs, G. (2010) Assessment of trabecular bone structure using MDCT: comparison of 64- and 320-slice CT using HR-pQCT as the reference standard. *European Radiology*, Vol.20, No.2, (February 2010), pp. 458–468, ISSN 0938-7994

*European Journal of Radiology*, Vol.71, No.3, (September 2009), pp. 392–397, ISSN

**6. References** 

(Electronic)

### **3.5 Magnetic resonance imaging (MRI)**

Magnetic resonance imaging (MRI) is a non-ionizing method that uses a strong magnetic field in combination with specialized sequences of radio-frequency pulses to generate highresolution 3D images of cortical and trabecular bone in vivo. Therefore, it is well suitable for assessing bone structure clinically (Link, 2010). With technical advances in MRI, such as optimized coil design, fast gradients, high gradients and high field strength, MRI scanners provide an in vivo spatial resolution close to the diameter of a single trabecula. MRI signal of trabecular bone itself is not visualized and trabeculae appear as a signal void, surrounded by high-intensity fatty bone marrows. As a result, the bone structure is assessed indirectly via measurements of the surrounding marrow and other soft tissues. Advances in the past decade have focused on image acquisition and analysis techniques to overcome inherent obstacles in MR imaging of bone. With the advent of parallel imaging, motion correlation techniques and new sequences, the limits of spatial resolution and scan time can be further overcome. This non-ionizing, 3D imaging technique is a very attractive tool to analyze trabecular bone structure, investigating bone structure and metabolism in osteoporosis or osteoarthritis. Various studies have been undertaken to optimize image acquisition and post processing, and to calibrate and validate measurements of the trabecular architecture. However, methods can be technically challenging to achieve and optimize.

### **4. Conclusion**

Bone fragility, composite description of bone's biomechanical properties, is directly related to bone's susceptibility to fracture and is inversely related to bone's fracture resistance. As fractures compromise the quality of life and shorten life expectancy, the sophisticated bone imaging modalities play an important role in clearly and accurately identifying the presence and features of fragility fractures. The analysis of bone mass and bone microstructure is an exciting field in the assessment of osteoporotic risk. With the recent advances in MRI and CT, including the introduction of clinical μCT, imaging of true bone structure is becoming more feasible. These non-invasive sophisticated imaging techniques help us to gain more insight into the potential mechanism of metabolic bone diseases, particularly osteoporosis. However, further research is required for improvements in reproducibility, standardization and clinical application of these methods. New technological advances may further refine the imaging of osteoporotic bone and assessment of fracture risk. Recently various computer-aided diagnosis systems were developed for assessment of osteoporosis risks. The dental clinics took numerous panoramic radiographs for examining dental diseases worldwide. Several investigators demonstrated significant associations between mandibular cortical indices on panoramic radiographs and BMD of the skeleton generally, such as the spine and femur, biochemical markers of bone turnover and risk of osteoporotic fractures (Taguchi, 2010). So the computer-aided diagnosis system, based on digital panoramic radiography, may offer a new triage screening for osteoporosis risk in the near future.

### **5. Acknowledgment**

The authors thank Dr. Ken-ichi Tezuka, Department of Tissue and Organ Development, Gifu University Graduate School of Medicine, for providing the micro-CT system used in this study.

### **6. References**

192 Osteoporosis

Magnetic resonance imaging (MRI) is a non-ionizing method that uses a strong magnetic field in combination with specialized sequences of radio-frequency pulses to generate highresolution 3D images of cortical and trabecular bone in vivo. Therefore, it is well suitable for assessing bone structure clinically (Link, 2010). With technical advances in MRI, such as optimized coil design, fast gradients, high gradients and high field strength, MRI scanners provide an in vivo spatial resolution close to the diameter of a single trabecula. MRI signal of trabecular bone itself is not visualized and trabeculae appear as a signal void, surrounded by high-intensity fatty bone marrows. As a result, the bone structure is assessed indirectly via measurements of the surrounding marrow and other soft tissues. Advances in the past decade have focused on image acquisition and analysis techniques to overcome inherent obstacles in MR imaging of bone. With the advent of parallel imaging, motion correlation techniques and new sequences, the limits of spatial resolution and scan time can be further overcome. This non-ionizing, 3D imaging technique is a very attractive tool to analyze trabecular bone structure, investigating bone structure and metabolism in osteoporosis or osteoarthritis. Various studies have been undertaken to optimize image acquisition and post processing, and to calibrate and validate measurements of the trabecular architecture.

However, methods can be technically challenging to achieve and optimize.

Bone fragility, composite description of bone's biomechanical properties, is directly related to bone's susceptibility to fracture and is inversely related to bone's fracture resistance. As fractures compromise the quality of life and shorten life expectancy, the sophisticated bone imaging modalities play an important role in clearly and accurately identifying the presence and features of fragility fractures. The analysis of bone mass and bone microstructure is an exciting field in the assessment of osteoporotic risk. With the recent advances in MRI and CT, including the introduction of clinical μCT, imaging of true bone structure is becoming more feasible. These non-invasive sophisticated imaging techniques help us to gain more insight into the potential mechanism of metabolic bone diseases, particularly osteoporosis. However, further research is required for improvements in reproducibility, standardization and clinical application of these methods. New technological advances may further refine the imaging of osteoporotic bone and assessment of fracture risk. Recently various computer-aided diagnosis systems were developed for assessment of osteoporosis risks. The dental clinics took numerous panoramic radiographs for examining dental diseases worldwide. Several investigators demonstrated significant associations between mandibular cortical indices on panoramic radiographs and BMD of the skeleton generally, such as the spine and femur, biochemical markers of bone turnover and risk of osteoporotic fractures (Taguchi, 2010). So the computer-aided diagnosis system, based on digital panoramic radiography, may offer a new triage screening for osteoporosis risk in the near future.

The authors thank Dr. Ken-ichi Tezuka, Department of Tissue and Organ Development, Gifu University Graduate School of Medicine, for providing the micro-CT system used in

**3.5 Magnetic resonance imaging (MRI)** 

**4. Conclusion** 

**5. Acknowledgment** 

this study.


**11** 

Zohreh Hamidi

*Islamic Republic of Iran* 

*Endocrinology and Metabolism Research Institute of Tehran University of Medical Sciences (EMRI-TUMS)* 

**What We Learn from Bone Complications in** 

**Congenital Diseases? Thalassemia, an Example** 

The thalassemias, a group of inherited disorders of hemoglobin synthesis, are the most common monogenetic diseases worldwide and are curable by bone marrow transplantation (BMT). Many patients achieve a lifelong disease-free period after BMT. This has focused attentions on disease and treatment complications, for example bone complications. Some of bone disorders occur before and after transplantation and some of them (osteoporosis) and their complications are life threatening. For a better understanding of the bone complications in thalassemia, a brief review of normal bone is required. However, because thalassemia is a curable congenital disease and with an ethical background, the investigation of bone disorders in thalassemic patients (before and after transplantation), can provide a model of calcium and bone metabolism. This model, based on clinical and research findings before and after transplantation, can enlighten factors affecting bone and mineral metabolism throughout the life (disease period and cure period can be considered as periods of bone loss and bone gain through-out the normal life). This model can help in the understanding and management of bone disorders in other bone diseases and in primary osteoporosis. As a resident of a country with a large population of thalassemic patients (Iran), it is author's special interest that such studies help these patients achieve a better quality of life and decrease the burden of this disease not only in Iran but also in other

The term thalassemia, has two components thalassa (sea) and haima (blood), both from Greek. Beta-thalassemia includes three main forms: thalassemia major ("Cooley's Anemia" or "Mediterranean Anemia"), Thalassemia Intermedia and Thalassemia Minor ("beta-thalassemia carrier", "beta-thalassemia trait" or "heterozygous beta-thalassemia") (Galanello & Origa, 2010).

The thalassemias, hereditary hematologic disorders, are caused by defective synthesis of one or more of the hemoglobin (Hb) chains (Muncie & Campbell, 2009). Hb molecule is a

In this review the author's focus is on β-thalassemia major and its bone complications.

**1. Introduction** 

countries worldwide.

**2.2 Definition** 

**2. What is thalassemia** 

**2.1 Disease name and synonyms** 


## **What We Learn from Bone Complications in Congenital Diseases? Thalassemia, an Example**

### Zohreh Hamidi

*Endocrinology and Metabolism Research Institute of Tehran University of Medical Sciences (EMRI-TUMS) Islamic Republic of Iran* 

### **1. Introduction**

194 Osteoporosis

Kokoroghiannis, C.; Charopoulos, I.; Lyritis, G.; Raptou, P.; Karachalios, T. & Papaioannou,

Lenchik, L.; Shi, R.; Register, TC.; Beck, SR.; Langefeld, CD. & Carr, JJ. (2004) Measurement

Link, TM. (2010) The Founder's Lecture 2009: advances in imaging of osteoporosis and

Link, T.; Vieth, V.; Stehling, C.; Lotter, A.; Beer, A.; Newitt, D. & Majumdar, S. (2003) High

McCollough, CH.; Guimarães, L. & Fletcher, JG. (2009) In defense of body CT. *American* 

Taguchi, A. (2010) Triage screening for osteoporosis in dental clinics using panoramic

Wasnich, RD. (1996) Vertebral fracture epidemiology. *Bone*, Vol.18, No.3 Suppl., (May 1996),

Vol.28, No.1, (January 2004), pp. 134-139, ISSN 0363-8715

0364-2348 (Print); 1432-2161 (Electronic)

(Print); 1546-3141 (Electronic)

(Print); 1601-0825 ( Electronic)

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ISSN 0938-7994 (Print); 1432-1084 (Electronic)

8756-3282

N. (2009) Correlation of pQCT bone strength index with mechanical testing in distraction osteogenesis. *Bone*, Vol.45, No.3, (Semptember 2009), pp. 512-516, ISSN

of trabecular bone mineral density in the thoracic spine using cardiac gated quantitative computed tomography. *Journal of Computer Assisted Tomograpgy*,

osteoarthritis. *Skeletal Radiology*, Vol.39, No.10, (October 2010), pp. 943–955, ISSN

resolution MRI versus Multislice spiral CT - Which technique depicts the trabecular bone structure best? *European Radiology*, Vol.13, No.4, (April 2003), pp. 663-671,

*Journal of Roentgenology,* Vol.193, No.1, (July 2009), pp. 28–39, ISSN 0361-803X

radiographs. *Oral Diseases*, Vol.16, No.4, (May 2010), pp. 316-327, ISSN 1354-523X

The thalassemias, a group of inherited disorders of hemoglobin synthesis, are the most common monogenetic diseases worldwide and are curable by bone marrow transplantation (BMT). Many patients achieve a lifelong disease-free period after BMT. This has focused attentions on disease and treatment complications, for example bone complications. Some of bone disorders occur before and after transplantation and some of them (osteoporosis) and their complications are life threatening. For a better understanding of the bone complications in thalassemia, a brief review of normal bone is required. However, because thalassemia is a curable congenital disease and with an ethical background, the investigation of bone disorders in thalassemic patients (before and after transplantation), can provide a model of calcium and bone metabolism. This model, based on clinical and research findings before and after transplantation, can enlighten factors affecting bone and mineral metabolism throughout the life (disease period and cure period can be considered as periods of bone loss and bone gain through-out the normal life). This model can help in the understanding and management of bone disorders in other bone diseases and in primary osteoporosis. As a resident of a country with a large population of thalassemic patients (Iran), it is author's special interest that such studies help these patients achieve a better quality of life and decrease the burden of this disease not only in Iran but also in other countries worldwide.

### **2. What is thalassemia**

### **2.1 Disease name and synonyms**

The term thalassemia, has two components thalassa (sea) and haima (blood), both from Greek. Beta-thalassemia includes three main forms: thalassemia major ("Cooley's Anemia" or "Mediterranean Anemia"), Thalassemia Intermedia and Thalassemia Minor ("beta-thalassemia carrier", "beta-thalassemia trait" or "heterozygous beta-thalassemia") (Galanello & Origa, 2010). In this review the author's focus is on β-thalassemia major and its bone complications.

### **2.2 Definition**

The thalassemias, hereditary hematologic disorders, are caused by defective synthesis of one or more of the hemoglobin (Hb) chains (Muncie & Campbell, 2009). Hb molecule is a

What We Learn from Bone Complications in Congenital Diseases? Thalassemia, an Example 197

rarely results from gross gene deletion. In addition to the variation in the phenotype resulting from allelic heterogeneity at the beta globin locus, the phenotype of betathalassemia can also be modified by the action of genetic factors mapping outside the globin

Fessas (1963), as cited in Sankaran & Nathan, 2010, described unbalanced globin chain synthesis, as the cause of the b-thalassemia syndromes. Intraerythroblastic inclusions of unpaired a-globin molecules , results disease manifestations (Sankaran & Nathan, 2010). Galanello & Origa explain two mechanisms for increase the clinical and hematological severity in beta-thalassemia heterozygote patients. In first mechanism, an excess of unassembled alpha chains (resulting in premature destruction of red blood cell precursors) is caused by the coinheritance of both heterozygous beta-thalassemia and triple or quadruple alpha globin gene arrangement, that increases the magnitude of the imbalance of alpha/non-alpha globin chain synthesis. In the other mechanism, premature destruction of red blood depends on the presence of a mutation in the beta globin gene, which causes extreme instability of the beta globin chains and the synthesis of truncated beta chain

Most individuals with the thalassemia trait are found incidentally when their complete blood count shows mild microcytic anemia. Hemoglobin electrophoresis with the beta

Individuals with beta halassemia major are diagnosed during infancy. Symptoms appear during the second six months of life. The most common symptoms are pallor, irritability, growth retardation, abdominal swelling, and jaundice. Beta thalassemia intermedia patients (with microcytic anemia, but milder symptoms) have start of disease later in their life (Muncie & Campbell, 2009). Genetic sideroblastic anemias, congenital dyserythropoietic anemias, and other conditions with high levels of HbF (such as juvenile myelomonocytic leukemia and

Hemolytic anemia, poor growth, and skeletal abnormalities during infancy, are major sign and symptoms of beta thalassemia major (Muncie & Campbell, 2009). Growth retardation, pallor, jaundice, poor musculature, hepatosplenomegaly, leg ulcers, the development of masses from extramedullary hematopoiesis, and skeletal changes (results of the bone marrow expansion) are found in untreated or poorly transfused individuals with thalassemia major (Galanello & Origa, 2010). Thalassemia major patients are diagnosed within the first 2 years and require regular blood transfusions to survive (Sankaran & Nathan, 2010). Iron overload is the result of regular blood transfusions. Complications of iron over load includs endocrine complications (growth retardation, failure of sexual maturation, diabetes mellitus, and insufficiency of the parathyroid, thyroid, pituitary, and less commonly, adrenal glands), dilated myocardiopathy, liver fibrosis and cirrhosis. Patients with thalassemia intermedia present later in life with moderate anemia and do not require regular transfusions. Though the thalassemia intermedia patients, come to medical attention later, may show an extended list of complications like hypertrophy of erythroid

aplastic anemia) are considered as differential diagnosis (Galanello & Origa, 2010).

gene cluster and not influencing fetal hemoglobin (Cao & Galanello, 2010).

**2.5 Pathophysiology of thalassemia** 

products (Galanello & Origa, 2010).

thalassemia trait usually has elevated levels of HbA2.

**2.7 Signs, symptoms and complications of thalassemia** 

**2.6 Diagnosis of thalassemia** 

tetramer composed of 4 -globin polypeptide ( 2 alpha-globin and 2 beta-globin) plus a heme prosthetic group, to form the complete molecule. In the α-thalassemias, defective production of α-globin chains results in an unstable Hb causes and mild to moderate hemolytic and hypochromic anemia (Sankaran & Nathan, 2010). Beta thalassemia is caused by reduced or absent synthesis of beta globin chains. Hemolysis and impaired erythropoiesis is the result of this imbalance of globin chains. Fatal hydrops fetalis, is seen in cases of Alpha thalassemia major with hemoglobin Bart's (Muncie & Campbell, 2009).

Beta-thalassemia minor (carrier state) patients , are clinically asymptomatic (they are diagnosed, generally accidental by specific hematological features). Thalassemia major patients are severely transfusion-dependent. Thalassemia intermedia patients, ranging in severity from the asymptomatic carrier patients to the severe transfusion-dependent patients (Cao & Galanello, 2010).

Galanello and Origa, in their article (Galanello & Origa, 2010) suggested the following classification:

	- Thalassemia major
	- Thalassemia intermedia
	- Thalassemia minor
	- HbC/Beta-thalassemia
	- HbE/Beta-thalassemia
	- HbS/Beta-thalassemia (clinical condition more similar to sickle cell disease than to thalassemia major or intermedia)
	- Beta-thalassemia-tricothiodystrophy
	- X-linked thrombocytopenia with thalassemia

### **2.3 Epidemiology of thalassemia**

The total annual incidence of symptomatic individuals is estimated to be 1 in 100,000 worldwide and 1 in 10,000 in the European Union (Galanello & Origa, 2010). Approximately 5% of the world's population has a globin variant, and only 1.7% has the alpha or beta thalassemia trait. Thalassemia affects men and women equally and occurs in approximately 4.4 of every 10,000 live births. Alpha thalassemia is most common in persons of African and Southeast Asian descent, and beta thalassemia occurs most often in persons of Mediterranean, African, and Southeast Asian descent. The thalassemia trait affects 5-30% of persons in these ethnic groups (Muncie & Campbell, 2009).

### **2.4 Genetics of thalassemia**

The extent of imbalance between the alpha and non-alpha globin chains, relates to the clinical severity of beta-thalassemia. Cao & Galanello suggest that the beta globin (HBB) gene maps in the short arm of chromosome 11, in a region also containing the delta globin gene, the embryonic epsilon gene, the fetal A-gamma and G-gamma genes, and a pseudogene (\_B1). Single nucleotide substitutions, deletions, or insertions of oligonucleotides that leads to frame shift, are the majority of mutations. Beta-thalassemia

rarely results from gross gene deletion. In addition to the variation in the phenotype resulting from allelic heterogeneity at the beta globin locus, the phenotype of betathalassemia can also be modified by the action of genetic factors mapping outside the globin gene cluster and not influencing fetal hemoglobin (Cao & Galanello, 2010).

### **2.5 Pathophysiology of thalassemia**

196 Osteoporosis

tetramer composed of 4 -globin polypeptide ( 2 alpha-globin and 2 beta-globin) plus a heme prosthetic group, to form the complete molecule. In the α-thalassemias, defective production of α-globin chains results in an unstable Hb causes and mild to moderate hemolytic and hypochromic anemia (Sankaran & Nathan, 2010). Beta thalassemia is caused by reduced or absent synthesis of beta globin chains. Hemolysis and impaired erythropoiesis is the result of this imbalance of globin chains. Fatal hydrops fetalis, is seen in cases of Alpha

Beta-thalassemia minor (carrier state) patients , are clinically asymptomatic (they are diagnosed, generally accidental by specific hematological features). Thalassemia major patients are severely transfusion-dependent. Thalassemia intermedia patients, ranging in severity from the asymptomatic carrier patients to the severe transfusion-dependent

Galanello and Origa, in their article (Galanello & Origa, 2010) suggested the following

HbS/Beta-thalassemia (clinical condition more similar to sickle cell disease than to

The total annual incidence of symptomatic individuals is estimated to be 1 in 100,000 worldwide and 1 in 10,000 in the European Union (Galanello & Origa, 2010). Approximately 5% of the world's population has a globin variant, and only 1.7% has the alpha or beta thalassemia trait. Thalassemia affects men and women equally and occurs in approximately 4.4 of every 10,000 live births. Alpha thalassemia is most common in persons of African and Southeast Asian descent, and beta thalassemia occurs most often in persons of Mediterranean, African, and Southeast Asian descent. The thalassemia trait affects 5-30%

The extent of imbalance between the alpha and non-alpha globin chains, relates to the clinical severity of beta-thalassemia. Cao & Galanello suggest that the beta globin (HBB) gene maps in the short arm of chromosome 11, in a region also containing the delta globin gene, the embryonic epsilon gene, the fetal A-gamma and G-gamma genes, and a pseudogene (\_B1). Single nucleotide substitutions, deletions, or insertions of oligonucleotides that leads to frame shift, are the majority of mutations. Beta-thalassemia

thalassemia major with hemoglobin Bart's (Muncie & Campbell, 2009).

patients (Cao & Galanello, 2010).

 Thalassemia major Thalassemia intermedia Thalassemia minor

 HbC/Beta-thalassemia HbE/Beta-thalassemia


**2.3 Epidemiology of thalassemia** 

**2.4 Genetics of thalassemia** 


thalassemia major or intermedia)

Beta-thalassemia-tricothiodystrophy



X-linked thrombocytopenia with thalassemia

of persons in these ethnic groups (Muncie & Campbell, 2009).

classification:


Fessas (1963), as cited in Sankaran & Nathan, 2010, described unbalanced globin chain synthesis, as the cause of the b-thalassemia syndromes. Intraerythroblastic inclusions of unpaired a-globin molecules , results disease manifestations (Sankaran & Nathan, 2010). Galanello & Origa explain two mechanisms for increase the clinical and hematological severity in beta-thalassemia heterozygote patients. In first mechanism, an excess of unassembled alpha chains (resulting in premature destruction of red blood cell precursors) is caused by the coinheritance of both heterozygous beta-thalassemia and triple or quadruple alpha globin gene arrangement, that increases the magnitude of the imbalance of alpha/non-alpha globin chain synthesis. In the other mechanism, premature destruction of red blood depends on the presence of a mutation in the beta globin gene, which causes extreme instability of the beta globin chains and the synthesis of truncated beta chain products (Galanello & Origa, 2010).

### **2.6 Diagnosis of thalassemia**

Most individuals with the thalassemia trait are found incidentally when their complete blood count shows mild microcytic anemia. Hemoglobin electrophoresis with the beta thalassemia trait usually has elevated levels of HbA2.

Individuals with beta halassemia major are diagnosed during infancy. Symptoms appear during the second six months of life. The most common symptoms are pallor, irritability, growth retardation, abdominal swelling, and jaundice. Beta thalassemia intermedia patients (with microcytic anemia, but milder symptoms) have start of disease later in their life (Muncie & Campbell, 2009). Genetic sideroblastic anemias, congenital dyserythropoietic anemias, and other conditions with high levels of HbF (such as juvenile myelomonocytic leukemia and aplastic anemia) are considered as differential diagnosis (Galanello & Origa, 2010).

### **2.7 Signs, symptoms and complications of thalassemia**

Hemolytic anemia, poor growth, and skeletal abnormalities during infancy, are major sign and symptoms of beta thalassemia major (Muncie & Campbell, 2009). Growth retardation, pallor, jaundice, poor musculature, hepatosplenomegaly, leg ulcers, the development of masses from extramedullary hematopoiesis, and skeletal changes (results of the bone marrow expansion) are found in untreated or poorly transfused individuals with thalassemia major (Galanello & Origa, 2010). Thalassemia major patients are diagnosed within the first 2 years and require regular blood transfusions to survive (Sankaran & Nathan, 2010). Iron overload is the result of regular blood transfusions. Complications of iron over load includs endocrine complications (growth retardation, failure of sexual maturation, diabetes mellitus, and insufficiency of the parathyroid, thyroid, pituitary, and less commonly, adrenal glands), dilated myocardiopathy, liver fibrosis and cirrhosis. Patients with thalassemia intermedia present later in life with moderate anemia and do not require regular transfusions. Though the thalassemia intermedia patients, come to medical attention later, may show an extended list of complications like hypertrophy of erythroid

What We Learn from Bone Complications in Congenital Diseases? Thalassemia, an Example 199

In United States and Europe (as developed countries), there are approximately 10,000 homozygous patients with thalassemia. In such countries, due to effective prevention methods, the number of new cases is progressively decreasing. The result of high-quality medical care is longer life expectancy and a relatively good quality of life. BMT and gene therapy, is performed in such countires. The need of Western cultures is to develop improved support for patients with thalassemia and their families (Rund & Rachmilewitz, 2005). In a recent study by Hamidi et al, in Iran, low bone mass was significantly less prevalent in thalassemic patients in comparison to previous studies (Hamidi et al, 2010). Good bone health in patients may also be due to better and developing health network services in Iran and in other countries with high populations of these patients, thus providing a good health service. In Iran there are more than 300 transplanted thalassemic

The treatment situation of thalassemia patients is different in less developed countries. It is very important because big population of thalassemic patients live there. Safe transfusion and chelation are not universally available. Consequently, many patients with thalassemia in underdeveloped nations die in childhood or adolescence (Rund & Rachmilewitz, 2005).

Following recent medical advances in transfusion, iron chelation and BMT therapy, prognosis in these patients has improved substantially in the last 20 years. However, the main cause of death in patients with iron overload, remains cardiac disease (Galanello & Origa, 2010).

 As a congenital disease, bone disorders in thalassemic patients are mainly due to bone growth problems and begin in childhood, thus a brief insight into normal bone growth

Schonau, explains the first phase of bone development so: in development period of embryo, the axial skeleton and extremities are initially in the form of cartilage. The first spontaneous mineralization occurs in the diaphysis. As a result of the activities of osteoclasts and osteoblasts, this mentioned tissue will be replaced by the mature bone matrix. Bones' longitudinal growth take place in the specialized epiphyseal growth plates in which chondrocytes synthesize cartilage matrix, that will be changed to primary and secondary spongiosa in the metaphyseal junction. The growth of The axial skeleton thickness happens due to periostal and endosteal growth(Schonau, 1998). Turn-over of the bones is necessary for either normal mineralized bone matrix maintenance or bone's growth. In healthy adults, resorption and formation of bones take place together in the remodeling process. Though this process is important for maintaining normal skeletal integrity, it does not have any role in changes in bone shape. Diversely, growth of childhood skeletal takes place in bone modeling, a process in which increased bone mass and changes in bone shape, happens. If bone resorption exceeds bone formation a problem occurred named Osteopenia. Which can occur in 2 different ways. It happens when bone resorption exceeds bone formation or when bone formation diminishes, but resorption is normal. (von Scheven, 2007). When muscular strength and parallel biomechanical usage increase, an increase in cortical thickness and area must be happened. The ratio of cortical thickness to bone

**2.9.4 Treatment of thalassemia in developed versus underdeveloped countries** 

patients (Abolghasemi et al., 2007; Ghavamzadeh, 2009).

and related matters are discussed in the following section.

**2.10 Prognosis in thalassemia** 

**3. Normal bone growth** 

**3.1 Normal bone development** 

marrow with medullary and extramedullary hematopoiesis and its complications (osteoporosis, masses of erythropoietic tissue that primarily affect the spleen, liver, lymph nodes, chest and spine, and bone deformities as well as typical facial changes), gallstones, painful leg ulcers and increased predisposition to thrombosis. Moderate anemia may be the only sign of thalassemia minor patients and they are in general, clinically asymptomatic (Galanello & Origa, 2010).

#### **2.8 Genetic counseling and prenatal diagnosis in thalassemia**

As there is big population of thalassemic patients in some countries and there is high carrier rate for thallassemic mutations in certain populations (explained before in part 2.3), population screening is ongoing in them. Availability of genetic counseling and prenatal diagnosis, makes such screening in these countries more usefull (Cao & Galanello, 2010) and use of prenatal diagnosis may be stressed in such countries (Galanello & Origa, 2010).

Analysis of DNA extracted from fetal cells obtained by amniocentesis (at 15–18 weeks gestation), in high-risk pregnancies in which both members are defined carriers of betathalassemia, is possible for prenatal diagnosis. Chorionic villus sampling is useful and is performed at approximately 10–12 weeks gestation (Cao & Galanello, 2010).

#### **2.9 Treatment of thalassemia**

Many patients with b-thalassemia, and some patients with severe forms of a-thalassemia, require regular transfusions to survive. In the case of b-thalassemia, this therapy has an important effect on reducing the massive ineffective erythropoiesis and organ infiltration and bone destruction that is seen in β-thalassemia patients that are untreated. (Sankaran & Nathan, 2010). With multiple transfusions, iron overload and organ failure (particularly cardiac iron overload and heart failure) are the leading causes of death (Au, 2011), Therefore, after 10–12 transfusions, chelation therapy (an effective but non-absorbable iron chelator, such as desferrioxamine B (DFO) with a short plasma half-life) is initiated 5–7 days a week by 12-hour continuous subcutaneous infusion via a portable pump (Cao & Galanello, 2010).

#### **2.9.1 Splenectomy**

Splenectomy is recommended if the annual red cell requirement exceeds 180-200 ml/kg of RBC (assuming that the Hct of the unit of red cells is about 75%). Symptoms of splenic enlargement, leukopenia and/or thrombocytopenia and increasing iron overload despite good chelation, are considered as other indication for splenectomy (Galanello & Origa, 2010).

#### **2.9.2 Bone marrow transplantation (BMT) in thalassemia**

It is explained extensively in part 5.

#### **2.9.3 Therapies under investigation in thalassemia**

The potential of new chelation strategies, including combination or alternate treatment with available chelators, induction of HbF synthesis that can reduce the severity of betathalassemia by improving the imbalance between alpha and non-alpha globin chains, several pharmacologic compounds including 5-azacytidine, decytabine, butyrate derivatives and gene therapy in the management of beta-thalassemia syndromes are described by Cao and Galanello, Sankaran and Nathan as under investigation therapies (Cao & Galanello, 2010; Sankaran & Nathan, 2010).

### **2.9.4 Treatment of thalassemia in developed versus underdeveloped countries**

In United States and Europe (as developed countries), there are approximately 10,000 homozygous patients with thalassemia. In such countries, due to effective prevention methods, the number of new cases is progressively decreasing. The result of high-quality medical care is longer life expectancy and a relatively good quality of life. BMT and gene therapy, is performed in such countires. The need of Western cultures is to develop improved support for patients with thalassemia and their families (Rund & Rachmilewitz, 2005). In a recent study by Hamidi et al, in Iran, low bone mass was significantly less prevalent in thalassemic patients in comparison to previous studies (Hamidi et al, 2010). Good bone health in patients may also be due to better and developing health network services in Iran and in other countries with high populations of these patients, thus providing a good health service. In Iran there are more than 300 transplanted thalassemic patients (Abolghasemi et al., 2007; Ghavamzadeh, 2009).

The treatment situation of thalassemia patients is different in less developed countries. It is very important because big population of thalassemic patients live there. Safe transfusion and chelation are not universally available. Consequently, many patients with thalassemia in underdeveloped nations die in childhood or adolescence (Rund & Rachmilewitz, 2005).

### **2.10 Prognosis in thalassemia**

198 Osteoporosis

marrow with medullary and extramedullary hematopoiesis and its complications (osteoporosis, masses of erythropoietic tissue that primarily affect the spleen, liver, lymph nodes, chest and spine, and bone deformities as well as typical facial changes), gallstones, painful leg ulcers and increased predisposition to thrombosis. Moderate anemia may be the only sign of thalassemia minor patients and they are in general, clinically asymptomatic

As there is big population of thalassemic patients in some countries and there is high carrier rate for thallassemic mutations in certain populations (explained before in part 2.3), population screening is ongoing in them. Availability of genetic counseling and prenatal diagnosis, makes such screening in these countries more usefull (Cao & Galanello, 2010) and use of prenatal diagnosis may be stressed in such countries (Galanello & Origa, 2010). Analysis of DNA extracted from fetal cells obtained by amniocentesis (at 15–18 weeks gestation), in high-risk pregnancies in which both members are defined carriers of betathalassemia, is possible for prenatal diagnosis. Chorionic villus sampling is useful and is

Many patients with b-thalassemia, and some patients with severe forms of a-thalassemia, require regular transfusions to survive. In the case of b-thalassemia, this therapy has an important effect on reducing the massive ineffective erythropoiesis and organ infiltration and bone destruction that is seen in β-thalassemia patients that are untreated. (Sankaran & Nathan, 2010). With multiple transfusions, iron overload and organ failure (particularly cardiac iron overload and heart failure) are the leading causes of death (Au, 2011), Therefore, after 10–12 transfusions, chelation therapy (an effective but non-absorbable iron chelator, such as desferrioxamine B (DFO) with a short plasma half-life) is initiated 5–7 days a week by 12-hour

Splenectomy is recommended if the annual red cell requirement exceeds 180-200 ml/kg of RBC (assuming that the Hct of the unit of red cells is about 75%). Symptoms of splenic enlargement, leukopenia and/or thrombocytopenia and increasing iron overload despite good chelation, are considered as other indication for splenectomy (Galanello & Origa, 2010).

The potential of new chelation strategies, including combination or alternate treatment with available chelators, induction of HbF synthesis that can reduce the severity of betathalassemia by improving the imbalance between alpha and non-alpha globin chains, several pharmacologic compounds including 5-azacytidine, decytabine, butyrate derivatives and gene therapy in the management of beta-thalassemia syndromes are described by Cao and Galanello, Sankaran and Nathan as under investigation therapies (Cao & Galanello,

**2.8 Genetic counseling and prenatal diagnosis in thalassemia** 

performed at approximately 10–12 weeks gestation (Cao & Galanello, 2010).

continuous subcutaneous infusion via a portable pump (Cao & Galanello, 2010).

**2.9.2 Bone marrow transplantation (BMT) in thalassemia** 

**2.9.3 Therapies under investigation in thalassemia** 

(Galanello & Origa, 2010).

**2.9 Treatment of thalassemia** 

**2.9.1 Splenectomy** 

It is explained extensively in part 5.

2010; Sankaran & Nathan, 2010).

Following recent medical advances in transfusion, iron chelation and BMT therapy, prognosis in these patients has improved substantially in the last 20 years. However, the main cause of death in patients with iron overload, remains cardiac disease (Galanello & Origa, 2010).

 As a congenital disease, bone disorders in thalassemic patients are mainly due to bone growth problems and begin in childhood, thus a brief insight into normal bone growth and related matters are discussed in the following section.

### **3. Normal bone growth**

### **3.1 Normal bone development**

Schonau, explains the first phase of bone development so: in development period of embryo, the axial skeleton and extremities are initially in the form of cartilage. The first spontaneous mineralization occurs in the diaphysis. As a result of the activities of osteoclasts and osteoblasts, this mentioned tissue will be replaced by the mature bone matrix. Bones' longitudinal growth take place in the specialized epiphyseal growth plates in which chondrocytes synthesize cartilage matrix, that will be changed to primary and secondary spongiosa in the metaphyseal junction. The growth of The axial skeleton thickness happens due to periostal and endosteal growth(Schonau, 1998). Turn-over of the bones is necessary for either normal mineralized bone matrix maintenance or bone's growth. In healthy adults, resorption and formation of bones take place together in the remodeling process. Though this process is important for maintaining normal skeletal integrity, it does not have any role in changes in bone shape. Diversely, growth of childhood skeletal takes place in bone modeling, a process in which increased bone mass and changes in bone shape, happens. If bone resorption exceeds bone formation a problem occurred named Osteopenia. Which can occur in 2 different ways. It happens when bone resorption exceeds bone formation or when bone formation diminishes, but resorption is normal. (von Scheven, 2007). When muscular strength and parallel biomechanical usage increase, an increase in cortical thickness and area must be happened. The ratio of cortical thickness to bone

What We Learn from Bone Complications in Congenital Diseases? Thalassemia, an Example 201

formation, thus limiting the medullary space. In contrast, in boys, androgens stimulate periosteal formation, bone diameter, and cortical thickness (Rabinovich, 2004). Also, van Kuijk suggests that, both the starting age of the pubertal spurt and the growth process happens earlier in girls, but the duration of the growth spurt and the maximal peak of growth are greater in boys. Increase in bone density starts around the age of 10 in girls and

As Marini and Brandi categorized in their 2010 article (Marini & Brandi, 2010), the main osteoporosis candidate genes are: Calciotrophic and sex hormones and their receptors ((i) Vitamin D receptor (VDR), (ii) Parathyroid hormone (PTH) and PTH receptor (PTHR), (iii) Estrogen Receptor Alpha and Beta (ERα and ERβ), (iv) Calcitonin (CT) and its receptor (CTR), (v) Aromatase (CYP19A1), (vi) Androgen receptor (AR), (vii) Calcium-sensing receptor (CaSR), (viii) Glucocorticoid receptor (GR)), cytokines, growth factors and local regulators ((i) Interleukin-6 (IL6), (ii) Insulin-like growth factor 1 (IGF-I), (iii) Transforming growth factor β1 (TGFβ-1), (iv) Bone morphogenetic protein 7 (BMP7, OP1), (v) Bone morphogenetic protein 4 (BMP4), (vi) Bone morphogenetic protein 2 (BMP2)), Bone matrix proteins ((i) Collagen type I alpha1 (COLIA1), (ii) Collagen type I alpha2 (COLI-A2), (iii) Osteopontin (OPN, SPP1), (iv) Osteocalcin (OCN, BGLAP), (v) Osteonectin (ON, SPARC)) and miscellaneous genes such as (i) Low-density lipoprotein receptor-related protein 5 (LRP5), (ii) Low-density lipoprotein receptor-related protein 6 (LRP6), (iii) Receptor activator of nuclear factor kappa B (RANK), (iv) RANK ligand (RANKL), (v) Osteoprotegerin (OPG), (vi) Sclerotin (SOST), (vii) Chloride channel 7(CLCN7) and (viii)

Congenital connective tissue disorders such as osteogenesis imperfecta and Ehler–Danlos syndrome are important causes of pediatric osteoporosis. Neuromuscular disorders (cerebral palsy and Duchenne muscular dystrophy), childhood cancer, endocrine disorders (Turner Syndrome and juvenile diabetes mellitus), and inborn errors of metabolism (Gaucher disease) and chronic diseases like thalassemia are secondary causes of pediatric osteoporosis include. Don't forget pharmacological treatment, that are used for treatment of common pediatric conditions (iatrogenic causes. Among these, Glucocorticoids and anticonvulsants are known causes. Some add various forms of chemotherapy to this list (Bogunovic et al., 2009). However idiopathic juvenile osteoporosis is an acknowledged cause of osteoporosis in children and may it is the cause of a higher than expected prevalence of

Bone density measurement by dual energy X-ray absorptiometry (DEXA) the standard method for bone mineral Densitometry. It is also one of most non-invasive techniques for the assessment of bone mass (Hamidi et al., 2008). Not surprising, it is used for many pediatric studies that produced many papers in the field of bone densitometry and in body composition (Van Kuijk, 2010). The WHO based the diagnosis of postmenopausal osteoporosis on the presence of a BMD T-score of 2.5 or greater below the mean for young women (Hamidi et al., 2008). The term "low bone mineral density for age" was mentioned

Methylenetetrahydrofolate reductase (MTHFR) (Marini &Brandi, 2010).

around the age of 12 in boys. (Van Kuijk, 2010).

**3.4 Genetics of low bone mass** 

**3.5 Low bone mass in pediatrics** 

inadequate BMD in the pediatric population.

**3.6 Problems with DXA in pediatrics** 

diameter (corticalis index) increases as child grows up (Schonau, 1998). The velocity of increase of bone density in children, mostly mimics height growth velocity. It means, a first gradual phase of bone acquisition happens in early childhood and a more accelerated phase of accumulation, approximately 8% per year, occurs during adolescence. (von Scheven, 2007). A decrease phase of bone density happens after 20 or 30 years old, before that, bones mass increases to peak bone mass (PBM). Schonau, suggests that the percentage of ash weight of the individual skeletal sections however does not change significantly with age. On the other hand, physiological content of mature bone tissue (matrix plus minerals) does not change essentially with age and represents a kind of "constant." Morogulis (1931) as cited in Schonau, 1998 , also showed that the calcium and phosphate contents of the of very different animal species's skeletal systems were nearly the same . In contrast the water content does change. Up to years 20 the water content in bone tissue decreases . It is because of the high vascularity of the bones during the elevated phase of remodeling and modeling processes in growth time. It decreases later. (Schonau, 1998).

#### **3.2 How peak bone mass is gained**

The increase of total skeletal calcium(from approximately 25 g at birth to 900 and 1200 g in adult females and males, respectively), is gotten through bone growth, modeling and remodeling, which proceed at different rates at various skeletal sites. (Rabinovich, 2004). During childhood and adolescence, changes in size and shape of the skeleton happens together. And also bone grow up in width and and cortical thickness. Genetic, hormonal and environmental factors influence all these processes. (Bianchi, 2007). Bone mass increase is faster in adolescence , 25% of the PBM acquired during the two-year period close to peak height velocity. Rabinovich suggests that maximal rates of bone mineral accrual lag behind peak height velocity by 6–12 months, resulting in relatively undermineralized bone and increased fracture risk in the peri-pubertal years. At peak height velocity, males and females have reached 90% of their adult stature but have acquired only 57% of their adult total body bone mineral content (BMC). Bone mineral accrual continues after linear growth is complete, but the timing of PBM remains debatable (Rabinovich, 2004). About 85% of human skeleton is cortical bone and 15% is trabecular. The bone gain and loss during growth or in later age affects these 2 parts, in different ways. Hormonal/metabolic factors influence strongly the trabecular bone density througout the sexual maturation. Cortical bone consolidates slower. Bianchi states that Although the timing of peak values has not been precisely determined, the PBM is probably reached at the end of the second decade in the axial skeleton (predominantly trabecular bone), but only later in the appendicular skeleton (predominantly cortical bone) (Bianchi, 2007). Rabinovich says that is suggested that, though at least 90% of PBM is achieved by age 18, 5–12% of bone mineral density is reached during the third decade (Rabinovich, 2004). Heritable factors is supposed to attribute to approximately 60–80% of the variations in peak bone mass(Bachrach, 2001), Bianchi results that these changes are not only continuous, but also subject to great individual variation, mostly related to the variability of pubertal development, and this is essential for the correct evaluation of BMD in young subjects (Bianchi, 2007).

#### **3.3 Gender differences**

Rabinovich explains difference between girls and boys in growing bone: during puberty, estrogen in girls inhibits periosteal formation while stimulating endocortical bone formation, thus limiting the medullary space. In contrast, in boys, androgens stimulate periosteal formation, bone diameter, and cortical thickness (Rabinovich, 2004). Also, van Kuijk suggests that, both the starting age of the pubertal spurt and the growth process happens earlier in girls, but the duration of the growth spurt and the maximal peak of growth are greater in boys. Increase in bone density starts around the age of 10 in girls and around the age of 12 in boys. (Van Kuijk, 2010).

### **3.4 Genetics of low bone mass**

200 Osteoporosis

diameter (corticalis index) increases as child grows up (Schonau, 1998). The velocity of increase of bone density in children, mostly mimics height growth velocity. It means, a first gradual phase of bone acquisition happens in early childhood and a more accelerated phase of accumulation, approximately 8% per year, occurs during adolescence. (von Scheven, 2007). A decrease phase of bone density happens after 20 or 30 years old, before that, bones mass increases to peak bone mass (PBM). Schonau, suggests that the percentage of ash weight of the individual skeletal sections however does not change significantly with age. On the other hand, physiological content of mature bone tissue (matrix plus minerals) does not change essentially with age and represents a kind of "constant." Morogulis (1931) as cited in Schonau, 1998 , also showed that the calcium and phosphate contents of the of very different animal species's skeletal systems were nearly the same . In contrast the water content does change. Up to years 20 the water content in bone tissue decreases . It is because of the high vascularity of the bones during the elevated phase of remodeling and modeling

The increase of total skeletal calcium(from approximately 25 g at birth to 900 and 1200 g in adult females and males, respectively), is gotten through bone growth, modeling and remodeling, which proceed at different rates at various skeletal sites. (Rabinovich, 2004). During childhood and adolescence, changes in size and shape of the skeleton happens together. And also bone grow up in width and and cortical thickness. Genetic, hormonal and environmental factors influence all these processes. (Bianchi, 2007). Bone mass increase is faster in adolescence , 25% of the PBM acquired during the two-year period close to peak height velocity. Rabinovich suggests that maximal rates of bone mineral accrual lag behind peak height velocity by 6–12 months, resulting in relatively undermineralized bone and increased fracture risk in the peri-pubertal years. At peak height velocity, males and females have reached 90% of their adult stature but have acquired only 57% of their adult total body bone mineral content (BMC). Bone mineral accrual continues after linear growth is complete, but the timing of PBM remains debatable (Rabinovich, 2004). About 85% of human skeleton is cortical bone and 15% is trabecular. The bone gain and loss during growth or in later age affects these 2 parts, in different ways. Hormonal/metabolic factors influence strongly the trabecular bone density througout the sexual maturation. Cortical bone consolidates slower. Bianchi states that Although the timing of peak values has not been precisely determined, the PBM is probably reached at the end of the second decade in the axial skeleton (predominantly trabecular bone), but only later in the appendicular skeleton (predominantly cortical bone) (Bianchi, 2007). Rabinovich says that is suggested that, though at least 90% of PBM is achieved by age 18, 5–12% of bone mineral density is reached during the third decade (Rabinovich, 2004). Heritable factors is supposed to attribute to approximately 60–80% of the variations in peak bone mass(Bachrach, 2001), Bianchi results that these changes are not only continuous, but also subject to great individual variation, mostly related to the variability of pubertal development, and this is

essential for the correct evaluation of BMD in young subjects (Bianchi, 2007).

Rabinovich explains difference between girls and boys in growing bone: during puberty, estrogen in girls inhibits periosteal formation while stimulating endocortical bone

processes in growth time. It decreases later. (Schonau, 1998).

**3.2 How peak bone mass is gained** 

**3.3 Gender differences** 

As Marini and Brandi categorized in their 2010 article (Marini & Brandi, 2010), the main osteoporosis candidate genes are: Calciotrophic and sex hormones and their receptors ((i) Vitamin D receptor (VDR), (ii) Parathyroid hormone (PTH) and PTH receptor (PTHR), (iii) Estrogen Receptor Alpha and Beta (ERα and ERβ), (iv) Calcitonin (CT) and its receptor (CTR), (v) Aromatase (CYP19A1), (vi) Androgen receptor (AR), (vii) Calcium-sensing receptor (CaSR), (viii) Glucocorticoid receptor (GR)), cytokines, growth factors and local regulators ((i) Interleukin-6 (IL6), (ii) Insulin-like growth factor 1 (IGF-I), (iii) Transforming growth factor β1 (TGFβ-1), (iv) Bone morphogenetic protein 7 (BMP7, OP1), (v) Bone morphogenetic protein 4 (BMP4), (vi) Bone morphogenetic protein 2 (BMP2)), Bone matrix proteins ((i) Collagen type I alpha1 (COLIA1), (ii) Collagen type I alpha2 (COLI-A2), (iii) Osteopontin (OPN, SPP1), (iv) Osteocalcin (OCN, BGLAP), (v) Osteonectin (ON, SPARC)) and miscellaneous genes such as (i) Low-density lipoprotein receptor-related protein 5 (LRP5), (ii) Low-density lipoprotein receptor-related protein 6 (LRP6), (iii) Receptor activator of nuclear factor kappa B (RANK), (iv) RANK ligand (RANKL), (v) Osteoprotegerin (OPG), (vi) Sclerotin (SOST), (vii) Chloride channel 7(CLCN7) and (viii) Methylenetetrahydrofolate reductase (MTHFR) (Marini &Brandi, 2010).

### **3.5 Low bone mass in pediatrics**

Congenital connective tissue disorders such as osteogenesis imperfecta and Ehler–Danlos syndrome are important causes of pediatric osteoporosis. Neuromuscular disorders (cerebral palsy and Duchenne muscular dystrophy), childhood cancer, endocrine disorders (Turner Syndrome and juvenile diabetes mellitus), and inborn errors of metabolism (Gaucher disease) and chronic diseases like thalassemia are secondary causes of pediatric osteoporosis include. Don't forget pharmacological treatment, that are used for treatment of common pediatric conditions (iatrogenic causes. Among these, Glucocorticoids and anticonvulsants are known causes. Some add various forms of chemotherapy to this list (Bogunovic et al., 2009). However idiopathic juvenile osteoporosis is an acknowledged cause of osteoporosis in children and may it is the cause of a higher than expected prevalence of inadequate BMD in the pediatric population.

### **3.6 Problems with DXA in pediatrics**

Bone density measurement by dual energy X-ray absorptiometry (DEXA) the standard method for bone mineral Densitometry. It is also one of most non-invasive techniques for the assessment of bone mass (Hamidi et al., 2008). Not surprising, it is used for many pediatric studies that produced many papers in the field of bone densitometry and in body composition (Van Kuijk, 2010). The WHO based the diagnosis of postmenopausal osteoporosis on the presence of a BMD T-score of 2.5 or greater below the mean for young women (Hamidi et al., 2008). The term "low bone mineral density for age" was mentioned

What We Learn from Bone Complications in Congenital Diseases? Thalassemia, an Example 203

and development. As it is believed that one-third to one-half of the total mineralization in the lumbar spine in adult women is accumulated during the 3 years around the onset of puberty. Therefore Rabinovich concludes that, comparing the BMD of a well-grown 13-yearold girl who is in mid-puberty with that of a small pre-pubertal 13-year-old with juvenile arthritis is fraught with problems. She suggests that a DXA scan is not needed to tell who has the lower BMD. The question then is, is the BMD finding in this small pre-pubertal girl normal? (Rabinovich, 2004). As van Kuijk suggested, children with chronic disorders or medication, should never be compared with age-matched reference (normal) values. They should be compared with children with the same maturation status (skeletal age) (Van

Fragility fractures are raising in pediatric population. This may be due to growing number of chronic disease in this population. It caused the increase of use of DXA in children. Healthy children with frequent fragility fracture, have been the focus of research. This is changing, may be because escalating of children with chronic diseases and fragility fractures. When an atraumatic event, cause fracture, fragility fracture come true. The difficulty looms here because as Bogunovic et al state, in young children especially, distinction between traumatic and atraumatic fractures may prove to be a challenge (Bogunovic et al., 2009). Other side of this problem, appear there, when there are many papers on fractures in childhood, but very few of these focus to identify fragility fractures, and fewer focused on the concept of osteoporosis in the young in relation to fractures. Bianchi reminds us that fractures, especially in infants, and especially if multiple or repeated, may be the consequence of violence and child abuse. However, fractures are common events in children. Landin, 1997, as cited in Bianchi, 2007, estimated that 42% of boys and 27% of girls sustain a fracture between 0 and 16 years of age. The must fractures in them, occurs between 10 and 15 years and forearm is the most common site (Bianchi, 2007). Is low BMD a risk factor for fractures? Bone mass may contribute to fracture risk in childhood (Bogunovic et al., 2009). Adverse reactions to cow milk, low dietary calcium intake, early age at first fracture, asthma and overweight (Goulding et al., 2005), and low physical activity are suggested as risk factors for fractures in children. Others suggested that lower BMD for body size, lower milk intake and lower physical activity related with recurrent fractures (Manias et al., 2006). Carbonated beverages also had some relations to fragility fractures. In children with chronic diseases, no systematically collected data is available. Bianchi reviewed that and suggested that some studies found no significant differences in the fracture rate between patients and controls. In contrast, many studies found an increased fracture risk in children affected by various diseases such as acute lymphoblastic leukemia, cerebral palsy, celiac

disease, organ transplantation and glucocorticoids users (Bianchi, 2007).

Unfortunately, though general measures (optimizing the intake of calories, vitamin D and calcium; providing appropriate weight-bearing activity; replacing GH or sex steroids; and minimizing doses of glucocorticoids) are recommended for better acquisition and maintaining of bone mass in children, they may not be sufficient to prevent or restore deficits in bone mass. Anti-resorptive agents (eg. Bisphosphonates), found valuable in treating some disorders, such as steroid-induced osteoporosis. In steroid-induced

**3.8 Treatment of low bone mass in children** 

Kuijk, 2010).

**3.7 Fractures in pediatrics** 

at the "2007 ISCD Pediatric Position Development Conference" as a criterion for low bone mass in children, and is described as a child with a Z-score below -2.0. The difference between adult and pediatric criterion for low bone mass is that children have not reached PBM, yet. Instead, a child's Z-score (comparison of BMD of patient to age and sex matched normal children in reference data of pediatric software) must be noticed. (Daniels et al., 2003). However, must not forget that DXA has challenging aspects in pediatrics densitometry. True bone density is defined as BMC (g) divided by volume (cm3). Bogunovic explains that as DXA is a 2-dimentional projectional technique. In DXA , a two-dimensional projection, measures a three-dimensional object, bone. As a result, the BMD measured by DXA is defined as BMC (g) divided by the projected area (cm2) not devided by the projected volume (cm3). As a consequence of this area measurement of density, smaller bones appear to have a lower BMD than larger bones (Bogunovic et al., 2009). Van Kuijk, reminds us that in adults, bone size does not change over time. In contrast, bone size changes in growing children in 3 dimensions. When measuring children using DXA and following them over time, growth is measured more than actual changes in bone density (Van Kuijk, 2010). Another challenge, as Bogunovic believes is that the assignment of DXA Z-scores is dependent on the comparison of the patient's BMD to normative childhood data for age and sex. The wide variation in height, and, therefore, of bone size in children complicates the interpretation of BMD results especially in short children. Longitudinal evaluation of a given patient over time is complicated by the ever-changing size of the growing skeleton. Furthermore, the rates of skeletal growth vary with each bony dimension (Bogunovic et al., 2009). All these problems, pose a question: To Do or Not to Do DXA for the measurement of bone density and fracture risk in children? In response we must remember some points related to DXA, 1) patients are exposed to less radiation when measuring BMD by DXA, which is very important in children, 2) it is less fearful for children (less noisy with no tunnel) 3) DEXA is used worldwide and many pediatric studies have been published in the field of bone densitometry and in body composition studies, by using this method and 4) Studies suggest that bone mass may contribute to fracture risk in childhood (Van Kuijk, 2010). Therefore, the answer may be that carrying out DXA for the measurement of bone density and fracture risk in children, is a helpful method, although, it must be remembered, as Bogunovic reminds us, that bone fragility in children extends beyond a single BMD measurement and is influenced by bone geometry and body size and the diagnosis of osteoporosis requires the presence of both a clinically significant fracture history and low bone mass (Bogunovic et al., 2009).

#### **3.6.1 Special considerations in the comparison of normal children and children with chronic disease, some points on the BMD of chronically ill children**

As explained above, the measurement of BMC (g/cm) and BMD (g/cm2) are not only dependent on the mineral density of cortical and spongious bone, but also on the geometric configuration. This situation is of great importance in pediatrics. Schonau concludes that if BMC or BMD measurement results in decreased values for children with short stature (e. g., with "smaller bones"), this does not necessarily describe a mineral deficiency or a mineralization disorder, as is often thought (Schonau, 1998). Wide variation in age at onset and progression of puberty is another problem. It means a wide variation in the age at attainment of PBM. Some diseases, like juvenile arthritis, is thought to delay pubertal onset and development. As it is believed that one-third to one-half of the total mineralization in the lumbar spine in adult women is accumulated during the 3 years around the onset of puberty. Therefore Rabinovich concludes that, comparing the BMD of a well-grown 13-yearold girl who is in mid-puberty with that of a small pre-pubertal 13-year-old with juvenile arthritis is fraught with problems. She suggests that a DXA scan is not needed to tell who has the lower BMD. The question then is, is the BMD finding in this small pre-pubertal girl normal? (Rabinovich, 2004). As van Kuijk suggested, children with chronic disorders or medication, should never be compared with age-matched reference (normal) values. They should be compared with children with the same maturation status (skeletal age) (Van Kuijk, 2010).

### **3.7 Fractures in pediatrics**

202 Osteoporosis

at the "2007 ISCD Pediatric Position Development Conference" as a criterion for low bone mass in children, and is described as a child with a Z-score below -2.0. The difference between adult and pediatric criterion for low bone mass is that children have not reached PBM, yet. Instead, a child's Z-score (comparison of BMD of patient to age and sex matched normal children in reference data of pediatric software) must be noticed. (Daniels et al., 2003). However, must not forget that DXA has challenging aspects in pediatrics densitometry. True bone density is defined as BMC (g) divided by volume (cm3). Bogunovic explains that as DXA is a 2-dimentional projectional technique. In DXA , a two-dimensional projection, measures a three-dimensional object, bone. As a result, the BMD measured by DXA is defined as BMC (g) divided by the projected area (cm2) not devided by the projected volume (cm3). As a consequence of this area measurement of density, smaller bones appear to have a lower BMD than larger bones (Bogunovic et al., 2009). Van Kuijk, reminds us that in adults, bone size does not change over time. In contrast, bone size changes in growing children in 3 dimensions. When measuring children using DXA and following them over time, growth is measured more than actual changes in bone density (Van Kuijk, 2010). Another challenge, as Bogunovic believes is that the assignment of DXA Z-scores is dependent on the comparison of the patient's BMD to normative childhood data for age and sex. The wide variation in height, and, therefore, of bone size in children complicates the interpretation of BMD results especially in short children. Longitudinal evaluation of a given patient over time is complicated by the ever-changing size of the growing skeleton. Furthermore, the rates of skeletal growth vary with each bony dimension (Bogunovic et al., 2009). All these problems, pose a question: To Do or Not to Do DXA for the measurement of bone density and fracture risk in children? In response we must remember some points related to DXA, 1) patients are exposed to less radiation when measuring BMD by DXA, which is very important in children, 2) it is less fearful for children (less noisy with no tunnel) 3) DEXA is used worldwide and many pediatric studies have been published in the field of bone densitometry and in body composition studies, by using this method and 4) Studies suggest that bone mass may contribute to fracture risk in childhood (Van Kuijk, 2010). Therefore, the answer may be that carrying out DXA for the measurement of bone density and fracture risk in children, is a helpful method, although, it must be remembered, as Bogunovic reminds us, that bone fragility in children extends beyond a single BMD measurement and is influenced by bone geometry and body size and the diagnosis of osteoporosis requires the presence of both a clinically significant fracture history and low

**3.6.1 Special considerations in the comparison of normal children and children with** 

As explained above, the measurement of BMC (g/cm) and BMD (g/cm2) are not only dependent on the mineral density of cortical and spongious bone, but also on the geometric configuration. This situation is of great importance in pediatrics. Schonau concludes that if BMC or BMD measurement results in decreased values for children with short stature (e. g., with "smaller bones"), this does not necessarily describe a mineral deficiency or a mineralization disorder, as is often thought (Schonau, 1998). Wide variation in age at onset and progression of puberty is another problem. It means a wide variation in the age at attainment of PBM. Some diseases, like juvenile arthritis, is thought to delay pubertal onset

**chronic disease, some points on the BMD of chronically ill children** 

bone mass (Bogunovic et al., 2009).

Fragility fractures are raising in pediatric population. This may be due to growing number of chronic disease in this population. It caused the increase of use of DXA in children. Healthy children with frequent fragility fracture, have been the focus of research. This is changing, may be because escalating of children with chronic diseases and fragility fractures. When an atraumatic event, cause fracture, fragility fracture come true. The difficulty looms here because as Bogunovic et al state, in young children especially, distinction between traumatic and atraumatic fractures may prove to be a challenge (Bogunovic et al., 2009). Other side of this problem, appear there, when there are many papers on fractures in childhood, but very few of these focus to identify fragility fractures, and fewer focused on the concept of osteoporosis in the young in relation to fractures. Bianchi reminds us that fractures, especially in infants, and especially if multiple or repeated, may be the consequence of violence and child abuse. However, fractures are common events in children. Landin, 1997, as cited in Bianchi, 2007, estimated that 42% of boys and 27% of girls sustain a fracture between 0 and 16 years of age. The must fractures in them, occurs between 10 and 15 years and forearm is the most common site (Bianchi, 2007). Is low BMD a risk factor for fractures? Bone mass may contribute to fracture risk in childhood (Bogunovic et al., 2009). Adverse reactions to cow milk, low dietary calcium intake, early age at first fracture, asthma and overweight (Goulding et al., 2005), and low physical activity are suggested as risk factors for fractures in children. Others suggested that lower BMD for body size, lower milk intake and lower physical activity related with recurrent fractures (Manias et al., 2006). Carbonated beverages also had some relations to fragility fractures. In children with chronic diseases, no systematically collected data is available. Bianchi reviewed that and suggested that some studies found no significant differences in the fracture rate between patients and controls. In contrast, many studies found an increased fracture risk in children affected by various diseases such as acute lymphoblastic leukemia, cerebral palsy, celiac disease, organ transplantation and glucocorticoids users (Bianchi, 2007).

#### **3.8 Treatment of low bone mass in children**

Unfortunately, though general measures (optimizing the intake of calories, vitamin D and calcium; providing appropriate weight-bearing activity; replacing GH or sex steroids; and minimizing doses of glucocorticoids) are recommended for better acquisition and maintaining of bone mass in children, they may not be sufficient to prevent or restore deficits in bone mass. Anti-resorptive agents (eg. Bisphosphonates), found valuable in treating some disorders, such as steroid-induced osteoporosis. In steroid-induced

What We Learn from Bone Complications in Congenital Diseases? Thalassemia, an Example 205

in combination with the receptor activator of nuclear factor-κB ligand (RANKL), leads to the

These two molecules are expressed by bone marrow stromal cells, also (Voskaridou & Terpos, 2004). Wittrant et al names the cells of the mononuclear phagocytic lineage including osteoclast progenitors and mature osteoclasts as well as placental trophoblasts, uterine decidual cells, smooth muscle cells, microglia, renal mesangial cells and osteoblasts, as other sites that express CSF-1R (Wittrant et al., 2009). PTH administration in 7-14 first days, to enhances RANKL- and M-CSF–stimulated osteoclast formation and bone resorption was shown in vivo (Jacome-Galarza et al., 2011). Thyroxine, 1,25-dihydroxyvitamin D3, and cytokines that use gp130 as part of their receptor, such as interleukin-6 (IL-6) and oncostatin M, are named as other factors which enhance RANKL expression (Voskaridou & Terpos,

Rankle/OPG system has a characteristic position in osteoporosis and metabolic bone disease. Osteoprotegerin (OPG), a secreted member of the tumor necrosis factor receptor superfamily, has been identified as an osteoblast-derived regulator of bone resorption . OPG neutralizes RANK that is essential for osteoclast formation and activation (Morabito et al., 2004). Alteration in the Rank/Rankl/OPG system may favors osteoclasts and osteoporosis

Marie & Kassem explain in detail that bone formation is dependent on the recruitment of a sufficient number of osteoblasts as well as the activity of individual osteoblasts. They suggest that osteoblastic cells are recruited to bone forming surfaces mainly from a group of skeletal stem cells with osteogenic differentiation potential (referred to as skeletal, mesenchymal stem cells (MSC), or stromal stem cells. Some believe that some of these cells are pericytes located on the outer surface of blood vessels and sinusoids in the bone marrow, though, the exact

Wnt signaling pathway is named as a key pathway involved in the regulation of bone mass. Johnson et al in an article in 2004, explained that Wnt signaling is also required for a diverse number of developmental events including mesoderm induction, organogenesis, CNS organization and limb patterning. In addition, a number of Wnt's have been implicated in vertebrate skeletal development. For example, there is evidence that Wnt3a, Wnt4, Wnt5a, Wnt5b, and Wnt7a all have important roles in chondrogenesis. Another member of the Wnt family, Wnt9A (formerly Wnt14), can induce morphological and molecular signs of joint formation when inappropriately expressed, indicating that Wnt9A plays a crucial role in the initiation of synovial joint development. Wnt9A expression can also lead to the arrest and reversal of chondrogenic differentiation in vitro (Johnson et al., 2004). We explained before, the PTH role in resorption. PTH also have anabolic effects and Marie & Kassem explain that the anabolic effects of PTH on bone formation are mediated through PTH receptordependent mechanisms. PTH enhances osteoblastic cell proliferation and function, extends the lifespan of mature osteoblasts through antiapoptotic effects, enhances Wnt signaling through inhibition of the Wnt antagonist, sclerostin, and enhances the local production of bone anabolic growth factors such as insulin-like growth factor 1 (IGF1) (Marie & Kassem, 2011). Though the differentiation of osteoblasts is less well understood than the differentiation of osteoclasts (Voskaridou & Terpos, 2004), bone morphogenetic proteins (BMPs) are critical factors that stimulate the growth and differentiation of osteoblasts (Marie

location of mesenchymal stem cells in vivo is still debatable (Marie & Kassem, 2011).

formation of mature osteoclasts (Wittrant et al., 2009).

formation (Toumba & Skordis, 2010).

**4.1.2 Osteoblasts** 

2004).

osteoporosis, increased bone loss also contributes to the deficit, so anti-resorptive agents, seem affective. The ideal is treatment children to improve the failure of bone mineral acquisition, but they are not recommended yet (Bachrach, 2001). However, the use of different anti-osteoporotic agents (anabolic or anti-resorptive) in pediatric patients is not very common or recommended, especially in young children, due to a lack of large and systematic studies and comprehensive data supporting their efficacy or addressing their adverse effects in pediatric patients.

### **4. Bone and thalassemia**

Osteopenia and are observed in 40–50% of beta-thalassemia Major patients, and so osteoporosis can be considered prominent causes of co-morbidity in this population, which significantly increases fracture risk (Gaudio et al., 2010).

Before discussing bone disorders in thalassemia patients, it is necessary to understand normal bone function and remodeling.

#### **4.1 Bone in normal individuals**

Voskaridou & Terpos, explain the role of skeleton, bone properties and BMU as so: the skeleton provides mechanical support for the body and is a reservoir for normal mineral metabolism. Bone is an active tissue constantly being remodeled and changing metabolically through the balanced activity of osteoclasts and osteoblasts on trabecular surfaces. On a microscopic level, bone metabolism always occurs on the surface of the bone at focused sites, each of which is termed a bone metabolism unit (BMU) (Voskaridou & Terpos, 2004). Mundy suggests that the sequence is always the same, osteoclastic bone resorption followed by osteoblastic bone formation to repair the defect. The resorptive phase of the remodeling process has been estimated to last 10 days. This period is followed by repair of the defect by osteoblasts attracted to the site of the resorption defect which then presumably proceed to make new bone. This part of the process takes approximately 3 months (Mundy, 1999). After the lacunae are filled with osteoids, Voskaridou & Terpos state that this newly formed matrix is mineralized with hydroxyapatite, giving the BMU tensile strength (Voskaridou & Terpos, 2004).

### **4.1.1 Osteoclasts**

Hodge et al, describe Osteoclasts as multinucleated cells which differentiate from early myelomonocytic progenitors rather than more differentiated monocyte/macrophage progenitors (Hodge et al., 2004). Roodman describes their function as they reabsorb bone by secreting proteases which dissolve the matrix and produce acid that releases bone mineral into the extracellular space under the ruffled border of the plasma membrane of osteoclasts (Roodman, 2004). Voskaridou & Terpos say osteoclastogenesis requires contact between osteoclast precursors and stromal cells or osteoblasts. They say the adherence of osteoclasts to the bone surface is critical for the bone resorptive process, since agents that interfere with osteoclast attachment, such as cathepsin K, block bone resorption (Voskaridou & Terpos, 2004).

Wittrant et al, state the role of colony-stimulating factor-1 (CSF-1), released by osteoblasts, as it stimulates the proliferation of osteoclast progenitors via the c-fms receptor (CSF-1R) and, in combination with the receptor activator of nuclear factor-κB ligand (RANKL), leads to the formation of mature osteoclasts (Wittrant et al., 2009).

These two molecules are expressed by bone marrow stromal cells, also (Voskaridou & Terpos, 2004). Wittrant et al names the cells of the mononuclear phagocytic lineage including osteoclast progenitors and mature osteoclasts as well as placental trophoblasts, uterine decidual cells, smooth muscle cells, microglia, renal mesangial cells and osteoblasts, as other sites that express CSF-1R (Wittrant et al., 2009). PTH administration in 7-14 first days, to enhances RANKL- and M-CSF–stimulated osteoclast formation and bone resorption was shown in vivo (Jacome-Galarza et al., 2011). Thyroxine, 1,25-dihydroxyvitamin D3, and cytokines that use gp130 as part of their receptor, such as interleukin-6 (IL-6) and oncostatin M, are named as other factors which enhance RANKL expression (Voskaridou & Terpos, 2004).

Rankle/OPG system has a characteristic position in osteoporosis and metabolic bone disease. Osteoprotegerin (OPG), a secreted member of the tumor necrosis factor receptor superfamily, has been identified as an osteoblast-derived regulator of bone resorption . OPG neutralizes RANK that is essential for osteoclast formation and activation (Morabito et al., 2004). Alteration in the Rank/Rankl/OPG system may favors osteoclasts and osteoporosis formation (Toumba & Skordis, 2010).

#### **4.1.2 Osteoblasts**

204 Osteoporosis

osteoporosis, increased bone loss also contributes to the deficit, so anti-resorptive agents, seem affective. The ideal is treatment children to improve the failure of bone mineral acquisition, but they are not recommended yet (Bachrach, 2001). However, the use of different anti-osteoporotic agents (anabolic or anti-resorptive) in pediatric patients is not very common or recommended, especially in young children, due to a lack of large and systematic studies and comprehensive data supporting their efficacy or addressing their

Osteopenia and are observed in 40–50% of beta-thalassemia Major patients, and so osteoporosis can be considered prominent causes of co-morbidity in this population, which

Before discussing bone disorders in thalassemia patients, it is necessary to understand

Voskaridou & Terpos, explain the role of skeleton, bone properties and BMU as so: the skeleton provides mechanical support for the body and is a reservoir for normal mineral metabolism. Bone is an active tissue constantly being remodeled and changing metabolically through the balanced activity of osteoclasts and osteoblasts on trabecular surfaces. On a microscopic level, bone metabolism always occurs on the surface of the bone at focused sites, each of which is termed a bone metabolism unit (BMU) (Voskaridou & Terpos, 2004). Mundy suggests that the sequence is always the same, osteoclastic bone resorption followed by osteoblastic bone formation to repair the defect. The resorptive phase of the remodeling process has been estimated to last 10 days. This period is followed by repair of the defect by osteoblasts attracted to the site of the resorption defect which then presumably proceed to make new bone. This part of the process takes approximately 3 months (Mundy, 1999). After the lacunae are filled with osteoids, Voskaridou & Terpos state that this newly formed matrix is mineralized with hydroxyapatite, giving the BMU tensile strength (Voskaridou &

Hodge et al, describe Osteoclasts as multinucleated cells which differentiate from early myelomonocytic progenitors rather than more differentiated monocyte/macrophage progenitors (Hodge et al., 2004). Roodman describes their function as they reabsorb bone by secreting proteases which dissolve the matrix and produce acid that releases bone mineral into the extracellular space under the ruffled border of the plasma membrane of osteoclasts (Roodman, 2004). Voskaridou & Terpos say osteoclastogenesis requires contact between osteoclast precursors and stromal cells or osteoblasts. They say the adherence of osteoclasts to the bone surface is critical for the bone resorptive process, since agents that interfere with osteoclast attachment, such as cathepsin K, block bone resorption (Voskaridou &

Wittrant et al, state the role of colony-stimulating factor-1 (CSF-1), released by osteoblasts, as it stimulates the proliferation of osteoclast progenitors via the c-fms receptor (CSF-1R) and,

adverse effects in pediatric patients.

normal bone function and remodeling.

**4.1 Bone in normal individuals** 

Terpos, 2004).

Terpos, 2004).

**4.1.1 Osteoclasts** 

significantly increases fracture risk (Gaudio et al., 2010).

**4. Bone and thalassemia** 

Marie & Kassem explain in detail that bone formation is dependent on the recruitment of a sufficient number of osteoblasts as well as the activity of individual osteoblasts. They suggest that osteoblastic cells are recruited to bone forming surfaces mainly from a group of skeletal stem cells with osteogenic differentiation potential (referred to as skeletal, mesenchymal stem cells (MSC), or stromal stem cells. Some believe that some of these cells are pericytes located on the outer surface of blood vessels and sinusoids in the bone marrow, though, the exact location of mesenchymal stem cells in vivo is still debatable (Marie & Kassem, 2011).

Wnt signaling pathway is named as a key pathway involved in the regulation of bone mass. Johnson et al in an article in 2004, explained that Wnt signaling is also required for a diverse number of developmental events including mesoderm induction, organogenesis, CNS organization and limb patterning. In addition, a number of Wnt's have been implicated in vertebrate skeletal development. For example, there is evidence that Wnt3a, Wnt4, Wnt5a, Wnt5b, and Wnt7a all have important roles in chondrogenesis. Another member of the Wnt family, Wnt9A (formerly Wnt14), can induce morphological and molecular signs of joint formation when inappropriately expressed, indicating that Wnt9A plays a crucial role in the initiation of synovial joint development. Wnt9A expression can also lead to the arrest and reversal of chondrogenic differentiation in vitro (Johnson et al., 2004). We explained before, the PTH role in resorption. PTH also have anabolic effects and Marie & Kassem explain that the anabolic effects of PTH on bone formation are mediated through PTH receptordependent mechanisms. PTH enhances osteoblastic cell proliferation and function, extends the lifespan of mature osteoblasts through antiapoptotic effects, enhances Wnt signaling through inhibition of the Wnt antagonist, sclerostin, and enhances the local production of bone anabolic growth factors such as insulin-like growth factor 1 (IGF1) (Marie & Kassem, 2011). Though the differentiation of osteoblasts is less well understood than the differentiation of osteoclasts (Voskaridou & Terpos, 2004), bone morphogenetic proteins (BMPs) are critical factors that stimulate the growth and differentiation of osteoblasts (Marie

What We Learn from Bone Complications in Congenital Diseases? Thalassemia, an Example 207

magnitude (Papanastasiou et al., 2002). As Haidar et al., mention around 24% of curves showed spontaneous resolution, this was equally distributed among all but the right thoracic curve patterns. Left lumbar and thoraco-lumbar scoliosis improved at a rate of 22% and 33%, respectively. However, most of the curves showed a magnitude of less than 10°. This remarkable absence of progression and spontaneous resolution in small curves depicts the unique etiology of scoliosis in this hematologic condition. Of note, thoracic kyphosis increased with patient age, whereas lumbar lordosis decreased with age and followed the changes of thoracic kyphosis. The 'junction' thoracolumbar kyphosis increased with patient age, but independently from thoracic kyphosis and lumbar lordosis. However, neither scoliosis

Bone or joint pain, reported in 34% of participants during the 30 days before enrollment, in one study in all thalasemic patients. Vogiatzi et al., state that 6 percent required prescription pain medication and an additional 12.2% used analgesics as over-the-counter. They report that age, sex, and thalassemia syndrome were all independent predictors of the presence and severity of bone and joint pain and the odds of more severe pain, increased 47% for each 5-yr age increase. 40% of females, but only twenty-eight percent of males complained of recent pain. Bone pain was reported more frequently among b TM participants (40%) compared with b TI and E-b participants (16% and 19%, respectively) (Vogiatzi et al., 2009). As Haidar et al suggested, though arthralgia has been mainly attributed to iron overload or use of iron chelators, back pain is mainly associated with osteoporosis, compression fractures, and intervertebral disc degeneration. They report that in one study by the Thalassemia Clinical Research Network (TCRN), young adults with thalassemia experienced pain comparable to the general population, whereas older adults (aged 35+) experienced greater pain. There was an association between pain and low vitamin D level. (Haidar et al., 2011). Vogiatzi et al report that GH-deficient patients were reported to have more severe bone pain, as did those with a history of medicated heart disease, cirrhosis, or

Haidar et al. In an extended report about bone disease and skeletal complications in patients with β thalassemia major, suggest that a significant difference in disc degeneration severity has been demonstrated between TM patients and controls on MRI and radiographs. The pattern of disc degeneration was different in TM patients as they exhibited multilevel disease with all levels of the lumbar spine involved. Although no clear mechanism has been suggested for the development of disc changes in TM patients, an underlying metabolic basis has been suggested. They say that the degeneration of intervertebral discs results, in part, from weakening of the annulus fibrosus. The chelating agent, deferoxamine, commonly used in patients with TM, is thought to deleteriously affect the integrity and strength of the annulus fibrosus fibers. Alternatively, the injurious effect of iron overload is

Several sensitive techniques are available for the quantitative assessment of the degree of total bone mass. Bone density measurement by dual energy X-ray absorptiometry (DEXA)

magnitude nor progression was correlated to thoracic kyphosis (Haidar et al., 2011).

**4.2.1 Bone and joint pain** 

hepatitis C (Vogiatzi et al., 2009).

**4.2.2 Intervertebral disc changes** 

also postulated as a factor (Haidar et al., 2011).

**4.2.3 Osteoporosis** 

& Kassem, 2011). Voskaridou & Terpos name several factors such as Basic fibroblast growth factor (bFGF), Insulin-like growth factors (IGF, type I and II), Transforming growth factors (TGF, beta 1 and beta 2) and platelet-derived growth factor (PDGF) and a number of hormones, such as PTH, thyroxine, oestrogen, cortisol, insulin, and calcitonin, as well as vitamin D, are involved in the regulation of bone metabolism, effecting both progenitors and mature osteoblastic cells and osteoclasts (Voskaridou & Terpos, 2004).

#### **4.2 Bone complications in thalassemic patients**

Peculiar mongoloid appearance, caused by enlargement of the cranial and facial bones, combined with skin discoloration, anemia, splenomegaly and some enlargement of the liver were included in the first description of thalassemia by Cooley & Lee (Wonke, 1998). Galanello & Origa explain Skeletal changes include typical craniofacial changes such as bossing of the skull, prominent malar eminence, depression of the bridge of the nose, tendency for a mongoloid slant of the eye, and hypertrophy of the maxillae, which tend to expose the upper teeth (Galanello & Origa, 2010).

Some experts suggest that, the thalassemic anemia and the need for transfusion, as earlier as appear in the disease course, the facial changes are more prominent, and all agree that the disease course changes are only seen or are more prominent in untreated patients or in those with no regular transfusion program (Cao & Galanello, 2010). Tyler et al suggest that the skeletal changes in untreated thalassemia are due to ineffective erythropoiesis and expansion of the bone marrow which affect every part of the skeleton. These changes include osteoporosis, growth retardation, platyspondyly and kyphosis (Tyler et al., 2006). Anemia, hemosiderosis, iron chelation therapy, and associated hormonal disorders, are described as main causes of spinal deformity (Haidar et al., 2011). Salehi et al. , suggest that expanded erythropoiesis occurs at extra-medullary sites, most commonly resulting in a para-spinal mass but occasionally affecting organs containing pluripotential stem cells (Salehi et al., 2004). Tyler et al., state that skeletal dysplasia, predominantly affects the rapidly growing long bones, in particular the distal ulna, causing irregularity and sclerosis of the physeal–metaphyseal junction and causing splaying of the metaphysis. They say , Deferoxamine (DFX) also exacerbates the observed growth retardation. DFX-induced skeletal dysplasia, may cause toxicity, which is associated with visual and auditory impairment (Tyler et al., 2006).

Among the spinal deformities observed, Papanastasiou et al suggest that an increased prevalence of frontal curves was reported of at least, 5° in 67% of patients with TM. However, scoliosis curvatures of more than 10° and less than 14° were observed in 21.7% of examined patients. It seemed that location, direction, and pattern of the curvatures, age of onset, gender, and rate of progression of this type of scoliosis associated with TM, differed those in patients with idiopathic scoliosis. They, in their greater than 10-year study reported that the prevalence of frontal curves of at least 5° in 43 TM patients was approximately 80%. Scoliosis of at least 10° and not more than 19° was revealed in 28% to 35% of patients. The most common scoliosis curve pattern was the S-shaped (right thoracic, left lumbar). The prevalence of scoliosis was not gender related, irrespective of age and curve magnitude. Progression of scoliosis in the 10 year period was only detected in four (12%) of 34 patients with scoliosis of 5° to 14°, a rate much lower than that reported in patients with idiopathic scoliosis. Only one patient (2.9%) developed scoliosis of 65° that progressed to 85°, and no other patient developed scoliosis curves that required bracing or operative treatment. No correlation was shown between scoliosis progression and (remaining) growth potential, curve pattern, gender, or curve magnitude (Papanastasiou et al., 2002). As Haidar et al., mention around 24% of curves showed spontaneous resolution, this was equally distributed among all but the right thoracic curve patterns. Left lumbar and thoraco-lumbar scoliosis improved at a rate of 22% and 33%, respectively. However, most of the curves showed a magnitude of less than 10°. This remarkable absence of progression and spontaneous resolution in small curves depicts the unique etiology of scoliosis in this hematologic condition. Of note, thoracic kyphosis increased with patient age, whereas lumbar lordosis decreased with age and followed the changes of thoracic kyphosis. The 'junction' thoracolumbar kyphosis increased with patient age, but independently from thoracic kyphosis and lumbar lordosis. However, neither scoliosis magnitude nor progression was correlated to thoracic kyphosis (Haidar et al., 2011).

### **4.2.1 Bone and joint pain**

206 Osteoporosis

& Kassem, 2011). Voskaridou & Terpos name several factors such as Basic fibroblast growth factor (bFGF), Insulin-like growth factors (IGF, type I and II), Transforming growth factors (TGF, beta 1 and beta 2) and platelet-derived growth factor (PDGF) and a number of hormones, such as PTH, thyroxine, oestrogen, cortisol, insulin, and calcitonin, as well as vitamin D, are involved in the regulation of bone metabolism, effecting both progenitors

Peculiar mongoloid appearance, caused by enlargement of the cranial and facial bones, combined with skin discoloration, anemia, splenomegaly and some enlargement of the liver were included in the first description of thalassemia by Cooley & Lee (Wonke, 1998). Galanello & Origa explain Skeletal changes include typical craniofacial changes such as bossing of the skull, prominent malar eminence, depression of the bridge of the nose, tendency for a mongoloid slant of the eye, and hypertrophy of the maxillae, which tend to

Some experts suggest that, the thalassemic anemia and the need for transfusion, as earlier as appear in the disease course, the facial changes are more prominent, and all agree that the disease course changes are only seen or are more prominent in untreated patients or in those with no regular transfusion program (Cao & Galanello, 2010). Tyler et al suggest that the skeletal changes in untreated thalassemia are due to ineffective erythropoiesis and expansion of the bone marrow which affect every part of the skeleton. These changes include osteoporosis, growth retardation, platyspondyly and kyphosis (Tyler et al., 2006). Anemia, hemosiderosis, iron chelation therapy, and associated hormonal disorders, are described as main causes of spinal deformity (Haidar et al., 2011). Salehi et al. , suggest that expanded erythropoiesis occurs at extra-medullary sites, most commonly resulting in a para-spinal mass but occasionally affecting organs containing pluripotential stem cells (Salehi et al., 2004). Tyler et al., state that skeletal dysplasia, predominantly affects the rapidly growing long bones, in particular the distal ulna, causing irregularity and sclerosis of the physeal–metaphyseal junction and causing splaying of the metaphysis. They say , Deferoxamine (DFX) also exacerbates the observed growth retardation. DFX-induced skeletal dysplasia, may cause

toxicity, which is associated with visual and auditory impairment (Tyler et al., 2006).

Among the spinal deformities observed, Papanastasiou et al suggest that an increased prevalence of frontal curves was reported of at least, 5° in 67% of patients with TM. However, scoliosis curvatures of more than 10° and less than 14° were observed in 21.7% of examined patients. It seemed that location, direction, and pattern of the curvatures, age of onset, gender, and rate of progression of this type of scoliosis associated with TM, differed those in patients with idiopathic scoliosis. They, in their greater than 10-year study reported that the prevalence of frontal curves of at least 5° in 43 TM patients was approximately 80%. Scoliosis of at least 10° and not more than 19° was revealed in 28% to 35% of patients. The most common scoliosis curve pattern was the S-shaped (right thoracic, left lumbar). The prevalence of scoliosis was not gender related, irrespective of age and curve magnitude. Progression of scoliosis in the 10 year period was only detected in four (12%) of 34 patients with scoliosis of 5° to 14°, a rate much lower than that reported in patients with idiopathic scoliosis. Only one patient (2.9%) developed scoliosis of 65° that progressed to 85°, and no other patient developed scoliosis curves that required bracing or operative treatment. No correlation was shown between scoliosis progression and (remaining) growth potential, curve pattern, gender, or curve

and mature osteoblastic cells and osteoclasts (Voskaridou & Terpos, 2004).

**4.2 Bone complications in thalassemic patients** 

expose the upper teeth (Galanello & Origa, 2010).

Bone or joint pain, reported in 34% of participants during the 30 days before enrollment, in one study in all thalasemic patients. Vogiatzi et al., state that 6 percent required prescription pain medication and an additional 12.2% used analgesics as over-the-counter. They report that age, sex, and thalassemia syndrome were all independent predictors of the presence and severity of bone and joint pain and the odds of more severe pain, increased 47% for each 5-yr age increase. 40% of females, but only twenty-eight percent of males complained of recent pain. Bone pain was reported more frequently among b TM participants (40%) compared with b TI and E-b participants (16% and 19%, respectively) (Vogiatzi et al., 2009). As Haidar et al suggested, though arthralgia has been mainly attributed to iron overload or use of iron chelators, back pain is mainly associated with osteoporosis, compression fractures, and intervertebral disc degeneration. They report that in one study by the Thalassemia Clinical Research Network (TCRN), young adults with thalassemia experienced pain comparable to the general population, whereas older adults (aged 35+) experienced greater pain. There was an association between pain and low vitamin D level. (Haidar et al., 2011). Vogiatzi et al report that GH-deficient patients were reported to have more severe bone pain, as did those with a history of medicated heart disease, cirrhosis, or hepatitis C (Vogiatzi et al., 2009).

#### **4.2.2 Intervertebral disc changes**

Haidar et al. In an extended report about bone disease and skeletal complications in patients with β thalassemia major, suggest that a significant difference in disc degeneration severity has been demonstrated between TM patients and controls on MRI and radiographs. The pattern of disc degeneration was different in TM patients as they exhibited multilevel disease with all levels of the lumbar spine involved. Although no clear mechanism has been suggested for the development of disc changes in TM patients, an underlying metabolic basis has been suggested. They say that the degeneration of intervertebral discs results, in part, from weakening of the annulus fibrosus. The chelating agent, deferoxamine, commonly used in patients with TM, is thought to deleteriously affect the integrity and strength of the annulus fibrosus fibers. Alternatively, the injurious effect of iron overload is also postulated as a factor (Haidar et al., 2011).

#### **4.2.3 Osteoporosis**

Several sensitive techniques are available for the quantitative assessment of the degree of total bone mass. Bone density measurement by dual energy X-ray absorptiometry (DEXA)

What We Learn from Bone Complications in Congenital Diseases? Thalassemia, an Example 209

Some studies support that gender of thalassemic poatients affects not only the prevalence, but also the severity of osteoporosis syndrome in TM. However the results are contradicted and some studies showed no gender differences in patients with TM, when they were

Expansion of hematopoiesis and bone marrow expansion, caused severe bone deformities with marked facial and limb changes that were originally described by Cooley et al in 1927 in untreated thalassemia major patients (Jensen et al., 1998). As Wonke, also suggests, the bone marrow expansion due to ineffective erythropoiesis is a typical finding in patients with TM and is considered a major cause of bone destruction. The commonest sites for extramedullary hematopoiesis are the spleen, liver and chest; less common sites are paravertebral masses and brain lesions. As the ribs contain hematopoietic marrow at all ages, overactive marrow results in, osteoporosis of the ribs, localized lucencies, cortical erosions, and 'rib within rib' deformities (Wonke, 1998). Mechanical interruption of bone formation, leading to cortical thinning, increased distortion and fragility of the bones, occurs due to Marrow expansion (Voskaridou & Terpos, 2004). Tyler et al. refer to ineffective hematopoiesis as a cause of severe anemia and increased erythropoietin production, resulting in expansion of the bone marrow by a factor of 15 to 30. They suggest that even with an optimal transfusion regimen, the bone marrow remains hyperactive. The appearance of "cob-webbing" in the pelvis is the reason of the expanded bone marrow that destroys the medullary trabeculae with initial cortical and trabecular thinning and

Salehi et al., even reported spinal cord compression that is seen in these patients, which can cause neurologic compromise and is, in part, due to extramedullary hematopoiesis (Salehi et

Idiopathic hemochromatosis (Iron overload), are commonly associated with hypogonadism and diabetes, while the other endocrinopathies seen in patients with β-thalassemia major and Iron overload, are less common in them. As Perera et al. suggest, a significant predictor of endocrine failure is the duration of transfusion therapy (Perera et al., 2010). In below, we explain endocrine disorders in thalassemic patients, more extensively, as these disorders are

Homozygous b-thalassemias, have almost invariably growth retardation. Soliman et al . describe thes changes as significant size retardation that is observed in stature, sitting height, weight, biacromial (shoulder), and bicristal (iliac crest) breadths (Soliman et al., 2009). All studies do not show such results (Cao & Galanello, 2010). Soliman et al., state that after the age of 4 years, the longitudinal growth patterns, display rates consistently below those of normal controls and the bone age is frequently delayed after the age of 6–7 years. Growth retardation becomes markedly severe with failure of the pubertal growth spurt

major and important causes of bone complication in thalassemic patients.

**4.2.3.3 Gender differences in bone density in thalassemic patients** 

**4.2.3.4 Acquired factors contributing to reduced BMD in beta-thalassemia**

hypogonadal (Toumba & Skordis, 2010).

subsequent trabecular coarsening (Tyler et al., 2006).

*4.2.3.4.1 Bone marrow expansion* 

al., 2004).

4.2.3.4.2.1 General

4.2.3.4.2.2 Growth failure

*4.2.3.4.2 Endocrine complications* 

of the lumbar spine and femoral neck is recommended as one of the most reliable noninvasive techniques for the assessment of bone mass (Kanis, 1994).

According to the World Health Organization (WHO, 1994), osteoporosis is a disease characterized by low bone mass and micro-architectural deterioration of bone tissue, leading to enhanced bone fragility and a consequential increase in fracture risk. The WHO based the diagnosis of postmenopausal osteoporosis on the presence of a BMD T-score of 2.5 SD or greater below the mean for young women (Hamidi et al., 2008). The term "low bone mineral density for age" was mentioned at the "2007 ISCD Pediatric Position Development Conference" as a criterion for low bone mass in children, and is described as a child with a Z-score below -2.0 (Daniels et al., 2003).

In spite of adequate transfusion and iron chelation, Thalassemia-induced osteoporosis (TIO) is seen in 30–50% of TM patients, that can cause substantially compromised quality of life in thalassemic patients (Mamtani & Kulkarni, 2010).

### **4.2.3.1 Genetics of bone density in thalassemic patients**

Voskaridou and Terpos, reported that polymorphism at the Sp1 site of the collagen type Ia1 (COLIA 1) gene (collagen type I is the major bone matrix protein) was found in approximately 30% of TM patients who were heterozygotes (Ss) and in 4% who were homozygotes (SS) for the Sp1 polymorphism. They reported the female to male ratio was 2:1. This means that male patients with TM carrying the Sp1 mutation may develop severe osteoporosis of the spine and the hip more frequently than patients who do not carry this mutation. The COLIA 1 polymorphism has been also associated with reduced BMD in postmenopausal osteoporosis, and predisposes women to osteoporotic fractures (Voskaridou & Terpos, 2004). Marini & Brandi reported a similarity between this finding and genetic findings in non-thalassemic patients (Marini & Brandi, 2010).

A possible beneficial effect of BsmI on patient response to alendronate therapy should be emphasized (Gaudio et al., 2010). Haidar et al report the vitamin D receptor (VDR) BsmI and FokI polymorphisms to constitute risk factors for bone mineral damage, low BMD, and short stature in pre-pubertal and pubertal patients with TM, (Haidar et al., 2011).

As Gaudio et al say, it should be remembered that the pathogenesis of osteoporosis is multifactorial, and includes environmental (diet, lifestyle, and drugs) as well as acquired (bone marrow expansion, hemochromatosis, chelation therapy, hepatitis, deficiency of growth hormone or insulin growth factor I, and hypogonadism) and genetic factors (Gaudio et al., 2010).

#### **4.2.3.2 Altered modeling/remodeling in thalassemic patients**

Haidar et al, believe that most acquired factors act mainly through the inhibition of osteoblastic activity. They suggest that histomorphometry studies have revealed that increased osteoid thickness, increased osteoid maturation and mineralization lag time, and defective mineralization are common in TM pediatric patinets (Haidar et al., 2011). Mildly increased resorption found in adult patients with beta TM (Vogiatzi et al., 2010). Baldini et al explain an interesting hypothesis that the chronic request for blood cell production can play a role in the etiology of osteoporosis through overstimulation of the hematopoietic system, increasing the number of osteoclasts and osteoblasts resulting in accelerated bone turnover (Baldini et al., 2010). However, Domrongkitchaiporn et al., suggest that increased resorption may be a cause of hypogonadism in these patients (Domrongkitchaiporn et al., 2003).

### **4.2.3.3 Gender differences in bone density in thalassemic patients**

Some studies support that gender of thalassemic poatients affects not only the prevalence, but also the severity of osteoporosis syndrome in TM. However the results are contradicted and some studies showed no gender differences in patients with TM, when they were hypogonadal (Toumba & Skordis, 2010).

### **4.2.3.4 Acquired factors contributing to reduced BMD in beta-thalassemia**

### *4.2.3.4.1 Bone marrow expansion*

208 Osteoporosis

of the lumbar spine and femoral neck is recommended as one of the most reliable non-

According to the World Health Organization (WHO, 1994), osteoporosis is a disease characterized by low bone mass and micro-architectural deterioration of bone tissue, leading to enhanced bone fragility and a consequential increase in fracture risk. The WHO based the diagnosis of postmenopausal osteoporosis on the presence of a BMD T-score of 2.5 SD or greater below the mean for young women (Hamidi et al., 2008). The term "low bone mineral density for age" was mentioned at the "2007 ISCD Pediatric Position Development Conference" as a criterion for low bone mass in children, and is described as a child with a

In spite of adequate transfusion and iron chelation, Thalassemia-induced osteoporosis (TIO) is seen in 30–50% of TM patients, that can cause substantially compromised quality of life in

Voskaridou and Terpos, reported that polymorphism at the Sp1 site of the collagen type Ia1 (COLIA 1) gene (collagen type I is the major bone matrix protein) was found in approximately 30% of TM patients who were heterozygotes (Ss) and in 4% who were homozygotes (SS) for the Sp1 polymorphism. They reported the female to male ratio was 2:1. This means that male patients with TM carrying the Sp1 mutation may develop severe osteoporosis of the spine and the hip more frequently than patients who do not carry this mutation. The COLIA 1 polymorphism has been also associated with reduced BMD in postmenopausal osteoporosis, and predisposes women to osteoporotic fractures (Voskaridou & Terpos, 2004). Marini & Brandi reported a similarity between this finding

A possible beneficial effect of BsmI on patient response to alendronate therapy should be emphasized (Gaudio et al., 2010). Haidar et al report the vitamin D receptor (VDR) BsmI and FokI polymorphisms to constitute risk factors for bone mineral damage, low BMD, and

As Gaudio et al say, it should be remembered that the pathogenesis of osteoporosis is multifactorial, and includes environmental (diet, lifestyle, and drugs) as well as acquired (bone marrow expansion, hemochromatosis, chelation therapy, hepatitis, deficiency of growth hormone or insulin growth factor I, and hypogonadism) and genetic factors (Gaudio

Haidar et al, believe that most acquired factors act mainly through the inhibition of osteoblastic activity. They suggest that histomorphometry studies have revealed that increased osteoid thickness, increased osteoid maturation and mineralization lag time, and defective mineralization are common in TM pediatric patinets (Haidar et al., 2011). Mildly increased resorption found in adult patients with beta TM (Vogiatzi et al., 2010). Baldini et al explain an interesting hypothesis that the chronic request for blood cell production can play a role in the etiology of osteoporosis through overstimulation of the hematopoietic system, increasing the number of osteoclasts and osteoblasts resulting in accelerated bone turnover (Baldini et al., 2010). However, Domrongkitchaiporn et al., suggest that increased resorption

may be a cause of hypogonadism in these patients (Domrongkitchaiporn et al., 2003).

invasive techniques for the assessment of bone mass (Kanis, 1994).

Z-score below -2.0 (Daniels et al., 2003).

et al., 2010).

thalassemic patients (Mamtani & Kulkarni, 2010).

**4.2.3.1 Genetics of bone density in thalassemic patients** 

and genetic findings in non-thalassemic patients (Marini & Brandi, 2010).

**4.2.3.2 Altered modeling/remodeling in thalassemic patients** 

short stature in pre-pubertal and pubertal patients with TM, (Haidar et al., 2011).

Expansion of hematopoiesis and bone marrow expansion, caused severe bone deformities with marked facial and limb changes that were originally described by Cooley et al in 1927 in untreated thalassemia major patients (Jensen et al., 1998). As Wonke, also suggests, the bone marrow expansion due to ineffective erythropoiesis is a typical finding in patients with TM and is considered a major cause of bone destruction. The commonest sites for extramedullary hematopoiesis are the spleen, liver and chest; less common sites are paravertebral masses and brain lesions. As the ribs contain hematopoietic marrow at all ages, overactive marrow results in, osteoporosis of the ribs, localized lucencies, cortical erosions, and 'rib within rib' deformities (Wonke, 1998). Mechanical interruption of bone formation, leading to cortical thinning, increased distortion and fragility of the bones, occurs due to Marrow expansion (Voskaridou & Terpos, 2004). Tyler et al. refer to ineffective hematopoiesis as a cause of severe anemia and increased erythropoietin production, resulting in expansion of the bone marrow by a factor of 15 to 30. They suggest that even with an optimal transfusion regimen, the bone marrow remains hyperactive. The appearance of "cob-webbing" in the pelvis is the reason of the expanded bone marrow that destroys the medullary trabeculae with initial cortical and trabecular thinning and subsequent trabecular coarsening (Tyler et al., 2006).

Salehi et al., even reported spinal cord compression that is seen in these patients, which can cause neurologic compromise and is, in part, due to extramedullary hematopoiesis (Salehi et al., 2004).

### *4.2.3.4.2 Endocrine complications*

#### 4.2.3.4.2.1 General

Idiopathic hemochromatosis (Iron overload), are commonly associated with hypogonadism and diabetes, while the other endocrinopathies seen in patients with β-thalassemia major and Iron overload, are less common in them. As Perera et al. suggest, a significant predictor of endocrine failure is the duration of transfusion therapy (Perera et al., 2010). In below, we explain endocrine disorders in thalassemic patients, more extensively, as these disorders are major and important causes of bone complication in thalassemic patients.

### 4.2.3.4.2.2 Growth failure

Homozygous b-thalassemias, have almost invariably growth retardation. Soliman et al . describe thes changes as significant size retardation that is observed in stature, sitting height, weight, biacromial (shoulder), and bicristal (iliac crest) breadths (Soliman et al., 2009). All studies do not show such results (Cao & Galanello, 2010). Soliman et al., state that after the age of 4 years, the longitudinal growth patterns, display rates consistently below those of normal controls and the bone age is frequently delayed after the age of 6–7 years. Growth retardation becomes markedly severe with failure of the pubertal growth spurt

What We Learn from Bone Complications in Congenital Diseases? Thalassemia, an Example 211

Pregnancy reported generally safe if baseline cardiac function is good (Rund & Rachmilewitz, 2005). Psihogios et al., suggested that with optimal therapy, most young adults with homozygous β-thalassemia can achieve reproductive, sexual, and social

There are different reports on the prevalence of diabetes in thalassemia major, however, Holger Cario reported that the prevalence is about 5%, while impaired glucose tolerance is

Immune system activation against pancreatic beta cells in beta-thalassemia patients, is reported and pancreatic iron deposition is considered as factors that triggers the autoimmune response (iron deposisions act as environmental factor) and immune response, in turn, contributes to selective beta-cell damage (Najafipour et al., 2008). Perera et la.,did not report family history as a risk factor in thalassemic patient (Perera et al., 2010). In the study by Najafipour et al., risk factors reported for impaired glucose metabolism were, age, amount of blood transfused and duration of blood transfusion. Because not all of the patients with thalassemia major could be correctly diagnosed by fasting glucose alone, the authors preferred to use the oral glucose tolerance test (OGTT) rather than fasting blood glucose levels (BGLs) for the diagnosis of abnormal glucose tolerance in thalassemic patients

Duration of transfusion therapy, in some studies was the strongest predictor for the development of diabetes (every decade of transfusion exposure further increasing the odds of developing diabetes by 2.5 times). The fact that diabetes mellitus is generally seen in the 3rd or 4th decade, may be is explainable by these findings.. Perera et al state that it is prudent to begin screening for diabetes after the 1st decade of transfusions (regular 6th monthly or annual) by assessing fasting BGLs followed by a 75-g 2-h OGTT if fasting results

Glyburide treatment and antidiabetic compounds improve insulin sensitivity. Treatment with basal-bolus insulin therapy is also used in these patients. However must not forget that effective iron chelation may improve glucose tolerance (Perera et al., 2010; Cario et al., 2003). Some believe that HbA1c is not a good tool for measuring glycemic control because of reduced red cell lifespan, ineffective hematopoiesis and frequent blood transfusions (affect the validity of HbA1c results). They propose serum fructosamine as an alternative way of monitoring glycemic control, though there is some limitations in its use. Blood glucose self monitoring and regular pre-transfusion venous blood glucose measurements may be use for measuring glycemic control, as an alternative ways in these patinets (Perera et al., 2010).

The severity of thyroid dysfunction is variable in thalasemic patients and the reports of prevalence are very different. Najafipour et al, reported the prevalence of hypothyroidism in their patients 16%, but found the prevalence of 13% to 60% in different studies of patients with thalassemia. However they believe that milder forms of thyroid dysfunction are much more common in thalassemic patients (Najafipour et al., 2008). Primary thyroid damage (from iron

hypogonadism becomes available (Perera et al., 2010).

found in up to 27% of patients (Cario et al., 2003).

experiences similar to those of their healthy peers (Psihogios et al., 2002). 4.2.3.4.2.5 Impaired glucose tolerance and diabetes mellitus in thalassemia

4.2.3.4.2.4 Fertility in thalassemia

(Najafipour et al., 2008).

are abnormal (Perera et al., 2010).

4.2.3.4.2.6 Hypothyroidism in thalassemia

reasonable until further clarification of the relationship between zinc deficiency and

(Soliman et al., 2009). Though hemosiderosis-induced damage of the endocrine glands is one of the main causes for their growth failure, Cao & Galanello, Muncie & Campbell, Toumba & Skordis and Soliman et al, state that other factors could considerably contribute to the etiology of this growth delay including (i) chronic anemic hypoxia secondary to low hemoglobin concentration (Muncie & Campbell, 2009) (ii) toxicity of desferrioxamine treatment (Cao & Galanello, 2010); (iii) increased energy expenditure due to high erythopoietic turnover and cardiac work; (iv) nutritional deficiencies including calories, folic-acid, zinc, and vitamin A (Soliman et al., 2009); (v) disturbed calcium homeostasis and bone disease (Toumba & Skordis, 2010) (vi) hepatic and pancreatic dysfunction (Soliman et al., 2009).

Perera et al., emphasize that normal stature is rarely attained, even in the well-managed patient. They report the administration of GH in some centers internationally at the judgment of individual clinicians, but the role or response to GH is not clearly understood in these patients and probably has no clear benefit unless GH deficiency is confirmed by formal testing (generally as a consequence of early childhood pituitary failure) (Perera et al., 2010).

#### 4.2.3.4.2.3 Delayed puberty/hypogonadism in thalassemia

Both primary and secondary sexual development are usually delayed in both genders in bthalassemia major (Vogiatzi et al., 2005). An association between hypogonadotrophic hypogonadism and osteoporosis in adult patients with TM has been reported in the past. Jensen et al (1998), found that hypogonadotrophic hypogonadism is a substantial contributor to the development of osteoporosis. Hypogonadotrophic hypogonadism is the commonest endocrinological complication in β-thalassaemia major and is present in 42% of patients (Jensen et al., 1998). Perera et al. describe the finding in thses patients as menarche is frequently delayed by an average of 1–2 years, breast development is poor and female patients frequently have oligomenorrhoea/amenorrhoea even if menarche occurs. Men frequently have poor or absent virilization, reduced libido and oligo/azospermia. They report both genders less fertile and commonly require reproductive assistance to achieve a successful pregnancy (Perera et al., 2010). Toumba & Skordis explains the complacation as disruption of gonadotrophin production (due to iron deposition in gonadotrophic cells) and delayed puberty and hypogonadotrophic hypogonadism. They say secondary amenorrhea will invariably develop with time, especially in patients poorly compliant with chelation therapy. Also primary is common. Men also develop hypogonadotrophic hypogonadism and secondary gonadal failure. So low testosterone secretion is common. They report also primary gonadal failure due to iron deposition in the testes and ovaries. (Toumba & Skordis, 2010).

Perera et al,, in an overview of endocrinopathies associated with b-thalassemia major, (2010), highlighted the high prevalence of hypogonadism with resultant growth failure and infertility, and suggested the following approach and managent protocol in these patients:


reasonable until further clarification of the relationship between zinc deficiency and hypogonadism becomes available (Perera et al., 2010).

#### 4.2.3.4.2.4 Fertility in thalassemia

210 Osteoporosis

(Soliman et al., 2009). Though hemosiderosis-induced damage of the endocrine glands is one of the main causes for their growth failure, Cao & Galanello, Muncie & Campbell, Toumba & Skordis and Soliman et al, state that other factors could considerably contribute to the etiology of this growth delay including (i) chronic anemic hypoxia secondary to low hemoglobin concentration (Muncie & Campbell, 2009) (ii) toxicity of desferrioxamine treatment (Cao & Galanello, 2010); (iii) increased energy expenditure due to high erythopoietic turnover and cardiac work; (iv) nutritional deficiencies including calories, folic-acid, zinc, and vitamin A (Soliman et al., 2009); (v) disturbed calcium homeostasis and bone disease (Toumba & Skordis, 2010) (vi) hepatic and pancreatic dysfunction (Soliman et

Perera et al., emphasize that normal stature is rarely attained, even in the well-managed patient. They report the administration of GH in some centers internationally at the judgment of individual clinicians, but the role or response to GH is not clearly understood in these patients and probably has no clear benefit unless GH deficiency is confirmed by formal testing

Both primary and secondary sexual development are usually delayed in both genders in bthalassemia major (Vogiatzi et al., 2005). An association between hypogonadotrophic hypogonadism and osteoporosis in adult patients with TM has been reported in the past. Jensen et al (1998), found that hypogonadotrophic hypogonadism is a substantial contributor to the development of osteoporosis. Hypogonadotrophic hypogonadism is the commonest endocrinological complication in β-thalassaemia major and is present in 42% of patients (Jensen et al., 1998). Perera et al. describe the finding in thses patients as menarche is frequently delayed by an average of 1–2 years, breast development is poor and female patients frequently have oligomenorrhoea/amenorrhoea even if menarche occurs. Men frequently have poor or absent virilization, reduced libido and oligo/azospermia. They report both genders less fertile and commonly require reproductive assistance to achieve a successful pregnancy (Perera et al., 2010). Toumba & Skordis explains the complacation as disruption of gonadotrophin production (due to iron deposition in gonadotrophic cells) and delayed puberty and hypogonadotrophic hypogonadism. They say secondary amenorrhea will invariably develop with time, especially in patients poorly compliant with chelation therapy. Also primary is common. Men also develop hypogonadotrophic hypogonadism and secondary gonadal failure. So low testosterone secretion is common. They report also primary gonadal failure due to iron deposition in the testes and ovaries. (Toumba & Skordis, 2010). Perera et al,, in an overview of endocrinopathies associated with b-thalassemia major, (2010), highlighted the high prevalence of hypogonadism with resultant growth failure and infertility, and suggested the following approach and managent protocol in these patients: 1. Formal surveillance from the age of 10–12 years to identify changes associated with puberty, including the development of primary or secondary sexual characteristics. Consideration of an endocrine consultation in cases of suspected delayed puberty. 2. In adults, in addition to regular clinical review, annual monitoring of gonadotropin levels and sex hormone levels for both men and women should be organized. If clinically indicated, use of appropriate hormone replacement therapy in cases of

3. Regular monitoring (1–3 times/year) of zinc levels, especially if patient is on deferiprone. In cases of zinc deficiency, supplementation to normal levels would also be

(generally as a consequence of early childhood pituitary failure) (Perera et al., 2010).

4.2.3.4.2.3 Delayed puberty/hypogonadism in thalassemia

al., 2009).

hypogonadism.

Pregnancy reported generally safe if baseline cardiac function is good (Rund & Rachmilewitz, 2005). Psihogios et al., suggested that with optimal therapy, most young adults with homozygous β-thalassemia can achieve reproductive, sexual, and social experiences similar to those of their healthy peers (Psihogios et al., 2002).

4.2.3.4.2.5 Impaired glucose tolerance and diabetes mellitus in thalassemia

There are different reports on the prevalence of diabetes in thalassemia major, however, Holger Cario reported that the prevalence is about 5%, while impaired glucose tolerance is found in up to 27% of patients (Cario et al., 2003).

Immune system activation against pancreatic beta cells in beta-thalassemia patients, is reported and pancreatic iron deposition is considered as factors that triggers the autoimmune response (iron deposisions act as environmental factor) and immune response, in turn, contributes to selective beta-cell damage (Najafipour et al., 2008). Perera et la.,did not report family history as a risk factor in thalassemic patient (Perera et al., 2010). In the study by Najafipour et al., risk factors reported for impaired glucose metabolism were, age, amount of blood transfused and duration of blood transfusion. Because not all of the patients with thalassemia major could be correctly diagnosed by fasting glucose alone, the authors preferred to use the oral glucose tolerance test (OGTT) rather than fasting blood glucose levels (BGLs) for the diagnosis of abnormal glucose tolerance in thalassemic patients (Najafipour et al., 2008).

Duration of transfusion therapy, in some studies was the strongest predictor for the development of diabetes (every decade of transfusion exposure further increasing the odds of developing diabetes by 2.5 times). The fact that diabetes mellitus is generally seen in the 3rd or 4th decade, may be is explainable by these findings.. Perera et al state that it is prudent to begin screening for diabetes after the 1st decade of transfusions (regular 6th monthly or annual) by assessing fasting BGLs followed by a 75-g 2-h OGTT if fasting results are abnormal (Perera et al., 2010).

Glyburide treatment and antidiabetic compounds improve insulin sensitivity. Treatment with basal-bolus insulin therapy is also used in these patients. However must not forget that effective iron chelation may improve glucose tolerance (Perera et al., 2010; Cario et al., 2003). Some believe that HbA1c is not a good tool for measuring glycemic control because of reduced red cell lifespan, ineffective hematopoiesis and frequent blood transfusions (affect the validity of HbA1c results). They propose serum fructosamine as an alternative way of monitoring glycemic control, though there is some limitations in its use. Blood glucose self monitoring and regular pre-transfusion venous blood glucose measurements may be use for measuring glycemic control, as an alternative ways in these patinets (Perera et al., 2010).

#### 4.2.3.4.2.6 Hypothyroidism in thalassemia

The severity of thyroid dysfunction is variable in thalasemic patients and the reports of prevalence are very different. Najafipour et al, reported the prevalence of hypothyroidism in their patients 16%, but found the prevalence of 13% to 60% in different studies of patients with thalassemia. However they believe that milder forms of thyroid dysfunction are much more common in thalassemic patients (Najafipour et al., 2008). Primary thyroid damage (from iron

What We Learn from Bone Complications in Congenital Diseases? Thalassemia, an Example 213

are found in 24-hour urine collection. Bone X-rays are characteristic for osteoporosis. Abnormal cerebral CT findings are reported to be related to hypoparathyroidism in

Vitamin C deficiency in iron-overloaded patients, is seen with increases the risk of osteoporotic fractures at the level of ephysial lines (Wonke, 1998). Vitamin D deficiency (although it is not reported in all studies in thalassemic patients) is also implicated in the pathogenesis of osteoporosis in TM patients due to the regulatory effect of vitamin D in both osteoclasts and osteoblasts. Adequate calcium intake during skeletal development can increase bone mass in adolescents (Voskaridou & Terpos, 2004). It was shown that increased caloric dietary intake significantly increased IGF-I levels in thalassemic children. Soliman et al., emphasized that aggressive nutritional therapy and/or GH/IGF-I therapy with vitamin D supplementation and/or calcium may improve bone growth and mineralization and prevent the development of osteoporosis and consequent fractures in these patients. They report that many studies, have also shown that improving caloric intake and supplying micronutrients including vitamin D, zinc, and carnitine have a positive effect on linear growth that can be mediated through increasing IGF-I synthesis (Soliman et al., 2009).

Liver diseases is a known risk factor for osteoporosis (Toumba & Skordis, 2010). The effect of iron overload in the liver is so huge and prominent that determination of liver iron concentration in a liver biopsy specimen shows a high correlation with total body iron accumulation and is considered the gold standard for the evaluation of iron overload (Galanello & Origa, 2010). Complications of iron overload include involvement of the liver (chronic hepatitis, fibrosis, and cirrhosis) (Cao & Galanello, 2010). Several factors are implicated in the reduction of bone mass in TM as well as liver disease (La Rosa et al., 2005). Growth retardation and short stature in these patients and low vitamin D are described as

As described, iron overload causes many complications in thalassemic disease which affect bone. However, there are some bone complications that are related to iron overload directly. Some authors suggest direct iron toxicity on osteoblasts (Origa et al., 2005; Galanello & Origa, 2010). Mahachoklertwattana et al, suggest that iron deposition in bone may impair osteoid maturation and inhibit mineralization locally, resulting in focal osteomalacia (Mahachoklertwattana et al., 2003). Although all studies do not agree with these findings (Domrongkitchaiporn et al., 2003), the mechanism by which iron interferes with osteoid maturation and mineralization is explained by Toumba & Skordis as the incorporation of iron into crystals of calcium hydroxyapatite, which consequently affects the growth of calcium hydroxyapatite crystals and increases osteoids in bone tissue (Toumba & Skordis, 2010). Mahachoklertwattana reported a study on the effect of iron overload on bone remodeling in animals showed decreased osteoblast recruitment and collagen synthesis, resulting in a decreased rate of bone formation. Iron deposits in bone and low circulating IGF-I levels may partly contribute to the above findings (Mahachoklertwattana et al., 2003). Domrongkitchaiporn et al., described extensive iron staining on trabecular surfaces and a marked reduction in trabecular bone volume without significant alteration in bone

thalassemics (Karimi et al., 2009; Angelopoulos et al., 2006 (a)).

*4.2.3.4.4 Liver disease in thalassemia* 

*4.2.3.4.5 Iron overload in thalassemia* 

complications of liver disease (Baldini et al., 2010).

*4.2.3.4.3 Nutrition, Vitamins, Calcium, minerals and calorie intake in thalassemia* 

infiltration) or secondary problems (due to pituitary dysfunction due to hemosiderosis of thyrotroph cells) are reported in these patients. Duration of transfusion therapy, has been the strongest predictor for development of hypothyroidism (Perera et al., 2010).

#### 4.2.3.4.2.7 Short stature in thalassemia

As an important complication of thalassemia major, we discuss short stature in an independent section, not attached to growth failure. Najafipour et al, reported that 49% of thalassemic patients had a height standard deviation score less than -2 and 83% of thalassemic patients had a height standard deviation score less than -1. Normal stature is rare even in optimally treated patients. (Najafipour et al., 2008).

Even in well treated patients, it is prevalent and this is may be due to endocrine disorders, lifestyle, iron overload and high doses of desferrioxamine (DFX) when tissue iron burden is not very high (Ferrara et al., 2002).

### 4.2.3.4.2.8 Hypopituitarism in thalassemia

Hypogonadotropic hypogonadism occures in a large proportion of patients, because pituitary gland is one of the most vulnerable target organs to the early toxic effects of iron overload(Cao et al., 2011). Pan-hypopituitarism is a rare (especial in patients with good chelation therapy). Perera et al, describe the usual sequence for onset of pituitary dysfunction as begins with FSH, LH, GH and followes by ACTH and TSH (Perera et al., 2010).

4.2.3.4.2.9 The Rankl/OPG system in thalassemia

The increase in RANKL, followed by unmodified OPG levels, with the consequent increase in the RANKL/OPG ratio may represent the cause of uncoupling in bone turnover observed in thalassemia patients (Toumba & Skordis, 2010). Haidar et la, report a negative correlation between 17-b estradiol in female and the RANKL and RANKL and free testosterone in male thalassemia patients. They reason that there is a role for the RANKL/OPG system on the action of sex steroids on bone (Haidar et al., 2011).

4.2.3.4.2.10 GH and IGF1 axis in thalassemia

According to the importance of the GH and IGF1 axis, we investigate this axis in detail in the following:

Despite normal response to provocation, some studies have shown that spontaneous GH secretion is defective in some short patients with TM,. Soliman et al, emphasize that these data means the GH–IGF-I–IGFBP-3 axis in thalassemic children is defective. Structural abnormalities of their pituitary glands is also reported in association with defective GH secretion in thalassemic children. Impaired liver functions (secondary to siderosis and/or chronic viral hepatitis) may cause low IGF-I synthesis. Interestingly, Soliman et al, suggest that increased caloric dietary intake significantly increased IGF-I levels in thalassemic pediatric patinets (Soliman et al., 2009).

4.2.3.4.2.11 Parathyroid gland dysfunction in thalassemia

Hypoparathyroidism is another factor contributes to osteopenia and subsequently osteoporosis. It is believed that this complication develops more in late adolescence A recent study reported a prevalence of up to 13.5% with no sex differences (Angelopoulos et al., 2006 (a)). Main causes of hypoparathyroidism, are iron deposition on parathyroid cells (Galanello & Origa, 2010). Typical biochemical picture of hypoparathyroidism with low calcium and high phosphate levels, is seen in these patinets. Low calcium and phosphorus are found in 24-hour urine collection. Bone X-rays are characteristic for osteoporosis. Abnormal cerebral CT findings are reported to be related to hypoparathyroidism in thalassemics (Karimi et al., 2009; Angelopoulos et al., 2006 (a)).

#### *4.2.3.4.3 Nutrition, Vitamins, Calcium, minerals and calorie intake in thalassemia*

Vitamin C deficiency in iron-overloaded patients, is seen with increases the risk of osteoporotic fractures at the level of ephysial lines (Wonke, 1998). Vitamin D deficiency (although it is not reported in all studies in thalassemic patients) is also implicated in the pathogenesis of osteoporosis in TM patients due to the regulatory effect of vitamin D in both osteoclasts and osteoblasts. Adequate calcium intake during skeletal development can increase bone mass in adolescents (Voskaridou & Terpos, 2004). It was shown that increased caloric dietary intake significantly increased IGF-I levels in thalassemic children. Soliman et al., emphasized that aggressive nutritional therapy and/or GH/IGF-I therapy with vitamin D supplementation and/or calcium may improve bone growth and mineralization and prevent the development of osteoporosis and consequent fractures in these patients. They report that many studies, have also shown that improving caloric intake and supplying micronutrients including vitamin D, zinc, and carnitine have a positive effect on linear growth that can be mediated through increasing IGF-I synthesis (Soliman et al., 2009).

#### *4.2.3.4.4 Liver disease in thalassemia*

212 Osteoporosis

infiltration) or secondary problems (due to pituitary dysfunction due to hemosiderosis of thyrotroph cells) are reported in these patients. Duration of transfusion therapy, has been the

As an important complication of thalassemia major, we discuss short stature in an independent section, not attached to growth failure. Najafipour et al, reported that 49% of thalassemic patients had a height standard deviation score less than -2 and 83% of thalassemic patients had a height standard deviation score less than -1. Normal stature is

Even in well treated patients, it is prevalent and this is may be due to endocrine disorders, lifestyle, iron overload and high doses of desferrioxamine (DFX) when tissue iron burden is

Hypogonadotropic hypogonadism occures in a large proportion of patients, because pituitary gland is one of the most vulnerable target organs to the early toxic effects of iron overload(Cao et al., 2011). Pan-hypopituitarism is a rare (especial in patients with good chelation therapy). Perera et al, describe the usual sequence for onset of pituitary dysfunction as begins with FSH,

The increase in RANKL, followed by unmodified OPG levels, with the consequent increase in the RANKL/OPG ratio may represent the cause of uncoupling in bone turnover observed in thalassemia patients (Toumba & Skordis, 2010). Haidar et la, report a negative correlation between 17-b estradiol in female and the RANKL and RANKL and free testosterone in male thalassemia patients. They reason that there is a role for the RANKL/OPG system on the

According to the importance of the GH and IGF1 axis, we investigate this axis in detail in

Despite normal response to provocation, some studies have shown that spontaneous GH secretion is defective in some short patients with TM,. Soliman et al, emphasize that these data means the GH–IGF-I–IGFBP-3 axis in thalassemic children is defective. Structural abnormalities of their pituitary glands is also reported in association with defective GH secretion in thalassemic children. Impaired liver functions (secondary to siderosis and/or chronic viral hepatitis) may cause low IGF-I synthesis. Interestingly, Soliman et al, suggest that increased caloric dietary intake significantly increased IGF-I levels in thalassemic

Hypoparathyroidism is another factor contributes to osteopenia and subsequently osteoporosis. It is believed that this complication develops more in late adolescence A recent study reported a prevalence of up to 13.5% with no sex differences (Angelopoulos et al., 2006 (a)). Main causes of hypoparathyroidism, are iron deposition on parathyroid cells (Galanello & Origa, 2010). Typical biochemical picture of hypoparathyroidism with low calcium and high phosphate levels, is seen in these patinets. Low calcium and phosphorus

strongest predictor for development of hypothyroidism (Perera et al., 2010).

rare even in optimally treated patients. (Najafipour et al., 2008).

LH, GH and followes by ACTH and TSH (Perera et al., 2010).

4.2.3.4.2.9 The Rankl/OPG system in thalassemia

action of sex steroids on bone (Haidar et al., 2011).

4.2.3.4.2.10 GH and IGF1 axis in thalassemia

pediatric patinets (Soliman et al., 2009).

4.2.3.4.2.11 Parathyroid gland dysfunction in thalassemia

the following:

4.2.3.4.2.7 Short stature in thalassemia

not very high (Ferrara et al., 2002).

4.2.3.4.2.8 Hypopituitarism in thalassemia

Liver diseases is a known risk factor for osteoporosis (Toumba & Skordis, 2010). The effect of iron overload in the liver is so huge and prominent that determination of liver iron concentration in a liver biopsy specimen shows a high correlation with total body iron accumulation and is considered the gold standard for the evaluation of iron overload (Galanello & Origa, 2010). Complications of iron overload include involvement of the liver (chronic hepatitis, fibrosis, and cirrhosis) (Cao & Galanello, 2010). Several factors are implicated in the reduction of bone mass in TM as well as liver disease (La Rosa et al., 2005). Growth retardation and short stature in these patients and low vitamin D are described as complications of liver disease (Baldini et al., 2010).

#### *4.2.3.4.5 Iron overload in thalassemia*

As described, iron overload causes many complications in thalassemic disease which affect bone. However, there are some bone complications that are related to iron overload directly. Some authors suggest direct iron toxicity on osteoblasts (Origa et al., 2005; Galanello & Origa, 2010). Mahachoklertwattana et al, suggest that iron deposition in bone may impair osteoid maturation and inhibit mineralization locally, resulting in focal osteomalacia (Mahachoklertwattana et al., 2003). Although all studies do not agree with these findings (Domrongkitchaiporn et al., 2003), the mechanism by which iron interferes with osteoid maturation and mineralization is explained by Toumba & Skordis as the incorporation of iron into crystals of calcium hydroxyapatite, which consequently affects the growth of calcium hydroxyapatite crystals and increases osteoids in bone tissue (Toumba & Skordis, 2010). Mahachoklertwattana reported a study on the effect of iron overload on bone remodeling in animals showed decreased osteoblast recruitment and collagen synthesis, resulting in a decreased rate of bone formation. Iron deposits in bone and low circulating IGF-I levels may partly contribute to the above findings (Mahachoklertwattana et al., 2003). Domrongkitchaiporn et al., described extensive iron staining on trabecular surfaces and a marked reduction in trabecular bone volume without significant alteration in bone

What We Learn from Bone Complications in Congenital Diseases? Thalassemia, an Example 215

these patients spend a significant amount of their time at health care centers, or overprotected by parents and caregivers. In summary, these findings confirm that the epidemiology of fractures in TM remains unique, as it is not correlated with risk taking behavior but is mainly due to vitamin D deficiency or low BMD which become more severe

Prevention is essential for the effective control of this potentially debilitating morbidity in TM. Annual follow-up of BMD, starting in adolescence, is considered crucial. Haidar et al., recommend that Physical activity must always be encouraged and smoking should be discouraged. Adequate iron chelation, adequate calcium and zinc intake in combination with the administration of vitamin D , may prevent bone loss and fractures later and in adulthood. Hypogonadism and its prevension and treatment in thalassemic patients is very important in management of bone complication in thalassemia (Haidar et al., 2011). Despite the aforementioned measures, patients with TM still continue to lose bone mass and require treatment. Hormonal replacement, Calcitonin, Hydroxyurea, Bisphosphonates (clodronate, alendronate, pamidronate, and zoledronic) are used in the management of osteoporosis in thalassemic patients. Calcitonin, may decrease bone pain. (Voskaridou & Terpos, 2004 and

Of course, it must be remembered that the use of these agents in pediatric patients is not very common or recommended, especially in young children, due to a lack of large systematic studies and comprehensive data supporting their efficacy or address their

The thalassemic patients live longer now. Therefore, it is necessary to assess the bone problems in adult thalassemic patients. The increased survival of these patients during the last decade is due to regular transfusion associated with adequate iron chelation. Specific bone deformities are more rare but osteopenia and osteoporosis are more common . Low bone mass occurs despite transfusions, effective chelation, calcium, and vitamin D supplementation and hormonal deficiency replacement (Baldini et al., 2010). Though hypogonadism is important in low bone mass in TM patients, it may not be overt. Even in eugonadal women, as a delay of menarche which is common, a subtle deficiency in ovarian function cannot be ruled out (Carmina et al, 2004). Napoli et al demonstrated, at least in women with thalassemia major, that hormone replacement therapy was unable to prevent bone loss. This suggests that several mechanisms potentially contribute to low bone mass. One of these mechanisms may be vitamin D deficiency. It should be noted that TM patients progressively develop iron overload, and it is possible that a deficiency in liver hydroxylation of vitamin D, or in vitamin D absorption, can appear in older thalassemic patients (Napoli et al., 2006). However, all studies are not agree with high prevalence of low Vit-D in thalassemic patinets. Another problem in these patients is GH-IGF1 axis. It was demonstrated that the GH–IGF-I–IGFBP-3 axis in thalassemic children is defective (Soliman et al., 2009) and it is shown that GH is important in adult life and that replacement therapy

with age in this cohort of patients. (Haidar et al., 2011). **4.2.3.6 Management of thalassemia-induced osteoporosis** 

Haidar et al., 2011).

adverse effects in pediatric patients.

**4.2.3.7 Bone mineral density in adult thalassemic patients** 

should not be ignored in adults with hypopituitarism (La Rosa et al., 2005).

Baldini et al., found that the femoral site is more influenced (by biochemical and clinical factors) than the spinal site. (Baldini et al., 2010). Christoforidis et al., suggested that optimal conventional treatment in β-thalassemia major can help to achieve normal bone mass

formation and bone resorption rates, as well as a significant reduction in BMD in 18 thalassemic patients (Domrongkitchaiporn et al., 2003). Thus, it seems that further studies are needed to address the effect of iron toxicity on bone metabolism in thalassemia.

#### *4.2.3.4.6 Chelation therapy in thalassemia*

Chelation therapy is a known risk factor for bone problem in thalassemia patients (Origa et al., 2005; Vogiatzi et al., 2010) Growth failure and bone abnormalities, and cartilage alterations are reported as chelating therapy complication (Toumba & Skordis, 2010). Wonke et al., described the role of desferrioxamine in osteoporosis of thalassemic patients as follows: Desferrioxamine inhibits DNA synthesis, fibroblast proliferation and collagen formation, and may also cause zinc deficiency. Growth arrest and a reduction in growth velocity, difficulty in walking, frequently complain of pain in the hips and lower back is seen in patients who receive inappropriately high doses of desferrioxamine, specially when the iron burden is low, (Wonke, 1998).

#### *4.2.3.4.7 Physical activity in thalassemia*

As Haidar et al. Suggest, the association between mechanical stress and bone mass was first recorded by Galileo in 1683, who noted the relationship between body weight and bone size. They say that the low bone mass in TM patients is associated with reduced physical activity due to complications of the disease and overprotective parents, who do not encourage muscle activity (Haidar et al., 2011). However, bone disease management in these patients now includes increased physical activity (Rund & Rachmilewitz, 2005; Haidar et al., 2011; Wonke, 1998; Toumba & Skordis, 2010). What must not forget is that there is some conditions requiring special attention in recommending physical activity like severe heart disease , splenomegaly, and osteoporosis (Galanello & Origa, 2010).

#### **4.2.3.5 Fractures in thalassemia**

From self-reporting and a review of medical records, fractures occur in 36% of thalassemic patients, with 8.9% reporting three or more lifetime fractures. Extremity fractures are most common at 33%, followed by back and hip fractures at 3.6% (in one study, 10% of all fractures were reported in the spine, hip and pelvis). Low bone mass, sex hormone replacement therapy, and at least one iron overload-related endocrinopathy, was related to the prevalence of fracture. Multiple fractures are also a problem in TM patients (Haidar et al., 2011). Vogiatzi et al found The cumulative risk of fractures increased almost linearly with age. Overally, they didn't find,sex difference ; though among participants <20 years of age, males were more likely to have a fracture compared with females. Whites participants had reports of fracture rates more than Asian. Other their findings was that spine and femur BMD Z-score and total body BMC were negatively associated with fracture rate. For a 1-SD decrease in spine or femur BMD Z-score, the mean fracture rate increased by 37% or 47%, respectively (p < 0.001 for both) (Vogiatzi et al., 2009).

The peak age of fracture was the mid to late 30s. Interestingly, the percentage of subjects who remained fracture-free by the age of 18 years was significantly higher than population estimates of healthy children without hemoglobinopathies. There did not appear to be an increase in fracture prevalence during the adolescent growth spurt or surrounding the initiation of menstruation, as is typically observed in healthy reference cohorts. This may be attributed to anemia which leads to decreased physical activity and fewer opportunities for recreational fractures. There is decreased time available for sports and physical activity as these patients spend a significant amount of their time at health care centers, or overprotected by parents and caregivers. In summary, these findings confirm that the epidemiology of fractures in TM remains unique, as it is not correlated with risk taking behavior but is mainly due to vitamin D deficiency or low BMD which become more severe with age in this cohort of patients. (Haidar et al., 2011).

### **4.2.3.6 Management of thalassemia-induced osteoporosis**

214 Osteoporosis

formation and bone resorption rates, as well as a significant reduction in BMD in 18 thalassemic patients (Domrongkitchaiporn et al., 2003). Thus, it seems that further studies

Chelation therapy is a known risk factor for bone problem in thalassemia patients (Origa et al., 2005; Vogiatzi et al., 2010) Growth failure and bone abnormalities, and cartilage alterations are reported as chelating therapy complication (Toumba & Skordis, 2010). Wonke et al., described the role of desferrioxamine in osteoporosis of thalassemic patients as follows: Desferrioxamine inhibits DNA synthesis, fibroblast proliferation and collagen formation, and may also cause zinc deficiency. Growth arrest and a reduction in growth velocity, difficulty in walking, frequently complain of pain in the hips and lower back is seen in patients who receive inappropriately high doses of desferrioxamine, specially when

As Haidar et al. Suggest, the association between mechanical stress and bone mass was first recorded by Galileo in 1683, who noted the relationship between body weight and bone size. They say that the low bone mass in TM patients is associated with reduced physical activity due to complications of the disease and overprotective parents, who do not encourage muscle activity (Haidar et al., 2011). However, bone disease management in these patients now includes increased physical activity (Rund & Rachmilewitz, 2005; Haidar et al., 2011; Wonke, 1998; Toumba & Skordis, 2010). What must not forget is that there is some conditions requiring special attention in recommending physical activity like severe heart

From self-reporting and a review of medical records, fractures occur in 36% of thalassemic patients, with 8.9% reporting three or more lifetime fractures. Extremity fractures are most common at 33%, followed by back and hip fractures at 3.6% (in one study, 10% of all fractures were reported in the spine, hip and pelvis). Low bone mass, sex hormone replacement therapy, and at least one iron overload-related endocrinopathy, was related to the prevalence of fracture. Multiple fractures are also a problem in TM patients (Haidar et al., 2011). Vogiatzi et al found The cumulative risk of fractures increased almost linearly with age. Overally, they didn't find,sex difference ; though among participants <20 years of age, males were more likely to have a fracture compared with females. Whites participants had reports of fracture rates more than Asian. Other their findings was that spine and femur BMD Z-score and total body BMC were negatively associated with fracture rate. For a 1-SD decrease in spine or femur BMD Z-score, the mean fracture rate increased by 37% or 47%,

The peak age of fracture was the mid to late 30s. Interestingly, the percentage of subjects who remained fracture-free by the age of 18 years was significantly higher than population estimates of healthy children without hemoglobinopathies. There did not appear to be an increase in fracture prevalence during the adolescent growth spurt or surrounding the initiation of menstruation, as is typically observed in healthy reference cohorts. This may be attributed to anemia which leads to decreased physical activity and fewer opportunities for recreational fractures. There is decreased time available for sports and physical activity as

disease , splenomegaly, and osteoporosis (Galanello & Origa, 2010).

respectively (p < 0.001 for both) (Vogiatzi et al., 2009).

are needed to address the effect of iron toxicity on bone metabolism in thalassemia.

*4.2.3.4.6 Chelation therapy in thalassemia* 

the iron burden is low, (Wonke, 1998). *4.2.3.4.7 Physical activity in thalassemia* 

**4.2.3.5 Fractures in thalassemia** 

Prevention is essential for the effective control of this potentially debilitating morbidity in TM. Annual follow-up of BMD, starting in adolescence, is considered crucial. Haidar et al., recommend that Physical activity must always be encouraged and smoking should be discouraged. Adequate iron chelation, adequate calcium and zinc intake in combination with the administration of vitamin D , may prevent bone loss and fractures later and in adulthood. Hypogonadism and its prevension and treatment in thalassemic patients is very important in management of bone complication in thalassemia (Haidar et al., 2011). Despite the aforementioned measures, patients with TM still continue to lose bone mass and require treatment. Hormonal replacement, Calcitonin, Hydroxyurea, Bisphosphonates (clodronate, alendronate, pamidronate, and zoledronic) are used in the management of osteoporosis in thalassemic patients. Calcitonin, may decrease bone pain. (Voskaridou & Terpos, 2004 and Haidar et al., 2011).

Of course, it must be remembered that the use of these agents in pediatric patients is not very common or recommended, especially in young children, due to a lack of large systematic studies and comprehensive data supporting their efficacy or address their adverse effects in pediatric patients.

#### **4.2.3.7 Bone mineral density in adult thalassemic patients**

The thalassemic patients live longer now. Therefore, it is necessary to assess the bone problems in adult thalassemic patients. The increased survival of these patients during the last decade is due to regular transfusion associated with adequate iron chelation. Specific bone deformities are more rare but osteopenia and osteoporosis are more common . Low bone mass occurs despite transfusions, effective chelation, calcium, and vitamin D supplementation and hormonal deficiency replacement (Baldini et al., 2010). Though hypogonadism is important in low bone mass in TM patients, it may not be overt. Even in eugonadal women, as a delay of menarche which is common, a subtle deficiency in ovarian function cannot be ruled out (Carmina et al, 2004). Napoli et al demonstrated, at least in women with thalassemia major, that hormone replacement therapy was unable to prevent bone loss. This suggests that several mechanisms potentially contribute to low bone mass. One of these mechanisms may be vitamin D deficiency. It should be noted that TM patients progressively develop iron overload, and it is possible that a deficiency in liver hydroxylation of vitamin D, or in vitamin D absorption, can appear in older thalassemic patients (Napoli et al., 2006). However, all studies are not agree with high prevalence of low Vit-D in thalassemic patinets. Another problem in these patients is GH-IGF1 axis. It was demonstrated that the GH–IGF-I–IGFBP-3 axis in thalassemic children is defective (Soliman et al., 2009) and it is shown that GH is important in adult life and that replacement therapy should not be ignored in adults with hypopituitarism (La Rosa et al., 2005).

Baldini et al., found that the femoral site is more influenced (by biochemical and clinical factors) than the spinal site. (Baldini et al., 2010). Christoforidis et al., suggested that optimal conventional treatment in β-thalassemia major can help to achieve normal bone mass

What We Learn from Bone Complications in Congenital Diseases? Thalassemia, an Example 217

As stated by Klopfenstein et al. in the study by Petryk et al., the incidence of osteopenia was 18% and the incidence of osteoporosis was 16% prior to BMT, which increased to 33% and 18%, respectively, 1 year after transplantation (Klopfenstein et al., 1999). In the study by Schulte et al., the lowest BMD in the femoral neck was seen 24 months after transplantation (Schulte & Beelen, 2004). However, as BMT is the only curative treatment for thalassemia, some investigators showed that the changes in BMD after transplantation may change in a

Short stature is present in a significant number of transplanted thalassemic children. A close correlation between age at transplant and subsequent growth rate has been demonstrated (subjects who received BMT after 7 years of age, failed to achieve their full genetic potential), however, growth impairment in these subjects is due to multifactorial deranged function of the hypothalamic-pituitary-gonadal axis, abnormal hepatic conversion of steroid hormones to their active metabolites and defective hepatic biosynthesis of insulin-like growth factor (IGF-I). It is possible that iron overload is primarily involved in this phenomenon. Chronically transfused, inadequately chelated patients develop hepatocellular injury and late growth failure within the first decade of life. This is followed in adolescence by pubertal failure and dysfunction of various

It must be remembered that early experience suggested that the results of transplantation for thalassemia were particularly poor for patients older than 16 years. However, Lucarelli et al., found that when the revised regimen for class 3 pediatric patients was used for older class 3 patients, the results were much improved (Lucarelli et al., 1999). However, Kaste, et al., recommend routine screening of BMD for all alloBMT patients. They suggest that patients should be advised to evaluate all behaviors which adversely affect bone health eg. avoid smoking, limit intake of caffeine and carbonated beverages, establish a weight-bearing exercise regimen after orthopedic consultation, and ensure adequate dietary intake of calcium and vitamin D. Patients should also be treated for other conditions that affect BMD

In Iran, there is a large population of thalassemic patients and after Italy, the largest population of transplanted thalassemic patients. Thus, special attention to bone diseases before and after transplantation is necessary in these patients, and such studies may be

The thalassemias, a group of inherited disorders of hemoglobin synthesis, are the most common monogenetic diseases worldwide and these diseases are curable by BMT. Many patients achieve a lifelong disease-free period after BMT. Thus, special attention to bone diseases before and after transplantation in these patients is necessary, and such studies may be helpful in improving life quality in affected individuals. Coping with huge problems related to the main disease and during and after BMT, the provision of a normal and safe

positive direction (Leung et al., 2005).

endocrine organs (De Simone et al., 2001).

**5.2.2 Special consideration in older recipients** 

such as hypogonadism and hypothyroidism (Kaste, et al., 2004).

**6. What we have learned about bone and thalassemia** 

helpful in improving life quality in affected individuals.

**5.2.1 Special consideration in children (Short stature)** 

**5.2 Special considerations** 

acquisition. They stated major contributors to this, as the regression of marrow expansion due to regular transfusions, the prevention of endocrine complications following adequate chelation therapy, and the reduction in deferioxamine-induced bone toxicity with the additional administration of deferiprone. As patients with thalassemia are in greater danger of developing predisposing factors for osteoporosis, optimal bone acquisition, comparable to the normal population, is essential in order to reduce future risks of osteoporosis in adult life. They recommend close surveillance with regular screening, preventive intervention and early management of possible endocrine complications are important in order to secure normal bone health. Life prolongation for patients with thalassemia major also requires improvement in quality of life (Christoforidis et al., 2006). In addition, Baldini et al. suggested that transfusion and chelation treatment can prevent bone demineralization only when applied early in childhood (Baldini et al., 2010).

### **5. Bone and thalassemia after bone marrow transplantation**

#### **5.1 General**

Osteoporosis is increased in recipients of heart, kidney, lung, and liver transplants (Petropoulou al., 2010). Patients undergone bone marrow transplantation have some difference with other transplant recipients. Their underlying disease, organ dysfunction, age, and the median interval between diagnosis and transplantation is different. That interval is usually shorter for BMT. Kerschan-Schindl et al., conclude that BMT recipients may receive less pre-treatment impairing bone metabolism, experience fewer restrictions in mobility, and have a more normal nutritional status. Additionally, BMT recipients generally receive less subsequent immunosuppressive therapy which may induce osteopenia (Kerschan-Schindl et al., 2004).

Thalassemic patients are in an increased risk of accelerated bone loss and thus osteoporosis, because BMT is a curative treatment for thalassemia, and many patients achieve a lifelong disease-free period after BMT. Several factors inhance bone loss in them, including gonadal failure, prolonged immobility, decreased osteoprogenitor cells, conditioning regimens, vitamin D deficiency, secondary hyperparathyroidism, cyclosporine and high-corticosteroid use for graft-versus-host disease (D'Souza et al., 2006). Though some of them are not uncommon before transplantation (Angelopoulos et al., 2006 (b)).

Many investigators such as D'Souza et al. (D'Souza et al., 2006) and Schulte et al. (Schulte & Beelen, 2004) reported the significant lowering effect of corticosteroids on BMD in transplanted patients. However, their studies were not specifically on pediatric thalassemic patients, and a study by Daneils et al. did not find a statistically significant correlation between glucocorticoid exposure and BMD in transplanted children.

Kerschan-Schindl et al., suggest the amount of bone loss and the pattern of loss are controversial. The amount of bone loss within 1 year after transplantation varied and was approximately 2% for the lumbar spine and 12% for the femoral neck. At 5 years after allogeneic BMT, the lumbar spine BMD was within normal limits, but the femoral neck BMD was decreased; osteopenia was present in 43% and osteoporosis in 7% of patients (Kerschan-Schindl et al., 2004). Schulte & Beelen, demonstrated data of rapid bone loss during the first 6 months after transplantation (5.7% at the lumbar spine and 6.9% to 8.7% at the femoral neck sites) with no further decline between months 6 and 12, and recovery of bone mass during further follow-up (Schulte & Beelen, 2004).

As stated by Klopfenstein et al. in the study by Petryk et al., the incidence of osteopenia was 18% and the incidence of osteoporosis was 16% prior to BMT, which increased to 33% and 18%, respectively, 1 year after transplantation (Klopfenstein et al., 1999). In the study by Schulte et al., the lowest BMD in the femoral neck was seen 24 months after transplantation (Schulte & Beelen, 2004). However, as BMT is the only curative treatment for thalassemia, some investigators showed that the changes in BMD after transplantation may change in a positive direction (Leung et al., 2005).

### **5.2 Special considerations**

216 Osteoporosis

acquisition. They stated major contributors to this, as the regression of marrow expansion due to regular transfusions, the prevention of endocrine complications following adequate chelation therapy, and the reduction in deferioxamine-induced bone toxicity with the additional administration of deferiprone. As patients with thalassemia are in greater danger of developing predisposing factors for osteoporosis, optimal bone acquisition, comparable to the normal population, is essential in order to reduce future risks of osteoporosis in adult life. They recommend close surveillance with regular screening, preventive intervention and early management of possible endocrine complications are important in order to secure normal bone health. Life prolongation for patients with thalassemia major also requires improvement in quality of life (Christoforidis et al., 2006). In addition, Baldini et al. suggested that transfusion and chelation treatment can prevent bone demineralization only

Osteoporosis is increased in recipients of heart, kidney, lung, and liver transplants (Petropoulou al., 2010). Patients undergone bone marrow transplantation have some difference with other transplant recipients. Their underlying disease, organ dysfunction, age, and the median interval between diagnosis and transplantation is different. That interval is usually shorter for BMT. Kerschan-Schindl et al., conclude that BMT recipients may receive less pre-treatment impairing bone metabolism, experience fewer restrictions in mobility, and have a more normal nutritional status. Additionally, BMT recipients generally receive less subsequent immunosuppressive therapy which may induce osteopenia

Thalassemic patients are in an increased risk of accelerated bone loss and thus osteoporosis, because BMT is a curative treatment for thalassemia, and many patients achieve a lifelong disease-free period after BMT. Several factors inhance bone loss in them, including gonadal failure, prolonged immobility, decreased osteoprogenitor cells, conditioning regimens, vitamin D deficiency, secondary hyperparathyroidism, cyclosporine and high-corticosteroid use for graft-versus-host disease (D'Souza et al., 2006). Though some of them are not

Many investigators such as D'Souza et al. (D'Souza et al., 2006) and Schulte et al. (Schulte & Beelen, 2004) reported the significant lowering effect of corticosteroids on BMD in transplanted patients. However, their studies were not specifically on pediatric thalassemic patients, and a study by Daneils et al. did not find a statistically significant correlation

Kerschan-Schindl et al., suggest the amount of bone loss and the pattern of loss are controversial. The amount of bone loss within 1 year after transplantation varied and was approximately 2% for the lumbar spine and 12% for the femoral neck. At 5 years after allogeneic BMT, the lumbar spine BMD was within normal limits, but the femoral neck BMD was decreased; osteopenia was present in 43% and osteoporosis in 7% of patients (Kerschan-Schindl et al., 2004). Schulte & Beelen, demonstrated data of rapid bone loss during the first 6 months after transplantation (5.7% at the lumbar spine and 6.9% to 8.7% at the femoral neck sites) with no further decline between months 6 and 12, and recovery of

when applied early in childhood (Baldini et al., 2010).

**5.1 General** 

(Kerschan-Schindl et al., 2004).

**5. Bone and thalassemia after bone marrow transplantation** 

uncommon before transplantation (Angelopoulos et al., 2006 (b)).

between glucocorticoid exposure and BMD in transplanted children.

bone mass during further follow-up (Schulte & Beelen, 2004).

### **5.2.1 Special consideration in children (Short stature)**

Short stature is present in a significant number of transplanted thalassemic children. A close correlation between age at transplant and subsequent growth rate has been demonstrated (subjects who received BMT after 7 years of age, failed to achieve their full genetic potential), however, growth impairment in these subjects is due to multifactorial deranged function of the hypothalamic-pituitary-gonadal axis, abnormal hepatic conversion of steroid hormones to their active metabolites and defective hepatic biosynthesis of insulin-like growth factor (IGF-I). It is possible that iron overload is primarily involved in this phenomenon. Chronically transfused, inadequately chelated patients develop hepatocellular injury and late growth failure within the first decade of life. This is followed in adolescence by pubertal failure and dysfunction of various endocrine organs (De Simone et al., 2001).

### **5.2.2 Special consideration in older recipients**

It must be remembered that early experience suggested that the results of transplantation for thalassemia were particularly poor for patients older than 16 years. However, Lucarelli et al., found that when the revised regimen for class 3 pediatric patients was used for older class 3 patients, the results were much improved (Lucarelli et al., 1999). However, Kaste, et al., recommend routine screening of BMD for all alloBMT patients. They suggest that patients should be advised to evaluate all behaviors which adversely affect bone health eg. avoid smoking, limit intake of caffeine and carbonated beverages, establish a weight-bearing exercise regimen after orthopedic consultation, and ensure adequate dietary intake of calcium and vitamin D. Patients should also be treated for other conditions that affect BMD such as hypogonadism and hypothyroidism (Kaste, et al., 2004).

In Iran, there is a large population of thalassemic patients and after Italy, the largest population of transplanted thalassemic patients. Thus, special attention to bone diseases before and after transplantation is necessary in these patients, and such studies may be helpful in improving life quality in affected individuals.

### **6. What we have learned about bone and thalassemia**

The thalassemias, a group of inherited disorders of hemoglobin synthesis, are the most common monogenetic diseases worldwide and these diseases are curable by BMT. Many patients achieve a lifelong disease-free period after BMT. Thus, special attention to bone diseases before and after transplantation in these patients is necessary, and such studies may be helpful in improving life quality in affected individuals. Coping with huge problems related to the main disease and during and after BMT, the provision of a normal and safe

What We Learn from Bone Complications in Congenital Diseases? Thalassemia, an Example 219

The author thanks Dr. B. Larijani (the director of EMRI-TUMS), Dr. F. Mohseni, Dr. MR. Mohajeri Tehrani, Dr. AA. Hamidieh, Mrs. A. Oojaghi and the Special Medical Center of Charity Foundation for Special Disease of Iran for their valuable assistance in this study.

Abolghasemi, Hassan. Amid, Ali. Zeinali, Sirous. Radfar, Mohammad H. Eshghi, Peyman.

Angelopoulos (a), Nicholas G. Goula, Anastasia. Ombopoulos, Grigorios. Kaltzidou,

Angelopoulos (b), Nicholas G. Katounda, Eugenia. Rombopoulos, Grigorios. Goula,

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Bachrach, L K. (2001). Acquisition of optimal bone mass in childhood and adolescence.

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**8. Acknowledgements** 

**9. References** 

(Print)

*(Print)* 

*6, 1024-2708 (Print)* 

*1043-2760 (Print)* 

*2010), pp.* 1207-1213, 1432-0584 (Electronic)

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life for these patients is a humanitarian problem. Some special points on the prevention, diagnosis, management and monitoring of bone disease in thalassemic patients are listed below:


### **7. Conclusion**

With the expanding number of thalassemia and transplanted thalassemic patients worldwide, a better understanding of bone diseases is necessary to provide a better and safer life for these patients. The findings from these studies can be used in a model to better understand human bone diseases and help in the management of these conditions.

### **8. Acknowledgements**

The author thanks Dr. B. Larijani (the director of EMRI-TUMS), Dr. F. Mohseni, Dr. MR. Mohajeri Tehrani, Dr. AA. Hamidieh, Mrs. A. Oojaghi and the Special Medical Center of Charity Foundation for Special Disease of Iran for their valuable assistance in this study.

### **9. References**

218 Osteoporosis

life for these patients is a humanitarian problem. Some special points on the prevention, diagnosis, management and monitoring of bone disease in thalassemic patients are listed

Assessment of bone conditions in thalassemic patients before and after transplantation

 As a multifactorial disease (ineffective erythropoiesis and bone marrow expansion, endocrine complications, iron overload and iron chelation therapy (deferoxamine), vitamin deficiencies, and decreased physical activity all affect bone in thalassemic patients), the assessment of any of these risk factors and factors effecting them, are grounds for research which can be used to provide a better life for these patients. This is

 As a congenital disease that affects bone from an early age and is completely curable, the assessment of patients in a cohort before and after transplantation, provides an opportunity to investigate factors which affect bone in a positive or negative way, when bone is being destroyed by the main disease and when the main disease is

 Genetic studies provide a way of identifying the genes responsible for low bone mass in non-thalassemic and normal individuals, especially when there are similarities in genes which cause low bone mass in thalassemic patients and non-thalassemic osteoporotic

 It is questionable whether the international criteria for defining osteopenia and osteoporosis are relevant to patients with TM; also the diagnostic methods used for osteoporosis in thalassemic patients are questionable as multiple factors and micro-

 Progression from childhood to puberty and adulthood in these patients provides ground for extended and ethical research on cohort changes in bone density and bone metabolism between these periods. As screening for low bone mass is ethical and routine in pediatrics and adults, there is a unique opportunity to assess the correlation

Assessment of the effects of different preventive and treatment methods and drugs on

 With an ethical background for investigating bone problems in thalassemic patients, providing a model of calcium and bone metabolism, and factors affecting this metabolism, throughout the life (in periods of bone gain and bone loss), is possible. This is possible by using clinical and research findings in these patients. As thalassemia is a congenital disease which is also curable, finding ways for understanding and management of bone disease in other bone disorders and in primary osteoporosis is

With the expanding number of thalassemia and transplanted thalassemic patients worldwide, a better understanding of bone diseases is necessary to provide a better and safer life for these patients. The findings from these studies can be used in a model to better

understand human bone diseases and help in the management of these conditions.

structural characteristics are involved in the pathogenesis of osteoporosis.

between the diagnostic criteria for low BMD in adult and children.

bone and different risk factors that affect bone in these patients.

is ethical and many assessments are routine.

true for bone diseases following BMT.

below:

cured.

patients.

possible.

**7. Conclusion** 


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**12** 

Zohreh Hamidi

*Islamic Republic of Iran* 

*Endocrinology and Metabolism Research Institute of Tehran University of Medical Sciences (EMRI-TUMS),* 

**What's BMD and What We Do in a BMD Centre?** 

The main parts of osteoporosis clinics are BMD (Bone Mineral Densitometry) centers. For increasing our knowledge about osteoporosis we have to increase our knowledge about BMD (Bone Mineral Density), and increasing the knowledge about BMD has a close relationship with realizing the principles and appliances of BMD machines and DXA method. For specific development in a BMD department, we need to know some historical, technical and practical points about these method and machines. In this review, the last

It is very useful to know the history of BMD and DXA devices. The first marketing of this machine was in 1987 and in1994 this method described as gold standard for osteoporosis diagnosis by World Health Organisation (WHO). It means osteoporosis disease, as we know

As Kanis and Johnel reported in 2005, 9 countries from 20 countries (in Europe), had more than 10 DXA units per million of the population (the European standard). However it is unclear which percent of machines were dedicated in part or in full to clinical research. They conclude that the majority of countries are under-resourced. Inequity of geographical location, is an important problem, which is a known problem in Italy, Spain, Switzerland and the UK. (Kanis & Johnell,2005). However the distribution and utilization of these machines are increasing worldwide. This statistics seems interesting when you know there was almost 183 machines in Canada in 1998, and there was no such device in Prince Edward Island (of Canada) around 1998. In Canada there are almost 600 devices, nowadays. The

European standard is 0.11 DXA machine per 10 000 population (Mithal et al., 2009).

**1. Introduction** 

developments in this field are suggested, also.

**2.1 What we do in a BMD centre?**  1. Determine patient's BMD

**2. General information about BMD and BMD centres** 

2. Estimate the risk of fracture (pathologic fracture) in a patient

**2.2 Some historical points about dual X-ray absorptiometry** 

**2.3 Distribution of BMD devices around the world** 

now, was described in 1994 for the first time.(Lukaski, 1993; Kanis, 1994).


## **What's BMD and What We Do in a BMD Centre?**

### Zohreh Hamidi

*Endocrinology and Metabolism Research Institute of Tehran University of Medical Sciences (EMRI-TUMS), Islamic Republic of Iran* 

### **1. Introduction**

224 Osteoporosis

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management of osteoporosis in patients with beta thalassaemia. *British Journal of* 

stimulating factor-1 (CSF-1) directly inhibits receptor activator of nuclear factor- {kappa}B ligand (RANKL) expression by osteoblasts. *Endocrinology. Vol. 150, No. 11,*  The main parts of osteoporosis clinics are BMD (Bone Mineral Densitometry) centers. For increasing our knowledge about osteoporosis we have to increase our knowledge about BMD (Bone Mineral Density), and increasing the knowledge about BMD has a close relationship with realizing the principles and appliances of BMD machines and DXA method. For specific development in a BMD department, we need to know some historical, technical and practical points about these method and machines. In this review, the last developments in this field are suggested, also.

### **2. General information about BMD and BMD centres**

### **2.1 What we do in a BMD centre?**


### **2.2 Some historical points about dual X-ray absorptiometry**

It is very useful to know the history of BMD and DXA devices. The first marketing of this machine was in 1987 and in1994 this method described as gold standard for osteoporosis diagnosis by World Health Organisation (WHO). It means osteoporosis disease, as we know now, was described in 1994 for the first time.(Lukaski, 1993; Kanis, 1994).

### **2.3 Distribution of BMD devices around the world**

As Kanis and Johnel reported in 2005, 9 countries from 20 countries (in Europe), had more than 10 DXA units per million of the population (the European standard). However it is unclear which percent of machines were dedicated in part or in full to clinical research. They conclude that the majority of countries are under-resourced. Inequity of geographical location, is an important problem, which is a known problem in Italy, Spain, Switzerland and the UK. (Kanis & Johnell,2005). However the distribution and utilization of these machines are increasing worldwide. This statistics seems interesting when you know there was almost 183 machines in Canada in 1998, and there was no such device in Prince Edward Island (of Canada) around 1998. In Canada there are almost 600 devices, nowadays. The European standard is 0.11 DXA machine per 10 000 population (Mithal et al., 2009).

What's BMD and What We Do in a BMD Centre? 227

Fig. 2. Density (number /million of the population) of central DXA (spine/hip) units in non-

Kanis and Johnel, extensively explained the method used for estimation of required number of DXA machines in Europe. As the method is interesting and contained demographic and osteoporotic statistics in Europe, we repeat their explanation as extensive as is used in their article in 2005. Repeat the explanation may be helpful, clearing a guideline for clinicians and researchers, to calculate the requirement of DXA machines in their area or countries. They suggested the requirement for three scenario and in two category, requirements of DXA for

From total population of Europe, it is estimated that, 4 million of them were 65 years old women. The authors assumed that individuals over the 65 years would be tested over the

European countries in 2003 (from Kanis and Johnell, 2005).

risk assessment and requirements of DXA to monitor treatment.

**2.4.1 Requirements of DXA for risk assessment** 

**2.4 Requirement for DXA** 

Asian audit in 2009, show us a very different picture in Asia. DXA technology is relatively expensive and is not widely available in most developing Asian countries, especially in rural areas. There was only 450 DXA machines in China for a population of 1.3 billion. In Srilanka only 4 machines exist. (Mithal et al., 2009). In 2008, Indonesia had a total of only 34 DXA machines, half of them in Jakarta, for a population of 237 million (0.001 per 10,000 population)(IOF, 2011). One of the most extreme examples is found in India, reportedly, there was only approximately 100 DXA units, located in six cities. This inequity results in long waiting times or long distances to travel or in many cases, no access (Kanis & Johnell,2005) (Fig. 1. And Fig. 2.). With above examples about distribution of these machines around the world, we explain here the formula used for calculating standard requirement of these machines (this formula is calculated according to number of population and prevalence of risk factors in target population).

Fig. 1. Density (number /million of the population) of central DXA (spine/hip) units in different European countries in 2003 (from Kanis and Johnell, 2005).

Asian audit in 2009, show us a very different picture in Asia. DXA technology is relatively expensive and is not widely available in most developing Asian countries, especially in rural areas. There was only 450 DXA machines in China for a population of 1.3 billion. In Srilanka only 4 machines exist. (Mithal et al., 2009). In 2008, Indonesia had a total of only 34 DXA machines, half of them in Jakarta, for a population of 237 million (0.001 per 10,000 population)(IOF, 2011). One of the most extreme examples is found in India, reportedly, there was only approximately 100 DXA units, located in six cities. This inequity results in long waiting times or long distances to travel or in many cases, no access (Kanis & Johnell,2005) (Fig. 1. And Fig. 2.). With above examples about distribution of these machines around the world, we explain here the formula used for calculating standard requirement of these machines (this formula is calculated according to number of population and

Fig. 1. Density (number /million of the population) of central DXA (spine/hip) units in

different European countries in 2003 (from Kanis and Johnell, 2005).

prevalence of risk factors in target population).

Fig. 2. Density (number /million of the population) of central DXA (spine/hip) units in non-European countries in 2003 (from Kanis and Johnell, 2005).

### **2.4 Requirement for DXA**

Kanis and Johnel, extensively explained the method used for estimation of required number of DXA machines in Europe. As the method is interesting and contained demographic and osteoporotic statistics in Europe, we repeat their explanation as extensive as is used in their article in 2005. Repeat the explanation may be helpful, clearing a guideline for clinicians and researchers, to calculate the requirement of DXA machines in their area or countries. They suggested the requirement for three scenario and in two category, requirements of DXA for risk assessment and requirements of DXA to monitor treatment.

#### **2.4.1 Requirements of DXA for risk assessment**

From total population of Europe, it is estimated that, 4 million of them were 65 years old women. The authors assumed that individuals over the 65 years would be tested over the

What's BMD and What We Do in a BMD Centre? 229

and so don't need a further BMD test in the beginning of treatment (they did't cut the threshold for need to intervention). Additional BMD testing would be required in approximately 10% of women for the purposes of baseline investigation for treatment. If all 65-year-olds were screened, additional pre-treatment BMD tests would equal to 0.4/million scans (322 units) and approximately increase 2-fold after 2 years later. Thus, the steady state requirements would be 966 scanners or 1.33 units/million of the population. Women older than 65 years have a smaller population , but not surprisingly ,a larger proportion would cut an intervention threshold. For example, at the age of 80 years there are approximately 2.15 million women, but with the same test, 73% would be need treatment. But in 50 years old women, approximately 1% of their 5 million population would need treatment. The author emphasized that in women aged 65 years or more, approximately 35% will need treatment and require a BMD tests before and after treatment (2 years later). This gives an annual requirement for 4.6 million scans or 3686 scanning units and a requirement of 5.06/million of the general population. It means for the monitoring of treatment (in 65 y/o women and older), 6.39 uint/million is needed under scenario B. All of these, means the total number 10.6 scanning units/million of the population is needed for assessment plus monitoring of

The total number of all older patients performed DXA in the USA has grown up from 501,105 in 1996 to 2,195,548 in 2002. This 4 fold growth during 6 years related to increase the average of lifespan, increase public awareness of osteoporosis and development in therapeutic cares. The maximum application of DXA has been observed in central densitometry. The usage of this method maybe continued for the next few years. However, in some countries, DXA just applied for patients with certain ( or specific ) risk factors. There are national organization in other countries that prescribe DXA only for patients at multiple risks of osteoporosis. It cause

Results show a great increase in use of bone mass densitometry in Canada. DXA-BMD tests increase 10-fold between years 1993 to 2005, and approximately 500,000 scans perform per year. In Ontario, showed an excessive use of anti-osteoporotic drugs along with the reduction rate of hip and wrist fractures with the increase in BMD test.The growth rate of BMD test appeared to be decreased to 6 to 7% per year. The increase usage rate of BMD-test occurred mainly in 65 years old people or older (Legislative Assembly of

Lukaski, had a good review of instruments in dual x-ray absorptiometry. Because of its clear and good explanation about the complexity of matter, we mension it here, with almost no change. The first generation commercial dual-energy X-ray absorptiometry (DXA) system became available in 1987 after its initial progress in the late 1960s and 1970s. The three main companies, introduced three X-ray-based absorptiometry systems (approved by the Food and Drug Administration): QDR-1000W3 (Hologic Inc., Waltham, MA), DPX (Lunar Radiation Corp., Madison, WI) and XR-26 (Norland Corporation, Fort Atkinson, WI). Each system uses a source- that generates X-rays at two different energies- a detector and an

different statistics of use of DXA in different countries (Damilakis et al., 2010).

treatment in scenario B (Kanis & Johnell,2005).

**2.5 Secular trend of use of DXA** 

**3. Bone densitometry instruments** 

interface with a computer system.

Ontario, 2006).

**3.1 Instruments** 

ensuing 10 years and repeated BMD tests would perform in patient that need treatment or those patients at high risk on the basis of the screening BMD test.

The first scenario (scenario A or screening women with BMD), proposed monitor all women with at the age of 65 years. If the main goal was to measure BMD in all 65 years old women (4.045.000, 65 years old women), this required 3231 DXA units or 4.42 DXA/ million of the total population. In this first scenario, if we assumed that people with the age 66 years and older didn't screen and if they want to screen over a 10- year period, the needs for DXA units would be 6.79/million of total population, giving a total need 11.2 units/million.

The aim of second scenario (scenario B, or clinical case finding with selective use of BMD) was to screen 65 years old women with clinical risk factor referred for DXA at 10 yearly intervals. It means that we sent 65 y/o women for BMD, only when they were high risk for fracture. Finding patients at high risk was based on clinical risk factors. Patients were high risk, when 10-year probability of hip fracture in them (calculated upon risk factors), was 4% and more (This is also called intervention threshold, and the authors considered it a cut-off that treatment is needed for patients). Screening all these patients, need 767 DXA units or 1,05 scan/million of the population. No surprising, the population that need intervention and treatment advances with age. The probability of risk fracture is about 1% at the age of 50 and 52% at the age of 80 years old. Author emphasize that the absolute population size decreases the higher the starting age for testing. They calculated that assessment of women at the older age, (during 10 years period) would require an extra need of 2301 DXA units or 3.16/million of the population (total need for women 65 y/o and older equals to 4.21/million). At younger age, small population is selected for BMD test. So the requirements are not markedly differ by screening policy that starts at age of 50 years. At this age, only nearly 1% of women are selected for treatment. It would be required that more 50,000 DXA tests do for 50 years old women (that add 40 scanning units or 0.05 units/million machines to requirement). After added screened population aged more than 50 years over a 10 year term interval, the total requirement will be 4.5 unit/million. Compare it with 4.21 unit/million required only for screening of 65 y/o women and older. The third scenario (scenario C, or classic case finding strategy) enlisted only women with

strong risk factors for fracture, to do BMD. The authors suggested a different prevalence of risk factors in different age population (29% to 46% depending on age). For testing women of 65 years, 1481 units or 2.03 units/million of the population was required. If BMD considered in women aged more than 65 years and a risk factors prevalence as 46%, 3 million/year over a 10 year interval (30 million, for 10 years) would require testing . This is equal to 3.33 units/million of the population. On the other hand, if BMD tests considered for women aged 50 years or more with one or more these risk factors, BMD testing was needed in 36.9% of the female population aged 50 years or more. Authors calculated this would need 3842 scanning units or 5.3/million of the total population (It seems it is a yearly need, when the whole 10 year need is divided by 10). When only women with incident osteoporotic fracture and aged 65 years or older sent to BMD centers, requirement was 918 scanning visits or 1.3/million of the general population.

#### **2.4.2 Requirements of DXA to monitor treatment**

When women referred for treatment, 2 BMD tests may be required. One is at the time of diagnosis, and a second at an interval of 2 years. For scenario B, BMD tests would have been done in 24% of the population at the age of 65 years, some of them do not need treatment

ensuing 10 years and repeated BMD tests would perform in patient that need treatment or

The first scenario (scenario A or screening women with BMD), proposed monitor all women with at the age of 65 years. If the main goal was to measure BMD in all 65 years old women (4.045.000, 65 years old women), this required 3231 DXA units or 4.42 DXA/ million of the total population. In this first scenario, if we assumed that people with the age 66 years and older didn't screen and if they want to screen over a 10- year period, the needs for DXA units would be 6.79/million of total population, giving a total need 11.2 units/million. The aim of second scenario (scenario B, or clinical case finding with selective use of BMD) was to screen 65 years old women with clinical risk factor referred for DXA at 10 yearly intervals. It means that we sent 65 y/o women for BMD, only when they were high risk for fracture. Finding patients at high risk was based on clinical risk factors. Patients were high risk, when 10-year probability of hip fracture in them (calculated upon risk factors), was 4% and more (This is also called intervention threshold, and the authors considered it a cut-off that treatment is needed for patients). Screening all these patients, need 767 DXA units or 1,05 scan/million of the population. No surprising, the population that need intervention and treatment advances with age. The probability of risk fracture is about 1% at the age of 50 and 52% at the age of 80 years old. Author emphasize that the absolute population size decreases the higher the starting age for testing. They calculated that assessment of women at the older age, (during 10 years period) would require an extra need of 2301 DXA units or 3.16/million of the population (total need for women 65 y/o and older equals to 4.21/million). At younger age, small population is selected for BMD test. So the requirements are not markedly differ by screening policy that starts at age of 50 years. At this age, only nearly 1% of women are selected for treatment. It would be required that more 50,000 DXA tests do for 50 years old women (that add 40 scanning units or 0.05 units/million machines to requirement). After added screened population aged more than 50 years over a 10 year term interval, the total requirement will be 4.5 unit/million. Compare it with 4.21 unit/million required only for screening of 65 y/o women and older. The third scenario (scenario C, or classic case finding strategy) enlisted only women with strong risk factors for fracture, to do BMD. The authors suggested a different prevalence of risk factors in different age population (29% to 46% depending on age). For testing women of 65 years, 1481 units or 2.03 units/million of the population was required. If BMD considered in women aged more than 65 years and a risk factors prevalence as 46%, 3 million/year over a 10 year interval (30 million, for 10 years) would require testing . This is equal to 3.33 units/million of the population. On the other hand, if BMD tests considered for women aged 50 years or more with one or more these risk factors, BMD testing was needed in 36.9% of the female population aged 50 years or more. Authors calculated this would need 3842 scanning units or 5.3/million of the total population (It seems it is a yearly need, when the whole 10 year need is divided by 10). When only women with incident osteoporotic fracture and aged 65 years or older sent to BMD centers, requirement was 918

those patients at high risk on the basis of the screening BMD test.

scanning visits or 1.3/million of the general population.

When women referred for treatment, 2 BMD tests may be required. One is at the time of diagnosis, and a second at an interval of 2 years. For scenario B, BMD tests would have been done in 24% of the population at the age of 65 years, some of them do not need treatment

**2.4.2 Requirements of DXA to monitor treatment** 

and so don't need a further BMD test in the beginning of treatment (they did't cut the threshold for need to intervention). Additional BMD testing would be required in approximately 10% of women for the purposes of baseline investigation for treatment. If all 65-year-olds were screened, additional pre-treatment BMD tests would equal to 0.4/million scans (322 units) and approximately increase 2-fold after 2 years later. Thus, the steady state requirements would be 966 scanners or 1.33 units/million of the population. Women older than 65 years have a smaller population , but not surprisingly ,a larger proportion would cut an intervention threshold. For example, at the age of 80 years there are approximately 2.15 million women, but with the same test, 73% would be need treatment. But in 50 years old women, approximately 1% of their 5 million population would need treatment. The author emphasized that in women aged 65 years or more, approximately 35% will need treatment and require a BMD tests before and after treatment (2 years later). This gives an annual requirement for 4.6 million scans or 3686 scanning units and a requirement of 5.06/million of the general population. It means for the monitoring of treatment (in 65 y/o women and older), 6.39 uint/million is needed under scenario B. All of these, means the total number 10.6 scanning units/million of the population is needed for assessment plus monitoring of treatment in scenario B (Kanis & Johnell,2005).

### **2.5 Secular trend of use of DXA**

The total number of all older patients performed DXA in the USA has grown up from 501,105 in 1996 to 2,195,548 in 2002. This 4 fold growth during 6 years related to increase the average of lifespan, increase public awareness of osteoporosis and development in therapeutic cares. The maximum application of DXA has been observed in central densitometry. The usage of this method maybe continued for the next few years. However, in some countries, DXA just applied for patients with certain ( or specific ) risk factors. There are national organization in other countries that prescribe DXA only for patients at multiple risks of osteoporosis. It cause different statistics of use of DXA in different countries (Damilakis et al., 2010).

Results show a great increase in use of bone mass densitometry in Canada. DXA-BMD tests increase 10-fold between years 1993 to 2005, and approximately 500,000 scans perform per year. In Ontario, showed an excessive use of anti-osteoporotic drugs along with the reduction rate of hip and wrist fractures with the increase in BMD test.The growth rate of BMD test appeared to be decreased to 6 to 7% per year. The increase usage rate of BMD-test occurred mainly in 65 years old people or older (Legislative Assembly of Ontario, 2006).

### **3. Bone densitometry instruments**

### **3.1 Instruments**

Lukaski, had a good review of instruments in dual x-ray absorptiometry. Because of its clear and good explanation about the complexity of matter, we mension it here, with almost no change. The first generation commercial dual-energy X-ray absorptiometry (DXA) system became available in 1987 after its initial progress in the late 1960s and 1970s. The three main companies, introduced three X-ray-based absorptiometry systems (approved by the Food and Drug Administration): QDR-1000W3 (Hologic Inc., Waltham, MA), DPX (Lunar Radiation Corp., Madison, WI) and XR-26 (Norland Corporation, Fort Atkinson, WI). Each system uses a source- that generates X-rays at two different energies- a detector and an interface with a computer system.

What's BMD and What We Do in a BMD Centre? 231

Damilakis et al, remind us that the system for patients protection against radiation is based on 2 principles: (a) justification and (b) optimisation. Clinically justification of all X- ray exposures used for bone densitometry is very important. Examinations that do not influence

Preparing patients before bone densitometry is very important. For example metallic things such as jewelry or coins can cause artifact and careful checking for the presence of these items and proper positioning of patient before bone densitometry, will optimize the imaging quality and there will be no need to repeat imaging with additional radiation exposure. In pediatric examinations, proper interaction with the children and parents is essential. All actions should be taken to avoid movement of the child during imaging and to avoid repeating measurement. The duration time of DXA should be minimize and should take

Although the annual occupational doses from DXA is very lower than standard occupational radiation dose, but for a pregnant employee that declares pregnancy, special dose reduction should be applied. As Damilakis et al. suggest, The ICRP and European Commission recommend that pregnant individual be protected by the application of a dose up to 1 mGy. Of course, as they emphasize, the exclusion of pregnant workers from DXA examinations on the basis of radiogenic risks from occupational DXA exposure cannot be justified on scientific grounds. Because the scatter radiation can increase the exposure limits for pregnant workers, especially for fan-beam systems. Radiation protection measures should always be taken to ensure that the conceptus dose will be kept below 1 mGy during the declared pregnancy. For monitoring radiation dose, it is recommended to use personal

Correcting design of the room in which the imaging device has been installed, can influence in limiting the risk of radiation exposure in the workplace. Measurements performed by Larkin et al. as cited in Damilakis et al., 2010, showed that the scatter from fan-beam DXA systems can increase the limits for public exposure i.e. 1 mSv/year. In these cases, additional structural shielding might be required, especially when the distance from the imaging table to the adjacent wall is less than 1 m. They say, parameters like the workload, the material of the walls, the location of the operator and the location and use of rooms that adjoin the imaging room must also be remembered as important factors (Damilakis et al., 2010).

The proportion of beam of X- rays weaken (attenuating) during transporting through a complex material depend on composition of material, the thickness of material and any of its components. Soft tissues, which contain principally water and organic compounds create limitation to the flux (number of X-rays per unit area) of X-rays, and of course, this limitation is lesser than the limitation creates by bone tissue. The un-weakened or unattenuated energy, in the form of X-ray radiation, is detected by an external detector. In dual-energy X-ray system, there is a source that emits X-rays, which are collimated into a beam (there is a shutter that can turn on and turn off the beam, also). The source lies beneath the patient and the beam transports in a posterior-to-anterior direction, through the body of patient (bone and soft tissue), and goes upward to be detected by a detector, above the

**3.2.1 Dose reduction techniques for patients** 

into account patient's body size, if possible (Damilakis et al., 2010).

**3.3.1 Basic principles of dual-energy X-ray absorptiometry (DXA)** 

patient, lies in the arm of machine (Lukaski, 1993).

**3.2.2 Occupational radiation doses and shielding** 

patient care, must be avoided.

radiation meter at waist level.

**3.3 Hardware** 

These three DXA systems operate in different ways. The QDR-1000 and QDR- 1000W systems produce two X-ray beams of different energies by using an X-ray tube alternately pulsed at 70 and 140 kVp peaks. The DPX system uses a constant potential generator and a Cerium K-edge X-ray filtration to generate photons at two energies (40 and 76 keV). The Norland XR-26 unit also employs a constant potential X-ray generator, but it operates at 100 kVp and employs a Samarium filter (K-edge = 46.8 keV). Unlike the DPX and XR-26 systems, the QDR-1000W system has an internal calibration system that consists of a rotating filter wheel composed of three sections (two sections of epoxy-resin-based material consistent with the densities of bone and soft tissue and one section of air). In the QDR system, photons of only one energy are present at any one time, and the detector measures the intensity of the transmitted photons without energy discrimination. An integral line single detector is used in the Lunar DPX system. The XR-26 detector consists of thin and thick sodium iodide crystals (low intensity X rays are stopped by the thin crystal, and high intensity photons are trans mitted and detected by the second thick crystal).

An important advantage of the DXA systems is the increased photon flux emanating from the X-ray sources in comparison to the photon flux from the radioisotope source used in dual-photon absorptiometry. The increased photon flux improves the resolution and precision of the image and reduces the time for a scan. To assess soft tissue composition, the DXA systems use different forms of external calibration. The QDR and XR-26 systems rely on external standards, which are wedges made of aluminum and ucite (polymethylmethacrylate) calibrated against stearic acid as 100% fat, and dilute saline solution as 100% fat-free mineral free tissue. The DPX systems use a plastic polyoxymethylene (Delrin), as 40% fat equivalent and water (~5% fat) as standards (Lukaski, 1993). Recently, the name of Medi-link brand is added to list of machines in FRAX software. Fan beam models are added to DXA machines family and have different beam geometry from pencil beam models. They are explained later.

BMD devices are popular machines, because they are low X-ray radiating, don't need especial preparation for patients and they are not invasive but as it mentioned before, these instruments are not widely distributed in the world, and the expensive cost of these machines is a main reason for it. Properties of these devises that make them expensive are:


#### **3.2 Safety**

The special method used in these devices, make them low X-ray radiating. They don't need special shielding. We can evaluate the safety of DXA by the radiation dose that each patients or subjects receive. The average skin dose is 1-3 mrad per scan. The radiation dose of DXA is less than other radiologic methods, such as single-photon absorptiometry, dualphoton absorptiometry and quantitative digital radiography, conventional chest x-ray and many others. For example, skin exposures from environmental background are ~3.5 mrad/wk; from dental bite-wing posterior films, 334 mrad and from chest X-ray films, ~8-10 mrad. Thus, we can conclude; for routine measurement of human body composition and bone mineral status , DXA may be noticed a relatively safe method. Manufacturers suggest that it is safe from 1 meter (Lukaski, 1993).

These three DXA systems operate in different ways. The QDR-1000 and QDR- 1000W systems produce two X-ray beams of different energies by using an X-ray tube alternately pulsed at 70 and 140 kVp peaks. The DPX system uses a constant potential generator and a Cerium K-edge X-ray filtration to generate photons at two energies (40 and 76 keV). The Norland XR-26 unit also employs a constant potential X-ray generator, but it operates at 100 kVp and employs a Samarium filter (K-edge = 46.8 keV). Unlike the DPX and XR-26 systems, the QDR-1000W system has an internal calibration system that consists of a rotating filter wheel composed of three sections (two sections of epoxy-resin-based material consistent with the densities of bone and soft tissue and one section of air). In the QDR system, photons of only one energy are present at any one time, and the detector measures the intensity of the transmitted photons without energy discrimination. An integral line single detector is used in the Lunar DPX system. The XR-26 detector consists of thin and thick sodium iodide crystals (low intensity X rays are stopped by the thin crystal, and high intensity photons are trans mitted and detected by the second thick

An important advantage of the DXA systems is the increased photon flux emanating from the X-ray sources in comparison to the photon flux from the radioisotope source used in dual-photon absorptiometry. The increased photon flux improves the resolution and precision of the image and reduces the time for a scan. To assess soft tissue composition, the DXA systems use different forms of external calibration. The QDR and XR-26 systems rely on external standards, which are wedges made of aluminum and ucite (polymethylmethacrylate) calibrated against stearic acid as 100% fat, and dilute saline solution as 100% fat-free mineral free tissue. The DPX systems use a plastic polyoxymethylene (Delrin), as 40% fat equivalent and water (~5% fat) as standards (Lukaski, 1993). Recently, the name of Medi-link brand is added to list of machines in FRAX software. Fan beam models are added to DXA machines family and have different beam

BMD devices are popular machines, because they are low X-ray radiating, don't need especial preparation for patients and they are not invasive but as it mentioned before, these instruments are not widely distributed in the world, and the expensive cost of these machines is a main reason for it. Properties of these devises that make them expensive are:

The special method used in these devices, make them low X-ray radiating. They don't need special shielding. We can evaluate the safety of DXA by the radiation dose that each patients or subjects receive. The average skin dose is 1-3 mrad per scan. The radiation dose of DXA is less than other radiologic methods, such as single-photon absorptiometry, dualphoton absorptiometry and quantitative digital radiography, conventional chest x-ray and many others. For example, skin exposures from environmental background are ~3.5 mrad/wk; from dental bite-wing posterior films, 334 mrad and from chest X-ray films, ~8-10 mrad. Thus, we can conclude; for routine measurement of human body composition and bone mineral status , DXA may be noticed a relatively safe method. Manufacturers suggest that it

geometry from pencil beam models. They are explained later.

crystal).

Safety

**3.2 Safety** 

 The Hardware The Software

is safe from 1 meter (Lukaski, 1993).

#### **3.2.1 Dose reduction techniques for patients**

Damilakis et al, remind us that the system for patients protection against radiation is based on 2 principles: (a) justification and (b) optimisation. Clinically justification of all X- ray exposures used for bone densitometry is very important. Examinations that do not influence patient care, must be avoided.

Preparing patients before bone densitometry is very important. For example metallic things such as jewelry or coins can cause artifact and careful checking for the presence of these items and proper positioning of patient before bone densitometry, will optimize the imaging quality and there will be no need to repeat imaging with additional radiation exposure. In pediatric examinations, proper interaction with the children and parents is essential. All actions should be taken to avoid movement of the child during imaging and to avoid repeating measurement. The duration time of DXA should be minimize and should take into account patient's body size, if possible (Damilakis et al., 2010).

### **3.2.2 Occupational radiation doses and shielding**

Although the annual occupational doses from DXA is very lower than standard occupational radiation dose, but for a pregnant employee that declares pregnancy, special dose reduction should be applied. As Damilakis et al. suggest, The ICRP and European Commission recommend that pregnant individual be protected by the application of a dose up to 1 mGy. Of course, as they emphasize, the exclusion of pregnant workers from DXA examinations on the basis of radiogenic risks from occupational DXA exposure cannot be justified on scientific grounds. Because the scatter radiation can increase the exposure limits for pregnant workers, especially for fan-beam systems. Radiation protection measures should always be taken to ensure that the conceptus dose will be kept below 1 mGy during the declared pregnancy. For monitoring radiation dose, it is recommended to use personal radiation meter at waist level.

Correcting design of the room in which the imaging device has been installed, can influence in limiting the risk of radiation exposure in the workplace. Measurements performed by Larkin et al. as cited in Damilakis et al., 2010, showed that the scatter from fan-beam DXA systems can increase the limits for public exposure i.e. 1 mSv/year. In these cases, additional structural shielding might be required, especially when the distance from the imaging table to the adjacent wall is less than 1 m. They say, parameters like the workload, the material of the walls, the location of the operator and the location and use of rooms that adjoin the imaging room must also be remembered as important factors (Damilakis et al., 2010).

#### **3.3 Hardware**

#### **3.3.1 Basic principles of dual-energy X-ray absorptiometry (DXA)**

The proportion of beam of X- rays weaken (attenuating) during transporting through a complex material depend on composition of material, the thickness of material and any of its components. Soft tissues, which contain principally water and organic compounds create limitation to the flux (number of X-rays per unit area) of X-rays, and of course, this limitation is lesser than the limitation creates by bone tissue. The un-weakened or unattenuated energy, in the form of X-ray radiation, is detected by an external detector. In dual-energy X-ray system, there is a source that emits X-rays, which are collimated into a beam (there is a shutter that can turn on and turn off the beam, also). The source lies beneath the patient and the beam transports in a posterior-to-anterior direction, through the body of patient (bone and soft tissue), and goes upward to be detected by a detector, above the patient, lies in the arm of machine (Lukaski, 1993).

What's BMD and What We Do in a BMD Centre? 233

Fig. 3. Different methods of bone densitometry

#### **3.3.2 Specific technology of dual energy X-ray absorptiometers scanners (DXA)**

Before using dual x-ray absorptometry (when single-photon or single-x-ray absorptiometry used), the ROI (region of interest) of scanning, should be immersed in a water bath for densitometry (Fig. 3.). By use of water bath, the water and soft tissue (with almost the same attenuation), make a single compartment of attenuation (on the other hand, the influence of soft-tissue in the measurement significantly reduces and soft tissue don't contributed to measured absorption). They make one compartment and bone makes another compartment with its specific attenuation (than is very different and very higher that other compartment). This can lead to calculating of density of bone, because the attenuation of energy of x-ray beam is related to density of tissue. The density of soft-tissue (and water) is known and constant in almost all humans. The density of bone is not constant and changes one by one. By comparing the attenuation of energy of bone compartment of anyone to attenuation of energy of his soft tissue, machine can calculate the bone density. Without water bath, there is 3 compartment (air, soft tissue and bone), that machine can't separate them exactly and so can't differ between their density, and there is not single reference for comparing density of bone. So finding the exact density of bone would be impossible. Using of water-bath was a development for bone densitometry. But some big practical problems remained. It is practically, impossible to immerse whole body in water bath to measure the bone density of e.g. Spinal region or neck of femur. Water bath was useful for testing BMD of forearm. Remember spine and femur are most important parts of densitometry, because the important or fatal pathologic fracture occurs in these regions and measuring the BMD of e.g. forearm is not a good predictor of BMD or fracture in these important parts. The creating DXA methods, came helpful in solving this big problem. Imagine, using Dual x-ray absorptiometry (using 2 different energy beams) works as water bath in creating two distinguished compartment from compartments that were previously three different compartments of air, soft tissue and bone. The DXA (Dual X-ray absorptiometry) method depends on the differential absorption of two distinct beam energies - a high and low energy beam. When measuring bone, bone will normally have air and soft tissue around it. The high and low energy photons don't change in soft tissue, but the lower energy photon will be significantly reduced by bone tissue (high energy photon don't changes significantly). This difference in reduction of low energy beam, in two different tissue-bone and soft-tissue- can be used for measurement of bone density. On the other hand, the soft tissue component becomes the reference for determining the bone component (Royal Adelaide Hospital, 2009). When two different beams, pass from body compartments, the difference between their intensity before and after passing the soft tissue (and air), don't change (so, the air and soft tissue around the bone create a single compartment). This constant difference can be considered as 1 unit of difference. When two different beams, pass from bone tissue, the low energy beam attenuates significantly after passing bone, it means there is big difference in the intensity of low energy beam before and after passing bone. So the difference between intensity of two high and low energy beams increase significantly and may be multiple times of 1 unit difference reported for soft tissue (and air). This increase in difference is a result of attenuation of low beam energy in bone tissue and relates to bone density. If we have the density of soft tissue compartment, now we can calculate the density of bone. As mentioned before, the density of soft tissue is known and constant and is used as reference for determining bone density in DXA method. It means use of DXA, makes bone densitometry possible, without need to water bath that was needed in single x-ray absorptiomtery. Dual x-ray absorptiometry, makes axial bone densitometry in the conventional form that is performing now, possible (with patient lying on a table in normal atmosphere of an imaging room with no special preparation).

**3.3.2 Specific technology of dual energy X-ray absorptiometers scanners (DXA)**  Before using dual x-ray absorptometry (when single-photon or single-x-ray absorptiometry used), the ROI (region of interest) of scanning, should be immersed in a water bath for densitometry (Fig. 3.). By use of water bath, the water and soft tissue (with almost the same attenuation), make a single compartment of attenuation (on the other hand, the influence of soft-tissue in the measurement significantly reduces and soft tissue don't contributed to measured absorption). They make one compartment and bone makes another compartment with its specific attenuation (than is very different and very higher that other compartment). This can lead to calculating of density of bone, because the attenuation of energy of x-ray beam is related to density of tissue. The density of soft-tissue (and water) is known and constant in almost all humans. The density of bone is not constant and changes one by one. By comparing the attenuation of energy of bone compartment of anyone to attenuation of energy of his soft tissue, machine can calculate the bone density. Without water bath, there is 3 compartment (air, soft tissue and bone), that machine can't separate them exactly and so can't differ between their density, and there is not single reference for comparing density of bone. So finding the exact density of bone would be impossible. Using of water-bath was a development for bone densitometry. But some big practical problems remained. It is practically, impossible to immerse whole body in water bath to measure the bone density of e.g. Spinal region or neck of femur. Water bath was useful for testing BMD of forearm. Remember spine and femur are most important parts of densitometry, because the important or fatal pathologic fracture occurs in these regions and measuring the BMD of e.g. forearm is not a good predictor of BMD or fracture in these important parts. The creating DXA methods, came helpful in solving this big problem. Imagine, using Dual x-ray absorptiometry (using 2 different energy beams) works as water bath in creating two distinguished compartment from compartments that were previously three different compartments of air, soft tissue and bone. The DXA (Dual X-ray absorptiometry) method depends on the differential absorption of two distinct beam energies - a high and low energy beam. When measuring bone, bone will normally have air and soft tissue around it. The high and low energy photons don't change in soft tissue, but the lower energy photon will be significantly reduced by bone tissue (high energy photon don't changes significantly). This difference in reduction of low energy beam, in two different tissue-bone and soft-tissue- can be used for measurement of bone density. On the other hand, the soft tissue component becomes the reference for determining the bone component (Royal Adelaide Hospital, 2009). When two different beams, pass from body compartments, the difference between their intensity before and after passing the soft tissue (and air), don't change (so, the air and soft tissue around the bone create a single compartment). This constant difference can be considered as 1 unit of difference. When two different beams, pass from bone tissue, the low energy beam attenuates significantly after passing bone, it means there is big difference in the intensity of low energy beam before and after passing bone. So the difference between intensity of two high and low energy beams increase significantly and may be multiple times of 1 unit difference reported for soft tissue (and air). This increase in difference is a result of attenuation of low beam energy in bone tissue and relates to bone density. If we have the density of soft tissue compartment, now we can calculate the density of bone. As mentioned before, the density of soft tissue is known and constant and is used as reference for determining bone density in DXA method. It means use of DXA, makes bone densitometry possible, without need to water bath that was needed in single x-ray absorptiomtery. Dual x-ray absorptiometry, makes axial bone densitometry in the conventional form that is performing now, possible (with patient lying on a table in

normal atmosphere of an imaging room with no special preparation).

Fig. 3. Different methods of bone densitometry

What's BMD and What We Do in a BMD Centre? 235

the intercept was 0.59. Although the value of 0.59 was not statistically different from 0, the

Before to 2000, DXA measurements were conducted with a pencil-beam instrument (Lunar DPX, GE Lunar, Madison WI), and after that a fan-beam instrument was used. As Leslie et al suggested in 2011, instruments were cross-calibrated using anthropomorphic phantoms and 59 volunteers. They say there was no clinically significant differences (T-score differences <0.2). Densitometers showed stable long-term performance [CV<0.5%] and satisfactory in

Monitoring the performance of DXA after long time utilization is very important because any deterioration could change bone mineral density (BMD) measurements and affect clinical management. The importance of DXA in longitudinal trials of new osteoporosis therapies also need constant performance over years to confirm that any altration in bone density is real and not due to machine shifts or fluctuation. In this way, Wells and Ryan, assessed the performance of a 6-year-old bone densitometer (a Lunar DPX alpha), which has undertaken 1500 scans/year over this period. They concluded that the machine performs extremely well over a long period and after 6 years of Performing, measurements is very suitable to be fit for clinical use. It may be can be generalized to all main DXA devices in

At website of department of nuclear medicine, PET & bone densitometry of Royal Adelaide Hospital (Australia), at section of "Bone Densitometry Equipment", beam geometry of

First generation bone densitometers (isotope and x-ray) use this beam geometry. The photon beam is tightly collimated with one photon source and one detector (some scanners have two, usually photomultiplier tubes). The source and detector are rigidly coupled and moved together in a rectilinear manner to build an image of the bone being examined line by line. The disadvantage of this technology is the relatively slow scan speed (typically 2-4 minutes per scan site). However, the direct relationship between source and detector means that

The second generation of x-ray bone densitometer has a fan geometry, with a source which fans out in the short axis plane of the patient and is measured by an array of detectors in the

The bones are imaged in one pass along the long axis of the body (as illustrated at middle) providing an immediate advantage in scan speed which is typically about 1 minute on

The disadvantage of fan beam DXA is that the photon flux at the edges is lower than the middle of the image (due to the inverse square law). As a result, mass calculations may have some systematic error, although bone mineral density values have been shown to be

authors concluded that DXA under estimates ash weight (Lukaski, 1993).

vivo precision (CV 1.7% for L1–4 and 1.1% for the total hip) (Leslie et al., 2011)

**3.3.4 The long-term performance of DXA bone densitometers** 

calculated bone and tissue masses are less likely to be artefactual.

market (Wells & Ryan, 2000).

"DXA devices" are explained so:

**3.3.5 Beam geometry** 

**3.3.5.1 Pencil beam** 

**3.3.5.2 Fan beam** 

modern scanners.

same plane.

unaffected.

#### **3.3.3 Quality control**

For diagnosing longitudinal changes, assessment of precision error in bone mineral density (BMD) testing is very important (Leslie et al., 2007). Lukaski emphasizes that one parameter of quality control in the use of DXA is the precision of the measurements. Precision is generally reported as the coefficient of variation (CV), which is the standard deviation of repeated measurements expressed as a percentage of the mean of the measurements. The precision of DXA has been assessed for short-term (in vitro and in vivo) and for long-term (in vitro) (Lukaski, 1993).

The International Society for Clinical Densitometry (ISCD) has a standardized methodology for performing an in vivo precision study and recommends that this be performed by each densitometry center. Leslie at al., explain the ISCD procedure as gaining precision error from an assessment with 30 degrees of freedom (df; e.g., 30 subjecs with 2 scans each or 15 subjects with 3 scans each) drawn from the patient of referral population and using the root mean square (RMS) approach (RMS is not explained there) (Leslie et al., 2007).

Lukaski, reports that in first studies, short-term precision and long-term Precision, in different period times and different devices studied. Wahner et al. (1988), as cited in Lukaski; 1993, reported a short-term precision (repeat measurements on the same day) of 0.2 and 0.5% for BMC and BMD, respectively, and a long-term precision (for up to 6 mo) of 0.4% for BMD in lumbar spine phantoms made of hydroxyapatite. Duplicate scans performed on the same day in patients showed a difference of <1% between scans for BMC and BMD. Kelly et al. (1988), as cited in Lukaski; 1993, also observed high reproducibility (CV = 0.23%) of BMD measurements in spine phantoms measured over 6 months. Rencken et al. (1991), as cited in Lukaski; 1993, evaluated the precision of DXA measurements using six different QDR instruments at separate locations. Nine consecutive scans were performed on a single spine phantom at each site. The investigators reported an average precision for BMC and BMD of <1% (range: 0.3-0.6%). The average of the highest and lowest mean values was 1.1% for BMC and 1.07% for BMD. Mazess et al. (1989), as cited in Lukaski; 1993, reported a long-term precision in BMD measurements of 0.6% using a DPX system in a spine phantom over 6 mo. Estimates of 1.8 and 0.9% for the measurement of total body BMC and BMD, respectively, in 12 adults were also reported with a DPX instrument (Mazess et al. 1990, as cited in Lukaski; 1993). Johnson and Dawson-Hughes (1991), as cited in Lukaski; 1993, assessed long-term precision of BMD measurements in six volunteers scanned six times initially and at the same frequency 9 mo later. The short-term precision of BMD measurements in the spine, femoral neck and whole body were 1.08, 2.08 and 0.66%, respectively. The long-term precision was 1.01, 2.07 and 0.62%, respectively. The investigators also reported the precision in determining body composition variables; thus, the precision of whole-body BMC, fat-free mass and fat mass was 0.8, 1.1 and 2.7%, at the start of the study, and 1.2, 1.0, and 1.7%, respectively, after 9 months.

Another aspect of quality control is the accuracy of the DXA measurement. The extent to which DXA measurements represent true bone mineral status has been assessed by measuring the mineral content of cadaver vertebrae of known ash weights and volumes. Ho et al. (1990), as cited in Lukaski; 1993, measured BMC and BMD in lumbar vertebrae from 11 cadavers. The ash weights of 31 lumbar vertebrae and the DXA BMC values were significantly correlated (r = 0.963, SEE = 1.01 g; P< 0.001 ). The slope of the regression of ash weight as the dependent variable versus QDR-BMC as the independent variable was 1.0, but

For diagnosing longitudinal changes, assessment of precision error in bone mineral density (BMD) testing is very important (Leslie et al., 2007). Lukaski emphasizes that one parameter of quality control in the use of DXA is the precision of the measurements. Precision is generally reported as the coefficient of variation (CV), which is the standard deviation of repeated measurements expressed as a percentage of the mean of the measurements. The precision of DXA has been assessed for short-term (in vitro and in vivo) and for long-term

The International Society for Clinical Densitometry (ISCD) has a standardized methodology for performing an in vivo precision study and recommends that this be performed by each densitometry center. Leslie at al., explain the ISCD procedure as gaining precision error from an assessment with 30 degrees of freedom (df; e.g., 30 subjecs with 2 scans each or 15 subjects with 3 scans each) drawn from the patient of referral population and using the root

Lukaski, reports that in first studies, short-term precision and long-term Precision, in different period times and different devices studied. Wahner et al. (1988), as cited in Lukaski; 1993, reported a short-term precision (repeat measurements on the same day) of 0.2 and 0.5% for BMC and BMD, respectively, and a long-term precision (for up to 6 mo) of 0.4% for BMD in lumbar spine phantoms made of hydroxyapatite. Duplicate scans performed on the same day in patients showed a difference of <1% between scans for BMC and BMD. Kelly et al. (1988), as cited in Lukaski; 1993, also observed high reproducibility (CV = 0.23%) of BMD measurements in spine phantoms measured over 6 months. Rencken et al. (1991), as cited in Lukaski; 1993, evaluated the precision of DXA measurements using six different QDR instruments at separate locations. Nine consecutive scans were performed on a single spine phantom at each site. The investigators reported an average precision for BMC and BMD of <1% (range: 0.3-0.6%). The average of the highest and lowest mean values was 1.1% for BMC and 1.07% for BMD. Mazess et al. (1989), as cited in Lukaski; 1993, reported a long-term precision in BMD measurements of 0.6% using a DPX system in a spine phantom over 6 mo. Estimates of 1.8 and 0.9% for the measurement of total body BMC and BMD, respectively, in 12 adults were also reported with a DPX instrument (Mazess et al. 1990, as cited in Lukaski; 1993). Johnson and Dawson-Hughes (1991), as cited in Lukaski; 1993, assessed long-term precision of BMD measurements in six volunteers scanned six times initially and at the same frequency 9 mo later. The short-term precision of BMD measurements in the spine, femoral neck and whole body were 1.08, 2.08 and 0.66%, respectively. The long-term precision was 1.01, 2.07 and 0.62%, respectively. The investigators also reported the precision in determining body composition variables; thus, the precision of whole-body BMC, fat-free mass and fat mass was 0.8, 1.1 and 2.7%, at the

mean square (RMS) approach (RMS is not explained there) (Leslie et al., 2007).

start of the study, and 1.2, 1.0, and 1.7%, respectively, after 9 months.

Another aspect of quality control is the accuracy of the DXA measurement. The extent to which DXA measurements represent true bone mineral status has been assessed by measuring the mineral content of cadaver vertebrae of known ash weights and volumes. Ho et al. (1990), as cited in Lukaski; 1993, measured BMC and BMD in lumbar vertebrae from 11 cadavers. The ash weights of 31 lumbar vertebrae and the DXA BMC values were significantly correlated (r = 0.963, SEE = 1.01 g; P< 0.001 ). The slope of the regression of ash weight as the dependent variable versus QDR-BMC as the independent variable was 1.0, but

**3.3.3 Quality control** 

(in vitro) (Lukaski, 1993).

the intercept was 0.59. Although the value of 0.59 was not statistically different from 0, the authors concluded that DXA under estimates ash weight (Lukaski, 1993).

Before to 2000, DXA measurements were conducted with a pencil-beam instrument (Lunar DPX, GE Lunar, Madison WI), and after that a fan-beam instrument was used. As Leslie et al suggested in 2011, instruments were cross-calibrated using anthropomorphic phantoms and 59 volunteers. They say there was no clinically significant differences (T-score differences <0.2). Densitometers showed stable long-term performance [CV<0.5%] and satisfactory in vivo precision (CV 1.7% for L1–4 and 1.1% for the total hip) (Leslie et al., 2011)

### **3.3.4 The long-term performance of DXA bone densitometers**

Monitoring the performance of DXA after long time utilization is very important because any deterioration could change bone mineral density (BMD) measurements and affect clinical management. The importance of DXA in longitudinal trials of new osteoporosis therapies also need constant performance over years to confirm that any altration in bone density is real and not due to machine shifts or fluctuation. In this way, Wells and Ryan, assessed the performance of a 6-year-old bone densitometer (a Lunar DPX alpha), which has undertaken 1500 scans/year over this period. They concluded that the machine performs extremely well over a long period and after 6 years of Performing, measurements is very suitable to be fit for clinical use. It may be can be generalized to all main DXA devices in market (Wells & Ryan, 2000).

### **3.3.5 Beam geometry**

At website of department of nuclear medicine, PET & bone densitometry of Royal Adelaide Hospital (Australia), at section of "Bone Densitometry Equipment", beam geometry of "DXA devices" are explained so:

### **3.3.5.1 Pencil beam**

First generation bone densitometers (isotope and x-ray) use this beam geometry. The photon beam is tightly collimated with one photon source and one detector (some scanners have two, usually photomultiplier tubes). The source and detector are rigidly coupled and moved together in a rectilinear manner to build an image of the bone being examined line by line. The disadvantage of this technology is the relatively slow scan speed (typically 2-4 minutes per scan site). However, the direct relationship between source and detector means that calculated bone and tissue masses are less likely to be artefactual.

#### **3.3.5.2 Fan beam**

The second generation of x-ray bone densitometer has a fan geometry, with a source which fans out in the short axis plane of the patient and is measured by an array of detectors in the same plane.

The bones are imaged in one pass along the long axis of the body (as illustrated at middle) providing an immediate advantage in scan speed which is typically about 1 minute on modern scanners.

The disadvantage of fan beam DXA is that the photon flux at the edges is lower than the middle of the image (due to the inverse square law). As a result, mass calculations may have some systematic error, although bone mineral density values have been shown to be unaffected.

What's BMD and What We Do in a BMD Centre? 237

Measured BMD-Age-matched mean BMD Z-score=

It means after acquisition of absolute BMD of patients by Hardware, the software compute the difference between BMD of patient and young adult mean BMD (from reference data in the software). Then divide it on young adult population standard deviation, contained in the software, the result is T-score. When Z-score is under calculation, the software divides the difference between BMD of patient and age-matched mean BMD and divides it on agematched population standard deviation. The ability of calculating T—score and Z-score is

As the different brands, have different database, scientists tried to find ways to compare the

Genant et al, as inventors of sBMD, explained the methods of providing sBMD in their

We can t compare patient information between various DXA scanners, because there isn't any acceptable universal cross-calibration procedure or standard. Although operating on the same basic principles, normative databases, are specific and different for each scanner. The instruments show differences in scanner design, bone mineral calibration, and analysis algorithms. Lunar and Norland scanners rely on daily scanning of standards to provide a bone tissue equivalent calibration. Hologic uses an internal calibration system, which corrects for short-term instabilities. Also, the software used for analysis of the scans, is manufacturer specific (and unique), especially with regard *to* the edge detection algorithms used for separating bone and soft tissue regions. This implementation causes in variations in the defined bone area (cm2) and bone mineral content (BMC, g) and density (BMD) of the same subject on different systems. Genant et al, study was performed under the auspices of the International DXA Standardization Committee to establish appropriate cross-calibration parameters. Posteroanterior (PA) lumbar spine measurements of 100 women, ages 20-80 years (mean 52.6 ± 16, range of BMD = 0.4-1.6 g/cm2) were obtained on a Norland XR26 Mark II, a Lunar DPX-L, and a Hologic QDR 2000 densitometer using standard procedures (pencil beam mode for all three scanners). Area, BMC, and BMD results from the different scanners were compared for all patients. In addition, the European spine phantom (ESP) and the European spine phantom prototype (ESP prototype), as well as standard phantoms from all three manufacturers, were evaluated on the three systems. To reach universal scanner calibration, they used the intercept and slope of the patient's correlations and the value of the middle vertebra of the ESP as a reference point in a series of standardization formulas, and expressed the results as sBMD (mg/cm2). The correlations of the patients' spinal BMD values were excellent for each of the three scanner pairs. The average absolute difference in patient spinal BMD values (L2-L4) between Hologic and Norland was 0.012 g/cm' (1.3%); it was 0.113 g/cm' (11.7%) between Hologic and Lunar and 0.118 g/cm2 (12.2%) between Norland and Lunar. The phantoms' regression lines approximated those of the patient regression lines, and the phantoms with only one measurement point were very close to the patients' regression lines. After applying the standardization formulas, the average absolute variations for the 100 patients were 28 mg/cm2 (2.7%) for Hologich/Norland, 23 mg/cm2 (2.2%) for Hologic/Lunar, and 29 mg/cm2 (2.8%) for Norland/Lunar. Average BMD results for the patients before correction were 0.972 g/cm2

another interesting characteristic of software of these machines.

**3.4.1 Providing sBMD** 

article, so.

results of deferent machines. Now we suggest some of these methods.

Young adultpopulation SD

### **3.3.5.3 Narrow fan beam**

This is designed to overcome some of the limitations of the fan beam geometry. A small fan beam radiation (about 4cm wide at the detector) in the long axis is detected by an array of detectors. The beam scans the bones in the short patient axis on each individual sweep along the long axis of the patient with some beam overlap. Although slightly slower than a fan beam scanner (1-2 minutes per scan), the mass results should be more accurate as the photon flux has little variability in the area being measured (due to the beam overlap). You can see the schematic figure of different beam geometries in the Fig. 4, from mentioned website (Royal Adelaide Hospital, 2009).

Fig. 4. Beam geometry of DXA mechines (from website of Royal Adelaide Hospital (Australia)

### **3.4 Software**

The reference data of these machines, contain data of BMD tests of almost 5000 Caucasian white normal persons; around 20-80 y/o. Any brand of these machines has different reference data. It is clear that collecting such huge database, nowadays, seems impossible (especially due to cost and financial problems). This makes these method (DXA) and machines, unique. It seems impossible that any other method or brand can replace them in future, at least in near future.

Another ability of the software of this machines is, ability to calculate T-score and Z-score for patients (Shepherd &Blake, 2007):

> Measured BMD-Young adultmean BMD T-score= Young adultpopulation SD

$$\text{Z-score} = \frac{\text{Measured BMD-Age-matched mean BMD}}{\text{Young-adult population SD}}$$

It means after acquisition of absolute BMD of patients by Hardware, the software compute the difference between BMD of patient and young adult mean BMD (from reference data in the software). Then divide it on young adult population standard deviation, contained in the software, the result is T-score. When Z-score is under calculation, the software divides the difference between BMD of patient and age-matched mean BMD and divides it on agematched population standard deviation. The ability of calculating T—score and Z-score is another interesting characteristic of software of these machines.

As the different brands, have different database, scientists tried to find ways to compare the results of deferent machines. Now we suggest some of these methods.

#### **3.4.1 Providing sBMD**

236 Osteoporosis

This is designed to overcome some of the limitations of the fan beam geometry. A small fan beam radiation (about 4cm wide at the detector) in the long axis is detected by an array of detectors. The beam scans the bones in the short patient axis on each individual sweep along the long axis of the patient with some beam overlap. Although slightly slower than a fan beam scanner (1-2 minutes per scan), the mass results should be more accurate as the photon flux has little variability in the area being measured (due to the beam overlap). You can see the schematic figure of different beam geometries in the Fig. 4, from mentioned

Fig. 4. Beam geometry of DXA mechines (from website of Royal Adelaide Hospital

The reference data of these machines, contain data of BMD tests of almost 5000 Caucasian white normal persons; around 20-80 y/o. Any brand of these machines has different reference data. It is clear that collecting such huge database, nowadays, seems impossible (especially due to cost and financial problems). This makes these method (DXA) and machines, unique. It seems impossible that any other method or brand can replace them in

Another ability of the software of this machines is, ability to calculate T-score and Z-score

Measured BMD-Young adultmean BMD T-score=

Young adultpopulation SD

**3.3.5.3 Narrow fan beam** 

(Australia)

**3.4 Software** 

future, at least in near future.

for patients (Shepherd &Blake, 2007):

website (Royal Adelaide Hospital, 2009).

Genant et al, as inventors of sBMD, explained the methods of providing sBMD in their article, so.

We can t compare patient information between various DXA scanners, because there isn't any acceptable universal cross-calibration procedure or standard. Although operating on the same basic principles, normative databases, are specific and different for each scanner. The instruments show differences in scanner design, bone mineral calibration, and analysis algorithms. Lunar and Norland scanners rely on daily scanning of standards to provide a bone tissue equivalent calibration. Hologic uses an internal calibration system, which corrects for short-term instabilities. Also, the software used for analysis of the scans, is manufacturer specific (and unique), especially with regard *to* the edge detection algorithms used for separating bone and soft tissue regions. This implementation causes in variations in the defined bone area (cm2) and bone mineral content (BMC, g) and density (BMD) of the same subject on different systems. Genant et al, study was performed under the auspices of the International DXA Standardization Committee to establish appropriate cross-calibration parameters. Posteroanterior (PA) lumbar spine measurements of 100 women, ages 20-80 years (mean 52.6 ± 16, range of BMD = 0.4-1.6 g/cm2) were obtained on a Norland XR26 Mark II, a Lunar DPX-L, and a Hologic QDR 2000 densitometer using standard procedures (pencil beam mode for all three scanners). Area, BMC, and BMD results from the different scanners were compared for all patients. In addition, the European spine phantom (ESP) and the European spine phantom prototype (ESP prototype), as well as standard phantoms from all three manufacturers, were evaluated on the three systems. To reach universal scanner calibration, they used the intercept and slope of the patient's correlations and the value of the middle vertebra of the ESP as a reference point in a series of standardization formulas, and expressed the results as sBMD (mg/cm2). The correlations of the patients' spinal BMD values were excellent for each of the three scanner pairs. The average absolute difference in patient spinal BMD values (L2-L4) between Hologic and Norland was 0.012 g/cm' (1.3%); it was 0.113 g/cm' (11.7%) between Hologic and Lunar and 0.118 g/cm2 (12.2%) between Norland and Lunar. The phantoms' regression lines approximated those of the patient regression lines, and the phantoms with only one measurement point were very close to the patients' regression lines. After applying the standardization formulas, the average absolute variations for the 100 patients were 28 mg/cm2 (2.7%) for Hologich/Norland, 23 mg/cm2 (2.2%) for Hologic/Lunar, and 29 mg/cm2 (2.8%) for Norland/Lunar. Average BMD results for the patients before correction were 0.972 g/cm2

What's BMD and What We Do in a BMD Centre? 239

**4.2 What is the criteria for using other sites for densitometry? Calcaneus an example**  For densitometry we can also use appendicular skeleton. Particularly the calcaneus is an excellent site for measurements by a range of techniques. So we use it as an example for describing the rules of choosing ROI for bone mineral densitometry. The calcaneus is easily accessible with little overlying soft tissue. It is not a common fracture site but remember that in the spinal region, the most susceptible sites for fracture are at T7\_ T8 and T11\_L1, but we

The remodeling of trabecular bone is more active than cortical bone. It means trabecular bone is more active metabolically and more sensitive to metabolic bone changes. Calcaneus is made up, almost entirely of trabecular bone and may provide a more sensitive measurement site for finding early signs of diseases that affect mostly metablism. A number of studies suggested that bone mass of calcaneus may contribute to fracture risk in other sites and that its predictive power is not very different than that of spine and hip. The study by Cummings et al. as cited in Kang and speller; 1999, confirmed this in 65 years old women and over.Interestingly, many early single energy measurements of bone mineral were made in the calcaneus, because it is a peripheral site that can be immersed to water. The arrival of dual energy techniques changed the focus. Earlier studies validated a highly significant correlation between the ashed bone mass of cadaver calcanei and the measured BMC values of calcaneus by densitometry (r=0.97). Kang and Speller, describe calcaneus as a site with excellent accuracy that it's measurements can be made quickly and easily and with

Correct positioning among other factors is very important to ensure an optimal scan. Simonoski et al., emphasize that correct and consistent positioning and labelling of hip and lumbar spine (as the main job of operators), are important when evaluating serial assessments (monitoring of patients). It is important to follow manufacturer-specific

Structural abnormalities and artifacts can significantly influence the results. Independent factors, like body weight, may affect BMD results. However, in interpreting the results of a scan, first of all, it must be described whether the scan is valid with regards to positioning,

Fuleihan et al, assessed the effects of the machine, operator and subjects on error of measurements of bone density. They explained their technique for this assessment as an analysis applied to data from a prospective study of BMD measurements on spine phantoms and on pre- and postmenopausal women. Scans performed on the same day or up to 4 weeks apart with DXA (QDR IOOOW, Hologic). Their model assessed (or suggested) that : operators' and subjects' variability were the most causes of errors in measurements rather than machine performance (Fuleihan et al., 1995). Subjects are not changeable or controllable, but operators job can be under quality control and its quality develops by time (and experience). These machines, are not very extensively distributed, and any machine is unique in its way (the data of a second scan of a patients, can be compared to data on the same machine that first BMD is performed, only). These make finding expert operators for these machines, not very easy. What mentioned above, is the cause that operators are called "the heart" of BMD centers. So some-ones believe in this sentence "Never change your operators (in BMD departments) and if the change is inevitable, never change them again."

protocols to ensure appropriate comparisons with normative reference data.

measure bone mineral content to L1\_L4 because of less overlying soft tissue.

portable instruments. (Kang & Speller, 1999)

**4.3 Operators, the heart of a BMD center** 

artifact, and analysis, or not (Siminoski et al., 2005)

for Hologic, 1.100 g/cm2 for Lunar, and 0.969 g/cm2 for Norland. After correction, sBMD results for patients were 1045 mg/cm2 for Hologic, 1047 mg/cm2 for Lunar, and 1043 mg/cm2 for Norland. The standardization approach as performed in our study provided compatibility of DXA results obtained on different scanners. Finally the sBMD for different machines calculates as sBMD = 1.0761BMDnorland, sBMDl = 0.9522BMDlunar and sBMDh = 1.0755BMDhologic. (Genant et al., 1994).

### **3.4.2 Use of NHANES III**

When the reference-data of different machines (the young-adult mean BMD), used for defining T-score of patient, the variability within these reference data of different brands, substantially impacts osteoporosis prevalence with using this T-score-based approach. Binkley et al, emphasize that ideally, all bone mass measurement devices would use the same population to define the young-normal mean BMD and SD, a process that cause obtaining of similar T-scores with instruments of different manufacturers. Although use of a single large sample population to develop a unique normative database for all densitometers has been suggested, this process has not been possible. To increase coordination between diagnostic classification, the International Committee for Standards in Bone Measurement (ICSBM) agreed on a universal reference database for the femur based on NHANES III, the only large standardized reference database ever published (Binkley et al., 2005). Looker et al., mention that this data were gathered from 14646 men and women aged 20 years and older, using dual-energy X-ray absorptiometry, and included bone mineral density (BMD), bone mineral content (BMC) and area of bone scanned in four selected regions of interest (ROI) in the proximal femur: femur neck, trochanter, intertrochanter and total. These variables are separated by age and sex for non-Hispanic whites (NHW), non-Hispanic blacks (NHB) and Mexican Americans (MA). They emphasize that the updated data on BMD for the total femur ROI of NHW have been selected as the reference database for femur standardization efforts by the International Committee on Standards in Bone Measurements (Looker et al., 1998). The ICSBM published formulae to convert measured BMD into standardized BMD (of total femur), thereby allowing use of the NHANES III database by other brands' densitometer. The NHANES III data were acquired using Hologic densitometers (Binkley et al., 2005).

### **4. General consideration in bone mineral densitometry**

#### **4.1 Recommendation about ROIs that should assess**

Siminoski et al., have some recommendations about ROIs that are under measurement:


for Hologic, 1.100 g/cm2 for Lunar, and 0.969 g/cm2 for Norland. After correction, sBMD results for patients were 1045 mg/cm2 for Hologic, 1047 mg/cm2 for Lunar, and 1043 mg/cm2 for Norland. The standardization approach as performed in our study provided compatibility of DXA results obtained on different scanners. Finally the sBMD for different machines calculates as sBMD = 1.0761BMDnorland, sBMDl = 0.9522BMDlunar and sBMDh

When the reference-data of different machines (the young-adult mean BMD), used for defining T-score of patient, the variability within these reference data of different brands, substantially impacts osteoporosis prevalence with using this T-score-based approach. Binkley et al, emphasize that ideally, all bone mass measurement devices would use the same population to define the young-normal mean BMD and SD, a process that cause obtaining of similar T-scores with instruments of different manufacturers. Although use of a single large sample population to develop a unique normative database for all densitometers has been suggested, this process has not been possible. To increase coordination between diagnostic classification, the International Committee for Standards in Bone Measurement (ICSBM) agreed on a universal reference database for the femur based on NHANES III, the only large standardized reference database ever published (Binkley et al., 2005). Looker et al., mention that this data were gathered from 14646 men and women aged 20 years and older, using dual-energy X-ray absorptiometry, and included bone mineral density (BMD), bone mineral content (BMC) and area of bone scanned in four selected regions of interest (ROI) in the proximal femur: femur neck, trochanter, intertrochanter and total. These variables are separated by age and sex for non-Hispanic whites (NHW), non-Hispanic blacks (NHB) and Mexican Americans (MA). They emphasize that the updated data on BMD for the total femur ROI of NHW have been selected as the reference database for femur standardization efforts by the International Committee on Standards in Bone Measurements (Looker et al., 1998). The ICSBM published formulae to convert measured BMD into standardized BMD (of total femur), thereby allowing use of the NHANES III database by other brands' densitometer. The NHANES III data were acquired

= 1.0755BMDhologic. (Genant et al., 1994).

using Hologic densitometers (Binkley et al., 2005).

radius, 33% radius or proximal radius.

**4. General consideration in bone mineral densitometry** 

Siminoski et al., have some recommendations about ROIs that are under measurement: In the lumbar spine, using a minimum of 2 valid vertebra is recommended (if there is

amount of bone yields measurements of poor accuracy and reproducibility.

In the proximal femur, Ward's area should not be included in the report, as the small

If either hip or spine is not valid, forearm BMD is recommended. Preferred site is 1/3

 When the final report includes a graph of the patient's BMD, it should be based on the same anatomic levels that were used for numeric results; for example if L3 and L4 were excluded from spinal analysis because of degenerative objects, the graph should be

problems in L1-L4 vertebrae that cause exclusion one or 2 of them).

based on the combined value for L1 and L2(Siminoski et al., 2005).

**4.1 Recommendation about ROIs that should assess** 

**3.4.2 Use of NHANES III** 

#### **4.2 What is the criteria for using other sites for densitometry? Calcaneus an example**

For densitometry we can also use appendicular skeleton. Particularly the calcaneus is an excellent site for measurements by a range of techniques. So we use it as an example for describing the rules of choosing ROI for bone mineral densitometry. The calcaneus is easily accessible with little overlying soft tissue. It is not a common fracture site but remember that in the spinal region, the most susceptible sites for fracture are at T7\_ T8 and T11\_L1, but we measure bone mineral content to L1\_L4 because of less overlying soft tissue.

The remodeling of trabecular bone is more active than cortical bone. It means trabecular bone is more active metabolically and more sensitive to metabolic bone changes. Calcaneus is made up, almost entirely of trabecular bone and may provide a more sensitive measurement site for finding early signs of diseases that affect mostly metablism. A number of studies suggested that bone mass of calcaneus may contribute to fracture risk in other sites and that its predictive power is not very different than that of spine and hip. The study by Cummings et al. as cited in Kang and speller; 1999, confirmed this in 65 years old women and over.Interestingly, many early single energy measurements of bone mineral were made in the calcaneus, because it is a peripheral site that can be immersed to water. The arrival of dual energy techniques changed the focus. Earlier studies validated a highly significant correlation between the ashed bone mass of cadaver calcanei and the measured BMC values of calcaneus by densitometry (r=0.97). Kang and Speller, describe calcaneus as a site with excellent accuracy that it's measurements can be made quickly and easily and with portable instruments. (Kang & Speller, 1999)

#### **4.3 Operators, the heart of a BMD center**

Correct positioning among other factors is very important to ensure an optimal scan. Simonoski et al., emphasize that correct and consistent positioning and labelling of hip and lumbar spine (as the main job of operators), are important when evaluating serial assessments (monitoring of patients). It is important to follow manufacturer-specific protocols to ensure appropriate comparisons with normative reference data.

Structural abnormalities and artifacts can significantly influence the results. Independent factors, like body weight, may affect BMD results. However, in interpreting the results of a scan, first of all, it must be described whether the scan is valid with regards to positioning, artifact, and analysis, or not (Siminoski et al., 2005)

Fuleihan et al, assessed the effects of the machine, operator and subjects on error of measurements of bone density. They explained their technique for this assessment as an analysis applied to data from a prospective study of BMD measurements on spine phantoms and on pre- and postmenopausal women. Scans performed on the same day or up to 4 weeks apart with DXA (QDR IOOOW, Hologic). Their model assessed (or suggested) that : operators' and subjects' variability were the most causes of errors in measurements rather than machine performance (Fuleihan et al., 1995). Subjects are not changeable or controllable, but operators job can be under quality control and its quality develops by time (and experience). These machines, are not very extensively distributed, and any machine is unique in its way (the data of a second scan of a patients, can be compared to data on the same machine that first BMD is performed, only). These make finding expert operators for these machines, not very easy. What mentioned above, is the cause that operators are called "the heart" of BMD centers. So some-ones believe in this sentence "Never change your operators (in BMD departments) and if the change is inevitable, never change them again."

What's BMD and What We Do in a BMD Centre? 241

New investigations show prevalence of low BMD in children is very high and it is higher than expected range. Genetic, environmental and iatrogenic factor are 3 most important

Bogunovic et al., name causes of pediatric osteoporosis as idiopathic juvenile osteoporosis and heritable connective tissue disorders like osteogenesis imperfect and Ehler–Danlos. They also name a long list of factors as secondary causes of pediatric osteoporosis that include neuromuscular disorders (cerebral palsy and Duchenne muscular dystrophy), childhood cancer, endocrine disorders (Turner Syndrome and juvenile diabetes mellitus), and inborn errors of metabolism (Gaucher disease) and Chronic diseases like thalassemia. Anticonvulsants, glucocorticoids, and various forms of chemotherapy may adversely affect

Bone mass densitometry by dual X-ray absorptiometry (DEXA) of the lumbar spine and femoral neck is recommended as one of the most reliable and non-invasive technique for the assessment of bone mass (Hamidi et al., 2008). This method is very common around the world and many pediatric studies about bone densitometry and body composition have been published by using this method. (Van Kuijk, 2010).WHO osteoporosis diagnostic criteria should not be applied to children. We can't use T-score because children have not reached PBM, yet. Instead, in children, Z-score must be noticed, that it is a comparison of BMD of child to pediatric normative data. If the z- score is below -2 , we can use the term 'low bone density for chronologic age" (Daniels et al., 2003). DXA is reliable and accurate for adult but in children there is a challenge for it. As it is known, true bone density is a result of dividing BMC(g) by volume(cm3). In DXA , BMD is determined by dividing BMC by 2 dimensional area of a three dimensional objective (bone). By the use of these criteria smaller bone appear to have a lower BMD than larger bones. (Bogunovic et al., 2009). Bone size does not change, in adults, over time. On the contrary, bone size changes in growing children in 3 dimentions. When we screen children with DXA and follow them over time, we actually measure their growth instead of measuring actual changing in BMD.(Van Kuijk, 2010). It must be remembered that wide variation of height, and bone size in children makes interpretation of BMD difficult, especially in short children. Bogunovic et al., mention that longitudinal evaluation of a given patient over time is affected by the ever-changing size of the growing skeleton and the rates of skeletal growth vary with each bony dimension (Bogunovic et al., 2009). All this problems, cause to ask a question: Is it right to use DXA for measuring bone density and fracture risk in children or not? In response we emphasize some useful points about DXA. First it has fewer radiation than other methods, that is very important in radiology of children, 2) it is not a fearful (less noisy with no tunnel) method for children densitometry, 3) It is used worldwide and many pediatric studies, have been published in the field of bone densitometry and in the field of body composition studies, by using DXA method also 4) Studies about the relationship between bone density and fractures in healthy children, suggested that bone mass may contribute to fracture risk in childhood (Van Kuijk, 2010). So may be the answer is that performing DXA for measurement bone density and fracture risk in children, is a helpful method yet. However

**4.6 Pediatric consideration 4.6.1 Low bone mass in pediatrics** 

factor that lead to bone disorders in children.

normal skeletal maturation (Bogunovic et al., 2009).

**4.6.2 Problems with DXA in pediatric** 

#### **4.4 Material of a standard BMD report**

Shimonoseki et al, recommend that , a standard BMD report should include:


#### **4.5 Discordance**

Discordance makes difficulties in diagnosis of osteoporosis and management of osteoporotic patients. Moayyeri et al, explain, discordance in diagnosis of osteoporosis that is defined as presence of different categories of diagnosis based on T-score (osteoporosis, osteopenia, and normal) in two skeletal sites of an individual patient. They mansion that discordance has been divided into two groups: major and minor . When the different sites results, are close; i.e., normal in one site and osteopenic in the other site, or, when patient is diagnosed as osteopenic in one site and osteoporotic in the other site, minor discordance happens. When patient diagnosed normal in one site and is osteoporosis in another site, major discordance happens. (Moayyeri et al., 2005). In a clinical study, BMD measurements performed at lumbar spine both for baseline risk assessment and for monitoring purposes. Leslie et al. discuss a difficulty that clinician are confronted with highly discordant measurements and at the same time lumbar spine is worse than femoral neck and about how this should be integrated into the decision-making process. They discuss about different guideline recommendations in this situation. They say under NOF guideline, if t-score in lumbar spine is in osteoporotic range without consideration to estimated risk -by special soft-wares-, treatment should be recommended. In other national guideline such as those from the UK, till a 10 year fracture risk prediction from the femoral neck does not reach the intervention threshold, don't recommend any treatment for patients with osteoporotic lumbar spine. Canadian guidelines have attempted to show the issue of site discordance (in femur) by recommending use of the minimum T-score, in femur for diagnosis and treatment of osteoporosis. However, Leslie et al. suggest that this may systematically overestimates fracture risk and does not consider site-specific differences in fractures or the way BMD declines with age. They suggest that as lumbar spine and hip measurements are both performed for clinical purposes, using a procedure that accurately reflects the contribution of each measurement site to fracture risk, is clearly preferred, so they propose a a procedure for adjusting FRAX probability, based upon the T-score difference between the lumbar spine (LS) and femoral neck (FN). This procedure is termed "offset". They furmulated following rule: "Increase/decrease FRAX estimate for a major fracture by one tenth for each rounded T-score difference between LS and FN." (Leslie et al., 2011)

#### **4.6 Pediatric consideration**

240 Osteoporosis

 BMD results expressed in absolute values (g/cm2; 3 decimal places) and T-score (1 decimal place) for lumbar spine; proximal femur (total hip, femoral neck, and trochanter); and an alternate site (forearm BMD preferred: 1/3 radius, 33% radius or

 The fracture risk category (low, moderate, or high). It must be included major clinical factors that modify absolute fracture risk probability (with an indication of the

 A statement as to whether the change is statistically significant or not for serial measurements. The BMD centre's least significant change for each skeletal site (in

Discordance makes difficulties in diagnosis of osteoporosis and management of osteoporotic patients. Moayyeri et al, explain, discordance in diagnosis of osteoporosis that is defined as presence of different categories of diagnosis based on T-score (osteoporosis, osteopenia, and normal) in two skeletal sites of an individual patient. They mansion that discordance has been divided into two groups: major and minor . When the different sites results, are close; i.e., normal in one site and osteopenic in the other site, or, when patient is diagnosed as osteopenic in one site and osteoporotic in the other site, minor discordance happens. When patient diagnosed normal in one site and is osteoporosis in another site, major discordance happens. (Moayyeri et al., 2005). In a clinical study, BMD measurements performed at lumbar spine both for baseline risk assessment and for monitoring purposes. Leslie et al. discuss a difficulty that clinician are confronted with highly discordant measurements and at the same time lumbar spine is worse than femoral neck and about how this should be integrated into the decision-making process. They discuss about different guideline recommendations in this situation. They say under NOF guideline, if t-score in lumbar spine is in osteoporotic range without consideration to estimated risk -by special soft-wares-, treatment should be recommended. In other national guideline such as those from the UK, till a 10 year fracture risk prediction from the femoral neck does not reach the intervention threshold, don't recommend any treatment for patients with osteoporotic lumbar spine. Canadian guidelines have attempted to show the issue of site discordance (in femur) by recommending use of the minimum T-score, in femur for diagnosis and treatment of osteoporosis. However, Leslie et al. suggest that this may systematically overestimates fracture risk and does not consider site-specific differences in fractures or the way BMD declines with age. They suggest that as lumbar spine and hip measurements are both performed for clinical purposes, using a procedure that accurately reflects the contribution of each measurement site to fracture risk, is clearly preferred, so they propose a a procedure for adjusting FRAX probability, based upon the T-score difference between the lumbar spine (LS) and femoral neck (FN). This procedure is termed "offset". They furmulated following rule: "Increase/decrease FRAX estimate for a major fracture by one tenth for each rounded

corresponding absolute 10-year fracture risk of <10%, 10-20%, or >20%).

Shimonoseki et al, recommend that , a standard BMD report should include:

proximal radius) if either hip or spine is not valid. A statement about any limitations due to artifacts, if present.

g/cm2) should be included (Siminoski et al., 2005)

T-score difference between LS and FN." (Leslie et al., 2011)

**4.4 Material of a standard BMD report** 

 Patient identifiers. DXA scanner identifier.

**4.5 Discordance** 

#### **4.6.1 Low bone mass in pediatrics**

New investigations show prevalence of low BMD in children is very high and it is higher than expected range. Genetic, environmental and iatrogenic factor are 3 most important factor that lead to bone disorders in children.

Bogunovic et al., name causes of pediatric osteoporosis as idiopathic juvenile osteoporosis and heritable connective tissue disorders like osteogenesis imperfect and Ehler–Danlos. They also name a long list of factors as secondary causes of pediatric osteoporosis that include neuromuscular disorders (cerebral palsy and Duchenne muscular dystrophy), childhood cancer, endocrine disorders (Turner Syndrome and juvenile diabetes mellitus), and inborn errors of metabolism (Gaucher disease) and Chronic diseases like thalassemia. Anticonvulsants, glucocorticoids, and various forms of chemotherapy may adversely affect normal skeletal maturation (Bogunovic et al., 2009).

#### **4.6.2 Problems with DXA in pediatric**

Bone mass densitometry by dual X-ray absorptiometry (DEXA) of the lumbar spine and femoral neck is recommended as one of the most reliable and non-invasive technique for the assessment of bone mass (Hamidi et al., 2008). This method is very common around the world and many pediatric studies about bone densitometry and body composition have been published by using this method. (Van Kuijk, 2010).WHO osteoporosis diagnostic criteria should not be applied to children. We can't use T-score because children have not reached PBM, yet. Instead, in children, Z-score must be noticed, that it is a comparison of BMD of child to pediatric normative data. If the z- score is below -2 , we can use the term 'low bone density for chronologic age" (Daniels et al., 2003). DXA is reliable and accurate for adult but in children there is a challenge for it. As it is known, true bone density is a result of dividing BMC(g) by volume(cm3). In DXA , BMD is determined by dividing BMC by 2 dimensional area of a three dimensional objective (bone). By the use of these criteria smaller bone appear to have a lower BMD than larger bones. (Bogunovic et al., 2009). Bone size does not change, in adults, over time. On the contrary, bone size changes in growing children in 3 dimentions. When we screen children with DXA and follow them over time, we actually measure their growth instead of measuring actual changing in BMD.(Van Kuijk, 2010). It must be remembered that wide variation of height, and bone size in children makes interpretation of BMD difficult, especially in short children. Bogunovic et al., mention that longitudinal evaluation of a given patient over time is affected by the ever-changing size of the growing skeleton and the rates of skeletal growth vary with each bony dimension (Bogunovic et al., 2009). All this problems, cause to ask a question: Is it right to use DXA for measuring bone density and fracture risk in children or not? In response we emphasize some useful points about DXA. First it has fewer radiation than other methods, that is very important in radiology of children, 2) it is not a fearful (less noisy with no tunnel) method for children densitometry, 3) It is used worldwide and many pediatric studies, have been published in the field of bone densitometry and in the field of body composition studies, by using DXA method also 4) Studies about the relationship between bone density and fractures in healthy children, suggested that bone mass may contribute to fracture risk in childhood (Van Kuijk, 2010). So may be the answer is that performing DXA for measurement bone density and fracture risk in children, is a helpful method yet. However

What's BMD and What We Do in a BMD Centre? 243

 Other geometrical measures: In addition to the most common measures of geometry discussed above, a number of other measures have also been related to fracture; including a thinner femoral shaft cortex , a thinner femoral neck cortex , a smaller calcar femoral (a dense, vertically orientated bone present in the posteroemedial region of the femoral shaft under the lesser trochanter of the femur) , a narrower trochanteric width and smaller inner and outer pelvic diameters. In contrast, an increased femoral head

Fig. 5. Diagram illustrating some of the most common geometrical measurements made

**6. Finite element (An helpful method for better understanding of bone)** 

Two methods are must commonly used for assessing bone geometry, radiography and dual energy X-ray absorptiometry (DXA) (fan beam devices, more provide this service). Each of them; has its own advantages and disadvantages. Femoral geometry is important in determining both bone strength and fracture risk. The strongest associations with both outcomes appear to be a longer (Hip axis length) HAL and larger NSA (Neck-shaft angle)

Need to a mathematical tool for solving complex mathematical problems, is answered by inventing Finite-element modeling (FEM). It helps to understand patterns of stress, strain, deflections, heat transfer, fluid flow, etc., in computer models of organic structures. Ross, emphasize that FEM provides a method for addressing a range of questions that are otherwise intractable, or very difficult to solve -in vivo or in vitro- and is potentially one of the most powerful tools in the methodological tool of vertebrate biomechanics. For example, clarifying functional consequences of the remarkable histological and morphological diversity of the vertebrae, is one of the important aims of vertebrate biomechanics. Many of researches on various disorders or diseases of the bone, are relied on this structure-function relationship. Skeletal health during long term space flight, as well as interpretation of skeletons found in the fossil and archeological records, are benefitted from these researches. Ross mentions that form-

diameter has been related to increased bone strength.

from the proximal femur (from Gregory and Aspden, 2008).

(Gregory & Aspden, 2008).

we should emphasize that bone fragility in children extends beyond single BMD measurement, and bone geometry and body size influence it and in the diagnosis of osteoporosis, the presence of both a clinically significant fracture history and low bone mass, must be noticed (Bogunovic et al., 2009).

#### **4.6.3 Special consideration of comparison of normal children and children with chronic disease, some points in BMD of chronic ill children**

The measurement of BMC (g/cm) and BMD (g/cm2) are not only dependent on the mineral density of cortical and spongious bone, but also depend on the bone geometry. Lower BMD or BMC in shorter children may not describe a mineral deficiency or mineralization disorder, as is often thought, because the smaller bone may show lower BMD because of properties of DXA methods (Schonau,1998). BMD measurement in children is more affected by the wide variation of age at onset and progression of puberty. This leads to a wide variation in the age at reach of peak bone mass. It is thought the presence of a chronic disease, like juvenile arthritis, cause delay in pubertal onset and development. It has been estimated that one-third to one-half of the total mineralization in the lumbar spine in adult women is occurred during the 3 years around the onset of puberty. Therefore, we can t compare the BMD of a well-grown 13-year-old girl who is in mid-puberty with that of a small pre-pubertal 13-year-old with juvenile arthritis. Rabinovich remembers us that a DXA scan is not needed to tell who has the lower BMD. The question then is, is the BMD result in this small pre-pubertal girl normal? (Rabinovich, 2004).

As van Kuijk suggests, children with chronic disorders or medication, should never be compared with age-matched reference (normal) values. They should be compared with children with the same maturation status (skeletal age) (Van Kuijk, 2010).

### **5. Geometry (Another use of dual x-ray absorptiometry)**

Some important factors such as the shape and structure of bone and the risk of falling, affect susceptibility to fracture so BMD alone cannot exactly predict who will have fracture. As Gregory and Aspden emphasize, the geometry of the proximal femur is a vital component in determining a person's risk of hip fracture. When a trauma occurs, such as a fall, the shape and structure of the femur determines how the forces are passed through the bone from the point of impact and whether they surpass the inherent strength of the bone and result in a fracture or not. Geometry component is seen in the picture from Gregory and Aspden article (Fig. 5.)

They explained any of these components


Femoral neck axis length is the linear distance measured from the base of the greater trochanter to the apex of the femoral head. It is illustrated by points B to C in Fig. 5. Confusingly, it is also sometimes referred to in the literature as hip axis length.

Femoral neck width (FNW):

The narrowest distance across the femoral neck, often constrained to being perpendicular to the neck axis. The distance between points F and G in Fig. 5.

Neck-shaft angle:

Usually defined as the angle between the femoral neck axis and the shaft axis (angle at point H in Fig. 5).

we should emphasize that bone fragility in children extends beyond single BMD measurement, and bone geometry and body size influence it and in the diagnosis of osteoporosis, the presence of both a clinically significant fracture history and low bone mass,

The measurement of BMC (g/cm) and BMD (g/cm2) are not only dependent on the mineral density of cortical and spongious bone, but also depend on the bone geometry. Lower BMD or BMC in shorter children may not describe a mineral deficiency or mineralization disorder, as is often thought, because the smaller bone may show lower BMD because of properties of DXA methods (Schonau,1998). BMD measurement in children is more affected by the wide variation of age at onset and progression of puberty. This leads to a wide variation in the age at reach of peak bone mass. It is thought the presence of a chronic disease, like juvenile arthritis, cause delay in pubertal onset and development. It has been estimated that one-third to one-half of the total mineralization in the lumbar spine in adult women is occurred during the 3 years around the onset of puberty. Therefore, we can t compare the BMD of a well-grown 13-year-old girl who is in mid-puberty with that of a small pre-pubertal 13-year-old with juvenile arthritis. Rabinovich remembers us that a DXA scan is not needed to tell who has the lower BMD. The question then is, is the BMD result in

As van Kuijk suggests, children with chronic disorders or medication, should never be compared with age-matched reference (normal) values. They should be compared with

Some important factors such as the shape and structure of bone and the risk of falling, affect susceptibility to fracture so BMD alone cannot exactly predict who will have fracture. As Gregory and Aspden emphasize, the geometry of the proximal femur is a vital component in determining a person's risk of hip fracture. When a trauma occurs, such as a fall, the shape and structure of the femur determines how the forces are passed through the bone from the point of impact and whether they surpass the inherent strength of the bone and result in a fracture or not. Geometry component is seen in the picture from Gregory and

Hip axis length: The distance from greater trochanter to inner pelvic brim, shown

Femoral neck axis length is the linear distance measured from the base of the greater trochanter to the apex of the femoral head. It is illustrated by points B to C in Fig. 5.

The narrowest distance across the femoral neck, often constrained to being perpendicular to

Usually defined as the angle between the femoral neck axis and the shaft axis (angle at point

Confusingly, it is also sometimes referred to in the literature as hip axis length.

the neck axis. The distance between points F and G in Fig. 5.

**4.6.3 Special consideration of comparison of normal children and children with** 

**chronic disease, some points in BMD of chronic ill children** 

this small pre-pubertal girl normal? (Rabinovich, 2004).

Aspden article (Fig. 5.)

Neck-shaft angle:

H in Fig. 5).

They explained any of these components

between points A and C in Fig. 5 Femoral neck axis length (FNAL):

Femoral neck width (FNW):

children with the same maturation status (skeletal age) (Van Kuijk, 2010).

**5. Geometry (Another use of dual x-ray absorptiometry)** 

must be noticed (Bogunovic et al., 2009).

 Other geometrical measures: In addition to the most common measures of geometry discussed above, a number of other measures have also been related to fracture; including a thinner femoral shaft cortex , a thinner femoral neck cortex , a smaller calcar femoral (a dense, vertically orientated bone present in the posteroemedial region of the femoral shaft under the lesser trochanter of the femur) , a narrower trochanteric width and smaller inner and outer pelvic diameters. In contrast, an increased femoral head diameter has been related to increased bone strength.

Fig. 5. Diagram illustrating some of the most common geometrical measurements made from the proximal femur (from Gregory and Aspden, 2008).

Two methods are must commonly used for assessing bone geometry, radiography and dual energy X-ray absorptiometry (DXA) (fan beam devices, more provide this service). Each of them; has its own advantages and disadvantages. Femoral geometry is important in determining both bone strength and fracture risk. The strongest associations with both outcomes appear to be a longer (Hip axis length) HAL and larger NSA (Neck-shaft angle) (Gregory & Aspden, 2008).

### **6. Finite element (An helpful method for better understanding of bone)**

Need to a mathematical tool for solving complex mathematical problems, is answered by inventing Finite-element modeling (FEM). It helps to understand patterns of stress, strain, deflections, heat transfer, fluid flow, etc., in computer models of organic structures. Ross, emphasize that FEM provides a method for addressing a range of questions that are otherwise intractable, or very difficult to solve -in vivo or in vitro- and is potentially one of the most powerful tools in the methodological tool of vertebrate biomechanics. For example, clarifying functional consequences of the remarkable histological and morphological diversity of the vertebrae, is one of the important aims of vertebrate biomechanics. Many of researches on various disorders or diseases of the bone, are relied on this structure-function relationship. Skeletal health during long term space flight, as well as interpretation of skeletons found in the fossil and archeological records, are benefitted from these researches. Ross mentions that form-

What's BMD and What We Do in a BMD Centre? 245

Zare, Mrs. P. Athari, Mrs. MR. Dadras, Mrs. M. Mirzaee , Mr. D. Sadeghian and Mrs. A.

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**10. References** 

function relationships of the skeleton are therefore of concern to bioengineers, clinicians, biological anthropologists, and paleontologists, and FEM provides a method for studying them. He also suggests that the availability of increasingly powerful computers at progressively more affordable prices has made FEM an accessible tool for biomechanists and the wide use of FEM in clinical research is now imitating many basic science researches (Ross, 2005). Finite element can be helpful in femoral characteristics finding as helpful as is in spinal vertebrae and finding the mechanisms and risk factors for fracture.

### **7. Recent progress in bone imaging for osteoporosis research**

Development in bone imaging techniques have provided tools for analyzing bone structure at the macro-, micro- and nano-level. Ito, provided a list of recent progress in bone imaging as


The author, suggests that further progress in bone imaging technology is promising to bring new aspects of bone structure in relation to bone strength to light, and to establish a means for analyzing bone structural properties in the everyday clinical setting (Ito, 2011).

### **8. Conclusion**

Tanner in his article reminds us the Bonnick suggestion (noted in the preface of the most recent edition of the author's book on bone densitometry in clinical practice)". . . as strange as it may seem, the technology itself is in danger of becoming so devalued that improvements in accessibility and advances in applications may be lost." (Bonnick SL. as cited in Tanner, 2011 from book "Bone densitometry in clinical practice: application and interpretation"(current clinical practice series). 3rd ed. Totowa, New Jersey:Humana Press; 2010). The future of DXA bone density testing is challenged by reimbursement, complicated guidelines, and the controversy over the monitoring of treatment. Nevertheless, bone health assessment and fracture risk prediction rely on quality bone density measurement using DXA (Tanner, 2011).

### **9. Acknowledgement**

Author must thank Dr. B. Larijani (the director of EMRI-TUMS), Dr. A. Soltani, Dr. AR. Khalili, Dr. H. Adibi, Dr.E. Rahimi, Mrs. S. Azizi , Mrs. M. Hajiloo , Miss S. Shirazi, Mrs. F. Zare, Mrs. P. Athari, Mrs. MR. Dadras, Mrs. M. Mirzaee , Mr. D. Sadeghian and Mrs. A. Oojaghi for their valuable assistance in this study.

### **10. References**

244 Osteoporosis

function relationships of the skeleton are therefore of concern to bioengineers, clinicians, biological anthropologists, and paleontologists, and FEM provides a method for studying them. He also suggests that the availability of increasingly powerful computers at progressively more affordable prices has made FEM an accessible tool for biomechanists and the wide use of FEM in clinical research is now imitating many basic science researches (Ross, 2005). Finite element can be helpful in femoral characteristics finding as helpful as is in spinal

Development in bone imaging techniques have provided tools for analyzing bone structure at the macro-, micro- and nano-level. Ito, provided a list of recent progress in bone imaging as High-resolution CT (HR-CT) and high-resolution magnetic resonance (HR-MR). They are in vivo quantitative techniques for assessing the microstructure of trabecular bone noninvasively and non-destructively. Compared with MR imaging, CT-based techniques have the advantage of directly visualizing the bone in the axial skeleton, with high spatial resolution (of course, disadvantage of delivering a considerable radiation dose remains). Micro-CT (μCT) and Synchrotron μCT (SR-CT). The farmer provides a higher resolution of the microstructure and is principally applicable in vitro, has undergone technological advances such that it is now able to elucidate the physiological skeletal change mechanisms associated with aging and determine the effects of therapeutic intervention on the bone microstructure. In particular, synchrotron μCT (SR-CT) provides a more

 DXA-based hip structure analysis (HSA) and CT-based HAS. DXA-based HSA is a convenient tool for analyzing biomechanical properties and for assuming crosssectional hip geometry based on two-dimensional (2D) data. CT-based HSA provides these parameters three-dimensionally in robust relationship with biomechanical properties, at the cost of greater radiation exposure and the lengthy time required for

The author, suggests that further progress in bone imaging technology is promising to bring new aspects of bone structure in relation to bone strength to light, and to establish a means

Tanner in his article reminds us the Bonnick suggestion (noted in the preface of the most recent edition of the author's book on bone densitometry in clinical practice)". . . as strange as it may seem, the technology itself is in danger of becoming so devalued that improvements in accessibility and advances in applications may be lost." (Bonnick SL. as cited in Tanner, 2011 from book "Bone densitometry in clinical practice: application and interpretation"(current clinical practice series). 3rd ed. Totowa, New Jersey:Humana Press; 2010). The future of DXA bone density testing is challenged by reimbursement, complicated guidelines, and the controversy over the monitoring of treatment. Nevertheless, bone health assessment and fracture risk prediction rely on quality bone density measurement using DXA (Tanner, 2011).

Author must thank Dr. B. Larijani (the director of EMRI-TUMS), Dr. A. Soltani, Dr. AR. Khalili, Dr. H. Adibi, Dr.E. Rahimi, Mrs. S. Azizi , Mrs. M. Hajiloo , Miss S. Shirazi, Mrs. F.

for analyzing bone structural properties in the everyday clinical setting (Ito, 2011).

vertebrae and finding the mechanisms and risk factors for fracture.

detailed view of trabecular structure at the nano-level.

the analytical procedure.

**8. Conclusion** 

**9. Acknowledgement** 

**7. Recent progress in bone imaging for osteoporosis research** 


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**Secondary Osteoporosis** 


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Khan, Aliya. Lentle, Brian C. Levesque, Jacques. Lyons, David J. Tarulli, Giuseppe. Brown, Jacques P. Recommendations for bone mineral density reporting in Canada. *Canadian Association of Radiologists journal. Vol. 56, No. 3, (Jun 2005), pp. 178-188,*

guidelines and concerns. *Current opinion in rheumatology, Vol. 23, No. 4, (Jul 2011),* 

*British journal of radiology*, Vol. 73, No. 871, (Jul 2000), pp. 737-739, 0007-1285 (Print)

**13** 

*College of Medicine,* 

*Republic of Korea* 

*The Catholic University of Korea* 

**Patchy Osteoporosis in** 

**Complex Regional Pain Syndrome** 

Complex regional pain syndrome (CRPS), formerly known as "reflex sympathetic dystrophy" and "causalgia", is a syndrome that refers to a chronic pain condition associated with autonomic disturbances of vasomotor and sudomotor origin (Birklein et al., 1998), along with trophic skin changes and patchy demineralization of the bones (Poplawski et al., 1983). CRPS is classified into type I and II; the former can develop after minor or remote trauma like stroke, spinal cord injury or myocardial infarction (Wasner et al., 1998); the latter can develop after a large peripheral nerve lesion (Janig & Baron, 2003). The syndrome corresponding to what was formerly described as reflex sympathetic dystrophy is now termed as CRPS type I; causalgia is now termed as CRPS type II (Merseky & Bogduk, 1994). Although the mechanism of CRPS has not been elucidated yet, recent studies indicate that it is a complex disorder that involves both the central and peripheral nervous systems (Daemen et al., 1998; Huygen et al., 2001). CRPS pathogenesis is heterogeneous and complex, which makes its treatment challenging. Pharmacological therapies of CRPS include anti-inflammatory drugs, systemic corticosteroid (Kingery, 1997), antidepressants, opioid (Mackey & Feinberg, 2007), anticonvulsants, free-radical scavengers, vasodilatory medication (Perez et al., 2010) and even bisphosphonate agents (Adami et al., 1997; Manicourt et al., 2004; Robinson et al., 2004; Varenna et al., 2000). In addition, vitamin C is recommended to prevent the occurrence of

However, there is yet no single pharmacological agent or treatment algorithm that can resolve all of its heterogenic features. The efficacy for most pharmacological agents remains largely empirical, with the exception of bisphosphonate agents, which are the only agents with proven efficacy for CRPS based on multiple controlled trials (Adami et al., 1997; Brunner et al., 2009; Mackey & Feinberg, 2007;, Manicourt et al., 2004, Robinson et al., 2004,

In order to understand how these bisphosphonate agents are useful in CRPS treatment, it is imperative to understand the pathogenesis of patchy osteoporosis in CRPS. This section will first review CRPS, then it will introduce the different experimental animal models. Finally this section will discuss the different treatment agents that have been studied for patchy

**1. Introduction** 

Varenna et al., 2000).

osteoporosis.

CRPS type I after wrist fracture (Perez et al., 2010).

Geun-Young Park, Sun Im and Seong Hoon Lim

## **Patchy Osteoporosis in Complex Regional Pain Syndrome**

Geun-Young Park, Sun Im and Seong Hoon Lim *College of Medicine, The Catholic University of Korea Republic of Korea* 

### **1. Introduction**

Complex regional pain syndrome (CRPS), formerly known as "reflex sympathetic dystrophy" and "causalgia", is a syndrome that refers to a chronic pain condition associated with autonomic disturbances of vasomotor and sudomotor origin (Birklein et al., 1998), along with trophic skin changes and patchy demineralization of the bones (Poplawski et al., 1983). CRPS is classified into type I and II; the former can develop after minor or remote trauma like stroke, spinal cord injury or myocardial infarction (Wasner et al., 1998); the latter can develop after a large peripheral nerve lesion (Janig & Baron, 2003). The syndrome corresponding to what was formerly described as reflex sympathetic dystrophy is now termed as CRPS type I; causalgia is now termed as CRPS type II (Merseky & Bogduk, 1994). Although the mechanism of CRPS has not been elucidated yet, recent studies indicate that it is a complex disorder that involves both the central and peripheral nervous systems (Daemen et al., 1998; Huygen et al., 2001). CRPS pathogenesis is heterogeneous and complex, which makes its treatment challenging. Pharmacological therapies of CRPS include anti-inflammatory drugs, systemic corticosteroid (Kingery, 1997), antidepressants, opioid (Mackey & Feinberg, 2007), anticonvulsants, free-radical scavengers, vasodilatory medication (Perez et al., 2010) and even bisphosphonate agents (Adami et al., 1997; Manicourt et al., 2004; Robinson et al., 2004; Varenna et al., 2000). In addition, vitamin C is recommended to prevent the occurrence of CRPS type I after wrist fracture (Perez et al., 2010).

However, there is yet no single pharmacological agent or treatment algorithm that can resolve all of its heterogenic features. The efficacy for most pharmacological agents remains largely empirical, with the exception of bisphosphonate agents, which are the only agents with proven efficacy for CRPS based on multiple controlled trials (Adami et al., 1997; Brunner et al., 2009; Mackey & Feinberg, 2007;, Manicourt et al., 2004, Robinson et al., 2004, Varenna et al., 2000).

In order to understand how these bisphosphonate agents are useful in CRPS treatment, it is imperative to understand the pathogenesis of patchy osteoporosis in CRPS. This section will first review CRPS, then it will introduce the different experimental animal models. Finally this section will discuss the different treatment agents that have been studied for patchy osteoporosis.

Patchy Osteoporosis in Complex Regional Pain Syndrome 251

Plain radiographs can be used to evaluate the demineralization status, but these show positive findings only in the chronic stages. Three-phase bone scintigraphy is a highly specific and sensitive test for CRPS (Demangeat et al., 1998). The classical finding on bone scintigraphy is increased periarticular activity in the affected limb (Todorovic-Tirnamic et al., 1995). Autonomic function can be tested by infrared thermography. Also, skin temperature differences may be helpful for the diagnosis of CRPS; however, these typical temperature side differences are not static descriptors but comprise changes that can be

The complex cascade of CRPS is postulated to initiate after the sensitization of C-nociceptive fibers and release of neuropeptides, which are linked to vasodilatation and hypersensitization of nerve endings (Guo et al., 2004; Kurvers, 1998; Schurmann et al., 1999). Osteoclasts are also activated and this in turn leads to nociceptor stimulation and

A medical history of asthma, migraine, osteoporosis, a recent history of menstrual cyclerelated problems or preexisting neuropathies are common pre-existing problems or conditions often concomitantly found in CRPS patients. Therefore finding a common mediator that is both present in these conditions and CRPS could help to reveal the possible triggering factors. The mediators (de Mos et al., 2008; Karacan et al., 2004; Toda et al., 2006) that have been linked among asthma, migraine and CPRS are the neuropeptides calcitoningene related peptide, substance P (de Mos et al., 2008), mast cell products (Bradding et al., 2006) and transcription factors such as nuclear factor kappa B (Barnes, 2006; Reuter et al., 2002). Inflammatory cytokines such as interleukin 1, tumor necrosis factor alpha have also been suggested to be common denominators among CRPS, osteporosis and menstrual cycle related disorders, but their definite roles need to be established through continuous

Why does bone loss occur in CRPS? Some have postulated that immobilization plays a role in CRPS. Suyama et al, have (Suyama et al., 2002) observed a reduction in BMD 1 to 7 weeks postsurgery with an increase in the number of osteoclasts at 2, 3, and 5 weeks in their CRPS model. They have suggested that one possible mechanism would be the increase of bone resorption with immobilization. Another possible mechanism suggested by others (Whiteside et al., 2006) would be that bone loss in CRPS models may be due to altered nerve signaling and not attributable to limb disuse or reduced mechanical loading associated with pain. Experimental studies have shown that substance P release is involved in the

The exact pathological mechanism of patchy osteoporosis in CRPS and altered nerve signaling is still poorly understood, some consider to be attributable to a regional sympathetic hyperactivity of sympathetic dysfunction (Goldstein et al., 2000; He et al., 2011; Kurvers et al., 1998; Laroche et al., 1997). Sympathetic deregulation causes vasomotor irregularities, and an imbalance between vasoconstriction and vasodilatation, which in turn influences the blood supply to the bone. Other studies have shown that the immune and skeletal systems are closely related to maintain the homeostasis of the bone but when this

critically dependent on environmental temperature (Wasner et al., 2001).

sensitization (Mach et al., 2002; Sevcik et al., 2004) leading to a vicious cycle.

studies (Marie et al., 1993; Zarrabeitia et al., 1991).

pathogenesis of bony changes induced by CRPS (Gaus et al., 2003).

**3. Patchy osteoporosis** 

**3.1 Pathomechanism** 

**2.3 Pathomechanism** 

## **2. Clinical findings of CRPS**

### **2.1 Overview of CRPS**

CRPS is painful and it can affect one or more extremities (de Mos et al., 2008). It usually occurs following a physical injury, such as, after fracture or surgery. But spontaneous onset without any triggering factor may occur as well (Veldman et al., 1993). According to a case control study (de Mos et al., 2008), fracture was the most common precipitating injury in 49% of the cases. The mixed etiologies of CRPS are evidenced in its heterogeneous constellation of clinical symptoms. In the acute stages, hallmarks include mechanical hyperalgesia, edema, increased sweating, skin temperature and hair growth (Doury, 1988; Janig & Baron, 2003). After some time, CRPS symptoms progress from a warm to a cold stage, with decrease of skin temperature, formation of skin atrophy and bony osteoporotic changes (van der Laan et al., 1998).

### **2.2 Diagnosis**

CRPS diagnosis is based on its clinical presentation, whereby the diagnostic criteria as developed by the International Association for the Study of Pain (IASP) is most widely accepted (Stanton-Hicks et al., 1995). The IASP task force proposed a definition based on four criteria (Harden et al., 2007). (Table 1) In addition, involuntary movements, muscle spasm, paresis, pseudoparalysis, skin, muscle and bone atrophy, hyperhidrosis and changes in hair and nail growth, can also be observed (Perez et al., 2010; Veldman et al., 1993).

#### **General definition of the syndrome:**

CRPS describes an array of painful conditions that are characterized by a continuing (spontaneous and/or evoked) regional pain that is seemingly disproportionate in time or degree to the usual course of any known trauma or other lesion. The pain is regional (not in a specific nerve territory or dermatome) and usually has a distal predominance of abnormal sensory, motor, sudomotor, vasomotor, and/or trophic findings. The syndrome shows variable progression over time

#### **To make the clinical diagnosis, the following criteria must be met:**

	- Sensory: Reports of hyperesthesia and/or allodynia

Vasomotor: Reports of temperature asymmetry and/or skin color changes and/or skin color asymmetry

Sudomotor/Edema: Reports of edema and/or sweating changes and/or sweating asymmetry Motor/Trophic: Reports of decreased range of motion and/or motor dysfunction (weakness, tremor, dystonia) and/or trophic changes (hair, nail, skin)

3. Must display at least one sign at time of evaluation in two or more of the following categories: Sensory: Evidence of hyperalgesia (to pinprick) and/or allodynia (to light touch and/or temperature sensation and/or deep somatic pressure and/or joint movement)

Vasomotor: Evidence of temperature asymmetry (>1°C) and/or skin color changes and/or asymmetry

Sudomotor/Edema: Evidence of edema and/or sweating changes and/or sweating asymmetry Motor/Trophic: Evidence of decreased range of motion and/or motor dysfunction (weakness, tremor, dystonia) and/or trophic changes (hair, nail, skin)

**4.** There is no other diagnosis that better explains the signs and symptoms

For research purposes, as a rule, CRPS is diagnosed when least one of the symptoms in all of the four symptom categories and at least one sign (observed at evaluation) in two or more sign categories is manifested.

Table 1. Proposed clinical diagnostic criteria for CRPS

Plain radiographs can be used to evaluate the demineralization status, but these show positive findings only in the chronic stages. Three-phase bone scintigraphy is a highly specific and sensitive test for CRPS (Demangeat et al., 1998). The classical finding on bone scintigraphy is increased periarticular activity in the affected limb (Todorovic-Tirnamic et al., 1995). Autonomic function can be tested by infrared thermography. Also, skin temperature differences may be helpful for the diagnosis of CRPS; however, these typical temperature side differences are not static descriptors but comprise changes that can be critically dependent on environmental temperature (Wasner et al., 2001).

### **2.3 Pathomechanism**

250 Osteoporosis

CRPS is painful and it can affect one or more extremities (de Mos et al., 2008). It usually occurs following a physical injury, such as, after fracture or surgery. But spontaneous onset without any triggering factor may occur as well (Veldman et al., 1993). According to a case control study (de Mos et al., 2008), fracture was the most common precipitating injury in 49% of the cases. The mixed etiologies of CRPS are evidenced in its heterogeneous constellation of clinical symptoms. In the acute stages, hallmarks include mechanical hyperalgesia, edema, increased sweating, skin temperature and hair growth (Doury, 1988; Janig & Baron, 2003). After some time, CRPS symptoms progress from a warm to a cold stage, with decrease of skin temperature, formation of skin atrophy and bony osteoporotic

CRPS diagnosis is based on its clinical presentation, whereby the diagnostic criteria as developed by the International Association for the Study of Pain (IASP) is most widely accepted (Stanton-Hicks et al., 1995). The IASP task force proposed a definition based on four criteria (Harden et al., 2007). (Table 1) In addition, involuntary movements, muscle spasm, paresis, pseudoparalysis, skin, muscle and bone atrophy, hyperhidrosis and changes in hair and nail growth, can also be observed (Perez et al., 2010; Veldman et al., 1993).

CRPS describes an array of painful conditions that are characterized by a continuing (spontaneous and/or evoked) regional pain that is seemingly disproportionate in time or degree to the usual course of any known trauma or other lesion. The pain is regional (not in a specific nerve territory or dermatome) and usually has a distal predominance of abnormal sensory, motor, sudomotor,

Vasomotor: Reports of temperature asymmetry and/or skin color changes and/or skin color

Vasomotor: Evidence of temperature asymmetry (>1°C) and/or skin color changes and/or

Sudomotor/Edema: Evidence of edema and/or sweating changes and/or sweating asymmetry Motor/Trophic: Evidence of decreased range of motion and/or motor dysfunction (weakness,

Sudomotor/Edema: Reports of edema and/or sweating changes and/or sweating asymmetry Motor/Trophic: Reports of decreased range of motion and/or motor dysfunction (weakness,

3. Must display at least one sign at time of evaluation in two or more of the following categories: Sensory: Evidence of hyperalgesia (to pinprick) and/or allodynia (to light touch and/or

For research purposes, as a rule, CRPS is diagnosed when least one of the symptoms in all of the four symptom categories and at least one sign (observed at evaluation) in two or more sign categories is

temperature sensation and/or deep somatic pressure and/or joint movement)

vasomotor, and/or trophic findings. The syndrome shows variable progression over time

2. Must report at least one symptom in three of the four following categories:

**To make the clinical diagnosis, the following criteria must be met:** 1. Continuing pain, which is disproportionate to any inciting event

tremor, dystonia) and/or trophic changes (hair, nail, skin)

tremor, dystonia) and/or trophic changes (hair, nail, skin) **4.** There is no other diagnosis that better explains the signs and symptoms

Table 1. Proposed clinical diagnostic criteria for CRPS

Sensory: Reports of hyperesthesia and/or allodynia

**2. Clinical findings of CRPS** 

changes (van der Laan et al., 1998).

**General definition of the syndrome:**

asymmetry

asymmetry

manifested.

**2.1 Overview of CRPS** 

**2.2 Diagnosis** 

The complex cascade of CRPS is postulated to initiate after the sensitization of C-nociceptive fibers and release of neuropeptides, which are linked to vasodilatation and hypersensitization of nerve endings (Guo et al., 2004; Kurvers, 1998; Schurmann et al., 1999). Osteoclasts are also activated and this in turn leads to nociceptor stimulation and sensitization (Mach et al., 2002; Sevcik et al., 2004) leading to a vicious cycle.

A medical history of asthma, migraine, osteoporosis, a recent history of menstrual cyclerelated problems or preexisting neuropathies are common pre-existing problems or conditions often concomitantly found in CRPS patients. Therefore finding a common mediator that is both present in these conditions and CRPS could help to reveal the possible triggering factors. The mediators (de Mos et al., 2008; Karacan et al., 2004; Toda et al., 2006) that have been linked among asthma, migraine and CPRS are the neuropeptides calcitoningene related peptide, substance P (de Mos et al., 2008), mast cell products (Bradding et al., 2006) and transcription factors such as nuclear factor kappa B (Barnes, 2006; Reuter et al., 2002). Inflammatory cytokines such as interleukin 1, tumor necrosis factor alpha have also been suggested to be common denominators among CRPS, osteporosis and menstrual cycle related disorders, but their definite roles need to be established through continuous studies (Marie et al., 1993; Zarrabeitia et al., 1991).

### **3. Patchy osteoporosis**

### **3.1 Pathomechanism**

Why does bone loss occur in CRPS? Some have postulated that immobilization plays a role in CRPS. Suyama et al, have (Suyama et al., 2002) observed a reduction in BMD 1 to 7 weeks postsurgery with an increase in the number of osteoclasts at 2, 3, and 5 weeks in their CRPS model. They have suggested that one possible mechanism would be the increase of bone resorption with immobilization. Another possible mechanism suggested by others (Whiteside et al., 2006) would be that bone loss in CRPS models may be due to altered nerve signaling and not attributable to limb disuse or reduced mechanical loading associated with pain. Experimental studies have shown that substance P release is involved in the pathogenesis of bony changes induced by CRPS (Gaus et al., 2003).

The exact pathological mechanism of patchy osteoporosis in CRPS and altered nerve signaling is still poorly understood, some consider to be attributable to a regional sympathetic hyperactivity of sympathetic dysfunction (Goldstein et al., 2000; He et al., 2011; Kurvers et al., 1998; Laroche et al., 1997). Sympathetic deregulation causes vasomotor irregularities, and an imbalance between vasoconstriction and vasodilatation, which in turn influences the blood supply to the bone. Other studies have shown that the immune and skeletal systems are closely related to maintain the homeostasis of the bone but when this

Patchy Osteoporosis in Complex Regional Pain Syndrome 253

vascular abnormalities (Kingery et al., 2003), it proved to be ineffective in preserving bone loss. Its use instead enhanced the widespread osteoporotic effects (Kingery et al., 2003). The dual and dichotomous roles of substance P in maintaining bone integrity in CRPS needs to

Substance P activation also leads to the over-expression of the inflammatory cytokines (Wei et al., 2009). Some of these cytokines play a role in the development of patchy osteoporosis in CRPS. Nerve growth factor is one of the cytokines activated by the substance P, and its activity leads to nociceptive sensitization, enhanced osteopenia with increased cytokine content (Sabsovich et al., 2008). Tumor necrosis factor alpha is another pro-inflammatory cytokine postulated to play a role in the development of CRPS changes after trauma and its expression is increased in CRPS patients (Huygen et al., 2001). Although the increased level of the tumor necrosis factor is an important mediator of regional nociceptive sensitization, it

In order to unravel the mechanisms underlying osteoporosis in CRPS, many animal models have been introduced. There are two broad categories of mechanisms underlying CRPS: (1) peripheral mechanisms: CRPS is primarily an inflammatory disease in the periphery (CRPS I) or a consequence of nerve damage (CRPS II), (2) central mechanisms that involve reorganization of the somatosensory, somatomotor and autonomic systems in the central nervous system triggered by a peripheral input (Drummond et al., 2001; Turner-Stokes, 2002; Wasner et al., 2003). Both the peripheral and central nervous systems play a role in the pathogenesis of CRPS. The peripheral mechanisms includes immune cell mediated inflammatory, autoimmune inflammatory processes, neurogenic inflammation and tissue hypoxia. (Daemen et al., 1998a; Daemen et al., 1998b; Kingery et al., 2003b; Kurvers et al., 1998; Offley et al., 2005; Schurmann et al., 2000). However, the amount of contribution of these two mechanisms and how they interact with each other to manifest in CPRS has not been determined yet. Keeping in mind of these two different mechanisms, and that CRPS can be either type I or II, several animal models that represent these features have been introduced but because of the inherent heterogenic features of CRPS, there is no absolute

Depending on the presence of peripheral nerve injury, three animal models will be discussed. For CRPS type I, the tibia fracture model and chronic ischemic model will be presented (Coderre et al., 2004; Guo et al., 2006; Ludwig et al., 2007). The chronic constriction injury (CCI) model of the sciatic nerve will be presented for CRPS type II (Bennett and Xie, 1988). Choosing the type of experimental model may depend on the objective of the research or researcher's habit. The methodologies of these different animal

Tibia fracture and cast rat model had been introduced for the animal model of CRPS type I, and is popularly used in laboratory studies (Guo et al., 2004; Guo et al., 2006; Sarangi et al., 1993). The method of induction for tibia fracture model is as follows: the hind limb of rat is wrapped in stockinet and the distal tibia is fractured. The hind limb is then wrapped in casting tape with the hip, knee, and ankle in flexed position. The cast extends from the

does not contribute to the enhanced bone loss (Sabsovich et al., 2008).

**4.1 Overview of laboratory research in CRPS** 

model that shows and reproduces all CRPS features.

**4.2 Tibia fracture and cast rat model** 

models are discussed to provide detail reference for the readers.

**4. Current laboratory research in osteoporosis related with CRPS** 

be further elucidated.

interaction is disrupted in CRPS; the balance favors bone loss. This complex cascade is postulated to initiate after sensitization of C-nociceptive fibers and release of neuropeptides, which are linked to vasodilatation, hypersensitization of nerve endings (Guo et al., 2004; Kurvers et al., 1995; Schurmann et al., 1999), and osteoclasts activation, which increase bone resorption, lead to nociceptor stimulation and sensitization (Mach et al., 2002; Sevcik et al., 2004).

#### **3.2 Characteristics**

Bone loss in CRPS occurs regionally with loss of the trabecular bone (Bickerstaff et al., 1991; Doury, 1988) with marked bone demineralization observed at the subchondral regions. Epiphyseal regions are predominantly affected, however no narrowing of joint space or bony sclerosis is observed. Recovery of lost bone mineral content is slow and may persist after several years from the initial diagnosis (Nilsson, 1966) and this persistent regional osteoporosis can predispose to other future fractures after minor injuries (Sarangi et al., 1993). Same as the clinical manifestation, studies that have used rat models of CRPS have shown that bone mineral density significantly decrease from the second week (Suyama et al., 2002) and this loss is known to persist for at least 20 weeks (Kingery et al., 2003).

### **3.3 Radiographic findings**

Bone changes can be observed by typical roentgenography but these changes are known to occur only after several months. However periarticular bone loss can be observed in radiograhs of CRPS limbs even within 3 weeks after injury (Bickerstaff et al., 1993). Bone mineral density, measured by dual energy xray abosorpotometry is reduced in the CRPS limbs in a periarticular distribution (Gue et al., 2004).

#### **3.4 Neuropeptides in patchy osteoporosis**

Substance P (Bianchi et al., 2008), one of the neuropeptides closely linked to the pathogenesis of CRPS, binds to NK1 receptors of postcapillary venules and causes vasodilation, increasing vascular permeability. The increased activity of this neuropeptide, which are elevated in serum samples from CRPS patients (Schinkel et al., 2006), are deemed to be responsible for the subsequent warmth and interstitial edema observed in CRPS through vasodilation and increased protein extravasation.

This substance P is also postulated to play a role in the development of patchy osteoporosis in CRPS. Studies have shown that substance P is known to stimulate osteoclast formation and active bone resorption through NK1-receptor found in the bone cells (Goto et al., 1998; Liu et al., 2007).

The exact mechanism of how substance P induces bone loss needs to be elucidated; substance P not only has osteoclastic effects but is known to have an osteogenic effect on bone marrow cells and to directly stimulate osteoblastic bone formation (Imai & Matsusue, 2002). The mechanism that favors osteoclastic activation, instead of osteoblastic activation, to result in bone loss in CRPS needs further studies. But in line with the current literature that supports abnormal osteoclastic activation through substance P in CRPS, it is reasonable to theorize that an agent that inhibits substance P would help to reduce osteoclast activation and its ensuing bone loss. This topic was evaluated in a study that used a substance P antagonist LY303870 (Kingery et al., 2003) and determined whether it was efficient in controlling osteoporosis. Although this antagonist was effective in the nociceptive and

interaction is disrupted in CRPS; the balance favors bone loss. This complex cascade is postulated to initiate after sensitization of C-nociceptive fibers and release of neuropeptides, which are linked to vasodilatation, hypersensitization of nerve endings (Guo et al., 2004; Kurvers et al., 1995; Schurmann et al., 1999), and osteoclasts activation, which increase bone resorption, lead to nociceptor stimulation and sensitization (Mach et al., 2002; Sevcik et al.,

Bone loss in CRPS occurs regionally with loss of the trabecular bone (Bickerstaff et al., 1991; Doury, 1988) with marked bone demineralization observed at the subchondral regions. Epiphyseal regions are predominantly affected, however no narrowing of joint space or bony sclerosis is observed. Recovery of lost bone mineral content is slow and may persist after several years from the initial diagnosis (Nilsson, 1966) and this persistent regional osteoporosis can predispose to other future fractures after minor injuries (Sarangi et al., 1993). Same as the clinical manifestation, studies that have used rat models of CRPS have shown that bone mineral density significantly decrease from the second week (Suyama et

al., 2002) and this loss is known to persist for at least 20 weeks (Kingery et al., 2003).

Bone changes can be observed by typical roentgenography but these changes are known to occur only after several months. However periarticular bone loss can be observed in radiograhs of CRPS limbs even within 3 weeks after injury (Bickerstaff et al., 1993). Bone mineral density, measured by dual energy xray abosorpotometry is reduced in the CRPS

Substance P (Bianchi et al., 2008), one of the neuropeptides closely linked to the pathogenesis of CRPS, binds to NK1 receptors of postcapillary venules and causes vasodilation, increasing vascular permeability. The increased activity of this neuropeptide, which are elevated in serum samples from CRPS patients (Schinkel et al., 2006), are deemed to be responsible for the subsequent warmth and interstitial edema observed in CRPS

This substance P is also postulated to play a role in the development of patchy osteoporosis in CRPS. Studies have shown that substance P is known to stimulate osteoclast formation and active bone resorption through NK1-receptor found in the bone cells (Goto et al., 1998;

The exact mechanism of how substance P induces bone loss needs to be elucidated; substance P not only has osteoclastic effects but is known to have an osteogenic effect on bone marrow cells and to directly stimulate osteoblastic bone formation (Imai & Matsusue, 2002). The mechanism that favors osteoclastic activation, instead of osteoblastic activation, to result in bone loss in CRPS needs further studies. But in line with the current literature that supports abnormal osteoclastic activation through substance P in CRPS, it is reasonable to theorize that an agent that inhibits substance P would help to reduce osteoclast activation and its ensuing bone loss. This topic was evaluated in a study that used a substance P antagonist LY303870 (Kingery et al., 2003) and determined whether it was efficient in controlling osteoporosis. Although this antagonist was effective in the nociceptive and

2004).

**3.2 Characteristics** 

**3.3 Radiographic findings** 

Liu et al., 2007).

limbs in a periarticular distribution (Gue et al., 2004).

through vasodilation and increased protein extravasation.

**3.4 Neuropeptides in patchy osteoporosis** 

vascular abnormalities (Kingery et al., 2003), it proved to be ineffective in preserving bone loss. Its use instead enhanced the widespread osteoporotic effects (Kingery et al., 2003). The dual and dichotomous roles of substance P in maintaining bone integrity in CRPS needs to be further elucidated.

Substance P activation also leads to the over-expression of the inflammatory cytokines (Wei et al., 2009). Some of these cytokines play a role in the development of patchy osteoporosis in CRPS. Nerve growth factor is one of the cytokines activated by the substance P, and its activity leads to nociceptive sensitization, enhanced osteopenia with increased cytokine content (Sabsovich et al., 2008). Tumor necrosis factor alpha is another pro-inflammatory cytokine postulated to play a role in the development of CRPS changes after trauma and its expression is increased in CRPS patients (Huygen et al., 2001). Although the increased level of the tumor necrosis factor is an important mediator of regional nociceptive sensitization, it does not contribute to the enhanced bone loss (Sabsovich et al., 2008).

### **4. Current laboratory research in osteoporosis related with CRPS**

### **4.1 Overview of laboratory research in CRPS**

In order to unravel the mechanisms underlying osteoporosis in CRPS, many animal models have been introduced. There are two broad categories of mechanisms underlying CRPS: (1) peripheral mechanisms: CRPS is primarily an inflammatory disease in the periphery (CRPS I) or a consequence of nerve damage (CRPS II), (2) central mechanisms that involve reorganization of the somatosensory, somatomotor and autonomic systems in the central nervous system triggered by a peripheral input (Drummond et al., 2001; Turner-Stokes, 2002; Wasner et al., 2003). Both the peripheral and central nervous systems play a role in the pathogenesis of CRPS. The peripheral mechanisms includes immune cell mediated inflammatory, autoimmune inflammatory processes, neurogenic inflammation and tissue hypoxia. (Daemen et al., 1998a; Daemen et al., 1998b; Kingery et al., 2003b; Kurvers et al., 1998; Offley et al., 2005; Schurmann et al., 2000). However, the amount of contribution of these two mechanisms and how they interact with each other to manifest in CPRS has not been determined yet. Keeping in mind of these two different mechanisms, and that CRPS can be either type I or II, several animal models that represent these features have been introduced but because of the inherent heterogenic features of CRPS, there is no absolute model that shows and reproduces all CRPS features.

Depending on the presence of peripheral nerve injury, three animal models will be discussed. For CRPS type I, the tibia fracture model and chronic ischemic model will be presented (Coderre et al., 2004; Guo et al., 2006; Ludwig et al., 2007). The chronic constriction injury (CCI) model of the sciatic nerve will be presented for CRPS type II (Bennett and Xie, 1988). Choosing the type of experimental model may depend on the objective of the research or researcher's habit. The methodologies of these different animal models are discussed to provide detail reference for the readers.

### **4.2 Tibia fracture and cast rat model**

Tibia fracture and cast rat model had been introduced for the animal model of CRPS type I, and is popularly used in laboratory studies (Guo et al., 2004; Guo et al., 2006; Sarangi et al., 1993). The method of induction for tibia fracture model is as follows: the hind limb of rat is wrapped in stockinet and the distal tibia is fractured. The hind limb is then wrapped in casting tape with the hip, knee, and ankle in flexed position. The cast extends from the

Patchy Osteoporosis in Complex Regional Pain Syndrome 255

Pharmacological therapy of CRPS encompasses a wide spectrum of medication; from antiinflammatory drugs, systemic corticosteroid (Kingery, 1997), antidepressants, opioid (Mackey & Feinberg, 2007), to anticonvulsants agents. Because the activation of bony osteoclasts is known to play significant role in CRPS pain generation, it is not surprising that aside from these central pain modulating medications, bone modulating agents are used in CRPS. These agents are known not only to alleviate pain but also to reverse and inhibit CRPS associated osteopenia (Whiteside et al., 2006). The two bone modulating agents in

Calcitonin has been traditionally used in bone pathologic conditions due to its efficacy on microvasculature, bone resorption and analgesic action (Friedman & Raisz, 1965). The use of calcitonin in CRPS has been shown through its possible mechanism in controlling bone pain. The results of calcitonin in clinical practice are still controversial; while some have questioned the efficacy (Kingery, 1997), others support its efficacy in CRPS pain (Perez et al., 2001). A recent review analysis also describes positive results for calcium-regulating drugs, including calcitonin, administered to CRPS patients (Fofouzanfar et al., 2002). Although calcitonin has some efficacy in pain, range of motion, with a rapid onset of action (Gobelet et al., 1992), whether its use has effect on the patchy osteoporosis in CRPS has not been

Bisphosphonates are analogues of inorganic pyrophosphates and are inhibitors of bone resorption. They act on the bone and inhibit the action of osteoclasts, thereby limiting bone resorption. Due to this mechanism, they have been found to be effective in the treatment of osteoporosis and other bone conditions. Bisphosphonates have been used traditionally for pathological bone conditions, such as osteoporosis, Paget's disease, cancer related bone pain, metastatic cancer, tumor related hypercalcemia, myeloma and vertebral fracture (Adami et al., 1997; Brunner et al., 2009; Bonabello et al., 2001; Fleisch, 1997; Fulfaro et al., 1998; Fulfaro et al., 2005). In CRPS, bisphosphonates have shown more promising results than calcitonin and many studies supports itse use in CRPS (Adami et al., 1997; Breuer et al., 2008; Manicourt et al., 2004; Robinson et al., 2004; Varenna et al., 2000), in fact, bisphosphonates are the only pharmacological agents with beneficial analgesic results confirmed through placebo controlled trials (Adami et al., 1997; Manicourt et al., 2004; Varenna et al., 2000). However, there is yet no consensus on the optimum dosage,

The role of bisphosphonate in the regulation of the substance P and hyperalgesia has been shown in an experimental study using ibandronate (Bianchi et al., 2008), a bisphosphonate agent. As stated earlier, substance P sensitizes afferent fibers and increases the sensitivity to nociceptive stimuli. It has been hypothesized that ibandronate prevents proton production by osteoclasts, and reduce the activation of specific ion channels and consequent production of substance P by primary afferents (Bianchi et al., 2008), thereby limiting hyperalgesia and bone loss. Also bony calcium homeostasis can influence the Ca2+ dependent endogenous regulation

**5. Treatment of patchy osteoporosis in CRPS 5.1 Overview of medication for patchy osteoporosis** 

reference are calcitonin and bisphosphonate agents.

validated through animal or clinical studies.

frequency, and duration of treatment in CPRS.

**5.3.1 Mechanism of bisphosphonate through experimental studies** 

**5.2 Calcitonin** 

**5.3 Bisphosphonate** 

metatarsals of the hindpaw up to a spica formed around the abdomen. At 4 weeks the cast is removed. This rat model shows changes in volume, temperature, nociception and osteoporosis of the hind limb.

This tibia fracture and cast model has several benefits. Most of all, this animal model represents the CRPS type 1. This model is theorized to induce post-junctional facilitation of substance P signaling. Because this model reproduces the typical symptoms of CRPS such as mechanical allodynia, paw thickness (edema), vasodilation and bone mineralization, it is commonly used in research studies that focus on the treatment and pathomechanism of CRPS. The exact mechanisms of how the intact peptidergic primary afferent neurons are activated after fracture and casting has not elucidated yet. Although there are many studies that have used this model to investigate the pathomechanism of CRPS type I, there are yet no studies that have exclusively focused on patchy osteoporosis with this model.

#### **4.3 Ischemic – Reperfusion injury model**

Another typical animal model for CRPS type I is the chronic ischemic model (Coderre et al., 2004; Xanthos et al., 2004). The femoral artery is dissected and ligated above the origin of the profunda femoris artery for the 3 hours with a small polyethylene tube. Ligation is performed tightly with the vessel walls pressed together and complete arterial occlusion is ensured under microscope. This method completely interrupts the arterial blood supply to the lower leg and hindpaw. The wound is closed by means of five sutures put on the skin. To prevent thrombosis of the artery, two subcutaneous injections of heparin are given subcutaneously, one at the beginning and one at the end of the period of ischemia. This ischemic injury shows change of skin temperature, spontaneous pain behavior, mechanical and cold allodynia and edema, and are consistent with CRPS type I.

Previous research revealed that CRPS type I may depend on chronic tissue ischemia that is dependent on, or exacerbated by, an indirect sympathetic–afferent coupling with an intervening role of enhanced a-adrenoceptor mediated vasoconstriction. The ischemiareperfusion injury model is another animal model for CRPS type I that is produced based on this mechanism.

#### **4.4 Chronic constriction injury (CCI) model**

The CCI model; first introduced by Bennett and Xie (1998); is a classic model for CRPS and has been commonly used in various studies. In this model the common sciatic nerve is exposed at the level of the middle of the thigh by blunt dissection through the biceps femoris. Proximal to the sciatic's trifurcation, about 7 mm of nerve is freed from adhering tissue and 4 ligatures are loosely tied loosely around it with 1 mm spacing. The length of the ligated nerve is approximately 4-5 mm long.

This model is known to represent CRPS type II. This model shows changes of skin thickness, temperature, mechanical sensitivity and bony changes such as patchy osteoporosis. This model has been the model most frequently used to study the patchy osteoporosis in CRPS. Patchy osteoporosis resembling that of CRPS can also be induced by the sciatic nerve transsection (Kingery et al., 2003a; Kingery et al., 2003b). This model is also used for studies on CRPS type II. However, the CCI model had shown several benefits for weight bearing than the sciatic nerve trans-section model. Many of the laboratory researches on patchy osteoporosis in CRPS are mostly based on the CCI model.

### **5. Treatment of patchy osteoporosis in CRPS**

### **5.1 Overview of medication for patchy osteoporosis**

Pharmacological therapy of CRPS encompasses a wide spectrum of medication; from antiinflammatory drugs, systemic corticosteroid (Kingery, 1997), antidepressants, opioid (Mackey & Feinberg, 2007), to anticonvulsants agents. Because the activation of bony osteoclasts is known to play significant role in CRPS pain generation, it is not surprising that aside from these central pain modulating medications, bone modulating agents are used in CRPS. These agents are known not only to alleviate pain but also to reverse and inhibit CRPS associated osteopenia (Whiteside et al., 2006). The two bone modulating agents in reference are calcitonin and bisphosphonate agents.

#### **5.2 Calcitonin**

254 Osteoporosis

metatarsals of the hindpaw up to a spica formed around the abdomen. At 4 weeks the cast is removed. This rat model shows changes in volume, temperature, nociception and

This tibia fracture and cast model has several benefits. Most of all, this animal model represents the CRPS type 1. This model is theorized to induce post-junctional facilitation of substance P signaling. Because this model reproduces the typical symptoms of CRPS such as mechanical allodynia, paw thickness (edema), vasodilation and bone mineralization, it is commonly used in research studies that focus on the treatment and pathomechanism of CRPS. The exact mechanisms of how the intact peptidergic primary afferent neurons are activated after fracture and casting has not elucidated yet. Although there are many studies that have used this model to investigate the pathomechanism of CRPS type I, there are yet

Another typical animal model for CRPS type I is the chronic ischemic model (Coderre et al., 2004; Xanthos et al., 2004). The femoral artery is dissected and ligated above the origin of the profunda femoris artery for the 3 hours with a small polyethylene tube. Ligation is performed tightly with the vessel walls pressed together and complete arterial occlusion is ensured under microscope. This method completely interrupts the arterial blood supply to the lower leg and hindpaw. The wound is closed by means of five sutures put on the skin. To prevent thrombosis of the artery, two subcutaneous injections of heparin are given subcutaneously, one at the beginning and one at the end of the period of ischemia. This ischemic injury shows change of skin temperature, spontaneous pain behavior, mechanical

Previous research revealed that CRPS type I may depend on chronic tissue ischemia that is dependent on, or exacerbated by, an indirect sympathetic–afferent coupling with an intervening role of enhanced a-adrenoceptor mediated vasoconstriction. The ischemiareperfusion injury model is another animal model for CRPS type I that is produced based on

The CCI model; first introduced by Bennett and Xie (1998); is a classic model for CRPS and has been commonly used in various studies. In this model the common sciatic nerve is exposed at the level of the middle of the thigh by blunt dissection through the biceps femoris. Proximal to the sciatic's trifurcation, about 7 mm of nerve is freed from adhering tissue and 4 ligatures are loosely tied loosely around it with 1 mm spacing. The length of the

This model is known to represent CRPS type II. This model shows changes of skin thickness, temperature, mechanical sensitivity and bony changes such as patchy osteoporosis. This model has been the model most frequently used to study the patchy osteoporosis in CRPS. Patchy osteoporosis resembling that of CRPS can also be induced by the sciatic nerve transsection (Kingery et al., 2003a; Kingery et al., 2003b). This model is also used for studies on CRPS type II. However, the CCI model had shown several benefits for weight bearing than the sciatic nerve trans-section model. Many of the laboratory researches on patchy

no studies that have exclusively focused on patchy osteoporosis with this model.

and cold allodynia and edema, and are consistent with CRPS type I.

osteoporosis of the hind limb.

this mechanism.

**4.3 Ischemic – Reperfusion injury model** 

**4.4 Chronic constriction injury (CCI) model** 

ligated nerve is approximately 4-5 mm long.

osteoporosis in CRPS are mostly based on the CCI model.

Calcitonin has been traditionally used in bone pathologic conditions due to its efficacy on microvasculature, bone resorption and analgesic action (Friedman & Raisz, 1965). The use of calcitonin in CRPS has been shown through its possible mechanism in controlling bone pain. The results of calcitonin in clinical practice are still controversial; while some have questioned the efficacy (Kingery, 1997), others support its efficacy in CRPS pain (Perez et al., 2001). A recent review analysis also describes positive results for calcium-regulating drugs, including calcitonin, administered to CRPS patients (Fofouzanfar et al., 2002). Although calcitonin has some efficacy in pain, range of motion, with a rapid onset of action (Gobelet et al., 1992), whether its use has effect on the patchy osteoporosis in CRPS has not been validated through animal or clinical studies.

#### **5.3 Bisphosphonate**

#### **5.3.1 Mechanism of bisphosphonate through experimental studies**

Bisphosphonates are analogues of inorganic pyrophosphates and are inhibitors of bone resorption. They act on the bone and inhibit the action of osteoclasts, thereby limiting bone resorption. Due to this mechanism, they have been found to be effective in the treatment of osteoporosis and other bone conditions. Bisphosphonates have been used traditionally for pathological bone conditions, such as osteoporosis, Paget's disease, cancer related bone pain, metastatic cancer, tumor related hypercalcemia, myeloma and vertebral fracture (Adami et al., 1997; Brunner et al., 2009; Bonabello et al., 2001; Fleisch, 1997; Fulfaro et al., 1998; Fulfaro et al., 2005). In CRPS, bisphosphonates have shown more promising results than calcitonin and many studies supports itse use in CRPS (Adami et al., 1997; Breuer et al., 2008; Manicourt et al., 2004; Robinson et al., 2004; Varenna et al., 2000), in fact, bisphosphonates are the only pharmacological agents with beneficial analgesic results confirmed through placebo controlled trials (Adami et al., 1997; Manicourt et al., 2004; Varenna et al., 2000). However, there is yet no consensus on the optimum dosage, frequency, and duration of treatment in CPRS.

The role of bisphosphonate in the regulation of the substance P and hyperalgesia has been shown in an experimental study using ibandronate (Bianchi et al., 2008), a bisphosphonate agent. As stated earlier, substance P sensitizes afferent fibers and increases the sensitivity to nociceptive stimuli. It has been hypothesized that ibandronate prevents proton production by osteoclasts, and reduce the activation of specific ion channels and consequent production of substance P by primary afferents (Bianchi et al., 2008), thereby limiting hyperalgesia and bone loss. Also bony calcium homeostasis can influence the Ca2+ dependent endogenous regulation

Patchy Osteoporosis in Complex Regional Pain Syndrome 257

varying from 30mg/day to 1mg/Kg/day, provided for three consecutive days. However no dose correlation was observed in these clinical trials (Maillefert et al., 1995). In contrast, some animal studies have shown a dose dependent antinociceptive effects (Bonabello et al., 2001)with pamidronate and clodronate. Etidronate and alendronate have not shown this dose dependent response and their analgesic effects were observed only with the highest dose. Similar to these experiments, in their study with CCI models, Im et al. has shown that different dosage and time of administration of oral alendronate leads to different results in bone mineral density of the tibia and tibia bone strength (Im et al., 2010). The high dosage group received 1mg/kg/day while the low dosage group received 0.1mg/kg/day. To determine whether the time of administration lead to significant differences, the high and low dosage groups were further divided into the early and late administered group. The early group received alendronate treatment immediately after CCI induction, while the late group received alendronate at the 14th day. Both groups received alendronate treatment until the 6th week of CCI induction. The results showed that different dosages and time of administration leads to different efficacies across different CRPS signs. While the hind paw thickness and temperature were significantly reduced only with high dosage administered immediately after CCI induction (Fig. 1, Fig. 2), bone strength and bone mineral density was significantly increased in the high dosage group, with both in the early and late admistered group (Fig. 3, Fig. 4). Bone loss in CRPS becomes manifest in the chronic stages and is known to progress over several months. Because bone loss predominates the later course of CRPS, the authors suggested that the high dosage alendronate, whether admnistred in the

early or late course of CRPS, can show significant efficacy in bone metabolism.

*P*<0.001 as compared with NT group, †*P*<0.001 as compared with SC group.

Abbreviations: CCI, chronic constriction injury; SC, sham control; NT, no treatment; LE, low dosage early treatment; HE, high dosage early treatment; LL, low dosage late treatment; HL, high dosage late treatment Fig. 1. Efficacy of oral alendronate in different dosage and time of administration in dorsalventral thicknesses of the affected hind-paw from Sprague-Dawley rats. (Adapted from Im, S., Lim, S.H., Lee, J.I., Ko, Y.J., Park, J.H., Hong, B.Y. & Park, G.Y. Effective dosage and administration schedule of oral alendronate for non-nociceptive symptoms in rats with chronic constriction injury. Journal of Korean Medical Science 2010; 25(6): 938-944)

\*

of pain sensitivity (Bonabello et al., 2001). Bisphosphonates can effect bone tissue by alternation of the calcium/phosphate product. It is postulated that it is through these mechanisms that bisphosphonate administration inhibits the release of neuropeptides that are responsible for the pain and other vasomotor changes in CRPS. Also, it is postulated that it is through these same mechanisms that bisphosphonate agents are useuful in limiting bone loss.

In fact, animal studies have shown bisphosphonates are effective in preserving CRPS associated bone loss. Chronic administration of zoledronate acid can lead to increased BMD in CCI animal models (Whiteside et al., 2006). The efficacy of alendronate in limiting bone loss in CCI rat model has been shown in a recent study (Im et al., 2010). In both the acute and chronic stages after CCI induction, alendronate treatment preserved bone mass with sustained efficacy in bone preservation, which was demonstrated through in vitro tibia BMD and tibia strength results.

#### **5.3.2 Clinical studies of bisphosphonate**

The role of bisphosphonates in CRPS is well supported by many clinical studies but most were focused on their efficacies in pain. There are already many reports that have advocated the use of bisphosphate agents for CRPS related hyperalgesia and pain (Adami et al., 1997; Breuer et al., 2008; Mackey & Feinberg, 2007; Manicourt et al., 2004; Robinson et al., 2004; Varenna et al., 2000). Results from clinical studies have postulated that alendroate reduces local bone resorption and is effective in CRPS pain by its nociceptive effects in bone. (Adami et al., 1997; Manicourt et al., 2004). For example, Varenna et al. have shown in their randomized, double blind placebo controlled study that a 10 day intravenous clondronate course is effective in the treatment of CRPS (Varenna et al., 2000). A recent clinical study of ibandronate, a potent bisphosphonate agent, has shown that its analgesic effects (Bianchi et al., 2008). However, most studies focused on their analgesic effects for bone pain rather than on their bone preserving effects.

Bone loss in CRPS predominate the chronic stages of CRPS and is accompanied by trophic changes. This patchy bone loss is difficult to reverse and as stated earlier, can lead to fractures even from trivial stress. Therefore, alongside with the management of pain, management of CRPS associated patchy osteoporosis is important to prevent such detrimental consequences.

The efficacy of bisphosphonate agents in patchy osteoporosis have been shown in some studies. A theraupetic role of bisphosphonates on clinical and densiometric recovery was shown in transient hip osteoporosis; a condition considered by many to be a prestage of CRPS (Mailis et al., 1992) with similar features commonly observed in CRPS. Administration of bisphosphonate in transient hip osteoporosis led to the recovery of bone densiometry along with complete pain resolution (Varenna et al., 1996). Similary, the efficacy of bisphosphonate therapy in the recovery of bone mineral content was also shown in CRPS (Adami et al., 1997). Adami et al. used intravenous alendronate and evaluated their pain, tenderness, swelling and bone mineral content of the affected arm. Although a change of bone mineral content was not observed in the unaffected side, the affected side bone mineral content rose significantly in comparison to baseline values. These results show that bisphosphonates are helpful in limiting CRPS associated pathcy osteoporosis.

#### **5.4 Dosage and administration of bisphosphonate in patchy osteoporosis**

With bisphosphonates as the agent with much clinical and experimental evidence to support its use in CRPS, the best dosage and timing of administration is an issue that has gained much focus. A study of dosage differentiation was previoulsy carried out with doses of pamidronate

of pain sensitivity (Bonabello et al., 2001). Bisphosphonates can effect bone tissue by alternation of the calcium/phosphate product. It is postulated that it is through these mechanisms that bisphosphonate administration inhibits the release of neuropeptides that are responsible for the pain and other vasomotor changes in CRPS. Also, it is postulated that it is through these same mechanisms that bisphosphonate agents are useuful in limiting bone loss. In fact, animal studies have shown bisphosphonates are effective in preserving CRPS associated bone loss. Chronic administration of zoledronate acid can lead to increased BMD in CCI animal models (Whiteside et al., 2006). The efficacy of alendronate in limiting bone loss in CCI rat model has been shown in a recent study (Im et al., 2010). In both the acute and chronic stages after CCI induction, alendronate treatment preserved bone mass with sustained efficacy in bone preservation, which was demonstrated through in vitro tibia

The role of bisphosphonates in CRPS is well supported by many clinical studies but most were focused on their efficacies in pain. There are already many reports that have advocated the use of bisphosphate agents for CRPS related hyperalgesia and pain (Adami et al., 1997; Breuer et al., 2008; Mackey & Feinberg, 2007; Manicourt et al., 2004; Robinson et al., 2004; Varenna et al., 2000). Results from clinical studies have postulated that alendroate reduces local bone resorption and is effective in CRPS pain by its nociceptive effects in bone. (Adami et al., 1997; Manicourt et al., 2004). For example, Varenna et al. have shown in their randomized, double blind placebo controlled study that a 10 day intravenous clondronate course is effective in the treatment of CRPS (Varenna et al., 2000). A recent clinical study of ibandronate, a potent bisphosphonate agent, has shown that its analgesic effects (Bianchi et al., 2008). However, most studies focused on their analgesic effects for bone pain rather than

Bone loss in CRPS predominate the chronic stages of CRPS and is accompanied by trophic changes. This patchy bone loss is difficult to reverse and as stated earlier, can lead to fractures even from trivial stress. Therefore, alongside with the management of pain, management of CRPS associated patchy osteoporosis is important to prevent such detrimental consequences. The efficacy of bisphosphonate agents in patchy osteoporosis have been shown in some studies. A theraupetic role of bisphosphonates on clinical and densiometric recovery was shown in transient hip osteoporosis; a condition considered by many to be a prestage of CRPS (Mailis et al., 1992) with similar features commonly observed in CRPS. Administration of bisphosphonate in transient hip osteoporosis led to the recovery of bone densiometry along with complete pain resolution (Varenna et al., 1996). Similary, the efficacy of bisphosphonate therapy in the recovery of bone mineral content was also shown in CRPS (Adami et al., 1997). Adami et al. used intravenous alendronate and evaluated their pain, tenderness, swelling and bone mineral content of the affected arm. Although a change of bone mineral content was not observed in the unaffected side, the affected side bone mineral content rose significantly in comparison to baseline values. These results show that

bisphosphonates are helpful in limiting CRPS associated pathcy osteoporosis.

**5.4 Dosage and administration of bisphosphonate in patchy osteoporosis** 

With bisphosphonates as the agent with much clinical and experimental evidence to support its use in CRPS, the best dosage and timing of administration is an issue that has gained much focus. A study of dosage differentiation was previoulsy carried out with doses of pamidronate

BMD and tibia strength results.

on their bone preserving effects.

**5.3.2 Clinical studies of bisphosphonate** 

varying from 30mg/day to 1mg/Kg/day, provided for three consecutive days. However no dose correlation was observed in these clinical trials (Maillefert et al., 1995). In contrast, some animal studies have shown a dose dependent antinociceptive effects (Bonabello et al., 2001)with pamidronate and clodronate. Etidronate and alendronate have not shown this dose dependent response and their analgesic effects were observed only with the highest dose.

Similar to these experiments, in their study with CCI models, Im et al. has shown that different dosage and time of administration of oral alendronate leads to different results in bone mineral density of the tibia and tibia bone strength (Im et al., 2010). The high dosage group received 1mg/kg/day while the low dosage group received 0.1mg/kg/day. To determine whether the time of administration lead to significant differences, the high and low dosage groups were further divided into the early and late administered group. The early group received alendronate treatment immediately after CCI induction, while the late group received alendronate at the 14th day. Both groups received alendronate treatment until the 6th week of CCI induction. The results showed that different dosages and time of administration leads to different efficacies across different CRPS signs. While the hind paw thickness and temperature were significantly reduced only with high dosage administered immediately after CCI induction (Fig. 1, Fig. 2), bone strength and bone mineral density was significantly increased in the high dosage group, with both in the early and late admistered group (Fig. 3, Fig. 4). Bone loss in CRPS becomes manifest in the chronic stages and is known to progress over several months. Because bone loss predominates the later course of CRPS, the authors suggested that the high dosage alendronate, whether admnistred in the early or late course of CRPS, can show significant efficacy in bone metabolism.

\* *P*<0.001 as compared with NT group, †*P*<0.001 as compared with SC group. Abbreviations: CCI, chronic constriction injury; SC, sham control; NT, no treatment; LE, low dosage early treatment; HE, high dosage early treatment; LL, low dosage late treatment; HL, high dosage late treatment

Fig. 1. Efficacy of oral alendronate in different dosage and time of administration in dorsalventral thicknesses of the affected hind-paw from Sprague-Dawley rats. (Adapted from Im, S., Lim, S.H., Lee, J.I., Ko, Y.J., Park, J.H., Hong, B.Y. & Park, G.Y. Effective dosage and administration schedule of oral alendronate for non-nociceptive symptoms in rats with chronic constriction injury. Journal of Korean Medical Science 2010; 25(6): 938-944)

\*

treatment

25(6): 938-944)

*P*<0.001 as compared with NT group †*P*<0.001 as compared with SC group.

problems to directly administer to humans.

Patchy Osteoporosis in Complex Regional Pain Syndrome 259

Abbreviations: CCI, chronic constriction injury; SC, sham control; NT, no treatment; LE, low dosage early treatment; HE, high dosage early treatment; LL, low dosage late treatment; HL, high dosage late

Fig. 4. Efficacy of oral alendronate in different dosage and time of administration in bone strength of the right tibia from Sprague-Dawley rats, obtained after the rats were sacrificed. (Adapted from Im, S., Lim, S.H., Lee, J.I., Ko, Y.J., Park, J.H., Hong, B.Y. & Park, G.Y. Effective dosage and administration schedule of oral alendronate for non-nociceptive symptoms in rats with chronic constriction injury. Journal of Korean Medical Science 2010;

Despite these results, studies that evaluate on the appropriate human dosage of bisphosphonates to alleviate CRPS associated bone loss are warranted in future studies. Although previous studies have shown variable efficacy of bisphosphonate agents with different dosages and time of administration for the different signs of CRPS, the dosage administered in the high dosage group was approximately 5–6 times higher than standard clinical dosages, thus, the high dosage used in experimental studies poses potential

Responses to bisphosphonates can vary depending on which agent is used and also on when and how these agents are administered. More experimental studies that asses the efficacy of different bisphosphonate dosages and time of administration in pain and temperature are needed to translate these findings to clinical usage. Also, it would be of interest to determine if prophylactic high dosage bisphosphonate administration in CRPS are helpful in limiting the bone loss that continues until the later stages of CRPS. Finally long term follow-up clinical data are needed to evaluate the efficacy of bisphosphonates in limiting bone loss through objective evidence from bone densiometry and bone markers.

\* *P*<0.001 as compared with NT group, †*P*<0.001 as compared with SC group. Abbreviations: CCI, chronic constriction injury; SC, sham control; NT, no treatment; LE, low dosage early treatment; HE, high dosage early treatment; LL, low dosage late treatment; HL, high dosage late treatment

Fig. 2. Efficacy of oral alendronate in different dosage and time of administration in skin temperature of the affected hind-paw from Sprague-Dawley rats. (Adapted from Im, S., Lim, S.H., Lee, J.I., Ko, Y.J., Park, J.H., Hong, B.Y. & Park, G.Y. Effective dosage and administration schedule of oral alendronate for non-nociceptive symptoms in rats with chronic constriction injury. Journal of Korean Medical Science 2010; 25(6): 938-944)

\* *P*<0.001 as compared with NT group, †*P*<0.001 as compared with SC group. Abbreviations: CCI, chronic constriction injury; SC, sham control; NT, no treatment; LE, low dosage early treatment; HE, high dosage early treatment; LL, low dosage late treatment; HL, high dosage late treatment

Fig. 3. Efficacy of oral alendronate in different dosage and time of administration in BMD of the affected tibia from Sprague-Dawley rats. (Adapted from Im, S., Lim, S.H., Lee, J.I., Ko, Y.J., Park, J.H., Hong, B.Y. & Park, G.Y. Effective dosage and administration schedule of oral alendronate for non-nociceptive symptoms in rats with chronic constriction injury. Journal of Korean Medical Science 2010; 25(6): 938-944)

Abbreviations: CCI, chronic constriction injury; SC, sham control; NT, no treatment; LE, low dosage early treatment; HE, high dosage early treatment; LL, low dosage late treatment; HL, high dosage late treatment Fig. 2. Efficacy of oral alendronate in different dosage and time of administration in skin temperature of the affected hind-paw from Sprague-Dawley rats. (Adapted from Im, S., Lim, S.H., Lee, J.I., Ko, Y.J., Park, J.H., Hong, B.Y. & Park, G.Y. Effective dosage and administration schedule of oral alendronate for non-nociceptive symptoms in rats with chronic constriction injury. Journal of Korean Medical Science 2010; 25(6): 938-944)

*P*<0.001 as compared with NT group, †*P*<0.001 as compared with SC group.

*P*<0.001 as compared with NT group, †*P*<0.001 as compared with SC group.

of Korean Medical Science 2010; 25(6): 938-944)

Abbreviations: CCI, chronic constriction injury; SC, sham control; NT, no treatment; LE, low dosage early treatment; HE, high dosage early treatment; LL, low dosage late treatment; HL, high dosage late treatment Fig. 3. Efficacy of oral alendronate in different dosage and time of administration in BMD of the affected tibia from Sprague-Dawley rats. (Adapted from Im, S., Lim, S.H., Lee, J.I., Ko, Y.J., Park, J.H., Hong, B.Y. & Park, G.Y. Effective dosage and administration schedule of oral alendronate for non-nociceptive symptoms in rats with chronic constriction injury. Journal

\*

\*

```
*
P<0.001 as compared with NT group
```
†*P*<0.001 as compared with SC group.

Abbreviations: CCI, chronic constriction injury; SC, sham control; NT, no treatment; LE, low dosage early treatment; HE, high dosage early treatment; LL, low dosage late treatment; HL, high dosage late treatment

Fig. 4. Efficacy of oral alendronate in different dosage and time of administration in bone strength of the right tibia from Sprague-Dawley rats, obtained after the rats were sacrificed. (Adapted from Im, S., Lim, S.H., Lee, J.I., Ko, Y.J., Park, J.H., Hong, B.Y. & Park, G.Y. Effective dosage and administration schedule of oral alendronate for non-nociceptive symptoms in rats with chronic constriction injury. Journal of Korean Medical Science 2010; 25(6): 938-944)

Despite these results, studies that evaluate on the appropriate human dosage of bisphosphonates to alleviate CRPS associated bone loss are warranted in future studies. Although previous studies have shown variable efficacy of bisphosphonate agents with different dosages and time of administration for the different signs of CRPS, the dosage administered in the high dosage group was approximately 5–6 times higher than standard clinical dosages, thus, the high dosage used in experimental studies poses potential problems to directly administer to humans.

Responses to bisphosphonates can vary depending on which agent is used and also on when and how these agents are administered. More experimental studies that asses the efficacy of different bisphosphonate dosages and time of administration in pain and temperature are needed to translate these findings to clinical usage. Also, it would be of interest to determine if prophylactic high dosage bisphosphonate administration in CRPS are helpful in limiting the bone loss that continues until the later stages of CRPS. Finally long term follow-up clinical data are needed to evaluate the efficacy of bisphosphonates in limiting bone loss through objective evidence from bone densiometry and bone markers.

Patchy Osteoporosis in Complex Regional Pain Syndrome 261

de Mos, M., Huygen, F.J., Dieleman, J.P., Koopman, J.S., Stricker, B.H. & Sturkenboom, M.C.

Demangeat, J.L., Constantinesco, A., Brunot, B., Foucher, G. & Farcot, J.M. (1988). Three-

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Forouzanfar, T., Koke, A.J., van Kleef, M., Weber, W.E. (2002). Treatment of complex

Friedman, J. & Raisz, L.G. (1965). Thyrocalcitonin: inhibitor of bone resorption in tissue

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#### **5.5 Neuropeptide modulators**

Because the pathogenesis of patchy osteoporosis is related to neurogenic inflammation and the production of substance P, many studies that targeted these neuropeptides have been published. As stated earlier, substance P activation also leads to the over-expression of the inflammatory cytokines (Wei et al., 2009), for example, nerve growth factor is one of the cytokines that leads to osteopenia. The use of a nerve growth factor antibody not only reduced nociception but to a modest degree, maintained further bone loss in the distal trabecular bone (Sabsovich et al., 2008). Pentoxifylline, a cytokine inhibitor, was used to evalute its effect in trabecular bone loss (Wei et al., 2009). Pentoxifylline had significant effects in the fracture induced up-regulation of inflammatory cytokines and reversed nociceptive sensitization and vascular abnormalities. However, it had insignificant effects on bone architecture as measured by microcomputed tomography in a tibia fracture model of CRPS. Although pentoxifylline treatment can induce osteoblastic differentiation, it had no significant effect on trabecular bone loss (Sabsovich et al., 2008).

Although the exact mechanism and relationship of osteoclastic activation, with subsequent activation of substance P and inflammatory cytokines needs further evaluation, most experimental studies have shown that only the agents that directly inhibit bone resorption through osteoclast inhibition have efficacy in preserving CRPS associated bone loss. To date, bisphosphonate agents are ideal for controlling the pain and for limiting bone loss in CRPS.

#### **6. Conclusion**

The main focus in CRPS both in clinical and experimental settings has been focused on hyperalgesia and vasomotor symptoms. The symptoms are manifest from the early stages of disease, are profound and affects patients' quality of life. In contrast, patchy osteoporosis in CRPS are not apparent until the later stages, and bone loss rarely causes any symptoms until a minor trauma leads to unexpected fractures. Despite the different clincal manifestations of hyperalgesia and osteoporosis, and the tendency to divide CRPS into different stages, all the signs of CRPS are in continuum and dependent on one another; one sign of CRPS does not stand alone and one can not exist without the other, therefore simply aiming the treatment focused on one aspect can not limit the heterogenic features of CRPS. Vasomotor and sudomotor signs and patchy osteoporosis in CRPS are triggered through similar pathways and neuropeptides are the mediators that link them together. To date, bisphosphonates in high dosages have been used with the aim to control these neuropeptides through osteoclastic modulation. Future studies and clinical trials are warranted for the treatment of CRPS patchy osteoporosis.

#### **7. References**


Because the pathogenesis of patchy osteoporosis is related to neurogenic inflammation and the production of substance P, many studies that targeted these neuropeptides have been published. As stated earlier, substance P activation also leads to the over-expression of the inflammatory cytokines (Wei et al., 2009), for example, nerve growth factor is one of the cytokines that leads to osteopenia. The use of a nerve growth factor antibody not only reduced nociception but to a modest degree, maintained further bone loss in the distal trabecular bone (Sabsovich et al., 2008). Pentoxifylline, a cytokine inhibitor, was used to evalute its effect in trabecular bone loss (Wei et al., 2009). Pentoxifylline had significant effects in the fracture induced up-regulation of inflammatory cytokines and reversed nociceptive sensitization and vascular abnormalities. However, it had insignificant effects on bone architecture as measured by microcomputed tomography in a tibia fracture model of CRPS. Although pentoxifylline treatment can induce osteoblastic differentiation, it had no

Although the exact mechanism and relationship of osteoclastic activation, with subsequent activation of substance P and inflammatory cytokines needs further evaluation, most experimental studies have shown that only the agents that directly inhibit bone resorption through osteoclast inhibition have efficacy in preserving CRPS associated bone loss. To date, bisphosphonate agents are ideal for controlling the pain and for limiting bone loss in CRPS.

The main focus in CRPS both in clinical and experimental settings has been focused on hyperalgesia and vasomotor symptoms. The symptoms are manifest from the early stages of disease, are profound and affects patients' quality of life. In contrast, patchy osteoporosis in CRPS are not apparent until the later stages, and bone loss rarely causes any symptoms until a minor trauma leads to unexpected fractures. Despite the different clincal manifestations of hyperalgesia and osteoporosis, and the tendency to divide CRPS into different stages, all the signs of CRPS are in continuum and dependent on one another; one sign of CRPS does not stand alone and one can not exist without the other, therefore simply aiming the treatment focused on one aspect can not limit the heterogenic features of CRPS. Vasomotor and sudomotor signs and patchy osteoporosis in CRPS are triggered through similar pathways and neuropeptides are the mediators that link them together. To date, bisphosphonates in high dosages have been used with the aim to control these neuropeptides through osteoclastic modulation. Future studies and clinical trials are warranted for the treatment of

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significant effect on trabecular bone loss (Sabsovich et al., 2008).

**5.5 Neuropeptide modulators** 

**6. Conclusion** 

CRPS patchy osteoporosis.

**7. References** 


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**14** 

*USA* 

**Osteoporosis in Microgravity Environments** 

*The Methodist Hospital, Orthopaedic Spine Advanced Technology Laboratory* 

All life on earth has evolved in, and via the adaption to, the presence of gravity. This includes humans who branched off from a distant ancestor about five to seven million years ago. On April 12, 1961, one such human---Yuri Gagarin of the Soviet Union---took off in Vostok 3KA for the first trip into outer space. Since then, numerous trips to the moon, the Skylab, and within the Space Shuttle have followed. With the recent completion of the International Space Station, the current focus is set on very long duration crewed missions to the station, the

As more and more humans head to space for longer and longer periods of time---out of desire or necessity---significant challenges will be faced. The *technological* challenges will undoubtedly be met. The past fifty years have taught us that given adequate time and financial resources nearly any technological hurdle can be jumped. The *biological* challenges are far greater. As noted, all human life on earth has evolved via adaption to gravity and long-term exposure to microgravity takes its toll; especially on the musculoskeletal,

In this chapter, we will review the known effects of long-term microgravity on the skeletal system, examine what is as-yet unknown, and explore possible interventions that might be

Osteoporosis occurring on earth in the presence of normal gravity is most often associated with aging and most significantly impacted by peak bone mass and the rate of bone loss thereafter. Peak bone mass is generally achieved while humans are in their early thirties and subsequent bone loss is impacted not only by aging and menopause (women), but by hereditary predispositions, exogenous factors (such as alcohol, smoking, inactivity, malnutrition, prescription medications, etc.), and disease states (such as endocrine disorders, renal disorders, rheumatologic disorders, etc.). Each of these causes results in a final common pathway leading to osteoporosis---an imbalance between bone formation and bone resorption. Fractures, primarily of the proximal femur ('hip'), vertebral bodies, and distal radius ('wrist') are significant risks and, as other chapters in this text have outlined,

establishment of a potential lunar outpost, and possible exploration of Mars.

cardiovascular, sensory-motor, and immune systems.

**2. The impact of microgravity at the cellular level** 

represent important causes of morbidity and potential mortality.

used to address these effects.

**2.1 Osteoporosis on earth** 

**1. Introduction** 

Bradley K. Weiner, Scott E. Parazynski and Ennio Tasciotti *Weill Cornell Medical College, Orthopaedic Surgery, Spinal Surgery,* 

*The Methodist Hospital Research Institute, Houston, Texas* 


## **Osteoporosis in Microgravity Environments**

Bradley K. Weiner, Scott E. Parazynski and Ennio Tasciotti

*Weill Cornell Medical College, Orthopaedic Surgery, Spinal Surgery, The Methodist Hospital, Orthopaedic Spine Advanced Technology Laboratory The Methodist Hospital Research Institute, Houston, Texas USA* 

### **1. Introduction**

264 Osteoporosis

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Clark, D.J. (2009). Pentoxifylline attenuates nociceptive sensitization and cytokine expression in a tibia fracture rat model of complex regional pain syndrome. European

induced osteopenia in rats is not due to a reduction in weight born on the affected

All life on earth has evolved in, and via the adaption to, the presence of gravity. This includes humans who branched off from a distant ancestor about five to seven million years ago. On April 12, 1961, one such human---Yuri Gagarin of the Soviet Union---took off in Vostok 3KA for the first trip into outer space. Since then, numerous trips to the moon, the Skylab, and within the Space Shuttle have followed. With the recent completion of the International Space Station, the current focus is set on very long duration crewed missions to the station, the establishment of a potential lunar outpost, and possible exploration of Mars.

As more and more humans head to space for longer and longer periods of time---out of desire or necessity---significant challenges will be faced. The *technological* challenges will undoubtedly be met. The past fifty years have taught us that given adequate time and financial resources nearly any technological hurdle can be jumped. The *biological* challenges are far greater. As noted, all human life on earth has evolved via adaption to gravity and long-term exposure to microgravity takes its toll; especially on the musculoskeletal, cardiovascular, sensory-motor, and immune systems.

In this chapter, we will review the known effects of long-term microgravity on the skeletal system, examine what is as-yet unknown, and explore possible interventions that might be used to address these effects.

### **2. The impact of microgravity at the cellular level**

### **2.1 Osteoporosis on earth**

Osteoporosis occurring on earth in the presence of normal gravity is most often associated with aging and most significantly impacted by peak bone mass and the rate of bone loss thereafter. Peak bone mass is generally achieved while humans are in their early thirties and subsequent bone loss is impacted not only by aging and menopause (women), but by hereditary predispositions, exogenous factors (such as alcohol, smoking, inactivity, malnutrition, prescription medications, etc.), and disease states (such as endocrine disorders, renal disorders, rheumatologic disorders, etc.). Each of these causes results in a final common pathway leading to osteoporosis---an imbalance between bone formation and bone resorption. Fractures, primarily of the proximal femur ('hip'), vertebral bodies, and distal radius ('wrist') are significant risks and, as other chapters in this text have outlined, represent important causes of morbidity and potential mortality.

Osteoporosis in Microgravity Environments 267

Systemically, microgravity induces osteoporosis via the above noted unique cellular changes *coupled* with an environment of nearly non-existent mechanical stresses where normal weight-bearing and the normal response of bone to proliferate accordingly (Wolff's Law) is altered. And this alteration differs than, say, that seen with immobilization. While patients placed in body casts and on bed rest (fully non-weightbearing) will suffer from osteoporortic changes, the amount of calcified bony tissue lost over three months is generally about 3%, tends to then level off at about three months (no further loss), and tends to be reversed with resumption of weight-bearing. In microgravity, the loss occurs at four times the rate, does not appear to level off, and appears to be much less reversible. Thus, the one-year trip to Mars is estimated to potentially result in a (devastating) greater than 25% reduction of bone mass. And this is in astronauts; predominantly male, at an age where their bone mass is at peak levels, exposed to no exogenous factors (smoking, excessive alcohol,

Simply, the combination of altered cellular form and function coupled with differences in bony response to microgravity systemically means that this form of osteoporosis bears relatively little relation to that seen on earth and that astronauts experience early, aggressive, continual bone loss. Predictably, systemic markers of bone resorption are greatly increased, while markers of bone formation are decreased[11] to levels rarely seen in onearth conditions. And, importantly, it is unclear whether these changes are fully reversible

Since the earliest days of human spaceflight, physiologists and NASA flight surgeons recognized the importance of exercise to maintain musculoskeletal and cardiovascular health. Owing to prolonged exposure to microgravity, Astronaut crews returning from America's first space station, Skylab, were too weak to stand upon return to earth. Exercise equipment thus became a requirement for all long duration space missions. A series of devices, including treadmills, stationary bicycles, rowing ergometers, simple resistive exercise systems and complex, reconfigurable "weight machines" have evolved in the years since, both in the Soviet-turned-Russian space program and now in the US-led International

Exercise devices designed to maintain cardiovascular fitness in the absence of gravity proved to be a more straightforward engineering goal: movement against a friction wheel can easily challenge the cardiopulmonary system. Providing resistive exercise challenge to the postural musculoskeletal system of sufficient intensity and quality has only recently been accomplished aboard the ISS. The Advanced Resistive Exercise Device (ARED) uses pistons to provide smooth exercise loads, and is highly reconfigurable for a wide array of

The world record duration in space is held by Dr. Valeri Polyakov, who spent 437 consecutive days in microgravity, landing in 1995. During his endurance mission he was required to exercise up to four hours a day. Human spaceflight is very costly, but is obviously undertaken to accomplish important scientific goals in life sciences, material science, fluid and combustion physics, global environmental monitoring and many other disciplines. Even with the improved exercise countermeasures and added knowledge of

**3. The impact of microgravity at the systemic level** 

etc.), in prime physical condition, and with no underlying disease states.

upon return to earth and 'normal' gravity conditions.

Space Station (ISS) program.

concentric and eccentric exercises.

**4. Bone health and present day human spaceflight** 

Osteoblast and osteoclast uncoupling is the primary source of this excessive resorption and biomechanical fragility of bone. If the cause can be determined, then reasonable solutions aimed at such uncoupling can be offered to address the problem. Bispohosphonates and, more primitively phosphate, can impede osteoclastic resorption. Calcium, Vitamin D, calcitonin, estrogen, exercise, smoking and alcohol restriction, and avoidance of particular medications can help halt bone loss. Fluoride (no longer used), parathytoid hormone, and aggressive exercise might result in bone mass gain.

### **2.2 Osteoporosis in microgravity**

Osteoporosis occurring as a result of microgravity is, from the perspective of the organism down to the lowest biological level, *different* than that encountered on earth.

#### **2.2.1 Cytoskeletal alterations**

Microgravity appears to significantly alter the cellular cytoskeleton. Proper cytoskeletal structure allows intracellular proteins to participate in important functions such as mitosis, cell motility, intracellular transport, and organization of organelles. Actin filaments, intermediate filaments, and microtubules are the key elements and they serve as a highly organized dynamic scaffold on which intracellular processes take place.

In microgravity, cellular structure, intracellular organization, and micro-fluid dynamics are altered[1]. Disruption of normal biochemical and physiological processes follows. Clement and Slenzka[2] have demonstrated that the spatial relationships between cellular organelles and structures are abnormal. And He[3] and Crawford-Young[4] have demonstrated that cellular cytoskeletal and microfilament dynamics are anomalous and might well be the source. Thus DNA replication, RNA transcription, protein migration, and ionic and molecular transport are perturbed.

#### **2.2.2 Mesenchymal stem cells**

The impact of these intracellular changes is felt by mesenchymal stem cells (MSC). MSC-- present in adult life in the periosteum of bones and within the bone marrow---differentiate into osteoblasts following appropriate signaling and presence within the proper mileau. Meyers[5], Yuge[6], Huang[7], and Pan[8] (in separate studies) have demonstrated via flow cytometry, transcriptional analyses, and proteomic analyses that MSCs ability to proliferate, to differentiate into osteoblasts, and to contribute to osteogenesis is inhibited by microgravity.

#### **2.2.3 Osteoblasts**

Osteoblasts are also directly compromised. Bucaro[9] has demonstrated findings that suggest that direct induction of osteoblast apoptosis occurs in microgravity. Apoptosis is differentiated from usual cell necrosis (where cells swell, burst and die) by characteristic intracellular changes including nuclear condensation and shrinkage and cytoplasmic vacuolization. Observed osteoblastic apoptosis likely results from cytoskeletal changes.

Additionally, Colleran[10] has noted that the cephallic fluid shift experienced by humans in microgravity might alter interstitial fluid pressures and flows and, given that osteoblasts survive somewhat tenuously in low flow areas, these shifts might result in cell functional compromise or death.

Osteoblast and osteoclast uncoupling is the primary source of this excessive resorption and biomechanical fragility of bone. If the cause can be determined, then reasonable solutions aimed at such uncoupling can be offered to address the problem. Bispohosphonates and, more primitively phosphate, can impede osteoclastic resorption. Calcium, Vitamin D, calcitonin, estrogen, exercise, smoking and alcohol restriction, and avoidance of particular medications can help halt bone loss. Fluoride (no longer used), parathytoid hormone, and

Osteoporosis occurring as a result of microgravity is, from the perspective of the organism

Microgravity appears to significantly alter the cellular cytoskeleton. Proper cytoskeletal structure allows intracellular proteins to participate in important functions such as mitosis, cell motility, intracellular transport, and organization of organelles. Actin filaments, intermediate filaments, and microtubules are the key elements and they serve as a highly

In microgravity, cellular structure, intracellular organization, and micro-fluid dynamics are altered[1]. Disruption of normal biochemical and physiological processes follows. Clement and Slenzka[2] have demonstrated that the spatial relationships between cellular organelles and structures are abnormal. And He[3] and Crawford-Young[4] have demonstrated that cellular cytoskeletal and microfilament dynamics are anomalous and might well be the source. Thus DNA replication, RNA transcription, protein migration, and ionic and

The impact of these intracellular changes is felt by mesenchymal stem cells (MSC). MSC-- present in adult life in the periosteum of bones and within the bone marrow---differentiate into osteoblasts following appropriate signaling and presence within the proper mileau. Meyers[5], Yuge[6], Huang[7], and Pan[8] (in separate studies) have demonstrated via flow cytometry, transcriptional analyses, and proteomic analyses that MSCs ability to proliferate, to differentiate into osteoblasts, and to contribute to osteogenesis is inhibited by

Osteoblasts are also directly compromised. Bucaro[9] has demonstrated findings that suggest that direct induction of osteoblast apoptosis occurs in microgravity. Apoptosis is differentiated from usual cell necrosis (where cells swell, burst and die) by characteristic intracellular changes including nuclear condensation and shrinkage and cytoplasmic vacuolization. Observed osteoblastic apoptosis likely results from cytoskeletal changes. Additionally, Colleran[10] has noted that the cephallic fluid shift experienced by humans in microgravity might alter interstitial fluid pressures and flows and, given that osteoblasts survive somewhat tenuously in low flow areas, these shifts might result in cell functional

down to the lowest biological level, *different* than that encountered on earth.

organized dynamic scaffold on which intracellular processes take place.

aggressive exercise might result in bone mass gain.

**2.2 Osteoporosis in microgravity** 

**2.2.1 Cytoskeletal alterations** 

molecular transport are perturbed.

**2.2.2 Mesenchymal stem cells** 

microgravity.

**2.2.3 Osteoblasts** 

compromise or death.

### **3. The impact of microgravity at the systemic level**

Systemically, microgravity induces osteoporosis via the above noted unique cellular changes *coupled* with an environment of nearly non-existent mechanical stresses where normal weight-bearing and the normal response of bone to proliferate accordingly (Wolff's Law) is altered. And this alteration differs than, say, that seen with immobilization. While patients placed in body casts and on bed rest (fully non-weightbearing) will suffer from osteoporortic changes, the amount of calcified bony tissue lost over three months is generally about 3%, tends to then level off at about three months (no further loss), and tends to be reversed with resumption of weight-bearing. In microgravity, the loss occurs at four times the rate, does not appear to level off, and appears to be much less reversible. Thus, the one-year trip to Mars is estimated to potentially result in a (devastating) greater than 25% reduction of bone mass. And this is in astronauts; predominantly male, at an age where their bone mass is at peak levels, exposed to no exogenous factors (smoking, excessive alcohol, etc.), in prime physical condition, and with no underlying disease states.

Simply, the combination of altered cellular form and function coupled with differences in bony response to microgravity systemically means that this form of osteoporosis bears relatively little relation to that seen on earth and that astronauts experience early, aggressive, continual bone loss. Predictably, systemic markers of bone resorption are greatly increased, while markers of bone formation are decreased[11] to levels rarely seen in onearth conditions. And, importantly, it is unclear whether these changes are fully reversible upon return to earth and 'normal' gravity conditions.

### **4. Bone health and present day human spaceflight**

Since the earliest days of human spaceflight, physiologists and NASA flight surgeons recognized the importance of exercise to maintain musculoskeletal and cardiovascular health. Owing to prolonged exposure to microgravity, Astronaut crews returning from America's first space station, Skylab, were too weak to stand upon return to earth. Exercise equipment thus became a requirement for all long duration space missions. A series of devices, including treadmills, stationary bicycles, rowing ergometers, simple resistive exercise systems and complex, reconfigurable "weight machines" have evolved in the years since, both in the Soviet-turned-Russian space program and now in the US-led International Space Station (ISS) program.

Exercise devices designed to maintain cardiovascular fitness in the absence of gravity proved to be a more straightforward engineering goal: movement against a friction wheel can easily challenge the cardiopulmonary system. Providing resistive exercise challenge to the postural musculoskeletal system of sufficient intensity and quality has only recently been accomplished aboard the ISS. The Advanced Resistive Exercise Device (ARED) uses pistons to provide smooth exercise loads, and is highly reconfigurable for a wide array of concentric and eccentric exercises.

The world record duration in space is held by Dr. Valeri Polyakov, who spent 437 consecutive days in microgravity, landing in 1995. During his endurance mission he was required to exercise up to four hours a day. Human spaceflight is very costly, but is obviously undertaken to accomplish important scientific goals in life sciences, material science, fluid and combustion physics, global environmental monitoring and many other disciplines. Even with the improved exercise countermeasures and added knowledge of

Osteoporosis in Microgravity Environments 269

noted cellular anomalies encountered. Aggressive exercise by astronauts---recommended at two hours per day of heavy resistance work---has made an impact; however, freeing up time for such activities is difficult given the operational needs during missions and, as space flight expands generally, the baseline cardiovascular capabilities of travelers will be more limited. Additionally, the aforementioned cellular changes render supplements (Calcium, vitamin D, etc.), medications (bisphosphonates, etc.) and hormones (testosterone, etc.) significantly less

The identification of new diagnostic or prognostic biomarkers has been gaining attention in the field of bone disease research leading to significant benefits in terms of efficient and timely treatment. Clearly novel strategies will need to be developed, and directed both at the molecular / cellular and bony systemic levels, and will need to be long lasting and simple to administer. In our minds, the ideal platform for the development of such novel strategies will rest upon nanotechnology. The size of nanomaterials mirrors that of most biological molecules and structures allowing size-matched communication and intervention important in diagnostics and therapeutics at the sub-cellular level and felt to be the source of

In this context, particular emphasis is placed on study of circulating proteome. The proteome represent the functional picture of the state of the cells because it constantly changes through its biochemical interactions with the genome and the environment. Protein turnovers and tissue microenvironment create a rich and heterogenic circulating mixture of protein fragments (low molecular weight peptidome, LMWP) that reflects both physiological and pathological processes. Despite its potential in clinical applications, profiling of the LMWP has proven to be a significant technical challenge because of the extremely high dynamic range of protein concentrations in blood and body fluids. Development of technologies that enable controlled fabrication of structure with nanoscale dimension can address the issues of the intrinsic complexity of the circulating low molecular weight peptidome [12,13]. Our group has developed diagnostic nanochannel-based lab-ona-chip technologies [Fig 1] that can allow for the detection of the earliest signs of disease, including osteoporosis, using penny-sized discs (satisfying the need for space preservation during space flight). This device is a size-exclusion method based on mesoporous silica thin film chips able to rapidly fractionate, and selectively enrich and protect peptides and proteins from enzymatic degradation. The mesoporous silica chip were produced by the evaporation-induced self –assembly procedure under acidic conditions using triblock

Physical properties of mesoporous silica such as pore dimension, pore texture, and chemical surface properties such as charge and further functionalization with selective ligands can be easily controlled and tuned to enhance the ability to detect traces of molecules. The ability to fabricate nanoscale devices and materials with a high degree of precision and accuracy, in combination with the recent advances in mass spectrometry, resulted in a powerful proteomic nanoscale platform for early disease diagnosis [16]. These lab-on-a-chip based diagnostic technologies can be either used as external devices or be implanted in the body of the astronaut. Implantable chips can feature molecularly driven sensors able to measure vital signs and readily respond to specific variation by releasing counteracting molecules. Diagnostics based on readily accessible body fluids can be also used to monitor in real time

effective in astronauts despite having a minor effect in microgravity animal models.

**6.1 Diagnostic platforms** 

bone cell dysfunction in microgravity.

copolymers as structural templates [14,15].

today, the overhead of spending up to two hours each and every day in space for the sole purpose of exercise is problematic.

ISS crewmembers actively work with strength and conditioning coaches throughout their preflight training. Using exercise monitoring hardware aboard ISS, these same coaches perform inflight assessments of the crew's conditioning while they are in space, and make exercise prescription modifications from Mission Control Houston, as required. Additionally, they oversee the crew's postflight physical rehabilitation, a process which may take several months to restore bone density to critical areas such as the hip and lumbar vertebral bodies.

Armed with an understanding of the whole body, cellular and subcellular processes involved in bone density maintenance in altered gravitational fields, more effective and efficient means to preserve musculoskeletal health is necessary to send humans beyond short stays aboard the ISS: Lunar outposts and expeditions to Mars are even more committing endeavors, and warrant substantial attention.

### **5. Future directions for research**

Despite a reasonable foundation of information, much work is needed to further delineate the impact of microgravity on bones at the cellular and systemic levels. Clearly the best strategy is to conduct experimental in-vivo human studies in space, but limited access to spaceflights and limited time during flight available to dedicate to these studies renders extensive (but necessary) study unachievable[1]. Accordingly, microgravity simulation has been the primary source of basic biological scientific information including most of what has been discussed thus far in this chapter.

On the celular level, simulation can be carried out within the rotating-wall vessel (RWV); a NASA-designed tissue culture bioreactor which simulates microgravity[1]. The bioreactor rotates horizontally such that, at an ideal speed, the contents achieve relative suspension simulating microgravity via dynamic equalibrium of forces---the contained cells / tissues remain in a state of long-term, suspended free-fall. The cells / tissues retain viability by being contained along with cell-specific growth media and oxygenation via active or passive diffusion provided by a silicon rubber membrane. To date however, relatively few studies have been carried out and there is significant need for further study on the cellular level as this level may be the key to differences relative to earthly osteoporosis. Additionally, comparison with studies performed in space will be required to validate the model and to ensure that changes noted are not unique to the system itself---in-vitro cellular behavior does not always mirror real life.

On the system / organism level, research has focused on animal models; most commonly hind-limb unloading and head-down bed rest (which has also been used in human volunteer subjects)[1]. While such models provide some insight into rapid bone loss, they are not fully satisfactory given that they fail to incite the noted cellular changes associated with microgravity and gravitational forces still compress bodily tissues whereas, in true microgravity, there is negative pressure experienced by tissues. It is clear that better models need to be developed.

#### **6. Potential future options for treatment and prevention**

Current options for the prevention and treatment of osteoporosis have proven far more successful on earth than in microgravity and this is likely commensurate with the above noted cellular anomalies encountered. Aggressive exercise by astronauts---recommended at two hours per day of heavy resistance work---has made an impact; however, freeing up time for such activities is difficult given the operational needs during missions and, as space flight expands generally, the baseline cardiovascular capabilities of travelers will be more limited. Additionally, the aforementioned cellular changes render supplements (Calcium, vitamin D, etc.), medications (bisphosphonates, etc.) and hormones (testosterone, etc.) significantly less effective in astronauts despite having a minor effect in microgravity animal models.

### **6.1 Diagnostic platforms**

268 Osteoporosis

today, the overhead of spending up to two hours each and every day in space for the sole

ISS crewmembers actively work with strength and conditioning coaches throughout their preflight training. Using exercise monitoring hardware aboard ISS, these same coaches perform inflight assessments of the crew's conditioning while they are in space, and make exercise prescription modifications from Mission Control Houston, as required. Additionally, they oversee the crew's postflight physical rehabilitation, a process which may take several months to restore bone density to critical areas such as the hip and lumbar vertebral bodies. Armed with an understanding of the whole body, cellular and subcellular processes involved in bone density maintenance in altered gravitational fields, more effective and efficient means to preserve musculoskeletal health is necessary to send humans beyond short stays aboard the ISS: Lunar outposts and expeditions to Mars are even more

Despite a reasonable foundation of information, much work is needed to further delineate the impact of microgravity on bones at the cellular and systemic levels. Clearly the best strategy is to conduct experimental in-vivo human studies in space, but limited access to spaceflights and limited time during flight available to dedicate to these studies renders extensive (but necessary) study unachievable[1]. Accordingly, microgravity simulation has been the primary source of basic biological scientific information including most of what has

On the celular level, simulation can be carried out within the rotating-wall vessel (RWV); a NASA-designed tissue culture bioreactor which simulates microgravity[1]. The bioreactor rotates horizontally such that, at an ideal speed, the contents achieve relative suspension simulating microgravity via dynamic equalibrium of forces---the contained cells / tissues remain in a state of long-term, suspended free-fall. The cells / tissues retain viability by being contained along with cell-specific growth media and oxygenation via active or passive diffusion provided by a silicon rubber membrane. To date however, relatively few studies have been carried out and there is significant need for further study on the cellular level as this level may be the key to differences relative to earthly osteoporosis. Additionally, comparison with studies performed in space will be required to validate the model and to ensure that changes noted are not unique to the system itself---in-vitro cellular behavior

On the system / organism level, research has focused on animal models; most commonly hind-limb unloading and head-down bed rest (which has also been used in human volunteer subjects)[1]. While such models provide some insight into rapid bone loss, they are not fully satisfactory given that they fail to incite the noted cellular changes associated with microgravity and gravitational forces still compress bodily tissues whereas, in true microgravity, there is negative pressure experienced by tissues. It is clear that better models

Current options for the prevention and treatment of osteoporosis have proven far more successful on earth than in microgravity and this is likely commensurate with the above

**6. Potential future options for treatment and prevention** 

purpose of exercise is problematic.

**5. Future directions for research** 

been discussed thus far in this chapter.

does not always mirror real life.

need to be developed.

committing endeavors, and warrant substantial attention.

The identification of new diagnostic or prognostic biomarkers has been gaining attention in the field of bone disease research leading to significant benefits in terms of efficient and timely treatment. Clearly novel strategies will need to be developed, and directed both at the molecular / cellular and bony systemic levels, and will need to be long lasting and simple to administer. In our minds, the ideal platform for the development of such novel strategies will rest upon nanotechnology. The size of nanomaterials mirrors that of most biological molecules and structures allowing size-matched communication and intervention important in diagnostics and therapeutics at the sub-cellular level and felt to be the source of bone cell dysfunction in microgravity.

In this context, particular emphasis is placed on study of circulating proteome. The proteome represent the functional picture of the state of the cells because it constantly changes through its biochemical interactions with the genome and the environment. Protein turnovers and tissue microenvironment create a rich and heterogenic circulating mixture of protein fragments (low molecular weight peptidome, LMWP) that reflects both physiological and pathological processes. Despite its potential in clinical applications, profiling of the LMWP has proven to be a significant technical challenge because of the extremely high dynamic range of protein concentrations in blood and body fluids. Development of technologies that enable controlled fabrication of structure with nanoscale dimension can address the issues of the intrinsic complexity of the circulating low molecular weight peptidome [12,13]. Our group has developed diagnostic nanochannel-based lab-ona-chip technologies [Fig 1] that can allow for the detection of the earliest signs of disease, including osteoporosis, using penny-sized discs (satisfying the need for space preservation during space flight). This device is a size-exclusion method based on mesoporous silica thin film chips able to rapidly fractionate, and selectively enrich and protect peptides and proteins from enzymatic degradation. The mesoporous silica chip were produced by the evaporation-induced self –assembly procedure under acidic conditions using triblock copolymers as structural templates [14,15].

Physical properties of mesoporous silica such as pore dimension, pore texture, and chemical surface properties such as charge and further functionalization with selective ligands can be easily controlled and tuned to enhance the ability to detect traces of molecules. The ability to fabricate nanoscale devices and materials with a high degree of precision and accuracy, in combination with the recent advances in mass spectrometry, resulted in a powerful proteomic nanoscale platform for early disease diagnosis [16]. These lab-on-a-chip based diagnostic technologies can be either used as external devices or be implanted in the body of the astronaut. Implantable chips can feature molecularly driven sensors able to measure vital signs and readily respond to specific variation by releasing counteracting molecules. Diagnostics based on readily accessible body fluids can be also used to monitor in real time

Osteoporosis in Microgravity Environments 271

releasing molecules in a burst or steady fashion over the course of days, weeks, or even months. These systems can also be tuned to release their payload in response to environmental stimuli (pH, temperature, blood concentrations, exposure to radiation, bone degeneration, etc.). The local delivery of antibiotics, dexamethasone, and growth factors (BMP-2) to the bone defect areas by PLGA/pSi microspheres reduced inflammation and stimulated new bone formation whilke simultaneously fighting bacterial growth. A wide variety of therapeutic and imaging agents have been successfully loaded into and released from pSi particles such as steroids [21], hormones [22], proteins[23], cancer drugs [24], or even secondary drug delivery vehicles including iron oxide nanoparticles [25], quantum dots, liposomes [26] and carbon nanotubes loaded with therapeutic drugs[18,27] to the diseased areas. In order to achieve the level of control on the release dynamics, it is possible to tailor both the pore size of the pSi during particles' fabrication or vary polymer type, molecular weight and density. Finally, the overall size of the polymer/pSi composites can also be tuned from nano level to micro level to suit certain applications by changing the polymer concentration, surfactant concentration, or the stirring speed. This hybrid system not only can reduce or abolish burst release, and prolong release kinetics, but also protect biomolecules from denaturation both during the drug loading process and while implanted in vivo. These particles have been successfully tested in different orthopedic tissue engineering applications in small and large animal models of bone

Fig. 2. Scanning electron microscopy (SEM) images of pSi particles reveals (A) uniform shape and size of particles, (B) the pore structure on the surface of the particles, and the (C)

fracture repair (manuscripts in preparation).

front and (D) rear surfaces of the particles.

the efficacy of therapeutic interventions. In their most complex configuration these implantable devices can be considered as artificial glands that sense the status of the body and adjust to it trying to bring back homeostasis. Nanotechnology based diagnostics offer higher detection capabilities due to the reduction of the size of the sensors, the increase of their sensitivity, the absence of non-specific reactions, and the multiplexing of the multiscale detectors that allow a wide range of intensities of the signal to be measured.

a-h, Schematic evolution of the chemical composition of the coating solution during the production of a mesoporous silica film. a, Fresh coating solution; b, Formation of micelles; c, Evaporation induced self assembly during spin-coating process; d, Zoomed in view of a pore after aging at elevated temperature. e, Bulk silicon wafer surface; f, Mesoporous silica film on a bulk silicon wafer. e-f, Cross-section of GX6 chip by SEM and TEM imaging respectively (scale bar is 500nm). i-n, images of the different chip surfaces and of the different masks that define the spotting areas.

Fig. 1. Production and assembly of MSC for proteomic applications

#### **6.2 Delivery systems**

We developed novel silicon-based theranostic nanoparticles [17-19] that have been used to achieve long-term, controlled, and targeted release of proteins and drugs that help halting or reversing osteoporosis. Among the molecules tested bone morphogenetic proteins (BMPs-- which are differentiation factors that facilitate the transition of mesenchymal stem cells to osteoblasts thereby encouraging bone formation) and bisphosphonates (which inhibit osteoclasts mediated bone resorption). The finely-tuned, extended, local delivery allowed by the use of these particles means that a single treatment can be administered pre-flight with effects felt for months on end (no need to 're-dose') and might prove to prevent or treat osteoporosis of microgravity. Nanoporous silica and PLGA composites are capable of

the efficacy of therapeutic interventions. In their most complex configuration these implantable devices can be considered as artificial glands that sense the status of the body and adjust to it trying to bring back homeostasis. Nanotechnology based diagnostics offer higher detection capabilities due to the reduction of the size of the sensors, the increase of their sensitivity, the absence of non-specific reactions, and the multiplexing of the multi-

a-h, Schematic evolution of the chemical composition of the coating solution during the production of a mesoporous silica film. a, Fresh coating solution; b, Formation of micelles; c, Evaporation induced self assembly during spin-coating process; d, Zoomed in view of a pore after aging at elevated temperature. e, Bulk silicon wafer surface; f, Mesoporous silica film on a bulk silicon wafer. e-f, Cross-section of GX6 chip by SEM and TEM imaging respectively (scale bar is 500nm). i-n, images of the different chip

We developed novel silicon-based theranostic nanoparticles [17-19] that have been used to achieve long-term, controlled, and targeted release of proteins and drugs that help halting or reversing osteoporosis. Among the molecules tested bone morphogenetic proteins (BMPs-- which are differentiation factors that facilitate the transition of mesenchymal stem cells to osteoblasts thereby encouraging bone formation) and bisphosphonates (which inhibit osteoclasts mediated bone resorption). The finely-tuned, extended, local delivery allowed by the use of these particles means that a single treatment can be administered pre-flight with effects felt for months on end (no need to 're-dose') and might prove to prevent or treat osteoporosis of microgravity. Nanoporous silica and PLGA composites are capable of

surfaces and of the different masks that define the spotting areas.

**6.2 Delivery systems** 

Fig. 1. Production and assembly of MSC for proteomic applications

scale detectors that allow a wide range of intensities of the signal to be measured.

releasing molecules in a burst or steady fashion over the course of days, weeks, or even months. These systems can also be tuned to release their payload in response to environmental stimuli (pH, temperature, blood concentrations, exposure to radiation, bone degeneration, etc.). The local delivery of antibiotics, dexamethasone, and growth factors (BMP-2) to the bone defect areas by PLGA/pSi microspheres reduced inflammation and stimulated new bone formation whilke simultaneously fighting bacterial growth. A wide variety of therapeutic and imaging agents have been successfully loaded into and released from pSi particles such as steroids [21], hormones [22], proteins[23], cancer drugs [24], or even secondary drug delivery vehicles including iron oxide nanoparticles [25], quantum dots, liposomes [26] and carbon nanotubes loaded with therapeutic drugs[18,27] to the diseased areas. In order to achieve the level of control on the release dynamics, it is possible to tailor both the pore size of the pSi during particles' fabrication or vary polymer type, molecular weight and density. Finally, the overall size of the polymer/pSi composites can also be tuned from nano level to micro level to suit certain applications by changing the polymer concentration, surfactant concentration, or the stirring speed. This hybrid system not only can reduce or abolish burst release, and prolong release kinetics, but also protect biomolecules from denaturation both during the drug loading process and while implanted in vivo. These particles have been successfully tested in different orthopedic tissue engineering applications in small and large animal models of bone fracture repair (manuscripts in preparation).

Fig. 2. Scanning electron microscopy (SEM) images of pSi particles reveals (A) uniform shape and size of particles, (B) the pore structure on the surface of the particles, and the (C) front and (D) rear surfaces of the particles.

Osteoporosis in Microgravity Environments 273

[28]. They also exhibit tremendous viability of MSC after cryo-preservation, allowing for long-term storage of prepared bio-porogens for immediate "on-demand" use in the clinic. Previously, we found that MSC isolated from compact bone (CB) tissue were more frequent in the total cell population and of greater colony-forming and tri-lineage differentiation

Fig. 4. MSC from compact bone (CB) produce larger and more defined colonies than those from bone marrow (BM) (A). The incidence of MSC from bulk cell populations is also nearly

All these biomaterials were based on the unique combination of I) nanostructured biomaterials able to mimic the extracellular matrices of either bone or cartilage with II) chemical and biochemical cues able to direct, control and preserve the phenotypes of both osteoblasts in their histological compartments. These biomaterials are made available as injectable hydrogel formulations thus reducing surgical invasiveness and improving the accuracy of the delivery to the targeted anatomical sites. Injectable composite hydrogels/pastes can be used for the spinal regions weakened by OP, with appropriate

These biomaterials can be functionalized and/or doped with chemical (e.g. strontium ions, oxygen transporters/scavangers) and biochemical (e.g. bioactive/biodocking peptides,

potential than MSC in bone marrow (BM) (Figure 4).

10x higher in CB than BM (B).

biomimetic and biomechanical characteristics.

Fig. 3. Release profiles of FITC-BSA from various examined PLGA/pSi microsphere formulations. (A) Total FITC-BSA released over 27 days, (B) first three day release.

#### **6.3 Injectable materials**

Beyond these diagnostic and drug-delivery applications, our group has also developed injectable gels that employ nanotechnologies to deliver mesenchymal stem cells, platelet rich plasma, and osteogeneic factors directly to areas of bony weakness. Thus, astronauts identified to have focal osteoporosis of, say, the proximal femur, might be treated by simple focal injection affording the in-vivo, in-situ rapid regeneration of lost bony mass.

These composites have proved their osteogenic capacity in vitro and through in vivo subcutaneous implants where ectopic bone was formed. The use of bio-porogens synthesized from natural and biodegradable materials, encourages bone formation and vascularization in vivo. These porogens particles house and release MSC, recruit endogenous cells and create extracellular matrix, synergistically promoting bone formation

0 10 20 30

*Time / day*

Fig. 3. Release profiles of FITC-BSA from various examined PLGA/pSi microsphere formulations. (A) Total FITC-BSA released over 27 days, (B) first three day release.

focal injection affording the in-vivo, in-situ rapid regeneration of lost bony mass.

Beyond these diagnostic and drug-delivery applications, our group has also developed injectable gels that employ nanotechnologies to deliver mesenchymal stem cells, platelet rich plasma, and osteogeneic factors directly to areas of bony weakness. Thus, astronauts identified to have focal osteoporosis of, say, the proximal femur, might be treated by simple

01234

*Time / day*

These composites have proved their osteogenic capacity in vitro and through in vivo subcutaneous implants where ectopic bone was formed. The use of bio-porogens synthesized from natural and biodegradable materials, encourages bone formation and vascularization in vivo. These porogens particles house and release MSC, recruit endogenous cells and create extracellular matrix, synergistically promoting bone formation

**6.3 Injectable materials** 

0

*Percent Release (%)*

**B**

20

40

60

*Percent Release (%)*

**A**

80

100

120

[28]. They also exhibit tremendous viability of MSC after cryo-preservation, allowing for long-term storage of prepared bio-porogens for immediate "on-demand" use in the clinic. Previously, we found that MSC isolated from compact bone (CB) tissue were more frequent in the total cell population and of greater colony-forming and tri-lineage differentiation potential than MSC in bone marrow (BM) (Figure 4).

Fig. 4. MSC from compact bone (CB) produce larger and more defined colonies than those from bone marrow (BM) (A). The incidence of MSC from bulk cell populations is also nearly 10x higher in CB than BM (B).

All these biomaterials were based on the unique combination of I) nanostructured biomaterials able to mimic the extracellular matrices of either bone or cartilage with II) chemical and biochemical cues able to direct, control and preserve the phenotypes of both osteoblasts in their histological compartments. These biomaterials are made available as injectable hydrogel formulations thus reducing surgical invasiveness and improving the accuracy of the delivery to the targeted anatomical sites. Injectable composite hydrogels/pastes can be used for the spinal regions weakened by OP, with appropriate biomimetic and biomechanical characteristics.

These biomaterials can be functionalized and/or doped with chemical (e.g. strontium ions, oxygen transporters/scavangers) and biochemical (e.g. bioactive/biodocking peptides,

Osteoporosis in Microgravity Environments 275

[15] Bouamrani A, Hu Y, Tasciotti E, Li L, Chiappini C, Liu X, et al. Mesoporous silica chips

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Muthupillai, R. D. Bolskar, L. Helm, M. Ferrari, L. J. Wilson, P. Decuzzi, Nano Tech.

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250.

2010, 5, 815.

China Chem. 2010 November 1; 53(11): 2257–2264.

selectively harvesting low molecular weight protein. acs nano. 2010; vol. 4 n 1, 439–

for selective enrichment and stabilization of low molecular weight proteome.

Nanotexture Optimization by Oxygen Plasma of Mesoporous Silica Thin Film for Enrichment of Low Molecular Weight Peptides Captured from Human Serum, Sci

Tour JM, Robertson F, Ferrari M. Mesoporous silicon particles as a multistage delivery system for imaging and therapeutic applications. Nat Nanotechnol. 2008

Shahzad MM, Liu X, Bhavane R, Gu J, Fakhoury JR, Chiappini C, Lu C, Matsuo K, Godin B, Stone RL, Nick AM, Lopez-Berestein G, Sood AK, Ferrari M. Sustained small interfering RNA delivery by mesoporous silicon particles. Cancer Res. 2010

silicon microparticles with endothelial cells in drug delivery to the vasculature.

Simmons, B. K. Weiner, M. Ferrari, and E. Tasciotti. Accepted by Advanced

genes) agents able to control cell phenotype and activity. Hydrogel formulations to be examined include collagen, gelatin, alginate, self-assembling peptides, or combinations thereof. The nano-features include peptides that bind to integral growth factors such as BMP-2 and VEGF and PRP. The scaffolds may be co-implanted with mesenchymal stem cells obtained from bone marrow and adipose aspirates. Finally, we have developed ways to reinforce biocompatible polymers with nanoparticles / nanowires that greatly increase their strength allowing for the replacement of bulky, heavy metallic devices currently used for fracture repair---the light-weight, injectable polymers ideal for transport on space flights and use for the repair of osteoporotic fractures once they occur.

### **7. References**


genes) agents able to control cell phenotype and activity. Hydrogel formulations to be examined include collagen, gelatin, alginate, self-assembling peptides, or combinations thereof. The nano-features include peptides that bind to integral growth factors such as BMP-2 and VEGF and PRP. The scaffolds may be co-implanted with mesenchymal stem cells obtained from bone marrow and adipose aspirates. Finally, we have developed ways to reinforce biocompatible polymers with nanoparticles / nanowires that greatly increase their strength allowing for the replacement of bulky, heavy metallic devices currently used for fracture repair---the light-weight, injectable polymers ideal for transport on space flights and

use for the repair of osteoporotic fractures once they occur.

microgravity. J Bone Min Res 20: 1858-1866, 2005.

[1] Blaber E, Marcal H, Burns B: Bioastronautics. Astrobiology 10: 463-473, 2010. [2] Clement G, Slenzka K. Fundamentals of space biology. Springer, New York 2006.

[3] He J, Zhang X, Gao Y, et al.: Effects of altered gravity on the cell cycle. Acat Astronaut.

[4] Crawford-Young SJ: Effects of microgravity on cell cytoskeleton and embryogenesis. Int

[5] Meyers VE, Zayzafoon M, Douglas JT, et al.: RhoA and cytoskeletal disruption mediate

[6] Yuge L, Kajiume T, Tahara H, et al.: Microgravity potentiates stem cell proliferatio while sustaining the capability of differentiation. Stem Cell Dev 15:921-929, 2006. [7] Huang Y, Dai ZQ, Ling SK, et al.: Gravity, a regulation factor in the differentiation of rat

[8] Pan Z, Yang J, Guo C, et al.: Effects of hindlimb unloading on ex vivo growth and

[9] Bucaro MA, Zahm AM, Risbud MV, et al.: The effect of simulated microgravity on

[10] Colleran PN, Wilkerson MK, Bloomfield SA, et al.: Alterations in skeletal perfusion with

[11] Callot-Augusseau A, Lafage MH, Soler C, et al.: Bone formation and resorption

[12] Sakamoto JH, van de Ven AL, Godin B, Blanco E, Serda RE, Grattoni A, Ziemys A,

[13] Ye Hu, Daniel H. Fine, Ennio Tasciotti, Ali Bouamrani and Mauro Ferrari, Nanodevices

[14] Hu, Y.; Bouamrani, A.; Tasciotti, E.; Li, L.; Liu, X.; Ferrari, M. Tailoring of the

bone marrow mesenchymal stem cells. J Biomed Sci 16: 87, 2009.

simulated microgravity. J Appl Physiol 89: 1046-1054, 2000.

reduced osteoblastogenesis of human mesenchymal stem cells in modeled

osteogenic potential of bone-marrow derived mesenchymal stem cells in rats. Stem

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biological markers in cosmonauts during and after a 180 day space flight. Clin

Bouamrani A, Hu T, Ranganathan SI, De Rosa E, Martinez JO, Smid CA, Buchanan RM, Lee SY, Srinivasan S, Landry M, Meyn A, Tasciotti E, Liu X, Decuzzi P, Ferrari M. Enabling individualized therapy through nanotechnology. Pharmacol Res. 2010

Nanotexture of Mesoporous Silica Films and their functionalized derivatives for

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selectively harvesting low molecular weight protein. acs nano. 2010; vol. 4 n 1, 439– 451.


**15** 

 *Greece* 

Yannis Dionyssiotis

**Neurological Osteoporosis in Disabilities** 

*University of Athens, Laboratory for Research of the Musculoskeletal System* 

Osteoporosis is characterized by low bone mass and destruction of the micro architecture of bone tissue, resulting in increased bone fragility and susceptibility to fractures (NIH 2001). The clinical usefulness of T-score at disabled people on the recognition of people with low BMD remains unclear according to ranking system of the World Health Organization (WHO 1994). Despite the increased number of risk factors in people with disabilities no guidelines are available on BMD measurements; so it would be more appropriate to use the term low bone mass instead of osteoporosis or osteopenia and also take into account the Z-score obtained from the measurement of bone densitometry which is the number of standard deviations above or below that normally expected for someone of similar age, sex, weight

In disabled subjects there are differences according to the type of injury (i.e. lesion with a level of injury vs. upper motor neuron pyramidal lesion), the type of lesion; complete (an absence of sensory or motor function below the neurological level, including the lowest sacral segment) vs. incomplete lesion (partial preservation of motor and/or sensory function below the neurological level, including the lowest sacral segment), the progression or not of the disease (i.e. progressive multiple sclerosis vs. complete paraplegia), life expectancy, the residual mobility and functionality, the ability to walk and stand (i.e. incomplete paraplegia vs. quadriplegia vs. high-low paraplegia), drug treatment (i.e. frequent corticosteroid therapy in multiple sclerosis vs. long-term therapy with anticoagulants in paraplegia), the degree of spasticity (i.e. flaccid vs. spastic paralysis) and it is necessary to take into account the issue of fatigue and muscle weakness. Depression in these subjects is usual; complicates the proposed treatments and limits mobility. Complete and incomplete disabled differ also in physical abilities. Moreover, subjects with complete injuries have greater bone loss than those with an incomplete injury (Garland et al., 1994) and as has already been shown in Brown-Sequard subjects (incomplete spinal cord lesion) where BMD of the more paretic

However, there are also similarities; for example the clinical equivalence of diseases with different physiopathology, location, evolution, etc. A severe form of multiple sclerosis (MS) can result in a wheelchair bound patient having a clinical figure equivalent to spinal cord injury paraplegia. One patient with MS may have better walking gait pattern in comparison with a patient with incomplete paraplegia but may also be unable to walk, bedridden and

**1. Introduction** 

and race in question (Dionyssiotis, 2011c, 2011d).

knee was lower than that of the stronger knee (Lazo et al., 2001).

vice versa (Dionyssiotis, 2011c, 2011d).

*Physical and Social Rehabilitation Center Amyntæo* 

[29] Murphy, M.B., Blashki, D., Buchanan, R.M., Yazdi, I.K., Ferrari, M., Simmons, P.Jl, and Tasciotti, E. Characterization of Umbilical Cord Blood-Derived and Adult Platelet-Rich Plasma for Mesenchymal Stem Cell Proliferation, Chemotaxis, and Cryopreservation. Submitted to Biomaterials.

## **Neurological Osteoporosis in Disabilities**

### Yannis Dionyssiotis

*Physical and Social Rehabilitation Center Amyntæo University of Athens, Laboratory for Research of the Musculoskeletal System Greece* 

### **1. Introduction**

276 Osteoporosis

[29] Murphy, M.B., Blashki, D., Buchanan, R.M., Yazdi, I.K., Ferrari, M., Simmons, P.Jl, and

preservation. Submitted to Biomaterials.

Tasciotti, E. Characterization of Umbilical Cord Blood-Derived and Adult Platelet-Rich Plasma for Mesenchymal Stem Cell Proliferation, Chemotaxis, and Cryo-

> Osteoporosis is characterized by low bone mass and destruction of the micro architecture of bone tissue, resulting in increased bone fragility and susceptibility to fractures (NIH 2001). The clinical usefulness of T-score at disabled people on the recognition of people with low BMD remains unclear according to ranking system of the World Health Organization (WHO 1994). Despite the increased number of risk factors in people with disabilities no guidelines are available on BMD measurements; so it would be more appropriate to use the term low bone mass instead of osteoporosis or osteopenia and also take into account the Z-score obtained from the measurement of bone densitometry which is the number of standard deviations above or below that normally expected for someone of similar age, sex, weight and race in question (Dionyssiotis, 2011c, 2011d).

> In disabled subjects there are differences according to the type of injury (i.e. lesion with a level of injury vs. upper motor neuron pyramidal lesion), the type of lesion; complete (an absence of sensory or motor function below the neurological level, including the lowest sacral segment) vs. incomplete lesion (partial preservation of motor and/or sensory function below the neurological level, including the lowest sacral segment), the progression or not of the disease (i.e. progressive multiple sclerosis vs. complete paraplegia), life expectancy, the residual mobility and functionality, the ability to walk and stand (i.e. incomplete paraplegia vs. quadriplegia vs. high-low paraplegia), drug treatment (i.e. frequent corticosteroid therapy in multiple sclerosis vs. long-term therapy with anticoagulants in paraplegia), the degree of spasticity (i.e. flaccid vs. spastic paralysis) and it is necessary to take into account the issue of fatigue and muscle weakness. Depression in these subjects is usual; complicates the proposed treatments and limits mobility. Complete and incomplete disabled differ also in physical abilities. Moreover, subjects with complete injuries have greater bone loss than those with an incomplete injury (Garland et al., 1994) and as has already been shown in Brown-Sequard subjects (incomplete spinal cord lesion) where BMD of the more paretic knee was lower than that of the stronger knee (Lazo et al., 2001).

> However, there are also similarities; for example the clinical equivalence of diseases with different physiopathology, location, evolution, etc. A severe form of multiple sclerosis (MS) can result in a wheelchair bound patient having a clinical figure equivalent to spinal cord injury paraplegia. One patient with MS may have better walking gait pattern in comparison with a patient with incomplete paraplegia but may also be unable to walk, bedridden and vice versa (Dionyssiotis, 2011c, 2011d).

Neurological Osteoporosis in Disabilities 279

both paraplegic groups vs. controls leading to reduction of cortical thickness, 19.78% vs. 16.98% in paraplegic groups respectively, whereas periosteal circumference was comparable

Fig. 1. Peripheral quantitative computed tomography (p QCT) tibia slices in control (a) and paraplegic subject (b), (scanner XCT 3000 Stratec, Medizintechnik, Pforzheim, Germany). Areas in red represent trabecular bone, while areas in grey represent fat; pQCT allows the measurements of true volumetric densities at a minimum exposure to X-rays, assess cortical and trabecular bone density separately as well as to evaluate the geometrical properties of long bones non-invasively, adapted from Dionyssiotis, 2011c, 2011d, with permission.

Regarding tetraplegic patients statistically significant differences were found in BMD of the spine, trochanteric region and upper limbs between paraplegic and tetraplegic patients but not in the femoral neck, pelvis, and lower extremities (Tzuzuku et al., 1999). Indeed, the effects on spinal BMD differed from previously published work in which the investigation was mainly

The importance of mechanical loading and site specificity to maintain or increase BMD is already shown (Lanyon, 1986). According to bone loss there are some interesting features in spinal cord injured subjects; demineralization is area dependent, occurs exclusively in the areas below the level of injury (Dauty et al., 2000), affecting mainly paralyzed extremities and increasing from proximal to distal regions i.e. in paraplegics weight bearing skeleton regions, as the distal end of femur and proximal tibia, which are rich in cancellous bone, while region of the diaphysis of the femur and tibia, rich in cortical bone is reserved (Eser et al., 2004; Kiratli et al., 2000; Dionyssiotis et al., 2007). Moreover, bone loss between trabecular and cortical bone compartment differs in mechanism, i.e. in the epiphyses is due to decrease in trabecular but in diaphysis cortical bone is maintained and bone is lost through endocortical resorption by reducing cortical wall thickness (Dionyssiotis et al., 2007;

focused in paraplegics (Biering-Sorensen et al., 1988, 1991; Leslie & Nance, 1993).

to controls (Fig. 1).

Eser et al., 2004).

In addition the role of factors which do not change, i.e.: race or gender is inadequately clarified. Studies in disabled women debate that bones are more affected compared to disabled men. In chronic spinal cord injured women a tendency to have lower bone mass than men (Coupaud et al., 2009) and higher rates of lower bone mass with lower T-scores compared to women with other disabilities have been reported (Smeltzer et al., 2005).

### **2. Spinal cord injury**

Bone loss in spinal cord injury (SCI) is a multifactorial disease in acute and chronic phase and can be enhanced by the lack of weight bearing, muscular tension on bone or other neural factors associated with the injury. Moreover, differentiation of the sympathetic nervous system after SCI is leading to venous and capillary vascular stasis. Some additional non-mechanical factors to stimulate bone loss include poor nutritional adequacy, gonadal changes and other endocrine disorders (Chantraine 1978; Chantraine et al., 1979b; Jiang et al., 2007; Maimoun et al., 2006).

#### **2.1 Bone mineral density**

In individuals with SCI bone loss begins immediately after injury (Bauman et al., 1997; Uebelhart et al., 1995). SCI related bone impairment below the level of injury is much greater compared with other conditions (i.e. age, immobilization, bed rest, lack of gravity environment). A reduction of bone mineral content (BMC) during the first years after the injury of 4% per month in regions rich in cancellous bone, and 2% per month on sites containing mainly cortical bone is reported (Wilmet et al., 1995). According to another study 25 out of 41 patients with SCI (61%) met WHO's criteria for osteoporosis, eight (19.5%) were osteopenic and only eight (19.5%) showed normal values (Lazo et al., 2001). In SCI children (boys and girls) values for bone mineral density (BMD) at the hip were approximately 60% of normal, or had a Z-score that indicated a 1.6-1.8 SD reduction in BMD compared with age- and sex-matched peers (Lauer et al., 2007).

In studies with peripheral quantitative computed tomography (p QCT) in spinal cord injured subjects bone loss in the epiphyses was 50% in the femur and 60% in the tibia, while in the diaphyses of these bones was 35% and 25%, respectively, meaning that bone loss in the epiphyses almost doubled the loss in the diaphyses (Eser et al., 2004). This study also showed that bone loss between trabecular and cortical bone compartment differs in mechanism, i.e. in the epiphyses bone is lost due to the decrease in trabecular, while in diaphysis, the cortical bone density is maintained and bone is lost due to endocortical resorption. In line with the previous study another p QCT study, performed in complete paraplegics with high (thoracic 4-7) and low (thoracic 8-12) neurological level of injury at the tibia, found a loss of trabecular (57.5% vs. 51%, in high vs. low paraplegics, respectively) and cortical bone (3.6% and 6.5%, respectively), suggesting that trabecular bone is more affected during the years of paralysis in comparison with cortical bone (Dionyssiotis et al., 2007). In the same study both paraplegic groups had a similar loss of total BMD (46.90% vs. 45.15%, in high vs. low paraplegics, respectively) suggesting that a homogenously deficit pattern occurs in the epiphyseal area, especially in the group of low paraplegics because the central and the peripheral of the cross sectional area of bone were similarly affected. On the contrary, in high paraplegics' group trabecular bone loss was higher suggesting an increasing endocortical remodeling keeping the total BMD similar. Concerning cortical geometric properties the results had shown an increased endosteal circumference between

In addition the role of factors which do not change, i.e.: race or gender is inadequately clarified. Studies in disabled women debate that bones are more affected compared to disabled men. In chronic spinal cord injured women a tendency to have lower bone mass than men (Coupaud et al., 2009) and higher rates of lower bone mass with lower T-scores compared to women with other disabilities have been reported (Smeltzer et al., 2005).

Bone loss in spinal cord injury (SCI) is a multifactorial disease in acute and chronic phase and can be enhanced by the lack of weight bearing, muscular tension on bone or other neural factors associated with the injury. Moreover, differentiation of the sympathetic nervous system after SCI is leading to venous and capillary vascular stasis. Some additional non-mechanical factors to stimulate bone loss include poor nutritional adequacy, gonadal changes and other endocrine disorders (Chantraine 1978; Chantraine et al., 1979b; Jiang et

In individuals with SCI bone loss begins immediately after injury (Bauman et al., 1997; Uebelhart et al., 1995). SCI related bone impairment below the level of injury is much greater compared with other conditions (i.e. age, immobilization, bed rest, lack of gravity environment). A reduction of bone mineral content (BMC) during the first years after the injury of 4% per month in regions rich in cancellous bone, and 2% per month on sites containing mainly cortical bone is reported (Wilmet et al., 1995). According to another study 25 out of 41 patients with SCI (61%) met WHO's criteria for osteoporosis, eight (19.5%) were osteopenic and only eight (19.5%) showed normal values (Lazo et al., 2001). In SCI children (boys and girls) values for bone mineral density (BMD) at the hip were approximately 60% of normal, or had a Z-score that indicated a 1.6-1.8 SD reduction in BMD compared with

In studies with peripheral quantitative computed tomography (p QCT) in spinal cord injured subjects bone loss in the epiphyses was 50% in the femur and 60% in the tibia, while in the diaphyses of these bones was 35% and 25%, respectively, meaning that bone loss in the epiphyses almost doubled the loss in the diaphyses (Eser et al., 2004). This study also showed that bone loss between trabecular and cortical bone compartment differs in mechanism, i.e. in the epiphyses bone is lost due to the decrease in trabecular, while in diaphysis, the cortical bone density is maintained and bone is lost due to endocortical resorption. In line with the previous study another p QCT study, performed in complete paraplegics with high (thoracic 4-7) and low (thoracic 8-12) neurological level of injury at the tibia, found a loss of trabecular (57.5% vs. 51%, in high vs. low paraplegics, respectively) and cortical bone (3.6% and 6.5%, respectively), suggesting that trabecular bone is more affected during the years of paralysis in comparison with cortical bone (Dionyssiotis et al., 2007). In the same study both paraplegic groups had a similar loss of total BMD (46.90% vs. 45.15%, in high vs. low paraplegics, respectively) suggesting that a homogenously deficit pattern occurs in the epiphyseal area, especially in the group of low paraplegics because the central and the peripheral of the cross sectional area of bone were similarly affected. On the contrary, in high paraplegics' group trabecular bone loss was higher suggesting an increasing endocortical remodeling keeping the total BMD similar. Concerning cortical geometric properties the results had shown an increased endosteal circumference between

**2. Spinal cord injury** 

al., 2007; Maimoun et al., 2006).

age- and sex-matched peers (Lauer et al., 2007).

**2.1 Bone mineral density** 

both paraplegic groups vs. controls leading to reduction of cortical thickness, 19.78% vs. 16.98% in paraplegic groups respectively, whereas periosteal circumference was comparable to controls (Fig. 1).

Fig. 1. Peripheral quantitative computed tomography (p QCT) tibia slices in control (a) and paraplegic subject (b), (scanner XCT 3000 Stratec, Medizintechnik, Pforzheim, Germany). Areas in red represent trabecular bone, while areas in grey represent fat; pQCT allows the measurements of true volumetric densities at a minimum exposure to X-rays, assess cortical and trabecular bone density separately as well as to evaluate the geometrical properties of long bones non-invasively, adapted from Dionyssiotis, 2011c, 2011d, with permission.

Regarding tetraplegic patients statistically significant differences were found in BMD of the spine, trochanteric region and upper limbs between paraplegic and tetraplegic patients but not in the femoral neck, pelvis, and lower extremities (Tzuzuku et al., 1999). Indeed, the effects on spinal BMD differed from previously published work in which the investigation was mainly focused in paraplegics (Biering-Sorensen et al., 1988, 1991; Leslie & Nance, 1993).

The importance of mechanical loading and site specificity to maintain or increase BMD is already shown (Lanyon, 1986). According to bone loss there are some interesting features in spinal cord injured subjects; demineralization is area dependent, occurs exclusively in the areas below the level of injury (Dauty et al., 2000), affecting mainly paralyzed extremities and increasing from proximal to distal regions i.e. in paraplegics weight bearing skeleton regions, as the distal end of femur and proximal tibia, which are rich in cancellous bone, while region of the diaphysis of the femur and tibia, rich in cortical bone is reserved (Eser et al., 2004; Kiratli et al., 2000; Dionyssiotis et al., 2007). Moreover, bone loss between trabecular and cortical bone compartment differs in mechanism, i.e. in the epiphyses is due to decrease in trabecular but in diaphysis cortical bone is maintained and bone is lost through endocortical resorption by reducing cortical wall thickness (Dionyssiotis et al., 2007; Eser et al., 2004).

Neurological Osteoporosis in Disabilities 281

Fig. 2. The duration of paralysis was inversely related with trabecular bone loss in spinal cord injured subjects. Exponential correlation between volumetric trabecular bone mineral density BMD trab and duration of paralysis in high paraplegics was found to fit best. On the contrary no significant decrease in BMD cort of the diaphyses was found in total paraplegic group. BMD parameters were measured by pQCT in 31 paraplegic men in chronic stage (>1.5 years of injury). Spinal cord injury paraplegic men were allocated into 2 subgroups based on the neurological level of injury; subgroup A (n=16, Thoracic (T)4-T7 neurological level of injury) and subgroup B (n=15, T8-T12 neurological level of injury). BMDtrab: BMD trabecular; BMDcort: BMD cortical; (adapted from Dionyssiotis et al., 2011a, with permission).

The role played by factors such as race or gender of patients is not yet clear documented, but studies indicated more loss in women than men (Garland et al., 2001). Loss of bone is closing fracture threshold from 1 to 5 years after injury (Szollar et al., 1998) and risk factors for fractures after spinal cord injury are gender (women are more at risk than men), age and duration of injury (increasing age and duration of injury increases the risk of fracture with a statistically significant increase in 10 years after injury), the type of injury (complete SCI subjects have more fractures than incomplete), low body mass index (BMI) and low bone

Spinal cord injury is a dynamic process that is related to alterations in both the central and peripheral sympathetic nervous system (SNS). Sympathetic denervation in SCI may cause arteriovenous shunts and a slowdown of intraosseous blood flow, thus increasing bone resorption (Chantraine et al., 1979). With high-level spinal cord lesions the SNS is disproportionately involved when compared with the parasympathetic nervous system. In a complete high-level SCI, functioning in the isolated spinal cord below the lesion becomes

density in the tibia (Garland et al., 2004a,b; Garland et al., 1992; Lazo et al., 2001).

**2.3. The role of central nervous system 2.3.1 Sympathetic denervation in SCI** 

Women with disabilities have a higher risk of losing bone mass compared to men because of the inevitable reduction in estrogen levels that occurs at menopause. Findings that women with serious disabilities have low bone density are not surprising and are probably related to the lack of activity (reduced mobility, reduced loading on bone) and worsening of the disability. Regarding women with complete SCI, the initial bone loss in the lumbar spine is negligible. Post injury over a period of years BMD in SCI women is maintained or increases compared with non-injured age-matched women, in whom BMD decreases during aging (Dionyssiotis, 2011c).

### **2.2 Duration of paralysis and bone steady state**

The duration of paralysis affects the degree of bone loss in regions below the level of injury. A study of 21 men with SCI with an average duration of 10.6 years, using dual-energy X-ray absorptiometry (DXA), expressed at various levels of injury an inverse relationship between BMD in the legs and the duration of the lesion (Clasey et al., 2004), while others found a weaker relationship regarding the microarchitecture of the distal end of tibia (Modlesky et al., 2004).

In a study which included paraplegics with duration of paralysis of 14 ± 11.5 years a positive correlation between the duration of paralysis and the degree of bone loss was found (Eser et al., 2004). The length of immobilization in the acute posttraumatic period increased bone loss in the legs, particularly in the proximal tibia; over 50% of bone mass was lost (in the affected areas) in the period of ten years after the injury (Dauty et al., 2000). When subjects categorized depending on the length of the lesion (0-1, 1-5, 6-9, 10-19, 20-29, 30-39, 40-49, and 50-59 years after the injury), in all age groups bone loss to the hip area occurs a year after the injury (Szollar et al., 1998).

Using DXA and QUS (quantitative ultrasound) measurements in 100 men with SCI, aged 18 to 60 years, it was found that bone density decreases over time in all measured points, while bone loss followed a linear pattern in the femoral neck and distal epiphysis, stabilized within three years after the injury. On the contrary, Z-scores of the distal region of the diaphysis of the tibia continued to decrease even beyond ten years after the injury (Zehnder et al, 2004). Duration of paralysis related bone loss in the legs of monozygotic twins with chronic paraplegia in comparison with their able-bodied co-twins has been also reported (Bauman et al., 1999).

The results of a comparison of chronic complete paraplegic men vs. controls in another study found a reduction of BMD in paraplegics' legs independent of the neurological level of lesion. BMD of the legs was negatively correlated with the duration of paralysis in the total paraplegic group, but after investigation according to the neurological level this correlation was due to the strong correlation of high paraplegics' legs BMD with the duration of paralysis, suggesting a possible influence of the neurological level of injury on the extent of bone loss (Dionyssiotis et al., 2008). A significant inverse relationship between percentage-matched in BMD leg, arm and trunk values and time since injury was found when varying levels of SCI were analyzed (Clasey et al., 2004).

Studies are supporting the concept of a new bone steady state at 16-24 months after injury, especially for bone metabolic process (Bauman WA 1997; Demirel et al., 1998; Szollar et al., 1998), but BMD decreases over the years at different areas and is inversely related to the time of the injury, which means continuous bone loss beyond the first two years after the injury (Coupaud et al., 2009; Dionyssiotis et al., 2008; Eser et al., 2004) (Fig. 2).

Women with disabilities have a higher risk of losing bone mass compared to men because of the inevitable reduction in estrogen levels that occurs at menopause. Findings that women with serious disabilities have low bone density are not surprising and are probably related to the lack of activity (reduced mobility, reduced loading on bone) and worsening of the disability. Regarding women with complete SCI, the initial bone loss in the lumbar spine is negligible. Post injury over a period of years BMD in SCI women is maintained or increases compared with non-injured age-matched women, in whom BMD decreases during aging

The duration of paralysis affects the degree of bone loss in regions below the level of injury. A study of 21 men with SCI with an average duration of 10.6 years, using dual-energy X-ray absorptiometry (DXA), expressed at various levels of injury an inverse relationship between BMD in the legs and the duration of the lesion (Clasey et al., 2004), while others found a weaker relationship regarding the microarchitecture of the distal end of tibia (Modlesky et

In a study which included paraplegics with duration of paralysis of 14 ± 11.5 years a positive correlation between the duration of paralysis and the degree of bone loss was found (Eser et al., 2004). The length of immobilization in the acute posttraumatic period increased bone loss in the legs, particularly in the proximal tibia; over 50% of bone mass was lost (in the affected areas) in the period of ten years after the injury (Dauty et al., 2000). When subjects categorized depending on the length of the lesion (0-1, 1-5, 6-9, 10-19, 20-29, 30-39, 40-49, and 50-59 years after the injury), in all age groups bone loss to the hip area occurs a

Using DXA and QUS (quantitative ultrasound) measurements in 100 men with SCI, aged 18 to 60 years, it was found that bone density decreases over time in all measured points, while bone loss followed a linear pattern in the femoral neck and distal epiphysis, stabilized within three years after the injury. On the contrary, Z-scores of the distal region of the diaphysis of the tibia continued to decrease even beyond ten years after the injury (Zehnder et al, 2004). Duration of paralysis related bone loss in the legs of monozygotic twins with chronic paraplegia in comparison with their able-bodied co-twins has been also reported

The results of a comparison of chronic complete paraplegic men vs. controls in another study found a reduction of BMD in paraplegics' legs independent of the neurological level of lesion. BMD of the legs was negatively correlated with the duration of paralysis in the total paraplegic group, but after investigation according to the neurological level this correlation was due to the strong correlation of high paraplegics' legs BMD with the duration of paralysis, suggesting a possible influence of the neurological level of injury on the extent of bone loss (Dionyssiotis et al., 2008). A significant inverse relationship between percentage-matched in BMD leg, arm and trunk values and time since injury was found

Studies are supporting the concept of a new bone steady state at 16-24 months after injury, especially for bone metabolic process (Bauman WA 1997; Demirel et al., 1998; Szollar et al., 1998), but BMD decreases over the years at different areas and is inversely related to the time of the injury, which means continuous bone loss beyond the first two years after the

injury (Coupaud et al., 2009; Dionyssiotis et al., 2008; Eser et al., 2004) (Fig. 2).

when varying levels of SCI were analyzed (Clasey et al., 2004).

(Dionyssiotis, 2011c).

al., 2004).

**2.2 Duration of paralysis and bone steady state** 

year after the injury (Szollar et al., 1998).

(Bauman et al., 1999).

Fig. 2. The duration of paralysis was inversely related with trabecular bone loss in spinal cord injured subjects. Exponential correlation between volumetric trabecular bone mineral density BMD trab and duration of paralysis in high paraplegics was found to fit best. On the contrary no significant decrease in BMD cort of the diaphyses was found in total paraplegic group. BMD parameters were measured by pQCT in 31 paraplegic men in chronic stage (>1.5 years of injury). Spinal cord injury paraplegic men were allocated into 2 subgroups based on the neurological level of injury; subgroup A (n=16, Thoracic (T)4-T7 neurological level of injury) and subgroup B (n=15, T8-T12 neurological level of injury). BMDtrab: BMD trabecular; BMDcort: BMD cortical; (adapted from Dionyssiotis et al., 2011a, with permission).

The role played by factors such as race or gender of patients is not yet clear documented, but studies indicated more loss in women than men (Garland et al., 2001). Loss of bone is closing fracture threshold from 1 to 5 years after injury (Szollar et al., 1998) and risk factors for fractures after spinal cord injury are gender (women are more at risk than men), age and duration of injury (increasing age and duration of injury increases the risk of fracture with a statistically significant increase in 10 years after injury), the type of injury (complete SCI subjects have more fractures than incomplete), low body mass index (BMI) and low bone density in the tibia (Garland et al., 2004a,b; Garland et al., 1992; Lazo et al., 2001).

### **2.3. The role of central nervous system**

#### **2.3.1 Sympathetic denervation in SCI**

Spinal cord injury is a dynamic process that is related to alterations in both the central and peripheral sympathetic nervous system (SNS). Sympathetic denervation in SCI may cause arteriovenous shunts and a slowdown of intraosseous blood flow, thus increasing bone resorption (Chantraine et al., 1979). With high-level spinal cord lesions the SNS is disproportionately involved when compared with the parasympathetic nervous system. In a complete high-level SCI, functioning in the isolated spinal cord below the lesion becomes

Neurological Osteoporosis in Disabilities 283

synthesis and secretion of bone components (Manolagas, 2000; Pereira et al., 2002). Finally, GCs promote ostoclasts and stimulate bone resorption (Weinstein et al., 2002). The mechanisms of GCs action in bone has been studied extensively. In patients receiving chronic per os GC, bone loss is admitted rapidly and is evident within 6 or even 3 months (Cosman et al., 1998). A study investigated the effect of intravenously (i.v.) administration of glucocorticoids in MS patients found no clear effect on bone loss: on the contrary they reported an increase in BMD of the lumbar spine (Schwid et al., 1996). Prolonged treatment with glucocorticoids results in increased risk of fractures, evident at 3 months, regardless of changes in BMD. High dose, short-term i.v. treatment with GCs leads directly to reduction of bone formation and increased bone resorption, as indicated by markers of bone turnover (De Vries et al. 2007; Van Staa et al., 2000). Osteopenia not osteoporosis was significantly more frequent in patients with MS compared with controls, especially in women who received high dose methylprednisolone pulses (HDMP) in relapses period making important the regularly monitoring of BMD in these patients. The authors concluded that disability and the subsequent immobilization osteoporosis is the more serious factor in this group and treatment with repeated HDMP pulses did not cause osteoporosis in MS subjects followed-up for almost 8 years unlike chronic corticosteroid therapy which induces osteoporosis and/or recovery of BMD is permitted without permanent skeletal damage (Zorzon et al., 2005). The lack of physical activity exacerbates osteoporosis. All MS patients should be considered high risk for osteoporosis. Prevention with calcium rich foods and dietary supplements containing vitamin D and antiosteoporotic drugs is necessary for these patients. Particular attention should be paid to transfers and falls prevention in this population to prevent fractures which occur easily and heal slowly (Cattaneo et al., 2007;

In osteoporosis molecular mechanisms leading to bone loss are inadequately explained. There is evidence of interaction between bone and immune system. T cells' activity could stimulate bone loss under certain circumstances such as estrogen deficiency. Women with post-menopausal osteoporosis have higher T cell activity than healthy post-menopausal subjects which could be also the case in inflammatory or autoimmune disorders like MS: receptor activator of nuclear factor kappa B ligand (RANKL) stimulates osteoclastogenesis and the same do cytokines, such as TNF-*α*, IL-1, or IL-11, all produced by T-cells activation, leading to bone destruction. On the contrary osteoprotegerin (OPG) is an osteoclastogenesis inhibitory factor preventing the function from RANKL. A balanced system of RANKL/OPG regulates bone metabolism. In MS this system is disturbed in favour of RANKL (Zhao et al.,

Disuse has been suggested as the main cause for loss of bone mass in patients immobilized because of stroke (Takamoto et al., 1995). However, this was not confirmed in a prospective study, in which only weak associations between bone loss and motor function, activities of daily living (ADL), or ambulation were found (Ramnemark et al., 1999a). This could be explained by the selected severely affected patients, but it does raise questions about other risk factors for the development of hemiosteoporosis apart from paresis and immobilization

The critical role in pathogenesis of osteoporosis is attributed to hormonal processes and osteoporosis itself is often defined as generalized skeletal disorder. Findings of tibial bone

Dionyssiotis, 2011b).

2008; Kurban et al., 2009).

(Ramnemark et al., 1999b).

**4. Stroke** 

independent of supraspinal control and has been termed decentralization of the SNS (Karlsson et al., 1998).

Loss of supraspinal control leads to dysregulation of those homeostatic mechanisms normally influenced by the SNS through loss of facilitation or lack of inhibition (Teasell et al., 2000). Today there is clinical evidence that the sympathetic regulation of bone does exist in humans and plays a clinically important role in diseases characterized by excessive sympathetic activity (Schwartzman, 2000). The scientific finding about sympathetic innervations of bone tissue (Takeda et al., 2002; Kondo et al., 2005) and its role in the regulation of bone remodelling is of major interest in situations where uncoupling between osteoclasts and osteoblasts occurs (Levasseur et al., 2003).

#### **2.3.2 Spasticity**

Controversial results have also been reported regarding the effect of spasticity on BMD in SCI paraplegics. A cross-sectional study of 41 SCI paraplegics reported less reduction of BMD in the spastic paraplegics SCI patients compared to the flaccid paraplegic SCI patients (Demirel et al., 1998). Others reported that spasticity may be protective against bone loss in SCI patients, however, without any preserving effect in the tibia (Dionyssiotis et al., 2011; Eser et al., 2005). A possible explanation for that could lie in the fact that in the present study all paraplegics were above thoracic (T)12 level with various degrees of spasticity according to the Ashworth scale. In addition, muscle spasms affecting the lower leg would mainly be extension spasms resulting in plantar flexion thus creating little resistance to the contracting muscles. Furthermore, the measuring sites of the tibia did not include any muscle insertions of either the knee or the ankle extensor muscles (Dionyssiotis et al., 2011a; Dionyssiotis, 2011c). Other investigators also have not been able to establish a correlation between BMD and muscle spasticity (Lofvenmark et al., 2009).

#### **3. Multiple sclerosis**

Reduced mobility has been implicated as an important factor in bone loss in patients suffering from multiple sclerosis (MS) and it seems to greatly influence the BMD of the femur. However, the high proportion of ambulatory patients with bone loss suggest additional non-mechanical factors (Cosman et al., 1998; Dionyssiotis, 2011b).

There is a high incidence of vitamin D deficiency in MS patients and is determined by levels of 25-hydroxy vitamin D <20ng/ml (Nieves et al., 1994). The reasons might be due to a combination of low dietary vitamin D intake and avoiding of sun exposure, and that because of MS symptoms may worsen after sun exposure (fatigue-related heat) leading these patients to avoid sun. Low testosterone alone in these populations does not explain bone loss and no clear effect of smoking or alcohol abuse to decreased bone mass could be established (Weinstock-Guttman et al., 2004).

Glucocorticoid (GC)-induced osteoporosis (OP-GC) is the main type of secondary osteoporosis (Canalis et al., 2004; Canalis et al., 2007; Lakatos et al., 2000; Mazziotti et al., 2006; Schwid et al., 1996; Shuhaibar et al., 2009). The mechanism is that excess GC causes a rapid and significant damage to bone quality. Now days we know that GCs act direct on bone mainly to the stromalosteoblastic lineage and at high concentrations alter differentiation, survival, and function of them causing a shift from osteoblastic to adipocytic differentiation of precursors; inducing apoptosis of mature osteoblasts; and inhibition of

independent of supraspinal control and has been termed decentralization of the SNS

Loss of supraspinal control leads to dysregulation of those homeostatic mechanisms normally influenced by the SNS through loss of facilitation or lack of inhibition (Teasell et al., 2000). Today there is clinical evidence that the sympathetic regulation of bone does exist in humans and plays a clinically important role in diseases characterized by excessive sympathetic activity (Schwartzman, 2000). The scientific finding about sympathetic innervations of bone tissue (Takeda et al., 2002; Kondo et al., 2005) and its role in the regulation of bone remodelling is of major interest in situations where uncoupling between

Controversial results have also been reported regarding the effect of spasticity on BMD in SCI paraplegics. A cross-sectional study of 41 SCI paraplegics reported less reduction of BMD in the spastic paraplegics SCI patients compared to the flaccid paraplegic SCI patients (Demirel et al., 1998). Others reported that spasticity may be protective against bone loss in SCI patients, however, without any preserving effect in the tibia (Dionyssiotis et al., 2011; Eser et al., 2005). A possible explanation for that could lie in the fact that in the present study all paraplegics were above thoracic (T)12 level with various degrees of spasticity according to the Ashworth scale. In addition, muscle spasms affecting the lower leg would mainly be extension spasms resulting in plantar flexion thus creating little resistance to the contracting muscles. Furthermore, the measuring sites of the tibia did not include any muscle insertions of either the knee or the ankle extensor muscles (Dionyssiotis et al., 2011a; Dionyssiotis, 2011c). Other investigators also have not been able to establish a correlation between BMD

Reduced mobility has been implicated as an important factor in bone loss in patients suffering from multiple sclerosis (MS) and it seems to greatly influence the BMD of the femur. However, the high proportion of ambulatory patients with bone loss suggest

There is a high incidence of vitamin D deficiency in MS patients and is determined by levels of 25-hydroxy vitamin D <20ng/ml (Nieves et al., 1994). The reasons might be due to a combination of low dietary vitamin D intake and avoiding of sun exposure, and that because of MS symptoms may worsen after sun exposure (fatigue-related heat) leading these patients to avoid sun. Low testosterone alone in these populations does not explain bone loss and no clear effect of smoking or alcohol abuse to decreased bone mass could be

Glucocorticoid (GC)-induced osteoporosis (OP-GC) is the main type of secondary osteoporosis (Canalis et al., 2004; Canalis et al., 2007; Lakatos et al., 2000; Mazziotti et al., 2006; Schwid et al., 1996; Shuhaibar et al., 2009). The mechanism is that excess GC causes a rapid and significant damage to bone quality. Now days we know that GCs act direct on bone mainly to the stromalosteoblastic lineage and at high concentrations alter differentiation, survival, and function of them causing a shift from osteoblastic to adipocytic differentiation of precursors; inducing apoptosis of mature osteoblasts; and inhibition of

additional non-mechanical factors (Cosman et al., 1998; Dionyssiotis, 2011b).

osteoclasts and osteoblasts occurs (Levasseur et al., 2003).

and muscle spasticity (Lofvenmark et al., 2009).

established (Weinstock-Guttman et al., 2004).

(Karlsson et al., 1998).

**2.3.2 Spasticity** 

**3. Multiple sclerosis** 

synthesis and secretion of bone components (Manolagas, 2000; Pereira et al., 2002). Finally, GCs promote ostoclasts and stimulate bone resorption (Weinstein et al., 2002). The mechanisms of GCs action in bone has been studied extensively. In patients receiving chronic per os GC, bone loss is admitted rapidly and is evident within 6 or even 3 months (Cosman et al., 1998). A study investigated the effect of intravenously (i.v.) administration of glucocorticoids in MS patients found no clear effect on bone loss: on the contrary they reported an increase in BMD of the lumbar spine (Schwid et al., 1996). Prolonged treatment with glucocorticoids results in increased risk of fractures, evident at 3 months, regardless of changes in BMD. High dose, short-term i.v. treatment with GCs leads directly to reduction of bone formation and increased bone resorption, as indicated by markers of bone turnover (De Vries et al. 2007; Van Staa et al., 2000). Osteopenia not osteoporosis was significantly more frequent in patients with MS compared with controls, especially in women who received high dose methylprednisolone pulses (HDMP) in relapses period making important the regularly monitoring of BMD in these patients. The authors concluded that disability and the subsequent immobilization osteoporosis is the more serious factor in this group and treatment with repeated HDMP pulses did not cause osteoporosis in MS subjects followed-up for almost 8 years unlike chronic corticosteroid therapy which induces osteoporosis and/or recovery of BMD is permitted without permanent skeletal damage (Zorzon et al., 2005). The lack of physical activity exacerbates osteoporosis. All MS patients should be considered high risk for osteoporosis. Prevention with calcium rich foods and dietary supplements containing vitamin D and antiosteoporotic drugs is necessary for these patients. Particular attention should be paid to transfers and falls prevention in this population to prevent fractures which occur easily and heal slowly (Cattaneo et al., 2007; Dionyssiotis, 2011b).

In osteoporosis molecular mechanisms leading to bone loss are inadequately explained. There is evidence of interaction between bone and immune system. T cells' activity could stimulate bone loss under certain circumstances such as estrogen deficiency. Women with post-menopausal osteoporosis have higher T cell activity than healthy post-menopausal subjects which could be also the case in inflammatory or autoimmune disorders like MS: receptor activator of nuclear factor kappa B ligand (RANKL) stimulates osteoclastogenesis and the same do cytokines, such as TNF-*α*, IL-1, or IL-11, all produced by T-cells activation, leading to bone destruction. On the contrary osteoprotegerin (OPG) is an osteoclastogenesis inhibitory factor preventing the function from RANKL. A balanced system of RANKL/OPG regulates bone metabolism. In MS this system is disturbed in favour of RANKL (Zhao et al., 2008; Kurban et al., 2009).

### **4. Stroke**

Disuse has been suggested as the main cause for loss of bone mass in patients immobilized because of stroke (Takamoto et al., 1995). However, this was not confirmed in a prospective study, in which only weak associations between bone loss and motor function, activities of daily living (ADL), or ambulation were found (Ramnemark et al., 1999a). This could be explained by the selected severely affected patients, but it does raise questions about other risk factors for the development of hemiosteoporosis apart from paresis and immobilization (Ramnemark et al., 1999b).

The critical role in pathogenesis of osteoporosis is attributed to hormonal processes and osteoporosis itself is often defined as generalized skeletal disorder. Findings of tibial bone

Neurological Osteoporosis in Disabilities 285

Children with cerebral palsy (CP) are growing slowly. The impact of this altered growth on skeletal development and bone density is a difference in linear growth which becomes more accentuated over time compared with their typically growing peers. In addition, as growth slows, the bone mineral density also falls further outside the normal range (Houlihan et al., 2009). Significantly decreased bone density is virtually universal in non-ambulatory children with moderate to severe CP after the age of 10 years (Henderson et al., 2002); Bone-mineral content and density were measured in a study by dual energy X-ray absorptiometry in the proximal femur, femoral neck, and total body of nutritionally adequate children (n=17; 11 girls, six boys; aged 7.6 to 13.8 years) with spastic cerebral palsy (CP) and found that nonindependent ambulators had lower z scores for total body BMD, femoral neck BMD, and BMC than independent ambulators (Chad et al., 2000). The potential causes of deficient bone mineralization in this population are multiple, including poor nutrition and abnormal vitamin D metabolism. Findings from recent studies (Shaw et al. 1994, Henderson et al. 1995, Wilmhurst et al. 1996) suggest that non-nutritional factors, such as ambulation, may

contribute to the alterations in body composition observed in children with CP.

**5.1.1 Weight bearing activities-cycling-body weight supported treadmill** 

The effect of standing in bone after SCI has been investigated by many researchers. A beneficial effect on bone mass using passive mechanical loading has been shown on preservation of bone mass in the region of the femoral shaft, but not at the proximal hip of standing and non-standing patients and relatively better-preserved densities in patients standing with braces than in those using a standing frame or standing wheelchair (Goemaere et al., 1994). A slower rate of bone loss in paraplegic subjects who did standing was expressed in a prospective study of 19 patients in acute SCI phase participated in early standing training program showed benefits concerning the reduction of cancellous bone loss compared to immobilized subjects (de Bruin and others 1999; Frey-Rindova and others 2000), while no correlation for passive standing-training to bone status was found in another p QCT study (Eser et al., 2005). Protection afforded by standing in the femoral diaphysis stands in contrast with the loss of bone in the proximal femur. This suggests that the transmission of forces through trabecular and cortical bone varies; so the less effective strain for the initiation of bone remodeling reaches faster cortical bone (Frost, 1992, 2001, 2003). Others also supported the concept of different strain thresholds bone remodeling control (Gutin & Kasper, 1992; LeBlanc et al., 2007; Smith et al., 2009). There is level 2 evidence (from 1 non-randomized prospective controlled trial) that Functional Electrical Stimulation (FES) - cycling did not improve or maintain bone at the tibial midshaft in the acute phase (Eser et al., 2003). Moreover, there is level 4 evidence (from 1 pre-post study) that 6 months of FES cycle ergometry increased regional lower extremity BMD over areas stimulated (Chen et al., 2005). Body weight supported treadmill training (BWSTT) did not alter the expected pattern of change in bone biochemical markers over time and bone density at

At a meeting of the American Society for Bone and Mineral Research results of a small randomised, placebo-controlled study among 20 children with cerebral palsy who used a similar, commercially available vibrating platform for 10 min per day, 5 days per week for 6 months were reported (Ward et al., 2001). A significant increase in tibial, but not lumbar-

**5.1 Interventions to prevent bone loss** 

fracture-prone sites (Giangregorio et al., 2009).

**5.1.2 Whole body vibration** 

changes in hemiplegic patients are not compatible with this view. The adaptations are found in trabecular bone in the epiphysis as well as in cortical bone in the diaphysis. They represent an individually different distribution of local changes which can be explained by the feedback principles of the muscle-bone-unit, in which bone strength is controlled by the muscle forces that act upon the bone. Muscle forces acting habitually on the paretic limb are considerably less than on the opposite side. This reduction of forces reduces the strain on bones. This leads to loss of bone mass and bone strength (Runge et al., 2004).

Determinants of bone mineral loss have been identified as duration of hemiplegia-induced immobilization and severity of palsy (Sato, 1996). A rapid and pronounced loss of BMD in the paretic extremities that progressed during the first year after stroke (Ramnemark et al., 1999a) more pronounced during the first few months after stroke onset (Hamdy et al., 1993). The lower extremities lost BMD bilaterally, but the losses were significant after 12 months in the affected femur, proximal femur and trochanter. In immobile patients, this could explain the loss of BMD in the nonaffected leg as compared with the nonaffected arm, which even increased in BMD, probably due to increased compensatory activity (Ramnemark et al., 1999a).

Hemiosteoporosis has previously been described as being caused by disuse and vitamin D deficiency (Sato et al, 1996), and in a randomized study a significant decrease in the rate of bone loss in stroke patients with a mean duration of 4.8 years after stroke when supplemental vitamin D was given (Sato et al., 1997). Bone mineral loss was more pronounced in the upper than in lower limbs, and the difference between sides was more marked in long-standing poststroke hemiparesis. The upper versus lower difference may reflect that hemiparesis from stroke is commonly more severe in the upper limb. Notably, BMD on the nonhemiplegic side is intermediate between that for the hemiplegic side and that in control subjects. The decrease in mobility of the intact limb, resulting from strokerelated need for assistance with activities of daily living, presumably results in mild osteoporosis paralleling the patient's overall degree of immobilization (Sato et al., 1998, 2000).

#### **5. Myelomeningocele and cerebral palsy**

Previous studies suggest that the level of neurological injury and mobility affect BMD in myelomeningocele (MMC). Studies concluded that loading of the lower limbs rather than child's potential ability to walk because of the level of neurological lesion or residual motor capacity of lower limbs is a prognostic criterion for the BMD (Apkon et al., 2009; Ausili et al., 2008; Quan et al., 1998). This theory is probably challenged by other studies that revealed low values of forearm BMD in individuals and indicate that in this patient osteoporosis can be caused by neurogenic and metabolic mechanisms. The fact is that these patients are loading the arms through the use of crutches and wheelchairs and BMD values in the upper extremities are expected to be higher in relation to immobilized people (Quan et al., 1998). Subjects with MMC may have hypercalciuria associated with immobilization and an additional risk factor for osteoporosis in these patients group (Quan et al., 2003). Others support that low-energetic fractures in MMC children may result from metabolic disturbances that are a consequence of excessive renal calcium loss or excessive fatty tissue content (Okurowska-Zawada et al., 2009).

changes in hemiplegic patients are not compatible with this view. The adaptations are found in trabecular bone in the epiphysis as well as in cortical bone in the diaphysis. They represent an individually different distribution of local changes which can be explained by the feedback principles of the muscle-bone-unit, in which bone strength is controlled by the muscle forces that act upon the bone. Muscle forces acting habitually on the paretic limb are considerably less than on the opposite side. This reduction of forces reduces the strain on

Determinants of bone mineral loss have been identified as duration of hemiplegia-induced immobilization and severity of palsy (Sato, 1996). A rapid and pronounced loss of BMD in the paretic extremities that progressed during the first year after stroke (Ramnemark et al., 1999a) more pronounced during the first few months after stroke onset (Hamdy et al., 1993). The lower extremities lost BMD bilaterally, but the losses were significant after 12 months in the affected femur, proximal femur and trochanter. In immobile patients, this could explain the loss of BMD in the nonaffected leg as compared with the nonaffected arm, which even increased in BMD, probably due to increased compensatory activity (Ramnemark et al.,

Hemiosteoporosis has previously been described as being caused by disuse and vitamin D deficiency (Sato et al, 1996), and in a randomized study a significant decrease in the rate of bone loss in stroke patients with a mean duration of 4.8 years after stroke when supplemental vitamin D was given (Sato et al., 1997). Bone mineral loss was more pronounced in the upper than in lower limbs, and the difference between sides was more marked in long-standing poststroke hemiparesis. The upper versus lower difference may reflect that hemiparesis from stroke is commonly more severe in the upper limb. Notably, BMD on the nonhemiplegic side is intermediate between that for the hemiplegic side and that in control subjects. The decrease in mobility of the intact limb, resulting from strokerelated need for assistance with activities of daily living, presumably results in mild osteoporosis paralleling the patient's overall degree of immobilization (Sato et al., 1998,

Previous studies suggest that the level of neurological injury and mobility affect BMD in myelomeningocele (MMC). Studies concluded that loading of the lower limbs rather than child's potential ability to walk because of the level of neurological lesion or residual motor capacity of lower limbs is a prognostic criterion for the BMD (Apkon et al., 2009; Ausili et al., 2008; Quan et al., 1998). This theory is probably challenged by other studies that revealed low values of forearm BMD in individuals and indicate that in this patient osteoporosis can be caused by neurogenic and metabolic mechanisms. The fact is that these patients are loading the arms through the use of crutches and wheelchairs and BMD values in the upper extremities are expected to be higher in relation to immobilized people (Quan et al., 1998). Subjects with MMC may have hypercalciuria associated with immobilization and an additional risk factor for osteoporosis in these patients group (Quan et al., 2003). Others support that low-energetic fractures in MMC children may result from metabolic disturbances that are a consequence of excessive renal calcium loss or excessive fatty tissue

bones. This leads to loss of bone mass and bone strength (Runge et al., 2004).

1999a).

2000).

**5. Myelomeningocele and cerebral palsy** 

content (Okurowska-Zawada et al., 2009).

Children with cerebral palsy (CP) are growing slowly. The impact of this altered growth on skeletal development and bone density is a difference in linear growth which becomes more accentuated over time compared with their typically growing peers. In addition, as growth slows, the bone mineral density also falls further outside the normal range (Houlihan et al., 2009). Significantly decreased bone density is virtually universal in non-ambulatory children with moderate to severe CP after the age of 10 years (Henderson et al., 2002); Bone-mineral content and density were measured in a study by dual energy X-ray absorptiometry in the proximal femur, femoral neck, and total body of nutritionally adequate children (n=17; 11 girls, six boys; aged 7.6 to 13.8 years) with spastic cerebral palsy (CP) and found that nonindependent ambulators had lower z scores for total body BMD, femoral neck BMD, and BMC than independent ambulators (Chad et al., 2000). The potential causes of deficient bone mineralization in this population are multiple, including poor nutrition and abnormal vitamin D metabolism. Findings from recent studies (Shaw et al. 1994, Henderson et al. 1995, Wilmhurst et al. 1996) suggest that non-nutritional factors, such as ambulation, may contribute to the alterations in body composition observed in children with CP.

#### **5.1 Interventions to prevent bone loss**

### **5.1.1 Weight bearing activities-cycling-body weight supported treadmill**

The effect of standing in bone after SCI has been investigated by many researchers. A beneficial effect on bone mass using passive mechanical loading has been shown on preservation of bone mass in the region of the femoral shaft, but not at the proximal hip of standing and non-standing patients and relatively better-preserved densities in patients standing with braces than in those using a standing frame or standing wheelchair (Goemaere et al., 1994). A slower rate of bone loss in paraplegic subjects who did standing was expressed in a prospective study of 19 patients in acute SCI phase participated in early standing training program showed benefits concerning the reduction of cancellous bone loss compared to immobilized subjects (de Bruin and others 1999; Frey-Rindova and others 2000), while no correlation for passive standing-training to bone status was found in another p QCT study (Eser et al., 2005). Protection afforded by standing in the femoral diaphysis stands in contrast with the loss of bone in the proximal femur. This suggests that the transmission of forces through trabecular and cortical bone varies; so the less effective strain for the initiation of bone remodeling reaches faster cortical bone (Frost, 1992, 2001, 2003). Others also supported the concept of different strain thresholds bone remodeling control (Gutin & Kasper, 1992; LeBlanc et al., 2007; Smith et al., 2009). There is level 2 evidence (from 1 non-randomized prospective controlled trial) that Functional Electrical Stimulation (FES) - cycling did not improve or maintain bone at the tibial midshaft in the acute phase (Eser et al., 2003). Moreover, there is level 4 evidence (from 1 pre-post study) that 6 months of FES cycle ergometry increased regional lower extremity BMD over areas stimulated (Chen et al., 2005). Body weight supported treadmill training (BWSTT) did not alter the expected pattern of change in bone biochemical markers over time and bone density at fracture-prone sites (Giangregorio et al., 2009).

### **5.1.2 Whole body vibration**

At a meeting of the American Society for Bone and Mineral Research results of a small randomised, placebo-controlled study among 20 children with cerebral palsy who used a similar, commercially available vibrating platform for 10 min per day, 5 days per week for 6 months were reported (Ward et al., 2001). A significant increase in tibial, but not lumbar-

Neurological Osteoporosis in Disabilities 287

Fig. 4. The Galileo Delta A TiltTable offers a wide variety of applications from relaxation to muscle training for a diverse range of patients who are unable to stand without support. The

Calcitonin in varying doses and methods of administration has given variable results in paraplegia (preferred dosage regimen, treatment duration, and administration route for adequate efficacy in SCI patients' remains unclear) (Chantraine et al., 1979a; Minaire, 1987). Likewise, the outcome using bisphosphonates has been variable. Etidronate produced longterm benefit in lower limb bone mineral density (BMD) in selected walking SCI patients (Roux et al., 1998); whereas tiludronate appeared effective in reducing bone resorption and preserving bone mass in a histomorphometric study in 20 paraplegic patients (Chappard et al., 1995). Intravenous pamidronate has been shown to attenuate bone loss in SCI and normalize serum calcium in immobilization hypercalcemia (Bauman et al., 2005). Alendronate (1000 times more potent than etidronate), in an open observational study, reversed BMD loss in men with established SCI increased both axial and trabecular bone density and has proven efficacy and safety in men treated for osteoporosis, prevents hypercalciuria and bone loss after bed rest and lower leg fracture (Moran de Brito et al., 2005; Zehnder et al., 2004). Six months after using zolendronic acid in the treatment group BMD showed differences in the response to treatment between the mixed trabecular/

motor driven adjustable tilt angle of the Galileo Delta TiltTable (90°) allows vibration training with reduced body weight from 0 to 100%. This is ideal for deconditioned and disabled patients for gradually increasing training weights up to full body weight. System for application in adults (max. body height: 1.90 m) and children (max. body height: 1.50 m).The Galileo Delta A TiltTable is exclusively available from the manufacturer Novotec

Medical GmbH., (with permission).

**5.1.3 Drugs** 

spine bone density in the treated group was found despite the simplicity, short duration of the "vibration", the young age of the children and the poor compliance (Eisman, 2001).

Fig. 3. Weight bearing in disabled subjects; using standing frames, functional walking with orthoses between bars and crutches, even push-ups in the wheelchair (in case of multiple sclerosis with a clinical equivalent like tetraplegia) bone can be loaded and bone loss rate would be slower (unpublished photos of Dionyssiotis Y).

After 6 months of whole body vibration (WBV) therapy in twenty children with cerebral palsy (age 6.2 to 12.3 years; 6 girls) randomized to either continue their school physiotherapy program unchanged or to receive 9 minutes of side-alternating WBV (Vibraflex Home Edition II®, Orthometrix Inc) not effect on areal BMD at the lumbar spine was observed, while areal BMD seemed to decrease somewhat in the cortical region of the femoral diaphysis. Authors explained that mechanical stimulation increases intracortical bone remodeling and thereby cortical porosity; moreover changes occurred in ways that are not reflected by areal BMD, but might be detectable by more sophisticated techniques such as such as peripheral quantitative computed tomography (Ruck et al., 2010). Low-intensity vibration (LIV) has shown to be associated with improvement in bone mineral density in post-menopausal women and children with cerebral palsy. Seven non-ambulatory subjects with SCI and ten able-bodied controls underwent transmission of a plantar-based LIV signal (0.27 +/- 0.11 g; 34 Hz) from the feet through the axial skeleton as a function of tilt-table angle (15, 30, and 45 degrees). SCI subjects and controls demonstrated equivalent transmission of LIV, with greater signal transmission observed at steeper angles of tilt which supports the possibility of the utility of LIV as a means to deliver mechanical signals in a form of therapeutic intervention to prevent/reverse skeletal fragility in the SCI population (Asselin et al., 2011).

spine bone density in the treated group was found despite the simplicity, short duration of the "vibration", the young age of the children and the poor compliance (Eisman, 2001).

Fig. 3. Weight bearing in disabled subjects; using standing frames, functional walking with orthoses between bars and crutches, even push-ups in the wheelchair (in case of multiple sclerosis with a clinical equivalent like tetraplegia) bone can be loaded and bone loss rate

After 6 months of whole body vibration (WBV) therapy in twenty children with cerebral palsy (age 6.2 to 12.3 years; 6 girls) randomized to either continue their school physiotherapy program unchanged or to receive 9 minutes of side-alternating WBV (Vibraflex Home Edition II®, Orthometrix Inc) not effect on areal BMD at the lumbar spine was observed, while areal BMD seemed to decrease somewhat in the cortical region of the femoral diaphysis. Authors explained that mechanical stimulation increases intracortical bone remodeling and thereby cortical porosity; moreover changes occurred in ways that are not reflected by areal BMD, but might be detectable by more sophisticated techniques such as such as peripheral quantitative computed tomography (Ruck et al., 2010). Low-intensity vibration (LIV) has shown to be associated with improvement in bone mineral density in post-menopausal women and children with cerebral palsy. Seven non-ambulatory subjects with SCI and ten able-bodied controls underwent transmission of a plantar-based LIV signal (0.27 +/- 0.11 g; 34 Hz) from the feet through the axial skeleton as a function of tilt-table angle (15, 30, and 45 degrees). SCI subjects and controls demonstrated equivalent transmission of LIV, with greater signal transmission observed at steeper angles of tilt which supports the possibility of the utility of LIV as a means to deliver mechanical signals in a form of therapeutic intervention to

prevent/reverse skeletal fragility in the SCI population (Asselin et al., 2011).

would be slower (unpublished photos of Dionyssiotis Y).

Fig. 4. The Galileo Delta A TiltTable offers a wide variety of applications from relaxation to muscle training for a diverse range of patients who are unable to stand without support. The motor driven adjustable tilt angle of the Galileo Delta TiltTable (90°) allows vibration training with reduced body weight from 0 to 100%. This is ideal for deconditioned and disabled patients for gradually increasing training weights up to full body weight. System for application in adults (max. body height: 1.90 m) and children (max. body height: 1.50 m).The Galileo Delta A TiltTable is exclusively available from the manufacturer Novotec Medical GmbH., (with permission).

### **5.1.3 Drugs**

Calcitonin in varying doses and methods of administration has given variable results in paraplegia (preferred dosage regimen, treatment duration, and administration route for adequate efficacy in SCI patients' remains unclear) (Chantraine et al., 1979a; Minaire, 1987). Likewise, the outcome using bisphosphonates has been variable. Etidronate produced longterm benefit in lower limb bone mineral density (BMD) in selected walking SCI patients (Roux et al., 1998); whereas tiludronate appeared effective in reducing bone resorption and preserving bone mass in a histomorphometric study in 20 paraplegic patients (Chappard et al., 1995). Intravenous pamidronate has been shown to attenuate bone loss in SCI and normalize serum calcium in immobilization hypercalcemia (Bauman et al., 2005). Alendronate (1000 times more potent than etidronate), in an open observational study, reversed BMD loss in men with established SCI increased both axial and trabecular bone density and has proven efficacy and safety in men treated for osteoporosis, prevents hypercalciuria and bone loss after bed rest and lower leg fracture (Moran de Brito et al., 2005; Zehnder et al., 2004). Six months after using zolendronic acid in the treatment group BMD showed differences in the response to treatment between the mixed trabecular/

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cortical regions (narrow neck and intertrochanteric) and the purely cortical shaft. With respect to cross-sectional geometry, bone cross-sectional area and sectional modulus (indices of resistance to axial and bending loads, where higher values would indicate a positive effect of treatment) increased at the hip and buckling ratio (an index of the instability of thin-walled cross sections, where lower values would suggest that the treatment is improving stability) decreased consistent with improved bone outcomes; at 12 months, narrow-neck femur values declined and intertrochanteric and femoral shaft BMD was maintained vs. placebo group which showed a decrease in bone outcomes and an increase in buckling ratio at the hip at 6 and 12 months, while with respect to bone prevention 4 mg i.v. were effective and well-tolerated to prevent BMD loss at the total hip and trochanter for up to 12 months following SCI (Bubbear et al; Shapiro et al., 2007).


Table 1. An algorithm for the screening and management of osteoporosis in subjects with spinal cord injury (should be read top to bottom starting with the left column); adapted from: Dionyssiotis Y. (2009). Bone loss in paraplegia: A diagnostic and therapeutic protocol. Osteoporos Int Vol. 20 (Suppl 1):S23-S176 (with permission).

### **6. References**

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cortical regions (narrow neck and intertrochanteric) and the purely cortical shaft. With respect to cross-sectional geometry, bone cross-sectional area and sectional modulus (indices of resistance to axial and bending loads, where higher values would indicate a positive effect of treatment) increased at the hip and buckling ratio (an index of the instability of thin-walled cross sections, where lower values would suggest that the treatment is improving stability) decreased consistent with improved bone outcomes; at 12 months, narrow-neck femur values declined and intertrochanteric and femoral shaft BMD was maintained vs. placebo group which showed a decrease in bone outcomes and an increase in buckling ratio at the hip at 6 and 12 months, while with respect to bone prevention 4 mg i.v. were effective and well-tolerated to prevent BMD loss at the total hip and trochanter for up

**Clinical examination and management of bone loss in SCI**

Table 1. An algorithm for the screening and management of osteoporosis in subjects with spinal cord injury (should be read top to bottom starting with the left column); adapted from: Dionyssiotis Y. (2009). Bone loss in paraplegia: A diagnostic and therapeutic protocol.

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**16** 

*Spain* 

**Post-Transplantation Bone Disease** 

*Metabolic Unit, Endocrine Service, University Hospital 12 de Octubre,* 

Solid organ or stem cell transplantation is a well established procedure in the treatment of endstage diseases (renal disease, chronic liver failure, end-stage pulmonary disease, heart failure). Improved outcome for these patients has allowed us to study some of the complications. One of these is metabolic bone disease, which can hinder their long-term survival and quality of life. In this chapter we have review our current understanding of the pathophysiology of bone loss before and after solid organ transplantation, and review recommendations for the prevention and treatment of osteoporosis in patients accepted into organ transplantation programs. There are a number of risk factors contributing to bone loss in these patients: hypogonadism, vitamin D deficiency, malabsorption, low body weight, physical inactivity, excessive use of tobacco or alcohol and immunosuppressive therapy. Management of pretransplant risk factors has improved, resulting in better bone mineral density (BMD) levels before transplantation (Guichelaar et al., 2006). After transplantation, rapid and marked bone loss is observed in the first 3-6 months. The speed of the bone loss suggests that corticosteroids are heavily involved. Greater bone loss at vertebral and hip sites and high rates of incident

Many factors contribute to the pathogenesis of osteoporosis after organ transplantation. These include bone disease preceding transplantation, immunosuppressive medications, nutritional and lifestyle factors, and derangements of the parathyroid-calcium-vitamin D and the pituitary gonadal axes (Table 1). However, specific pathophysiological features can

End-stage renal disease (ESRD) is associated with a form of bone disease that is generically referred as "renal osteodystrophy". Many mechanisms are involved in its pathophysiology including calcitriol deficiency, hypocalcemia, hyperphosphatemia, secondary hyperparathyroidism, metabolic acidosis, and aluminum overload. Kidney transplantation will improve many aspects of renal osteodystrophy, but parathyroid hyperplasia may not

fragility fractures have been reported (Leidig-Bruckner et al., 2001).

also be found in different forms of end-stage diseases.

regress even when normal kidney function returns.

**1. Introduction** 

**2. Pathogenetic factors** 

**2.1 Pre-existing bone disease** 

**2.1.1 Kidney disease** 

Federico G. Hawkins, Sonsoles Guadalix, Raquel Sanchez and Guillermo Martínez

*Faculty of Medicine University Complutense, Madrid,* 


## **Post-Transplantation Bone Disease**

Federico G. Hawkins, Sonsoles Guadalix, Raquel Sanchez and Guillermo Martínez *Metabolic Unit, Endocrine Service, University Hospital 12 de Octubre, Faculty of Medicine University Complutense, Madrid, Spain* 

### **1. Introduction**

298 Osteoporosis

Zhao, W., Liu, Y., Cahill. C.M., Yang. W., Rogers. J.T. & Huang. X. (2009). The role of T cells in osteoporosis, an update. *Int J Clin Exp Pathol,* Vol.20, No.2, pp.544-552. Zorzon, M., Zivadinov, R., Locatelli, L., Giuntini, D., Toncic, M., Bosco, A., Nasuelli, D.,

patients with multiple sclerosis. *Eur J Neurol,* Vol. 12, No. 7, pp. 550-556.

Bratina, A., Tommasi, M.A., Rudick, R.A & Cazzato, G. (2005). Long-term effects of intravenous high dose methylprednisolone pulses on bone mineral density in

> Solid organ or stem cell transplantation is a well established procedure in the treatment of endstage diseases (renal disease, chronic liver failure, end-stage pulmonary disease, heart failure). Improved outcome for these patients has allowed us to study some of the complications. One of these is metabolic bone disease, which can hinder their long-term survival and quality of life. In this chapter we have review our current understanding of the pathophysiology of bone loss before and after solid organ transplantation, and review recommendations for the prevention and treatment of osteoporosis in patients accepted into organ transplantation programs. There are a number of risk factors contributing to bone loss in these patients: hypogonadism, vitamin D deficiency, malabsorption, low body weight, physical inactivity, excessive use of tobacco or alcohol and immunosuppressive therapy. Management of pretransplant risk factors has improved, resulting in better bone mineral density (BMD) levels before transplantation (Guichelaar et al., 2006). After transplantation, rapid and marked bone loss is observed in the first 3-6 months. The speed of the bone loss suggests that corticosteroids are heavily involved. Greater bone loss at vertebral and hip sites and high rates of incident fragility fractures have been reported (Leidig-Bruckner et al., 2001).

### **2. Pathogenetic factors**

Many factors contribute to the pathogenesis of osteoporosis after organ transplantation. These include bone disease preceding transplantation, immunosuppressive medications, nutritional and lifestyle factors, and derangements of the parathyroid-calcium-vitamin D and the pituitary gonadal axes (Table 1). However, specific pathophysiological features can also be found in different forms of end-stage diseases.

### **2.1 Pre-existing bone disease**

### **2.1.1 Kidney disease**

End-stage renal disease (ESRD) is associated with a form of bone disease that is generically referred as "renal osteodystrophy". Many mechanisms are involved in its pathophysiology including calcitriol deficiency, hypocalcemia, hyperphosphatemia, secondary hyperparathyroidism, metabolic acidosis, and aluminum overload. Kidney transplantation will improve many aspects of renal osteodystrophy, but parathyroid hyperplasia may not regress even when normal kidney function returns.

Post-Transplantation Bone Disease 301

There are several histological subtypes of renal osteodystrophy. The most common is osteitis fibrosa, characterized by increased bone turnover and typically associated with high serum PTH levels (secondary hyperparathyroidism). Osteomalacia is the least common type, with low bone formation and accumulation of unmineralized osteoid. A mixed disease of both, combining increased resorption and increased osteoid, can also exist. Adynamic

Compared to the general population ESRD patients are 4.4 fold more likely to have a hip fracture and the prevalence of vertebral fracture is 21% higher (Alem et al., 2000). Some of the risk factors for fractures in general population are also seen in patients with renal osteodystrophy: older age, female gender, or low body weight. Specific risk factors in endstage renal patients are duration of dialysis and peripheral vascular disease (Sethman-Breen et al., 2000).Although BMD in patients with renal osteodystrophy tends to be lower in cortical sites (forearm and hip) than cancellous sites (spine), there is not a clear relationship between the different histological types of renal osteodystrophy and bone density (Gerakis et al., 2000). Furthermore, BMD does not consistently predict fractures after kidney transplantation (Grotz et al., 1994). It is important to note that measurement of bone mineral density (BMD) and WHO criteria cannot be used to diagnose osteoporosis in patients with ESRD. This is because any of the several possible histological forms of renal bone disease

Patients who are candidates for lung transplantation are highly likely to have osteoporosis before surgery. A retrospective study in patients with diffuse parenchymal lung disease referred for lung transplantation revealed that 30% and 49% of patients had lumbar or femoral osteoporosis respectively (Shane et al., 1996). Other authors found osteoporosis in 50% of the patients at lumbar spine and 61% at femoral neck (Tschopp et al., 2002). Several risk factors such as hypoxemia, malnutrition, vitamin D deficiency, smoking, decreased immobility and low body weight are involved. Cystic fibrosis is associated with additional risk factors such as hypogonadism, inflammatory bone-resorbing cytokines and pancreatic insufficiency that may impair the absorption of calcium and Vitamin D. In addition, most of the patients who undergo lung transplantation have experienced prior glucocorticoid

Osteoporosis and osteopenia are common in patients with severe congestive heart failure (CHF). Lumbar spine osteopenia has been found in 43% of patients, and spine osteoporosis (T-score ≤ -2.5 or Z-score ≤-2.0) in 12-40% of patients. Biochemical markers of bone turnover suggest the presence of increased bone resorption. Involved factors that contribute to bone loss include low serum 25-OH vitamin D, hypogonadism, immobilization and loop diuretic use. Long-term therapy with heparin has been associated with bone loss and vertebral fractures. However, in CHF oral anticoagulants (warfarin) usually are used chronically instead of heparin. Warfarin blocks vitamin K-dependent gamma-carboxylation of osteocalcin and impairs its binding with calcium. Secondary hyperparathyroidism may occur due to impaired renal function and abnormal vitamin D metabolism. Hypogonadotropic hypogonadism appears to be very common in males with CHF. Up to

bone disease is characterized by low bone formation without evidence of fibrosis.

may all be associated with low, normal or even elevated BMD.

**2.1.2 Lung disease** 

therapy (Tschopp et al., 2002).

**2.1.3 Cardiac disease** 


Table 1. Risk Factors contributing to bone fragility before transplantation

Vitamin D Deficiency and secondary Hyperparathyroidism

**General Risk factors** 

Inactivity / Immobilization

**End Stage Renal Disease** 

Adinamic bone disease

Mixed Uremic disease Metabolic Acidosis

Long term hemodyalysis


Chronic use of glucocorticoids

Pancreatic insufficiency (cystic fibrosis).

Medication: loop diuretics, heparin and warfarin.

Failure to attain peak bone mass (in patients who have cystic fibrosis).

Failure to attain peak bone mass (in patients with congenital heart disease).

Table 1. Risk Factors contributing to bone fragility before transplantation

Diabetic nephropathy

Medications: loop diuretics, heparin and warfarin.

Secondary hyperparathyroidism

Hypogonadism

Poor Nutrition Low body weight

Osteomalacia

Smoking

Hypercapnia Hypoxia

**Heart failure** 

Alcohol abuse

Chemotherapy

Mild renal insufficiency

**End-Stage Liver Disease** 

Cholestatic liver disease

**Bone marrow transplant recipients**  Chronic use of glucocorticoids

Growth hormone deficiency (in children)

There are several histological subtypes of renal osteodystrophy. The most common is osteitis fibrosa, characterized by increased bone turnover and typically associated with high serum PTH levels (secondary hyperparathyroidism). Osteomalacia is the least common type, with low bone formation and accumulation of unmineralized osteoid. A mixed disease of both, combining increased resorption and increased osteoid, can also exist. Adynamic bone disease is characterized by low bone formation without evidence of fibrosis.

Compared to the general population ESRD patients are 4.4 fold more likely to have a hip fracture and the prevalence of vertebral fracture is 21% higher (Alem et al., 2000). Some of the risk factors for fractures in general population are also seen in patients with renal osteodystrophy: older age, female gender, or low body weight. Specific risk factors in endstage renal patients are duration of dialysis and peripheral vascular disease (Sethman-Breen et al., 2000).Although BMD in patients with renal osteodystrophy tends to be lower in cortical sites (forearm and hip) than cancellous sites (spine), there is not a clear relationship between the different histological types of renal osteodystrophy and bone density (Gerakis et al., 2000). Furthermore, BMD does not consistently predict fractures after kidney transplantation (Grotz et al., 1994). It is important to note that measurement of bone mineral density (BMD) and WHO criteria cannot be used to diagnose osteoporosis in patients with ESRD. This is because any of the several possible histological forms of renal bone disease may all be associated with low, normal or even elevated BMD.

### **2.1.2 Lung disease**

Patients who are candidates for lung transplantation are highly likely to have osteoporosis before surgery. A retrospective study in patients with diffuse parenchymal lung disease referred for lung transplantation revealed that 30% and 49% of patients had lumbar or femoral osteoporosis respectively (Shane et al., 1996). Other authors found osteoporosis in 50% of the patients at lumbar spine and 61% at femoral neck (Tschopp et al., 2002). Several risk factors such as hypoxemia, malnutrition, vitamin D deficiency, smoking, decreased immobility and low body weight are involved. Cystic fibrosis is associated with additional risk factors such as hypogonadism, inflammatory bone-resorbing cytokines and pancreatic insufficiency that may impair the absorption of calcium and Vitamin D. In addition, most of the patients who undergo lung transplantation have experienced prior glucocorticoid therapy (Tschopp et al., 2002).

#### **2.1.3 Cardiac disease**

Osteoporosis and osteopenia are common in patients with severe congestive heart failure (CHF). Lumbar spine osteopenia has been found in 43% of patients, and spine osteoporosis (T-score ≤ -2.5 or Z-score ≤-2.0) in 12-40% of patients. Biochemical markers of bone turnover suggest the presence of increased bone resorption. Involved factors that contribute to bone loss include low serum 25-OH vitamin D, hypogonadism, immobilization and loop diuretic use. Long-term therapy with heparin has been associated with bone loss and vertebral fractures. However, in CHF oral anticoagulants (warfarin) usually are used chronically instead of heparin. Warfarin blocks vitamin K-dependent gamma-carboxylation of osteocalcin and impairs its binding with calcium. Secondary hyperparathyroidism may occur due to impaired renal function and abnormal vitamin D metabolism. Hypogonadotropic hypogonadism appears to be very common in males with CHF. Up to

Post-Transplantation Bone Disease 303

In the past two decades significant changes have occurred in the management of chronic liver disease, the waiting time for transplantation and immunosuppressive therapy. Recently an improvement in lumbar spine BMD T-scores pretransplant from -2.5 before 1990 to -1.7 after 1996 has been described (Guichelaar et al., 2006). This data can help to clarify the etiology of bone loss: the severity of liver disease has not changed, the duration of disease before transplantation has been extended and patients can reach older ages. However, nutritional status has improved and bilirubin values decreased. These factors may have

Bone marrow transplant (BMT) recipients have many known risk factors for developing bone loss: Failure to attain peak bone mass in children and adolescents, hypogonadism, inactivity and induction and consolidation regimens with high dose of chemotherapy, glucocorticoids and irradiation that may damage bone marrow stromal cells and colonyforming unit fibroblast , reducing osteoblastic differentiation. A study in patients before BMT (after chemotherapy) show osteopenia in 24% and osteoporosis in only 4% (Schulte et

Early bone loss has been observed in all solid organ transplants in the first 3 to 6 months, increasing the incidence of osteoporosis and osteopenia (Rodino et al., 1998; Leidig-Bruckner et al., 2001; Eastell et al., 1991). Bone loss primarily affects the spine and proximal femur. Some authors found greater impairment at this level (Keogh et al., 1999; Ninkovic et al., 2002). In patients who already have osteopenia or osteoporosis, this subsequent bone loss can result in a higher number of fractures (Eastell et al.., 1991; Leidig-Bruckner et al., 2001). Traditionally, it has been assumed that high doses of glucocorticoids required for immunosuppression play a major role in this loss. High doses (≥ 1 mg/kg/day) are commonly prescribed immediately after transplantation, with gradual dose reduction over several weeks or months. Total GCs exposure depends on the transplanted organ, number

The natural history of post-transplantation osteoporosis suggests that there are two main phases: the early one and the late one. The factors affecting the skeleton differ between this

The mechanisms associated with bone loss due to glucocorticoid treatment in the first phase

1) An increase in bone resorption as a result of increased urinary calcium, decrease in intestinal calcium absorption, secondary hyperparathyroidism and hypogonadotropic hypogonadism; 2) Activation of osteoclastogenesis caused by increase of RANKL and decrease of osteoprotegerin (OPG). 3) Corticosteroid treatment decrease the proliferation and function of osteoblasts (by inhibiting the gene expression of osteocalcin, collagen type 1

In addition to their direct effects on bone tissue, glucocorticoids can induce severe myopathy, impairing balance and mobility, decreasing weight-bearing activity and

**2.2 Related to transplantation: Immunossupressor drugs and other factors** 

of rejection episodes, and different immunosupressive regimens.

and IGF-I) and induces its apoptosis (Canalis et al., 2002). **(Fig 1)** 

contributed to increase BMD before transplantation.

**2.1.5 Bone marrow** 

**2.2.1 Glucocorticoids** 

al., 2000).

two phases.

are (Table 3):

increasing fall risk and fractures.

30% of males with CHF evaluated before transplantation have low levels of testosterone, and this proportion could further increase after cardiac transplantation (Cohen et al., 2003). We have found that trabecular bone loss was related to pretransplantation time of waiting. Also bone resorption markers were increased at this stage reflecting a high bone turnover (Garcia Delgado et al., 2000).

#### **2.1.4 Liver disease**

Osteoporosis and osteopenia are frequent complications of chronic liver disease. Its prevalence is high in patients waiting for liver transplant, especially in cholestatic liver disease. In the most important series, densitometric osteoporosis has been described between 31% to 44% (Lopez et al., 1993, Newton et al., 2001, Solerio et al., 2003;Ninkovic et al., 2001; Guichelaar et al.., 2006).

A low bone turnover state has been found in biochemical measurements and histomorphometric analysis (Diamond et al., 1989). Osteocalcin levels are low and correlate with bone formation rate on bone biopsies, and show increases after successful transplantation. However, some reports describe increases in parameters reflecting bone resorption (osteoclast number and bone resorption surface) (Cuthbert et al., 1984).

Reduced bone formation has been related to several toxic factors that could inhibit osteoblast function as excessive alcohol intake or hyperbilirrubinemia. Also a lower IGF-1 sinthesis, that has a direct trophic action upon the osteoblast could be involved. Glucocorticoid used simultaneously reduces bone formation and increases bone resorption. Vitamin D metabolism plays a pivotal role. Patients with end-stage liver disease frequently have low serum levels of 25(OH) vitamin D, since 25-hydroxylation of colecalciferol occurs at the hepatocyte. Fat malabsorption also decreases 25 (OH) vitamin D. In addition, increased vitamin D catabolism, reduced levels of vitamin D-binding protein (DBP), or reduced sunlight exposure can further decrease vitamin D serum levels. However, true osteomalacia is rare in cirrhotic patients (Table 2). Typically, successful liver transplantation reverses most of these factors. Hypogonadism frequently associated in these patients, could be partially responsible for the increased bone resorption.


Table 2. Involved factors in hepatic osteodystrophy.

30% of males with CHF evaluated before transplantation have low levels of testosterone, and this proportion could further increase after cardiac transplantation (Cohen et al., 2003). We have found that trabecular bone loss was related to pretransplantation time of waiting. Also bone resorption markers were increased at this stage reflecting a high bone turnover

Osteoporosis and osteopenia are frequent complications of chronic liver disease. Its prevalence is high in patients waiting for liver transplant, especially in cholestatic liver disease. In the most important series, densitometric osteoporosis has been described between 31% to 44% (Lopez et al., 1993, Newton et al., 2001, Solerio et al., 2003;Ninkovic et

A low bone turnover state has been found in biochemical measurements and histomorphometric analysis (Diamond et al., 1989). Osteocalcin levels are low and correlate with bone formation rate on bone biopsies, and show increases after successful transplantation. However, some reports describe increases in parameters reflecting bone

Reduced bone formation has been related to several toxic factors that could inhibit osteoblast function as excessive alcohol intake or hyperbilirrubinemia. Also a lower IGF-1 sinthesis, that has a direct trophic action upon the osteoblast could be involved. Glucocorticoid used simultaneously reduces bone formation and increases bone resorption. Vitamin D metabolism plays a pivotal role. Patients with end-stage liver disease frequently have low serum levels of 25(OH) vitamin D, since 25-hydroxylation of colecalciferol occurs at the hepatocyte. Fat malabsorption also decreases 25 (OH) vitamin D. In addition, increased vitamin D catabolism, reduced levels of vitamin D-binding protein (DBP), or reduced sunlight exposure can further decrease vitamin D serum levels. However, true osteomalacia is rare in cirrhotic patients (Table 2). Typically, successful liver transplantation reverses most of these factors. Hypogonadism frequently associated in these patients, could

resorption (osteoclast number and bone resorption surface) (Cuthbert et al., 1984).

be partially responsible for the increased bone resorption.

Reducing bone formation:






Table 2. Involved factors in hepatic osteodystrophy.

(Garcia Delgado et al., 2000).

al., 2001; Guichelaar et al.., 2006).

**2.1.4 Liver disease** 

In the past two decades significant changes have occurred in the management of chronic liver disease, the waiting time for transplantation and immunosuppressive therapy. Recently an improvement in lumbar spine BMD T-scores pretransplant from -2.5 before 1990 to -1.7 after 1996 has been described (Guichelaar et al., 2006). This data can help to clarify the etiology of bone loss: the severity of liver disease has not changed, the duration of disease before transplantation has been extended and patients can reach older ages. However, nutritional status has improved and bilirubin values decreased. These factors may have contributed to increase BMD before transplantation.

### **2.1.5 Bone marrow**

Bone marrow transplant (BMT) recipients have many known risk factors for developing bone loss: Failure to attain peak bone mass in children and adolescents, hypogonadism, inactivity and induction and consolidation regimens with high dose of chemotherapy, glucocorticoids and irradiation that may damage bone marrow stromal cells and colonyforming unit fibroblast , reducing osteoblastic differentiation. A study in patients before BMT (after chemotherapy) show osteopenia in 24% and osteoporosis in only 4% (Schulte et al., 2000).

### **2.2 Related to transplantation: Immunossupressor drugs and other factors 2.2.1 Glucocorticoids**

Early bone loss has been observed in all solid organ transplants in the first 3 to 6 months, increasing the incidence of osteoporosis and osteopenia (Rodino et al., 1998; Leidig-Bruckner et al., 2001; Eastell et al., 1991). Bone loss primarily affects the spine and proximal femur. Some authors found greater impairment at this level (Keogh et al., 1999; Ninkovic et al., 2002). In patients who already have osteopenia or osteoporosis, this subsequent bone loss can result in a higher number of fractures (Eastell et al.., 1991; Leidig-Bruckner et al., 2001). Traditionally, it has been assumed that high doses of glucocorticoids required for immunosuppression play a major role in this loss. High doses (≥ 1 mg/kg/day) are commonly prescribed immediately after transplantation, with gradual dose reduction over several weeks or months. Total GCs exposure depends on the transplanted organ, number of rejection episodes, and different immunosupressive regimens.

The natural history of post-transplantation osteoporosis suggests that there are two main phases: the early one and the late one. The factors affecting the skeleton differ between this two phases.

The mechanisms associated with bone loss due to glucocorticoid treatment in the first phase are (Table 3):

1) An increase in bone resorption as a result of increased urinary calcium, decrease in intestinal calcium absorption, secondary hyperparathyroidism and hypogonadotropic hypogonadism; 2) Activation of osteoclastogenesis caused by increase of RANKL and decrease of osteoprotegerin (OPG). 3) Corticosteroid treatment decrease the proliferation and function of osteoblasts (by inhibiting the gene expression of osteocalcin, collagen type 1 and IGF-I) and induces its apoptosis (Canalis et al., 2002). **(Fig 1)** 

In addition to their direct effects on bone tissue, glucocorticoids can induce severe myopathy, impairing balance and mobility, decreasing weight-bearing activity and increasing fall risk and fractures.

Post-Transplantation Bone Disease 305

Follistatin and Dan), while others act as Wnt antagonist: Frizzled-related protein (sFRP), Dickkopf (Dkk) and Cerberus. Glucocorticoids can affect these signaling pathways, but the exact mechanisms are not been clarified. Recent studies suggest that glucocorticoids induce an alteration in osteoblast function by increasing Wnt antagonists with the subsequent suppression of this pathway. Recent reseach has shown that dexametasone, increases follistatin and DAN (BMP antagonists), sFRP-1(Wnt antagonist) and axin-2 (inhibitor of Wnt signal) . Simultaneously, alendronate and PTH (1-34), which have demostrated to be effective in the treatment of steroid osteoporosis, were able to antagonize the increase in this

The potential impact of glucocorticoid dose as a determinant of bone loss is supported by the absence of bone loss at the lumbar spine and proximal femur in renal transplant patients treated with low doses of steroids and tacrolimus (Goffin et al., 2001). We have previously reported that steroid withdrawal in patients who have undergone a successful liver transplant accelerates the recovery of lumbar spine bone density without adverse effects on

Moreover, higher rates of fracture occurring after cardiac (Shane et al., 1996) and lung (Shane et al., 1999) transplantation, in which higher doses of steroids are use, would be

The late phase observed in the postrasplant period takes place when the glucocorticoid doses are usually tapered below 5 mg per day. Then, osteoblast function recovers and consequently, an increase in bone formation and recoupling of bone remodeling activity is observed. During this later phase, rates of bone loss slow and there may even be some recovery, particularly in cancellous bone (Kulak et al., 2006). It is also found that despite an initial decrease in post transplant BMD, biopsies in the iliac crest showed improvement in

In conclusion, current evidence suggests that bone loss after transplantation is caused by an initial increase in bone turnover and resorption, plus a decrease in bone formation. Later, increases in bone formation could overcome resorption. These changes would be consistent with the rapid decrease in BMD observed in the first months after transplantation and

The effect of these drugs in humans is difficult to study because they are used in conditions that by themselves affect bone remodeling, and they are rarely used in monotherapy so, the

The role of calcineurin inhibitors in post-transplant bone loss is unknown. Tacrolimus is a calcineurin inhibitor that suppresses T cell activation and the production and release of IL-2 and other cytokines. It induces severe trabecular bone loss in rats, but this effect appears to be less severe in humans (Epstein, 1996). Cyclosporin A (CyA), another calcineurin inhibitor, also appears to have adverse effects in mouse models, inducing high turnover and reducing bone mass. Some studies in humans suggest a similar effect in patients with liver (Giannini et al., 2000), and cardiac (Thiebaud et al., 1996) transplantation. In a research of 360 patients with liver transplantation due to chronic cholestatic liver disease, the post transplant bone gain was lower, and the number of fractures was higher in patients treated with CyA than in those receiving tacrolimus (Guichelaar et al., 2007). Other authors have found greater

consistent with their role in the pathogenesis of post transplant osteoporosis.

histomorphometric parameters 4 months later (Guichelaar et al., 2003).

potential deleterious effect of one single agent could not be ascertained.

proteins induced by dexametasone (Hayashi et al., 2008).

graft tolerance (Martínez Díaz-Guerra et al., 2002).

recovery to baseline values, as most of studies show.

**2.2.2 Other immunosuppressive drugs** 

Increase in bone resorption as a result of increased urinary calcium.

Decrease in intestinal calcium absorption.

Secondary hyperparathyroidism.

Hypogonadotropic hypogonadism.

Activation of osteoclastogenesis caused by increase of RANKL and decrease of osteoprotegerine (OPG) levels.

Decrease in proliferation and function of osteoblasts (by inhibiting the gene expression of osteocalcin, collagen type 1 and IGF-I).

Decrease anabolic effects of TGF-beta.

Induces Osteoblast apoptosis.

Table 3. Effects of high doses of glucocorticoids in bone loss.

Fig. 1. Effect of high doses of glucocorticoids in bone loss

**Effect of glucocorticoids in the WNT pathway:** The Wnt pathway and the Bone Morphogenetic Protein (BMP) seem to be involved in the pathogenesis of glucocorticoidinduced osteoporosis, suppressing osteoblast differentiation and activity. BMP and Wnt pathway are regulated by several mechanisms: one of them are proteins that act as extracellular antagonists of BMP (Noggin, Chordin, Twisted gastrulation, Grelin, Sclerostin,

Increase in bone resorption as a result of increased urinary calcium.

Table 3. Effects of high doses of glucocorticoids in bone loss.

Fig. 1. Effect of high doses of glucocorticoids in bone loss

**Effect of glucocorticoids in the WNT pathway:** The Wnt pathway and the Bone Morphogenetic Protein (BMP) seem to be involved in the pathogenesis of glucocorticoidinduced osteoporosis, suppressing osteoblast differentiation and activity. BMP and Wnt pathway are regulated by several mechanisms: one of them are proteins that act as extracellular antagonists of BMP (Noggin, Chordin, Twisted gastrulation, Grelin, Sclerostin,

Activation of osteoclastogenesis caused by increase of RANKL and decrease of

Decrease in proliferation and function of osteoblasts (by inhibiting the gene expression of

Decrease in intestinal calcium absorption.

Secondary hyperparathyroidism. Hypogonadotropic hypogonadism.

osteoprotegerine (OPG) levels.

Induces Osteoblast apoptosis.

osteocalcin, collagen type 1 and IGF-I). Decrease anabolic effects of TGF-beta.

Follistatin and Dan), while others act as Wnt antagonist: Frizzled-related protein (sFRP), Dickkopf (Dkk) and Cerberus. Glucocorticoids can affect these signaling pathways, but the exact mechanisms are not been clarified. Recent studies suggest that glucocorticoids induce an alteration in osteoblast function by increasing Wnt antagonists with the subsequent suppression of this pathway. Recent reseach has shown that dexametasone, increases follistatin and DAN (BMP antagonists), sFRP-1(Wnt antagonist) and axin-2 (inhibitor of Wnt signal) . Simultaneously, alendronate and PTH (1-34), which have demostrated to be effective in the treatment of steroid osteoporosis, were able to antagonize the increase in this proteins induced by dexametasone (Hayashi et al., 2008).

The potential impact of glucocorticoid dose as a determinant of bone loss is supported by the absence of bone loss at the lumbar spine and proximal femur in renal transplant patients treated with low doses of steroids and tacrolimus (Goffin et al., 2001). We have previously reported that steroid withdrawal in patients who have undergone a successful liver transplant accelerates the recovery of lumbar spine bone density without adverse effects on graft tolerance (Martínez Díaz-Guerra et al., 2002).

Moreover, higher rates of fracture occurring after cardiac (Shane et al., 1996) and lung (Shane et al., 1999) transplantation, in which higher doses of steroids are use, would be consistent with their role in the pathogenesis of post transplant osteoporosis.

The late phase observed in the postrasplant period takes place when the glucocorticoid doses are usually tapered below 5 mg per day. Then, osteoblast function recovers and consequently, an increase in bone formation and recoupling of bone remodeling activity is observed. During this later phase, rates of bone loss slow and there may even be some recovery, particularly in cancellous bone (Kulak et al., 2006). It is also found that despite an initial decrease in post transplant BMD, biopsies in the iliac crest showed improvement in histomorphometric parameters 4 months later (Guichelaar et al., 2003).

In conclusion, current evidence suggests that bone loss after transplantation is caused by an initial increase in bone turnover and resorption, plus a decrease in bone formation. Later, increases in bone formation could overcome resorption. These changes would be consistent with the rapid decrease in BMD observed in the first months after transplantation and recovery to baseline values, as most of studies show.

#### **2.2.2 Other immunosuppressive drugs**

The effect of these drugs in humans is difficult to study because they are used in conditions that by themselves affect bone remodeling, and they are rarely used in monotherapy so, the potential deleterious effect of one single agent could not be ascertained.

The role of calcineurin inhibitors in post-transplant bone loss is unknown. Tacrolimus is a calcineurin inhibitor that suppresses T cell activation and the production and release of IL-2 and other cytokines. It induces severe trabecular bone loss in rats, but this effect appears to be less severe in humans (Epstein, 1996). Cyclosporin A (CyA), another calcineurin inhibitor, also appears to have adverse effects in mouse models, inducing high turnover and reducing bone mass. Some studies in humans suggest a similar effect in patients with liver (Giannini et al., 2000), and cardiac (Thiebaud et al., 1996) transplantation. In a research of 360 patients with liver transplantation due to chronic cholestatic liver disease, the post transplant bone gain was lower, and the number of fractures was higher in patients treated with CyA than in those receiving tacrolimus (Guichelaar et al., 2007). Other authors have found greater

Post-Transplantation Bone Disease 307

not consistent across studies. Even patients with normal pre-transplant BMD may suffer fracture after transplantation. Therefore, it is usually not possible with current clinical tools to predict whether individual transplant recipients will fracture after transplantation.

In a nested case-control study of transplant recipients (kidney, liver, lung, heart), multivariate analysis showed that post-transplant fracture rate was highest among those with a history of hyperthyroidism, pretransplant diabetes, fracture, or corticosteroid use, and among those currently exposed to antidepressants, narcotics, sirolimus, and loop diuretics (Shane et al., 2009 uptodate). Use of bisphosphonates or calcitonin was also a

In some studies, the rate of post-transplant fracture is decreasing, in part due to increased recognition of the problem, which has resulted in changes in immunosuppressive regimens (reduction in dose and duration of glucocorticoids) and earlier identification and treatment

Rates of bone loss are greatest in the first 3-18 months and range from 4-9% at the spine and

After renal transplantation fractures affect appendicular sites (hips, long bones, ankles, feet) more commonly than axial sites (spine and ribs). The majority of fractures occur within the first 3 years. Fracture prevalence varies from 7-11% in nondiabetic renal transplant recipients, but is considerably higher in patient transplanted because of diabetic nephropathy and in those who receive kidney-pancreas transplants. (Nowacka-Cieciura et

With regard to the difference in the prevalence of fracture in end stage renal disease patients referred to kidney transplant or those who continued dialysis, a large study realized with 101,039 patients with end stage renal disease demonstrated that kidney transplantation was associated with a 34% greater risk of hip fracture than continued dialysis (Nisbeth et al.,

During the first year after lung transplantation, rates of bone loss at the lumbar spine and femoral neck range from 2 to 5%. In another study conducted with 70 patients awaiting lung transplantation the prevalence of vertebral fractures was 29% in patients with chronic obstructive pulmonary disease and 25% in patients with cystic fibrosis (Shane et al., 1996). Fracture rates are also high during the first year after lung transplantation, ranging from 18

The most rapid rate of bone loss occurs in the first year. Spinal BMD declines by 6-10% during the first 6 months, whereas femoral neck BMD falls by 6-11% in the first year. The rate of bone loss slows after the first year and spine BMD may increase after the third year (Cohen et al., 2003). Densitometric osteoporosis at the lumbar spine and femoral neck has been reported in approximately 28% and 20% respectively of long term transplant patients

Vertebral fracture incidence ranges from 20-36% during the first 1 to 3 years after cardiac transplantation. One prospective study shows that 36 percent of all patients and 54 percent

predictor of fracture, likely indicating the presence of pre-transplant osteoporosis.

for osteoporosis (Shane et al., 2004; Compston et al., 2003)

**3.1 Kidney transplantation** 

**3.2 Lung transplantation** 

**3.3 Cardiac transplantation** 

(Chou et al., 2006).

5-8% at the hip.

al., 2006)

1994).

to 37%.

fracture incidence in patiens receiving CyA treatment than in those treated with tacrolimus (Monegal et al., 2001).

In other liver transplanted recipients study, although bone mass losses were similar in patients on CyA regimen than in those on tacrolimus, histomorphometric changes after transplantation were different between groups. Patients treated with tacrolimus had an improvement in trabecular bone architecture compared with patients receiving CyA (Guichelaar et al., 2004). These findings suggest that patients treated with tacrolimus may have faster recovery of bone metabolism after the initial phase of bone loss compared with those treated with CyA.

A study comparing CsA monotherapy versus prednisone and azathioprine regimen in renal transplant recipients did not found any differences in bone loss or bone histomorphometric parameters (Cueto-Manzano et al., 2003). Furthermore, a major side-effect of CsA therapy is dose-related nephrotoxicity, often leading to secondary hyperparathyroidism, which may also adversely affect bone health.

Other immunosupresive agents such as Mycophenolate mofetil (104), rapamycin or azathioprine have shown no effects on bone in murine models (Maalouf et al., 2005).

#### **3. Bone loss and fractures after transplantation**

The majority of longitudinal studies show a decrease in bone mineral density at the lumbar spine and hip that occurs in the first year after solid organ transplantation. The amount of bone loss ranges between 3% and 10%, particularly in the first 3-6 months. Rapid bone loss and major involvement of lumbar spine (trabecular bone tissue) are findings probably related to the large doses of glucocorticoids used immediately after transplantation. Rates of lumbar spine bone loss slow thereafter, with stabilization by 6–12 months and even some recovery after liver, lung, and heart transplantation. However, most studies do not document recovery of bone mass at the hip. BMD changes after renal transplantation are different since continued bone loss after the rapid initial bone loss may be observed. Prevalence of densitometric osteoporosis is quite variable depending on type of organ transplantation and time elapsed since transplantation (Hawkins et al., 1994).

With regard to fractures, a high incidence of them (between 20% and 40% in most studies) has been documented. In heart and liver transplant recipients, the incidence of new fractures parallels the timing of the most rapid bone loss, with most fractures occurring within the first year after transplantation (Eastell R, 1991; Henderson et al., 1995; Shane et al., 1996; Ramsey-Goldman et al., 1999).

Fractures usually affect the spine and ribs in liver, cardiac, or lung recipients, whereas long bones are more easily fractured in renal transplant recipients. However, fracture incidence may have decreased in the last years. This is probably related to the wide implementation of immunosuppressive regimens that use lower doses of glucocorticoids and for a shorter period of time. Indeed, bone loss and fractures remain unacceptably high in several recent studies.

Risk factors for fractures after transplantation include older age, prevalent fractures before transplantation, postmenopausal status, and lower body mass index. Additional risk factors in renal transplant recipients include the presence of diabetes mellitus and prolonged dialysis. The predictive roles of pretransplantation BMD and cumulative glucocorticoid dose are controversial. Associations between these risk factors and bone loss or fractures are

fracture incidence in patiens receiving CyA treatment than in those treated with tacrolimus

In other liver transplanted recipients study, although bone mass losses were similar in patients on CyA regimen than in those on tacrolimus, histomorphometric changes after transplantation were different between groups. Patients treated with tacrolimus had an improvement in trabecular bone architecture compared with patients receiving CyA (Guichelaar et al., 2004). These findings suggest that patients treated with tacrolimus may have faster recovery of bone metabolism after the initial phase of bone loss compared with

A study comparing CsA monotherapy versus prednisone and azathioprine regimen in renal transplant recipients did not found any differences in bone loss or bone histomorphometric parameters (Cueto-Manzano et al., 2003). Furthermore, a major side-effect of CsA therapy is dose-related nephrotoxicity, often leading to secondary hyperparathyroidism, which may

Other immunosupresive agents such as Mycophenolate mofetil (104), rapamycin or

The majority of longitudinal studies show a decrease in bone mineral density at the lumbar spine and hip that occurs in the first year after solid organ transplantation. The amount of bone loss ranges between 3% and 10%, particularly in the first 3-6 months. Rapid bone loss and major involvement of lumbar spine (trabecular bone tissue) are findings probably related to the large doses of glucocorticoids used immediately after transplantation. Rates of lumbar spine bone loss slow thereafter, with stabilization by 6–12 months and even some recovery after liver, lung, and heart transplantation. However, most studies do not document recovery of bone mass at the hip. BMD changes after renal transplantation are different since continued bone loss after the rapid initial bone loss may be observed. Prevalence of densitometric osteoporosis is quite variable depending on type of organ

With regard to fractures, a high incidence of them (between 20% and 40% in most studies) has been documented. In heart and liver transplant recipients, the incidence of new fractures parallels the timing of the most rapid bone loss, with most fractures occurring within the first year after transplantation (Eastell R, 1991; Henderson et al., 1995; Shane et al., 1996;

Fractures usually affect the spine and ribs in liver, cardiac, or lung recipients, whereas long bones are more easily fractured in renal transplant recipients. However, fracture incidence may have decreased in the last years. This is probably related to the wide implementation of immunosuppressive regimens that use lower doses of glucocorticoids and for a shorter period of time. Indeed, bone loss and fractures remain unacceptably high in several recent

Risk factors for fractures after transplantation include older age, prevalent fractures before transplantation, postmenopausal status, and lower body mass index. Additional risk factors in renal transplant recipients include the presence of diabetes mellitus and prolonged dialysis. The predictive roles of pretransplantation BMD and cumulative glucocorticoid dose are controversial. Associations between these risk factors and bone loss or fractures are

azathioprine have shown no effects on bone in murine models (Maalouf et al., 2005).

transplantation and time elapsed since transplantation (Hawkins et al., 1994).

(Monegal et al., 2001).

those treated with CyA.

also adversely affect bone health.

Ramsey-Goldman et al., 1999).

studies.

**3. Bone loss and fractures after transplantation** 

not consistent across studies. Even patients with normal pre-transplant BMD may suffer fracture after transplantation. Therefore, it is usually not possible with current clinical tools to predict whether individual transplant recipients will fracture after transplantation.

In a nested case-control study of transplant recipients (kidney, liver, lung, heart), multivariate analysis showed that post-transplant fracture rate was highest among those with a history of hyperthyroidism, pretransplant diabetes, fracture, or corticosteroid use, and among those currently exposed to antidepressants, narcotics, sirolimus, and loop diuretics (Shane et al., 2009 uptodate). Use of bisphosphonates or calcitonin was also a predictor of fracture, likely indicating the presence of pre-transplant osteoporosis.

In some studies, the rate of post-transplant fracture is decreasing, in part due to increased recognition of the problem, which has resulted in changes in immunosuppressive regimens (reduction in dose and duration of glucocorticoids) and earlier identification and treatment for osteoporosis (Shane et al., 2004; Compston et al., 2003)

### **3.1 Kidney transplantation**

Rates of bone loss are greatest in the first 3-18 months and range from 4-9% at the spine and 5-8% at the hip.

After renal transplantation fractures affect appendicular sites (hips, long bones, ankles, feet) more commonly than axial sites (spine and ribs). The majority of fractures occur within the first 3 years. Fracture prevalence varies from 7-11% in nondiabetic renal transplant recipients, but is considerably higher in patient transplanted because of diabetic nephropathy and in those who receive kidney-pancreas transplants. (Nowacka-Cieciura et al., 2006)

With regard to the difference in the prevalence of fracture in end stage renal disease patients referred to kidney transplant or those who continued dialysis, a large study realized with 101,039 patients with end stage renal disease demonstrated that kidney transplantation was associated with a 34% greater risk of hip fracture than continued dialysis (Nisbeth et al., 1994).

### **3.2 Lung transplantation**

During the first year after lung transplantation, rates of bone loss at the lumbar spine and femoral neck range from 2 to 5%. In another study conducted with 70 patients awaiting lung transplantation the prevalence of vertebral fractures was 29% in patients with chronic obstructive pulmonary disease and 25% in patients with cystic fibrosis (Shane et al., 1996). Fracture rates are also high during the first year after lung transplantation, ranging from 18 to 37%.

### **3.3 Cardiac transplantation**

The most rapid rate of bone loss occurs in the first year. Spinal BMD declines by 6-10% during the first 6 months, whereas femoral neck BMD falls by 6-11% in the first year. The rate of bone loss slows after the first year and spine BMD may increase after the third year (Cohen et al., 2003). Densitometric osteoporosis at the lumbar spine and femoral neck has been reported in approximately 28% and 20% respectively of long term transplant patients (Chou et al., 2006).

Vertebral fracture incidence ranges from 20-36% during the first 1 to 3 years after cardiac transplantation. One prospective study shows that 36 percent of all patients and 54 percent

Post-Transplantation Bone Disease 309

BMT patients; its development may be facilitated by a deficit in bone marrow stromal stem

Elevated PTH levels have an adverse effect on bone health increasing turnover and

Some studies reflect a slight increase in PTH levels in the first month after transplantation. It could be related to vitamin D deficiency, calcium malabsorption or decreased tubular reabsorption of calcium, consequence of steroid treatment (Compston et al., 1996). PTH levels may remain elevated in the long-term due to chronic renal failure induced by

Inadequate levels of vitamin D have been described in patients with end-stage liver diseases prior to liver transplantation, and this may play a role in the aetiology of lower mineralization after transplantation. Our group found that 91% of liver transplanted patients had insufficient serum levels of 25(OH)D at transplantation time. After adequate supplementation, serum 25(OH)D levels increased from 3 months onwards (Guadalix et al., 2011). A positive correlation between serum 25(OH)D levels at 3 months and BMD increase at 6 months was found suggesting that this vitamin has a positive effect on mineralization (Crosbie et al., 1999). In our study serum 25(OH)D levels showed positive correlation with the percentage change in total hip and femoral neck BMD at 12 months of treatment (Guadalix et al., 2011). These results suggest that vitamin D could have a main role in bone

Bone turnover markers can provide information about the mechanisms of bone loss in posttransplant period.Our group has previously reported an increase in bone turnover markers such as osteocalcin after liver transplantation (Valero et al., 1995; Hawkins et al., 1994). No significant changes in urinary hydroxyproline, one and two years after transplant were found; however urinary excretion of NTX ( amino-terminal telopeptide of collagen type I) showed a significant decrease after two years compared with baseline values(Giannini et al., 2000), while other found that values of deoxypyridinoline doubled compared to baseline, two months after transplantation (Crosbie et al., 1999). We also found that β-CTX decreased as from 3 months both in patients on bisphosphonate treatment as in patients receiving only calcium plus vitamin D, reflecting a reduction of bone resorption after liver transplantation (Guadalix et al., 2011). Greater reductions in β-CTX may be obtained with intravenuous bisphosphonates. A significant decrease in urinary deoxypyridinoline in heart transplant recipienters after intravenous pamidronate traeatment (Shane et al., 1998) and in β-CTX levels 6 months after liver transplanted in 13 patients treated with intravenous zoledrónico acid (Misof et al., 2008) was found. Other investigators found an early increase (one and 3 months after heart transplantation) in resorption markers hydroxyproline, pyridonoline and desoxypyridinoline and a decreased in osteocalcin, recovering all baseline values at 6 months (Shane et al., 1997). Several studies have investigated the OPG / RANKL in the post-transplant period. Results are

**4. PTH. 25-OH-D. Bone remodeling in postransplantation bone disease** 

cell regeneration and low osteoblast number.

decreasing bone mass, especially in cortical bone.

cyclosporin (Floreani A, 2001; Crosbie et al., 1999).

loss prevention after liver transplantation.

**4.3 Bone remodeling in postransplantation bone disease** 

**4.1 PTH** 

**4.2 25-OH vitamin D** 

of women sustained a fracture after this procedure, 85 percent of which occurred within the first six months (Shane et al., 1996). Women with the lowest pretransplant hip BMD were at highest risk of fracture. In men, pretransplant BMD did not differ between those who went on to fracture and those who did not.

### **3.4 Liver transplantation**

Spine BMD declines by 2-24% during the first year in earlier studies, particularly during the first 3-6 months. Some authors report higher rates of bone loss and fracture in patients who have alcoholic cirrhosis, primary biliary cirrhosis, and primary sclerosing cholangitis (Lopez 1992). Rates of bone loss have been lower in more recent studies. In the second year after transplantation, lumbar BMD recovered or even exceeded baseline levels (Guichelaar et al., 2006). Although early studies showed a predominance of post-transplant bone loss and fractures in the lumbar spine (Compston et al., 2003), more recent studies reported higher bone loss at the hip (Keogh et al., 1999; Ninkovic et al., 2002; Crawford et al., 2006). It seems that there are differences in the natural evolution of lumbar and femoral BMD, with greater loss of femoral bone that persists after the first year after transplantation. As an example, after 3 years, BMD at the femoral neck improved, but still remained below baseline levels (Monegal A, 2001). Other studies found a decrease in BMD at the femoral neck at 6 and 12 months, even despite treatment with bisphosphonates, suggesting a lesser effect of these drugs at cortical bone (Keogh et al., 1999), (Ninkovic et al., 2002), (Monegal et al., 2009).

Fracture rates after liver transplantation are highest in the first 6-12 months. Range from 24 to 65% and the ribs and spine are the most common sites. Women with primary biliary cirrhosis and the most severe preexisting bone disease appear to be at greatest risk. In a study of 37 patients receiving liver transplantation between 1993 and 1995, an incidence of 27% of vertebral fractures in the first three months after transplantation was found (Ninkovic et al., 2000). A subsequent study of the same group, done between 1995 and 1998, showed that this incidence was only 5%. Between both studies there was a considerable reduction in the dose and duration of glucocorticoid treatment, although the use of cyclosporine and tacrolimus barely changed (Ninkovic et al., 2002).

#### **3.5 Bone marrow transplantation**

The pattern of bone loss after bone marrow transplantation (BMT) is different from other forms of osteoporosis, being more persistent and severe in cortical bones, such as femoral neck than in trabecular bones, such as lumbar spine (Hatutman et al., 2011)). Bone marrow transplant (BMT) recipients have many known risk factors for developing decreased bone mineral density after transplantation. The pathogenesis of bone disease following BMT differs from others form of post-transplantation osteoporosis; recipients are usually younger and the time from the diagnosis to the BMT does not exceed 2 years; history of prolonged bed rest is uncommon. Immunosuppressive drugs are used in relatively low doses and for short periods of time (Ebeling et al., 1999). Glucocorticoid use is restricted to the treatment of graft-versus- host disease (GVHD).

Lumbar spine BMD declines by 2-9% and femoral neck BMD falls 6-11% during the first year following transplantation. Lumbar spine BMD begins to recover after 12 months, returning to baseline levels at 48 months. The extent of recovery at the femoral neck is less (Schulte et al., 2004). The presence of chronic GVHD is another factor associated with higher risk of osteoporosis in these patients. Avascular necrosis develops in 10-20% of allogenic BMT patients; its development may be facilitated by a deficit in bone marrow stromal stem cell regeneration and low osteoblast number.

### **4. PTH. 25-OH-D. Bone remodeling in postransplantation bone disease**

#### **4.1 PTH**

308 Osteoporosis

of women sustained a fracture after this procedure, 85 percent of which occurred within the first six months (Shane et al., 1996). Women with the lowest pretransplant hip BMD were at highest risk of fracture. In men, pretransplant BMD did not differ between those who went

Spine BMD declines by 2-24% during the first year in earlier studies, particularly during the first 3-6 months. Some authors report higher rates of bone loss and fracture in patients who have alcoholic cirrhosis, primary biliary cirrhosis, and primary sclerosing cholangitis (Lopez 1992). Rates of bone loss have been lower in more recent studies. In the second year after transplantation, lumbar BMD recovered or even exceeded baseline levels (Guichelaar et al., 2006). Although early studies showed a predominance of post-transplant bone loss and fractures in the lumbar spine (Compston et al., 2003), more recent studies reported higher bone loss at the hip (Keogh et al., 1999; Ninkovic et al., 2002; Crawford et al., 2006). It seems that there are differences in the natural evolution of lumbar and femoral BMD, with greater loss of femoral bone that persists after the first year after transplantation. As an example, after 3 years, BMD at the femoral neck improved, but still remained below baseline levels (Monegal A, 2001). Other studies found a decrease in BMD at the femoral neck at 6 and 12 months, even despite treatment with bisphosphonates, suggesting a lesser effect of these drugs at cortical bone (Keogh et al., 1999), (Ninkovic et al., 2002), (Monegal et al., 2009). Fracture rates after liver transplantation are highest in the first 6-12 months. Range from 24 to 65% and the ribs and spine are the most common sites. Women with primary biliary cirrhosis and the most severe preexisting bone disease appear to be at greatest risk. In a study of 37 patients receiving liver transplantation between 1993 and 1995, an incidence of 27% of vertebral fractures in the first three months after transplantation was found (Ninkovic et al., 2000). A subsequent study of the same group, done between 1995 and 1998, showed that this incidence was only 5%. Between both studies there was a considerable reduction in the dose and duration of glucocorticoid treatment, although the use of

cyclosporine and tacrolimus barely changed (Ninkovic et al., 2002).

The pattern of bone loss after bone marrow transplantation (BMT) is different from other forms of osteoporosis, being more persistent and severe in cortical bones, such as femoral neck than in trabecular bones, such as lumbar spine (Hatutman et al., 2011)). Bone marrow transplant (BMT) recipients have many known risk factors for developing decreased bone mineral density after transplantation. The pathogenesis of bone disease following BMT differs from others form of post-transplantation osteoporosis; recipients are usually younger and the time from the diagnosis to the BMT does not exceed 2 years; history of prolonged bed rest is uncommon. Immunosuppressive drugs are used in relatively low doses and for short periods of time (Ebeling et al., 1999). Glucocorticoid use is restricted to the treatment

Lumbar spine BMD declines by 2-9% and femoral neck BMD falls 6-11% during the first year following transplantation. Lumbar spine BMD begins to recover after 12 months, returning to baseline levels at 48 months. The extent of recovery at the femoral neck is less (Schulte et al., 2004). The presence of chronic GVHD is another factor associated with higher risk of osteoporosis in these patients. Avascular necrosis develops in 10-20% of allogenic

on to fracture and those who did not.

**3.5 Bone marrow transplantation** 

of graft-versus- host disease (GVHD).

**3.4 Liver transplantation** 

Elevated PTH levels have an adverse effect on bone health increasing turnover and decreasing bone mass, especially in cortical bone.

Some studies reflect a slight increase in PTH levels in the first month after transplantation. It could be related to vitamin D deficiency, calcium malabsorption or decreased tubular reabsorption of calcium, consequence of steroid treatment (Compston et al., 1996). PTH levels may remain elevated in the long-term due to chronic renal failure induced by cyclosporin (Floreani A, 2001; Crosbie et al., 1999).

#### **4.2 25-OH vitamin D**

Inadequate levels of vitamin D have been described in patients with end-stage liver diseases prior to liver transplantation, and this may play a role in the aetiology of lower mineralization after transplantation. Our group found that 91% of liver transplanted patients had insufficient serum levels of 25(OH)D at transplantation time. After adequate supplementation, serum 25(OH)D levels increased from 3 months onwards (Guadalix et al., 2011). A positive correlation between serum 25(OH)D levels at 3 months and BMD increase at 6 months was found suggesting that this vitamin has a positive effect on mineralization (Crosbie et al., 1999). In our study serum 25(OH)D levels showed positive correlation with the percentage change in total hip and femoral neck BMD at 12 months of treatment (Guadalix et al., 2011). These results suggest that vitamin D could have a main role in bone loss prevention after liver transplantation.

#### **4.3 Bone remodeling in postransplantation bone disease**

Bone turnover markers can provide information about the mechanisms of bone loss in posttransplant period.Our group has previously reported an increase in bone turnover markers such as osteocalcin after liver transplantation (Valero et al., 1995; Hawkins et al., 1994). No significant changes in urinary hydroxyproline, one and two years after transplant were found; however urinary excretion of NTX ( amino-terminal telopeptide of collagen type I) showed a significant decrease after two years compared with baseline values(Giannini et al., 2000), while other found that values of deoxypyridinoline doubled compared to baseline, two months after transplantation (Crosbie et al., 1999). We also found that β-CTX decreased as from 3 months both in patients on bisphosphonate treatment as in patients receiving only calcium plus vitamin D, reflecting a reduction of bone resorption after liver transplantation (Guadalix et al., 2011). Greater reductions in β-CTX may be obtained with intravenuous bisphosphonates. A significant decrease in urinary deoxypyridinoline in heart transplant recipienters after intravenous pamidronate traeatment (Shane et al., 1998) and in β-CTX levels 6 months after liver transplanted in 13 patients treated with intravenous zoledrónico acid (Misof et al., 2008) was found. Other investigators found an early increase (one and 3 months after heart transplantation) in resorption markers hydroxyproline, pyridonoline and desoxypyridinoline and a decreased in osteocalcin, recovering all baseline values at 6 months (Shane et al., 1997). Several studies have investigated the OPG / RANKL in the post-transplant period. Results are

Post-Transplantation Bone Disease 311

determinant of the values of total and free testosterone). No relationship was found between post-transplant bone loss and testosterone levels, probably because patients were treated

In most studies, testosterone levels return to normal by 6 to 12 months after transplantation (Sambrook et al., 1994) but up to 20% of patients receiving prednisone and cyclosporine A may persist with low serum total testosterone levels 3 years after cardiac transplantation

Regarding the role of other immunosuppressive agents on gonadal function cyclosporine A decreases testosterone by affecting both the hypothalamic-pituitary- gonadal axis (Sikka et al., 1988) and by direct inhibition of testicular synthesis of testosterone in murine models (Seethalakshmi et al., 1990). However, cyclosporine did not seem to affect testosterone levels

Some authors recommend hormonal treatment in post transplant osteoporosis in men and premenopausal women with hypogonadism, if there are no contraindications (Shane et al., 2009 up-to-date). Androgen replacement therapy has shown skeletal benefit (increase in BMD) only in men with hypogonadism. It has been demonstrated in an uncontrolled study of postmenopausal liver transplantation recipients, that the use of transdermal estradiol was effective in increasing BMD of lumbar spine and femoral neck over a period of two years

The same measures used to prevent osteoporosis in the general population apply to transplant recipients, regardless of the pretransplant BMD measurement. It is recomended that all candidates for organ transplantation follow a throughfully evaluation in order to identificate and correct risk factors and to implement measures to improve bone health

> - Consider initiating preventive therapy in most patient (even those with normal BMD): calcium, vitamin D and




antiresorptive agents.

with calcitriol or alendronate.

in humans (Fleisher et al., 2008; Samojlik et al., 1992).

**6. Prevention and treatment of osteoporosis** 

**Before Transplantation After transplantation** 

Table 4. General recommendations for prevention and treatment of osteoporosis

**6.1 General measures before transplantation** 






calcium (1000-mg/day) and vitamin D

(Stempfle et al., 1999).

(Isoniemi et al., 2001).

osteoporosis.

osteodystrophy.

(800 IU).

prevalent fractures.

general guidelines.

(Table 4).

not homogeneous. High levels of both, OPG and RANKL in the first 14 days after liver transplantation compared to the control group were found (Fabrega et al., 2006). In the other hand, serum OPG in 57 patients at 3 and 6 months after cardiac transplantation wa correlated with bone loss at the lumbar spine and femoral neck sites, after 6 months. Serum OPG alone accounted for 67% of the variance of lumbar spine bone density changes over the first 6 months post transplantation leading to the conclussion that serum OPG levels decline consistently in all patients following initiation of immunosuppressive therapy and are independently correlated with changes in bone density (Fahrleitner et al., 2003).In another study in patients with kidney transplant, levels of OPG and RANKL did not differ between healthy volunteers and transplant patients (Malyszko et al., 2003).

### **5. Gonadal status and postransplatation bone disease**

Hypogonadotropic hypogonadism is frequently found both before and after transplantation and may play a role in the multifactorial pathogenesis of immunosuppression-induced bone loss. Sex-steroid deficiency in either sex results in an increase in bone turnover with an imbalance in bone formation and bone resorption. Few studies have assessed the status of gonadal function after transplantation and its relationship with bone mass. Many premenopausal women and men undergoing solid organ transplantation have temporary hypogonadism, most often related to the effects of glucocorticoids and chronic illnesses (Fleischer et al., 2008; Tauchmanovà et al., 2005). In some cases (i.e. chemotherapy and/or radiation therapy for hematopoietic stem cell transplantation), hypogonadism is permanent (Tauchmanovà et al., 2003). In men and women undergoing transplantation, testosterone and estrogen-progestin replacement, respectively, have been shown to slow bone loss (Isoniemi et al., 2001; Kananen et al., 2005). Hypogonadism is a common finding among patients with terminal liver disease, especially in males. Incidence was estimated up to 70% (Guichelaar et al., 2004). There are few studies about change in sex hormones after liver transplantation, some authors have reported an increase in free testosterone, although the recovery of normal levels has not been achieved in all patients (Floreani et al., 2001; Monegal et al., 2001). In a study of 10 liver transplant recipients followed for 12 months after transplantation, before transplantation, 90% of patients had a decrease in testosterone levels and reported decreased libido and erectile dysfunction .After transplant, total testosterone levels had doubled, and free testosterone increased tenfold. Patients reported early improvement in sexual function (6 to 8 weeks after transplantation). It was suggested that pretransplant abnormalities in gonadal function are mainly due to liver failure and are reversible in most patients (Madersbacher et al., 1996). In premenopausal women, normal menses usually resumes after liver transplantation (Mass et al., 1996).

Low levels of testosterone are quite common early after cardiac transplantation, and may be found in up to 50% of men (Guo et al., 1998). In addition, a significant relationship between low levels of serum testosterone and rates of femoral neck bone loss during the first 6 month after transplantation have been found by some authors (Shane et al., 1997). Fleischer et al., (2008) studied 108 male heart transplant patients. One month after transplantation, total testosterone levels were below normal in 63% of them while 33% had decreased levels of free testosterone. 15% of patients had elevated gonadotropin a month after transplantation, increasing to 29% at 6 months. These data suggest a suppression of the hypothalamicpituitary-gonadal axis immediately after transplantation, with subsequent recovery. Authors attributed this to steroid therapy. Prednisone dose was found to be the main

not homogeneous. High levels of both, OPG and RANKL in the first 14 days after liver transplantation compared to the control group were found (Fabrega et al., 2006). In the other hand, serum OPG in 57 patients at 3 and 6 months after cardiac transplantation wa correlated with bone loss at the lumbar spine and femoral neck sites, after 6 months. Serum OPG alone accounted for 67% of the variance of lumbar spine bone density changes over the first 6 months post transplantation leading to the conclussion that serum OPG levels decline consistently in all patients following initiation of immunosuppressive therapy and are independently correlated with changes in bone density (Fahrleitner et al., 2003).In another study in patients with kidney transplant, levels of OPG and RANKL did not differ between

Hypogonadotropic hypogonadism is frequently found both before and after transplantation and may play a role in the multifactorial pathogenesis of immunosuppression-induced bone loss. Sex-steroid deficiency in either sex results in an increase in bone turnover with an imbalance in bone formation and bone resorption. Few studies have assessed the status of gonadal function after transplantation and its relationship with bone mass. Many premenopausal women and men undergoing solid organ transplantation have temporary hypogonadism, most often related to the effects of glucocorticoids and chronic illnesses (Fleischer et al., 2008; Tauchmanovà et al., 2005). In some cases (i.e. chemotherapy and/or radiation therapy for hematopoietic stem cell transplantation), hypogonadism is permanent (Tauchmanovà et al., 2003). In men and women undergoing transplantation, testosterone and estrogen-progestin replacement, respectively, have been shown to slow bone loss (Isoniemi et al., 2001; Kananen et al., 2005). Hypogonadism is a common finding among patients with terminal liver disease, especially in males. Incidence was estimated up to 70% (Guichelaar et al., 2004). There are few studies about change in sex hormones after liver transplantation, some authors have reported an increase in free testosterone, although the recovery of normal levels has not been achieved in all patients (Floreani et al., 2001; Monegal et al., 2001). In a study of 10 liver transplant recipients followed for 12 months after transplantation, before transplantation, 90% of patients had a decrease in testosterone levels and reported decreased libido and erectile dysfunction .After transplant, total testosterone levels had doubled, and free testosterone increased tenfold. Patients reported early improvement in sexual function (6 to 8 weeks after transplantation). It was suggested that pretransplant abnormalities in gonadal function are mainly due to liver failure and are reversible in most patients (Madersbacher et al., 1996). In premenopausal women, normal

healthy volunteers and transplant patients (Malyszko et al., 2003).

**5. Gonadal status and postransplatation bone disease** 

menses usually resumes after liver transplantation (Mass et al., 1996).

Low levels of testosterone are quite common early after cardiac transplantation, and may be found in up to 50% of men (Guo et al., 1998). In addition, a significant relationship between low levels of serum testosterone and rates of femoral neck bone loss during the first 6 month after transplantation have been found by some authors (Shane et al., 1997). Fleischer et al., (2008) studied 108 male heart transplant patients. One month after transplantation, total testosterone levels were below normal in 63% of them while 33% had decreased levels of free testosterone. 15% of patients had elevated gonadotropin a month after transplantation, increasing to 29% at 6 months. These data suggest a suppression of the hypothalamicpituitary-gonadal axis immediately after transplantation, with subsequent recovery. Authors attributed this to steroid therapy. Prednisone dose was found to be the main determinant of the values of total and free testosterone). No relationship was found between post-transplant bone loss and testosterone levels, probably because patients were treated with calcitriol or alendronate.

In most studies, testosterone levels return to normal by 6 to 12 months after transplantation (Sambrook et al., 1994) but up to 20% of patients receiving prednisone and cyclosporine A may persist with low serum total testosterone levels 3 years after cardiac transplantation (Stempfle et al., 1999).

Regarding the role of other immunosuppressive agents on gonadal function cyclosporine A decreases testosterone by affecting both the hypothalamic-pituitary- gonadal axis (Sikka et al., 1988) and by direct inhibition of testicular synthesis of testosterone in murine models (Seethalakshmi et al., 1990). However, cyclosporine did not seem to affect testosterone levels in humans (Fleisher et al., 2008; Samojlik et al., 1992).

Some authors recommend hormonal treatment in post transplant osteoporosis in men and premenopausal women with hypogonadism, if there are no contraindications (Shane et al., 2009 up-to-date). Androgen replacement therapy has shown skeletal benefit (increase in BMD) only in men with hypogonadism. It has been demonstrated in an uncontrolled study of postmenopausal liver transplantation recipients, that the use of transdermal estradiol was effective in increasing BMD of lumbar spine and femoral neck over a period of two years (Isoniemi et al., 2001).

### **6. Prevention and treatment of osteoporosis**

### **6.1 General measures before transplantation**

The same measures used to prevent osteoporosis in the general population apply to transplant recipients, regardless of the pretransplant BMD measurement. It is recomended that all candidates for organ transplantation follow a throughfully evaluation in order to identificate and correct risk factors and to implement measures to improve bone health (Table 4).


Table 4. General recommendations for prevention and treatment of osteoporosis

Post-Transplantation Bone Disease 313

depends on patient characteristics, such as time of steroid therapy withdrawal, presence of other risk factors for low bone mineral density and fractures as well as information

Another approach to the management of transplanted patients is to apply similar guidelines as those used for the prevention of glucocorticoid-induced osteoporosis. There are several guidelines for the prevention of glucocorticoid-induced osteoporosis. Collectively, they suggest preventive therapy for patients with clinical risk factors for osteoporosis and fracture (age ≥65 years, previous fragility fracture) or in patients without other risk factors if

These potent antiresorptive agents are an obvious option in preventing the rapid bone loss, that occurs mainly in the early phase after transplantation. Bisphosphonates are considered the medical therapy of choice for the prevention of transplantation-related bone loss. Although there are conflicting data both oral and intravenous bisphosphonates appear to be

Below shows some of the results obtained with bisphosphonates treatment in different types

In a study of 99 subjects receiving stem cell transplantation, patients were randomly assigned to receive calcium and vitamin D or calcium and vitamin D plus pamidronate (60 mg intravenously six times over the first post-transplant year). Treatment with pamidronate prevented spine bone loss (0 percent in pamidronate group versus -2.9 percent in calcium group), and reduce hip bone loss (-5.5 percent and -7.8 percent in the pamidronate and

In a trial of 62 adults undergoing liver transplantation, patients were randomly assigned to receive infusions of zoledronic acid (4 mg) or placebo within seven days of transplantation. BMD was measured 3, 6, 9, and 12 months later. Zoledronic acid group lost significantly less bone at the hip at all time points (Crawford BA, 2006). In the spine, the zoledronic acid group lost less bone at three months, but the difference between the two groups was no longer significant at 12 months because of improvements between 3 and 12 months in the placebo group. Zoledronic acid sometimes caused postinfusion hypocalcemia and

Oral bisphosphonates are also effective in preventing bone loss after transplantation (Shane et al., 2004; Atamaz et al., 2006). As an example, in a trial of 98 subjects receiving a liver transplant, subjects randomly assigned to alendronate (70 mg weekly) versus no alendronate had significant increases in lumbar spine (5.1and 8.9 percent) and femoral neck (4.3 and 8.7 percent) BMD at 12 and 24 months, respectively, compared with the control group (Atamaz et

Our group studied the effect of risedronate in liver transplant patient. The main findings of our study are that liver transplanted patients with low bone mineral density who receive either Risendronate combined with calcium and vitamin D3 or vitamin D3 and calcium alone showed a significant increase in spine BMD at 12 months compared to baseline values. In addition, risedronate patients showed a significant increase in intertrochanteric BMD, but we were not able to find any significant differences between groups. Hence, these results suggest that weekly risedronate after liver transplantation combined with 1000 mg/day of calcium and 800 IU/day of vitamin D are not superior to the administration of calcium and vitamin D alone (Guadalix S, 2011). Significant

al., 2006). All subjects received calcium (1000 mg daily) and calcitriol (0.5 mcg daily).

provided by the measurement of BMD.

**6.2.1 Bisphosphonates** 

effective in these patients.

of transplants.

BMD T-score is below -1.0 or -1.5 (Shane E, 2009).

calcium-vitamin D groups, respectively) (Kananen et al., 2005).

temporary secondary hyperparathyroidism.

Lifestyle factors, such as immobilization, smoking, and alcohol abuse, should be avoided. Concomitant use of medications that can negatively impact skeletal health should be minimized whenever possible. Hypogonadism should be sought and corrected, particularly in males, where symptoms are easily confounded with those of preexisting chronic disease or adverse effects of concomitant medication. All patients should receive the recommended daily allowance for calcium (1000-15000 mg/day) and vitamin D (800 IU/day). Higher vitamin D doses should be given if the patient is vitamin D deficient (serum 25 hydroxyvitamin D level >20 ng/ml [50 nmol/L]). Although calcium and vitamin D do not prevent transplantation-related bone loss, randomized trials assessing antiresorptive therapy, such as bisphosphonates, have been carried out in the setting of concomitant calcium and vitamin D repletion.

Prevention of early bone loss after transplantion have been reported with specific resistance training programs (Mitchell et al., 2003). Regular weight-bearing exercise (30 minutes, three times per week) has proved also to be beneficial for the prevention and treatment of osteoporosis. Because of the high prevalence of osteopenia and osteoporosis in patients awaiting transplantation and the morbidity caused by osteoporosis after transplantation, it is recommended that candidates for organ transplantation undergo measurements of BMD of the hip and spine, preferably at the time of acceptance to the waiting list. Low BMD before transplantation has been pointed out as a risk factor for fractures after transplantation. In addition, spine radiographs should be performed to detect prevalent fractures .Patients who have a history of fracture or have osteoporosis on DXA (T-score ≤ - 2.5) before transplantation should be evaluated for secondary causes. When a secondary cause (i.e. hypogonadism) is identified, appropriate treatment is recommended prior to transplant. In addition to the treatment (when possible) of secondary causes, some patients may benefit from additional osteoporosis therapy, such as bisphosphonates, while awaiting transplant. Patients with osteopenia should be considered for prevention (calcium, vitamin D and/or antirresorptives) evaluating risk factors. Alternatively, patients with normal BMD can defer medical therapy until immediately after transplantation. For patients with endstage renal disease, an evaluation and treatment for renal osteodystrophy according to accepted guidelines is highly recommended.

#### **6.2 Therapeutic measures of post-transplantion bone loss**

Several drugs have been studied for the treatment of osteoporosis after transplantation. Many of these studies were done with small number of patients, were not randomized or not compared with control group. Also, patients were not selected based on T-score or risk factor (beyond the transplant). There is no consensus on candidates for the treatment or the drug of choice.**G**iven the accelerated bone loss that occurs immediately after transplantation many experts recommend preventive treatment for all patients receiving solid organ transplantation, regardless of pretransplant BMD (Maalouf NM, 2005; Cohen et al., 2006). This approach is based on observational data that show an overlap in BMD values between the pre-transplant patients with posttransplant fracture and those without fractures (Leidig-Bruckner et al., 2001; Shane et al., 1996). The lack of reliable clinical predictors to identify individual patients who will experience osteoporotic fractures renders all transplant recipients candidates for preventive therapy. Treatment should be started immediately after transplantation.

Since lumbar BMD starts to recover in many patients at 12 months after transplantation, long-term treatment may be unnecessary (Cohen et al., 2006). Duration of treatment

Lifestyle factors, such as immobilization, smoking, and alcohol abuse, should be avoided. Concomitant use of medications that can negatively impact skeletal health should be minimized whenever possible. Hypogonadism should be sought and corrected, particularly in males, where symptoms are easily confounded with those of preexisting chronic disease or adverse effects of concomitant medication. All patients should receive the recommended daily allowance for calcium (1000-15000 mg/day) and vitamin D (800 IU/day). Higher vitamin D doses should be given if the patient is vitamin D deficient (serum 25 hydroxyvitamin D level >20 ng/ml [50 nmol/L]). Although calcium and vitamin D do not prevent transplantation-related bone loss, randomized trials assessing antiresorptive therapy, such as bisphosphonates, have been carried out in the setting of concomitant

Prevention of early bone loss after transplantion have been reported with specific resistance training programs (Mitchell et al., 2003). Regular weight-bearing exercise (30 minutes, three times per week) has proved also to be beneficial for the prevention and treatment of osteoporosis. Because of the high prevalence of osteopenia and osteoporosis in patients awaiting transplantation and the morbidity caused by osteoporosis after transplantation, it is recommended that candidates for organ transplantation undergo measurements of BMD of the hip and spine, preferably at the time of acceptance to the waiting list. Low BMD before transplantation has been pointed out as a risk factor for fractures after transplantation. In addition, spine radiographs should be performed to detect prevalent fractures .Patients who have a history of fracture or have osteoporosis on DXA (T-score ≤ - 2.5) before transplantation should be evaluated for secondary causes. When a secondary cause (i.e. hypogonadism) is identified, appropriate treatment is recommended prior to transplant. In addition to the treatment (when possible) of secondary causes, some patients may benefit from additional osteoporosis therapy, such as bisphosphonates, while awaiting transplant. Patients with osteopenia should be considered for prevention (calcium, vitamin D and/or antirresorptives) evaluating risk factors. Alternatively, patients with normal BMD can defer medical therapy until immediately after transplantation. For patients with endstage renal disease, an evaluation and treatment for renal osteodystrophy according to

Several drugs have been studied for the treatment of osteoporosis after transplantation. Many of these studies were done with small number of patients, were not randomized or not compared with control group. Also, patients were not selected based on T-score or risk factor (beyond the transplant). There is no consensus on candidates for the treatment or the drug of choice.**G**iven the accelerated bone loss that occurs immediately after transplantation many experts recommend preventive treatment for all patients receiving solid organ transplantation, regardless of pretransplant BMD (Maalouf NM, 2005; Cohen et al., 2006). This approach is based on observational data that show an overlap in BMD values between the pre-transplant patients with posttransplant fracture and those without fractures (Leidig-Bruckner et al., 2001; Shane et al., 1996). The lack of reliable clinical predictors to identify individual patients who will experience osteoporotic fractures renders all transplant recipients candidates for

preventive therapy. Treatment should be started immediately after transplantation.

Since lumbar BMD starts to recover in many patients at 12 months after transplantation, long-term treatment may be unnecessary (Cohen et al., 2006). Duration of treatment

calcium and vitamin D repletion.

accepted guidelines is highly recommended.

**6.2 Therapeutic measures of post-transplantion bone loss** 

depends on patient characteristics, such as time of steroid therapy withdrawal, presence of other risk factors for low bone mineral density and fractures as well as information provided by the measurement of BMD.

Another approach to the management of transplanted patients is to apply similar guidelines as those used for the prevention of glucocorticoid-induced osteoporosis. There are several guidelines for the prevention of glucocorticoid-induced osteoporosis. Collectively, they suggest preventive therapy for patients with clinical risk factors for osteoporosis and fracture (age ≥65 years, previous fragility fracture) or in patients without other risk factors if BMD T-score is below -1.0 or -1.5 (Shane E, 2009).

#### **6.2.1 Bisphosphonates**

These potent antiresorptive agents are an obvious option in preventing the rapid bone loss, that occurs mainly in the early phase after transplantation. Bisphosphonates are considered the medical therapy of choice for the prevention of transplantation-related bone loss. Although there are conflicting data both oral and intravenous bisphosphonates appear to be effective in these patients.

Below shows some of the results obtained with bisphosphonates treatment in different types of transplants.

In a study of 99 subjects receiving stem cell transplantation, patients were randomly assigned to receive calcium and vitamin D or calcium and vitamin D plus pamidronate (60 mg intravenously six times over the first post-transplant year). Treatment with pamidronate prevented spine bone loss (0 percent in pamidronate group versus -2.9 percent in calcium group), and reduce hip bone loss (-5.5 percent and -7.8 percent in the pamidronate and calcium-vitamin D groups, respectively) (Kananen et al., 2005).

In a trial of 62 adults undergoing liver transplantation, patients were randomly assigned to receive infusions of zoledronic acid (4 mg) or placebo within seven days of transplantation. BMD was measured 3, 6, 9, and 12 months later. Zoledronic acid group lost significantly less bone at the hip at all time points (Crawford BA, 2006). In the spine, the zoledronic acid group lost less bone at three months, but the difference between the two groups was no longer significant at 12 months because of improvements between 3 and 12 months in the placebo group. Zoledronic acid sometimes caused postinfusion hypocalcemia and temporary secondary hyperparathyroidism.

Oral bisphosphonates are also effective in preventing bone loss after transplantation (Shane et al., 2004; Atamaz et al., 2006). As an example, in a trial of 98 subjects receiving a liver transplant, subjects randomly assigned to alendronate (70 mg weekly) versus no alendronate had significant increases in lumbar spine (5.1and 8.9 percent) and femoral neck (4.3 and 8.7 percent) BMD at 12 and 24 months, respectively, compared with the control group (Atamaz et al., 2006). All subjects received calcium (1000 mg daily) and calcitriol (0.5 mcg daily).

Our group studied the effect of risedronate in liver transplant patient. The main findings of our study are that liver transplanted patients with low bone mineral density who receive either Risendronate combined with calcium and vitamin D3 or vitamin D3 and calcium alone showed a significant increase in spine BMD at 12 months compared to baseline values. In addition, risedronate patients showed a significant increase in intertrochanteric BMD, but we were not able to find any significant differences between groups. Hence, these results suggest that weekly risedronate after liver transplantation combined with 1000 mg/day of calcium and 800 IU/day of vitamin D are not superior to the administration of calcium and vitamin D alone (Guadalix S, 2011). Significant

Post-Transplantation Bone Disease 315

lumbar spine BMD increased 5%, whereas those who received cyclical etidronate or nasal calcitonin, showed decreases in spine BMD (Garcia-Delgado et al., 1997). Also, alfacalcidol therapy has been associated with an increase in BMD or prevention of additional bone loss in renal (El-Agroudy et al., 2003) and cardiac recipients ( Van Cleemput et al., 1996).

Calcitriol may suppress bone resorption indirectly by facilitating intestinal calcium absorption and suppressing PTH secretion. Studies of calcitriol alone and those that compare calcitriol and bisphosphonates suggest that calcitriol may also prevent early posttransplant bone loss, particularly at the proximal femur. Positive effects on BMD have been found with higher doses of calcitriol (> 0.50 µgr/day) in heart, lung or renal transplantation, whereas lower doses (0.25 µgr/day) are relatively ineffective. Use of calcitriol requires close monitoring of serum and 24 hour urine calcium, because it is associated with hypercalcemia and hypercalciuria in >50% patients.In a study of 65 patients undergoing cardiac or single lung transplantation, patients were randomly allocated to receive placebo or calcitriol (0.5- 0.75 microg/day), the latter for either 12 months or 24 months. Bone loss at the proximal femur was significantly reduced or prevented by treatment with calcitriol for 2 years

Other randomized study compared the efficacy of 6 months treatment with either calcitriol (0.5 microg/day) or two cycles of etidronate plus calcium in preventing bone loss in 41 patients undergoing cardiac or lung transplantation. Compared with an untreated reference group, both therapies offered significant protection at 6 months in lumbar spine and etidronate provided significant protective carryover after therapy had been discontinued (Henderson et al., 2001).Although calcitriol appears to be effective in preventing bone loss after transplantation (Sambrook et al., 2000; Shane E, 2004) it should not be selected as firstline treatment because of their limited effectiveness and narrow therapeutic window.

Although calcitonin is effective in preventing bone loss in postmenopausal women, it has not been shown to be superior to calcium in transplant recipients (Välimäki et al., 1999). In one trial, the combination of continuos oral calcitriol (0.5 microg/day) and nasal salmon calcitonin (200 U/day) for the first 3 months was inferior to intravenous pamidronate (0.5 mg/kg body weight) every third month in attenuating bone loss three months after cardiac transplant but similar at 18 months in 26 cardiac transplant recipients (Bianda et al., 2000).

PTH 1-34 (teriparatide) has been shown to improve BMD in patients with glucocorticoidinduced osteoporosis, but there are few studies evaluating PTH for the prevention of posttransplant osteoporosis. It a small trial 24 kidney recipients patients were treated with 20 µg of teriparatide/daily/6 months, it was shown that femoral neck BMD was stable compared to the placebo group. Lumbar spine BDM and radial BMD, histomorphometric bone volume and bone matrix mineralization status remained unchanged in both groups. (Cejka et al., 2008). Recombinant parathyroid hormone (PTH) has not been well studied in this population. Patients who have received total body irradiation during hematopoietic stem cell transplantation or who have primary or secondary elevations in PTH are not candidates

compared with treatment with calcium alone (Sambrook et al., 2000).

**6.3.4 Recombinant parathyroid hormone (PTH)** 

for recombinant PTH therapy.

**6.3.2 Calcitriol** 

**6.3.3 Calcitonin** 

improvement in BMD at the lumbar spine was also observed 12 months after liver transploant in the control group. This response may be related to the administration of calcium and vitamin D3 itself, but also to improvement in general health, mobility, muscle mass, and nutrition as a consequence of better liver function.

A recent meta-analysis in 364 liver transplant patients from 6 randomized controlled trials have found that bisphosphonate therapy improved lumbar spine BMD by 0.03 g/cm2 (95% CI 0.01-0.05 g/cm2, p=0.02) at 12 months post-liver transplantation compared to the control group. However, a statistically significant change in femoral neck BMD could not be demonstrated in this meta-analysis. Data on fractures could not be analyzed (Kasturi et al., 2010). In a study of 34 lung transplant recipients (with cystic fibrosis antecedents), pamidronate therapy versus calcium and vitamin D showed a significant increase in bone mass at 2 years in lumbar spine and total femur. There was no difference in fracture incidence (Aris et al., 2000).

In patients after allogenic stem cell transplantation pamidronate reduced bone loss at the spine, femoral neck and hip by 5.6, 7.7 and 4.9% respectively after 12 month of treatment. However, at 24 month, only differences at BMD of total hip remained statistically significant between study groups (Grigg et al., 2006). Other study in 12 patients treated with zoledronic acid show that 12 month after infusion, total hip BMD increased in 75% of the patients and femoral neck BMD increased in 11 of 12 patients. Spinal BMD only increase in four (D'Souza et al., 2006).

Based upon the above trials, we suggest bisphosphonates as first choice for prevention of transplantation-related bone loss. There are few data to support the use of one bisphosphonate over another. Many of the trials used intravenous bisphosphonates due to ease of administration, especially in post-transplant patients who are required to take many oral medications. There are no trials comparing oral to intravenous bisphosphonates in the immediate post-transplant setting. The decision should be based upon individual patient preferences and abilities. The safety and efficacy of bisphosphonates for prevention of transplantation-related bone loss in patients with chronic kidney disease has not been carefully evaluated, and in general, there is limited data on the level of renal impairment at which bisphosphonate use should be avoided and whether this level is the same for iv bisphosphonates. In the majority of trials, individuals with serum creatinine concentrations above the upper limits of normal were excluded from participation. Despite these concerns, however, it is usually recommend their use after renal transplantation, at least during the first year when rates of bone loss are most rapid.

#### **6.3 Other therapies**

Replacement doses of calcium and vitamin D (400-1000 IU/day) do not prevent clinically significant bone loss after transplantation, but active metabolites of vitamin D could reduce post-transplantation bone loss, probably by reversing glucocorticoid-induced decreases in intestinal calcium absorption.

#### **6.3.1 Calcidiol (25-hydroxivitamin D) and alfacalcidol (1-hydroxivitamin D)**

In renal transplant recipients calcidiol (40 µgr/day) prevents spine and femoral bone loss and is associated with a significant decrease in vertebral deformities (Talalaj et al., 1996). Consistently with these findings, our group have found that in patients randomized immediately after cardiac transplantation to 32000 IU/week of oral calcidiol for 18 months,

lumbar spine BMD increased 5%, whereas those who received cyclical etidronate or nasal calcitonin, showed decreases in spine BMD (Garcia-Delgado et al., 1997). Also, alfacalcidol therapy has been associated with an increase in BMD or prevention of additional bone loss in renal (El-Agroudy et al., 2003) and cardiac recipients ( Van Cleemput et al., 1996).

### **6.3.2 Calcitriol**

314 Osteoporosis

improvement in BMD at the lumbar spine was also observed 12 months after liver transploant in the control group. This response may be related to the administration of calcium and vitamin D3 itself, but also to improvement in general health, mobility, muscle

A recent meta-analysis in 364 liver transplant patients from 6 randomized controlled trials have found that bisphosphonate therapy improved lumbar spine BMD by 0.03 g/cm2 (95% CI 0.01-0.05 g/cm2, p=0.02) at 12 months post-liver transplantation compared to the control group. However, a statistically significant change in femoral neck BMD could not be demonstrated in this meta-analysis. Data on fractures could not be analyzed (Kasturi et al., 2010). In a study of 34 lung transplant recipients (with cystic fibrosis antecedents), pamidronate therapy versus calcium and vitamin D showed a significant increase in bone mass at 2 years in lumbar spine and total femur. There was no difference in fracture

In patients after allogenic stem cell transplantation pamidronate reduced bone loss at the spine, femoral neck and hip by 5.6, 7.7 and 4.9% respectively after 12 month of treatment. However, at 24 month, only differences at BMD of total hip remained statistically significant between study groups (Grigg et al., 2006). Other study in 12 patients treated with zoledronic acid show that 12 month after infusion, total hip BMD increased in 75% of the patients and femoral neck BMD increased in 11 of 12 patients. Spinal BMD only increase in four (D'Souza

Based upon the above trials, we suggest bisphosphonates as first choice for prevention of transplantation-related bone loss. There are few data to support the use of one bisphosphonate over another. Many of the trials used intravenous bisphosphonates due to ease of administration, especially in post-transplant patients who are required to take many oral medications. There are no trials comparing oral to intravenous bisphosphonates in the immediate post-transplant setting. The decision should be based upon individual patient preferences and abilities. The safety and efficacy of bisphosphonates for prevention of transplantation-related bone loss in patients with chronic kidney disease has not been carefully evaluated, and in general, there is limited data on the level of renal impairment at which bisphosphonate use should be avoided and whether this level is the same for iv bisphosphonates. In the majority of trials, individuals with serum creatinine concentrations above the upper limits of normal were excluded from participation. Despite these concerns, however, it is usually recommend their use after renal transplantation, at least during the

Replacement doses of calcium and vitamin D (400-1000 IU/day) do not prevent clinically significant bone loss after transplantation, but active metabolites of vitamin D could reduce post-transplantation bone loss, probably by reversing glucocorticoid-induced decreases in

In renal transplant recipients calcidiol (40 µgr/day) prevents spine and femoral bone loss and is associated with a significant decrease in vertebral deformities (Talalaj et al., 1996). Consistently with these findings, our group have found that in patients randomized immediately after cardiac transplantation to 32000 IU/week of oral calcidiol for 18 months,

**6.3.1 Calcidiol (25-hydroxivitamin D) and alfacalcidol (1-hydroxivitamin D)** 

mass, and nutrition as a consequence of better liver function.

incidence (Aris et al., 2000).

first year when rates of bone loss are most rapid.

et al., 2006).

**6.3 Other therapies** 

intestinal calcium absorption.

Calcitriol may suppress bone resorption indirectly by facilitating intestinal calcium absorption and suppressing PTH secretion. Studies of calcitriol alone and those that compare calcitriol and bisphosphonates suggest that calcitriol may also prevent early posttransplant bone loss, particularly at the proximal femur. Positive effects on BMD have been found with higher doses of calcitriol (> 0.50 µgr/day) in heart, lung or renal transplantation, whereas lower doses (0.25 µgr/day) are relatively ineffective. Use of calcitriol requires close monitoring of serum and 24 hour urine calcium, because it is associated with hypercalcemia and hypercalciuria in >50% patients.In a study of 65 patients undergoing cardiac or single lung transplantation, patients were randomly allocated to receive placebo or calcitriol (0.5- 0.75 microg/day), the latter for either 12 months or 24 months. Bone loss at the proximal femur was significantly reduced or prevented by treatment with calcitriol for 2 years compared with treatment with calcium alone (Sambrook et al., 2000).

Other randomized study compared the efficacy of 6 months treatment with either calcitriol (0.5 microg/day) or two cycles of etidronate plus calcium in preventing bone loss in 41 patients undergoing cardiac or lung transplantation. Compared with an untreated reference group, both therapies offered significant protection at 6 months in lumbar spine and etidronate provided significant protective carryover after therapy had been discontinued (Henderson et al., 2001).Although calcitriol appears to be effective in preventing bone loss after transplantation (Sambrook et al., 2000; Shane E, 2004) it should not be selected as firstline treatment because of their limited effectiveness and narrow therapeutic window.

### **6.3.3 Calcitonin**

Although calcitonin is effective in preventing bone loss in postmenopausal women, it has not been shown to be superior to calcium in transplant recipients (Välimäki et al., 1999). In one trial, the combination of continuos oral calcitriol (0.5 microg/day) and nasal salmon calcitonin (200 U/day) for the first 3 months was inferior to intravenous pamidronate (0.5 mg/kg body weight) every third month in attenuating bone loss three months after cardiac transplant but similar at 18 months in 26 cardiac transplant recipients (Bianda et al., 2000).

### **6.3.4 Recombinant parathyroid hormone (PTH)**

PTH 1-34 (teriparatide) has been shown to improve BMD in patients with glucocorticoidinduced osteoporosis, but there are few studies evaluating PTH for the prevention of posttransplant osteoporosis. It a small trial 24 kidney recipients patients were treated with 20 µg of teriparatide/daily/6 months, it was shown that femoral neck BMD was stable compared to the placebo group. Lumbar spine BDM and radial BMD, histomorphometric bone volume and bone matrix mineralization status remained unchanged in both groups. (Cejka et al., 2008). Recombinant parathyroid hormone (PTH) has not been well studied in this population. Patients who have received total body irradiation during hematopoietic stem cell transplantation or who have primary or secondary elevations in PTH are not candidates for recombinant PTH therapy.

Post-Transplantation Bone Disease 317

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#### **6.3.5 New therapies**

Promising new agents for transplantation osteoporosis include new potent anticatabolic drugs such as human antibodies to receptor activator of nuclear factor kb-ligand (RANKL) (denosumab), and catepsin k inhibitors.

### **6.4 Monitoring**

There is no consensus on the optimal strategy for monitoring patients on therapy. Patients on antiresorptive therapy are measured BMD every year after transplantation. Patients with normal BMD can be follow up with DXA every two years, depending also of other risk factors . In patients who require continuous treatment with glucocorticoids (prednisone ≥ 5 mg / day), BMD measurement is recommended annually. An effort should be made to find the lowest prednisone dose compatible with graft survival.

### **7. Summary and conclusions**

Although bone loss and fractures after transplantation seem to be lower than those reported years ago, they remain being a main long term postransplant complication. An effective approach should incorporate pre-transplant measures to detect and to treat preexisting bone diseases. Oral or intravenous bisphosphonates, in conjunction with calcium and vitamin D, are effective in preventing post-transplantation bone loss when started shortly after grafting. The optimal dose, timing, and frequency, particularly of intravenous bisphosphonate administration, remain to be determined. At present, most controlled trials lack sufficient statistical power to demonstrate efficacy for fracture prevention, so treatment regimens are based on results of effects on the surrogate end-points, bone densitometry, and bone turnover markers. More studies are required to determine the best agent and route of administration to prevent this common complication of organ transplantation. The future challenge is to achieve adequate immunosuppression without corticosteroids, with drugs not damaging bone*.* This approach, together with improved bone health before the transplant would be an effective strategy to reduce post-transplant osteoporosis.

### **8. Acknowledgement**

The authors received funding from Fundación Mutua Madrileña (nº 2005-072) and from Asociacion para la investigacion de Osteoporosis y Enfermedades Endocrinas.

### **9. References**


Promising new agents for transplantation osteoporosis include new potent anticatabolic drugs such as human antibodies to receptor activator of nuclear factor kb-ligand (RANKL)

There is no consensus on the optimal strategy for monitoring patients on therapy. Patients on antiresorptive therapy are measured BMD every year after transplantation. Patients with normal BMD can be follow up with DXA every two years, depending also of other risk factors . In patients who require continuous treatment with glucocorticoids (prednisone ≥ 5 mg / day), BMD measurement is recommended annually. An effort should be made to find

Although bone loss and fractures after transplantation seem to be lower than those reported years ago, they remain being a main long term postransplant complication. An effective approach should incorporate pre-transplant measures to detect and to treat preexisting bone diseases. Oral or intravenous bisphosphonates, in conjunction with calcium and vitamin D, are effective in preventing post-transplantation bone loss when started shortly after grafting. The optimal dose, timing, and frequency, particularly of intravenous bisphosphonate administration, remain to be determined. At present, most controlled trials lack sufficient statistical power to demonstrate efficacy for fracture prevention, so treatment regimens are based on results of effects on the surrogate end-points, bone densitometry, and bone turnover markers. More studies are required to determine the best agent and route of administration to prevent this common complication of organ transplantation. The future challenge is to achieve adequate immunosuppression without corticosteroids, with drugs not damaging bone*.* This approach, together with improved bone health before the

transplant would be an effective strategy to reduce post-transplant osteoporosis.

Asociacion para la investigacion de Osteoporosis y Enfermedades Endocrinas.

The authors received funding from Fundación Mutua Madrileña (nº 2005-072) and from

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**7. Summary and conclusions** 

**8. Acknowledgement** 

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Monegal A, Guañabens N, Suárez MJ, Suárez F, Clemente G, García-González M, De la

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Ninkovic M, Love SA, Tom B, Alexander GJ, Compston JE. 2001 High prevalence of

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vertebral osteoporosis in lung transplant recipients. *Transplantation.* Aug

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Incidence of vertebral fractures in the first three months after orthotopic liver

osteoporosis in patients with chronic liver disease prior to liver transplantation.


**17** 

*Poland* 

**The Skeleton Abnormalities in Patients** 

Marek W. Karwacki and Wojciech Wozniak

*Institute of Mother and Child* 

**with Neurofibromatosis Type 1: Important** 

**Consequences of Abnormal Gene Function** 

*Nf-1 Outpatients Clinic & Department of Oncological Surgery for Children and Youth,* 

Neurofibromatosis type 1 [Nf-1, OMIM #1622001], formerly known as von Recklinghausen disease, is one of the most frequent disorders affecting mankind, inherited as an autosomal dominant trait. The relatively high prevalence, with an incidence at birth of approximately one in 2500 to 3500 live births, and a progressive nature of the disorder, notable for its phenotypic variability with almost 100% penetrance, as well as high proportion of sporadic cases (almost 50% of de novo mutations), constitute for the clinical magnitude of this disease. Multiple café au lait spots [CALs], axillary and inguinal freckling, multiple discrete cutaneous neurofibromas [NFM] and more prominent plexiform neurofibromas [PNF], and iris Lisch nodules constituted for the cardinal signs of the disease. Learning disabilities and attention deficits states, but usually with normal intelligence in adulthood, are present in at least 50% of individuals with Nf-1. Neurofibromatosis type 1 belongs to the group of disorders with significantly increased risk of tumorigenesis. The other significant manifestations of Nf-1 include bone dysplasias, clinically presented as progressive dystrophic scoliosis, vertebral dysplasia, overgrowth and tibial dysplasia with pseudarthrosis, and vasculopathy. Pubertal development is usually normal, but precocious puberty, especially in those with an optic chiasm glioma, as well as delayed puberty, may commonly occur in children with Nf-1. The life expectancy of Nf-1 patients is assumed to be reduced by 15 years. The most important causes of early death in these patients are malignant peripheral nerve sheath tumors and severe complications of vasculopathy

Despite the possibility of molecular testing, the diagnosis of Nf-1 is still based on clinical findings and is usually unequivocal in all but the young children (DeBella et al., 2000b). The diagnostic criteria for Nf-1 (Tabl. 1) were developed by the US National Institutes of Health (National Institute of Health [NIH], 1988) and are generally accepted worldwide for routine clinical use (Ferner et al., 2007; Williams et al., 2009). The disease is characterizes by extreme clinical variability, not only between unrelated, but also among affected individuals within a

<sup>1</sup>Online Mendelian Inheritance in Man, OMIM (TM). Johns Hopkins University, Baltimore, MD. MIM Number: #162200, 07/06/2011. World Wide Web URL: http://www.ncbi.nlm.nih.gov/omim/

(Friedman et al., 1999; Jett & Friedman, 2010; Larizza et al., 2009).

**1. Introduction** 


## **The Skeleton Abnormalities in Patients with Neurofibromatosis Type 1: Important Consequences of Abnormal Gene Function**

Marek W. Karwacki and Wojciech Wozniak *Nf-1 Outpatients Clinic & Department of Oncological Surgery for Children and Youth, Institute of Mother and Child* 

*Poland* 

### **1. Introduction**

322 Osteoporosis

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Välimäki MJ, Kinnunen K, Volin L, Tähtelä R, Löyttyniemi E, Laitinen K, Mäkelä P, Keto P,

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biphosphonates and vitamin D. Transplantation 1996;61:1495–9.

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on the hypothalamic-pituitary-gonadal axis in the male rat: mechanism of action.

Rosina F. 2003 Osteoporosis: still a typical complication of primary biliary

Weiss NS 2000 Risk factors for hip fracture among patients with end-stage renal

Efficiency of preventive treatment of glucocorticoid-induced osteoporosis with 25 hydroxyvitamin D3 and calcium in kidney transplant patients. Transplant Proc

Lombardi G, Rotoli B, Colao A 2003 . Gonadal status in reproductive age women after haematopoietic stem cell transplantation for haematological malignancies.

Lombardi G, Rotoli B, Colao A. 2005 Endocrine disorders during the first year

Cyclosporine induces high bone turnover and may contribute to bone loss after

2002.Osteoporosis before lung transplantation: association with low body mass

Prevention of bone loss in cardiac transplant recipients. A comparison of

bisphosphonates treatment in bone loss after liver transplantation. *Calcif Tissue* 

Nieminen M. 1999.A prospective study of bone loss and turnover after cardiac transplantation: effect of calcium supplementation with or without calcitonin.

Ruutu T. 1999; A prospective study of bone loss and turnover after allogeneic bone marrow transplantation: effect of calcium supplementation with or without

infusion of pamidronate prior to liver transplantation: a bone histomorphometric

Neurofibromatosis type 1 [Nf-1, OMIM #1622001], formerly known as von Recklinghausen disease, is one of the most frequent disorders affecting mankind, inherited as an autosomal dominant trait. The relatively high prevalence, with an incidence at birth of approximately one in 2500 to 3500 live births, and a progressive nature of the disorder, notable for its phenotypic variability with almost 100% penetrance, as well as high proportion of sporadic cases (almost 50% of de novo mutations), constitute for the clinical magnitude of this disease. Multiple café au lait spots [CALs], axillary and inguinal freckling, multiple discrete cutaneous neurofibromas [NFM] and more prominent plexiform neurofibromas [PNF], and iris Lisch nodules constituted for the cardinal signs of the disease. Learning disabilities and attention deficits states, but usually with normal intelligence in adulthood, are present in at least 50% of individuals with Nf-1. Neurofibromatosis type 1 belongs to the group of disorders with significantly increased risk of tumorigenesis. The other significant manifestations of Nf-1 include bone dysplasias, clinically presented as progressive dystrophic scoliosis, vertebral dysplasia, overgrowth and tibial dysplasia with pseudarthrosis, and vasculopathy. Pubertal development is usually normal, but precocious puberty, especially in those with an optic chiasm glioma, as well as delayed puberty, may commonly occur in children with Nf-1. The life expectancy of Nf-1 patients is assumed to be reduced by 15 years. The most important causes of early death in these patients are malignant peripheral nerve sheath tumors and severe complications of vasculopathy (Friedman et al., 1999; Jett & Friedman, 2010; Larizza et al., 2009).

Despite the possibility of molecular testing, the diagnosis of Nf-1 is still based on clinical findings and is usually unequivocal in all but the young children (DeBella et al., 2000b). The diagnostic criteria for Nf-1 (Tabl. 1) were developed by the US National Institutes of Health (National Institute of Health [NIH], 1988) and are generally accepted worldwide for routine clinical use (Ferner et al., 2007; Williams et al., 2009). The disease is characterizes by extreme clinical variability, not only between unrelated, but also among affected individuals within a

<sup>1</sup>Online Mendelian Inheritance in Man, OMIM (TM). Johns Hopkins University, Baltimore, MD. MIM Number: #162200, 07/06/2011. World Wide Web URL: http://www.ncbi.nlm.nih.gov/omim/

The Skeleton Abnormalities in Patients with

patients) (Radtke et al., 2007).

Neurofibromatosis Type 1: Important Consequences of Abnormal Gene Function 325

individual both mutations must be acquire in intact alleles, so the chance for that is much lower. Cells that have lost both copies of the tumor suppressor gene have a growth advantage over so called wild cells. In a susceptible environment, this 'second hit' may result in tumor formation (Larizza et al., 2009; Upadhyaya, 2011). This helps to explain the development of neurofibromas and other malignancies occurring in Nf-1 patients, but currently does not fully explain the role of neurofibromin on the development of other ailments, and osseous abnormalities in particular. However the precise role of neurofibromin is not yet fully elucidated, although neurofibromin deficiency causes multiple clinical effects, suggesting that this gene product has diverse functions in a variety of tissues. Distorted process is responsible not only for tumorigenesis, but also for memory processing (intellectual disability) and bone remodeling (typical bone deformity seen in Nf-1

Phenotype expression of *NF1* gene mutation is extremely variable, so even individuals from one family with identical germline mutation may have dramatically different clinical manifestations. Observed complexity and the diversity of constitutional *NF1* mutations occurring in Nf-1 patients will continue to make genotype-phenotype correlation almost impossible. Clinical variability of Nf-1 results most probably from a combination of founder mutation effect of *NF1* gene influenced by further action of other genes engaged in signal transduction, as well as other genetic, non-genetic, and stochastic factors (Jouhilahti et al., 2011). Till now more than 500 different mutations of the *NF1* gene have been identified, and most of them are unique to a particular family. Different, mostly loss-of-function mutations, have been observed repeatedly, but none has been found in more than a few percent of studied families (Radtke et al., 2007). In consequence, there are not so called hot spots sequences manifest along the entire gene length, what significantly complicated not only molecular testing but genetic counseling as well. Till now, only two clear correlations have been observed between particular mutant *NF1* alleles and consistent clinical phenotypes. In one, the whole *NF1* gene deletion is associated with more prominent presentation of the disease (Mensink et al., 2006). In another, characterized by 3-bp in-frame deletion of exon 17 (c.2970-2972 delAAT), the typical pigmentary features, but no cutaneous or surface plexiform neurofibromas, exist (Upadhyaya et al., 2007). Data concerning *NF1* mutation have accumulated slowly owing to the variability of the mutation types and the size and complexity of the gene, belongs to the longest in human genome. This also reflects the lack of a simple,

inexpensive, highly accurate DNA-based test for Nf-1 at present (Radtke et al., 2007).

patients are referred by Nf-1 clinic to other specialists as well.

Currently no treatments dedicated specifically to Nf-1 patients exist. Because of the increased risk of cancer and multiorgan involvement, Nf-1 patients required extensive medical surveillance, provided on the regular bases by the specific, highly specialized Nf-1 clinics (Karwacki & Wozniak, 2006). It obey a comprehensive standards, comprises of regular physical examination by a Nf-1 specialist, regular blood pressure and ophthalmologic monitoring, anthropometric and developmental assessment of children and periodical imaging, warrants follow-up of clinically suspected intracranial and other internal tumors, done by USG and/or MR imaging. CT scans are hardly recommended in NF-1 patients, but children in particular, as the imaging exerts the risk of irradiation and is of limited diagnostic value, especially in visualization of Nf-1 brain specific lesions, called undifferentiated bright objects [UBO](DeBella et al., 2000a). According to specific ailment,

single family carrying the same type of mutation, and even within a single person with Nf-1 at different times in life. Penetrance of *NF1* gene mutation is virtually complete (100% of penetration) after childhood and the frequency of more serious complications increases with age. Various manifestations of Nf-1 have different characteristic times of appearance (DeBella et al., 2000b; Boulanger & Larbrisseau, 2005; Friedman ed., 1999; Williams et al., 2009). The clinical NIH diagnostic criteria are both highly specific and highly sensitive only in adults. Less than half of youngest children with no family history of Nf-1 meet NIH criteria, although almost all do by adolescence. Yet, neonates who inherited *NF1* mutation from one of the parents can usually be identified within the first year of life by the presence of numerous CALs (DeBella et al., 2000b).

The presence of two or more of the following features is required for the diagnosis of Nf-1:


Table 1. The NIH diagnostic criteria for neurofibromatosis type 1

Neurofibromatosis type 1 is caused by heterozygous mutations (intragenic or microdeletion) in *NF1* tumor suppressor gene, located at 17q11.2. Its product, neurofibromin, has different biochemical interactions, including association to microtubules and participation in several signaling pathways, especially as a member of the GTPase-activating proteins. Its main physiological function is inactivation of energized *ras* oncogene. *NF1* mutation extinguish a gene function and leads to aberrant *ras* activity. *NF1* gene belongs to the family of tumor suppressor genes and neurofibromatosis type 1 is thought to be a hereditary malignancy syndrome, which is highly influenced by complex action of other genes, required in signal transmission processing. In human diseases predisposing to cancer, cells usually carry heterozygous germline, what means inherited, mutations in growth regulator genes that are essential for organized cell growth and differentiation. Affected individuals, such as Nf-1 patients, are at significant risk for development of benign or malignant tumors early in life. In case of Nf-1, the most distinguished types of neoplasia are tumors arising from peripheral and optic nerves sheath (Schwann cells), usually benign neurofibroma and optic nerve glioma or seldom, malignant peripheral nerve sheath tumor [MPNST]. MPNST usually growths as a result of malignant transformation of plexiform neurofibroma [PNF], a specific, clinically distinguished type of neurofibroma. The risk of transformation of PNF into MPNST is not higher than 10%, and have been finally evaluated in recent clinical trials (Upadhyaya, 2011). The overall risk of cancer development in Nf-1 patients surpass the healthy general population risk by 2.7 times (Walker et al., 2006). The risk of malignancy is higher in those patients because inherited nature of the first mutation released the entire process, and in consequence, only one additional acquire genetic alteration, resulted in loss of the wild allele of affected gene, is further necessary to facilitate tumorigenesis. In healthy

single family carrying the same type of mutation, and even within a single person with Nf-1 at different times in life. Penetrance of *NF1* gene mutation is virtually complete (100% of penetration) after childhood and the frequency of more serious complications increases with age. Various manifestations of Nf-1 have different characteristic times of appearance (DeBella et al., 2000b; Boulanger & Larbrisseau, 2005; Friedman ed., 1999; Williams et al., 2009). The clinical NIH diagnostic criteria are both highly specific and highly sensitive only in adults. Less than half of youngest children with no family history of Nf-1 meet NIH criteria, although almost all do by adolescence. Yet, neonates who inherited *NF1* mutation from one of the parents can usually be identified within the first year of life by the presence

The presence of two or more of the following features is required for the diagnosis of Nf-1: 1. Six or more café au lait macules over 5 mm in greatest diameter in prepubertal individuals and over 15 mm in greatest diameter in postpubertal individuals

2. Two or more neurofibromas of any type, or one plexiform neurofibroma

6. A distinctive osseous lesion such as sphenoid dysplasia or tibial pseudarthrosis

7. A first-degree relative (parent, sib, or offspring) with Nf-1 as defined by the above

Neurofibromatosis type 1 is caused by heterozygous mutations (intragenic or microdeletion) in *NF1* tumor suppressor gene, located at 17q11.2. Its product, neurofibromin, has different biochemical interactions, including association to microtubules and participation in several signaling pathways, especially as a member of the GTPase-activating proteins. Its main physiological function is inactivation of energized *ras* oncogene. *NF1* mutation extinguish a gene function and leads to aberrant *ras* activity. *NF1* gene belongs to the family of tumor suppressor genes and neurofibromatosis type 1 is thought to be a hereditary malignancy syndrome, which is highly influenced by complex action of other genes, required in signal transmission processing. In human diseases predisposing to cancer, cells usually carry heterozygous germline, what means inherited, mutations in growth regulator genes that are essential for organized cell growth and differentiation. Affected individuals, such as Nf-1 patients, are at significant risk for development of benign or malignant tumors early in life. In case of Nf-1, the most distinguished types of neoplasia are tumors arising from peripheral and optic nerves sheath (Schwann cells), usually benign neurofibroma and optic nerve glioma or seldom, malignant peripheral nerve sheath tumor [MPNST]. MPNST usually growths as a result of malignant transformation of plexiform neurofibroma [PNF], a specific, clinically distinguished type of neurofibroma. The risk of transformation of PNF into MPNST is not higher than 10%, and have been finally evaluated in recent clinical trials (Upadhyaya, 2011). The overall risk of cancer development in Nf-1 patients surpass the healthy general population risk by 2.7 times (Walker et al., 2006). The risk of malignancy is higher in those patients because inherited nature of the first mutation released the entire process, and in consequence, only one additional acquire genetic alteration, resulted in loss of the wild allele of affected gene, is further necessary to facilitate tumorigenesis. In healthy

of numerous CALs (DeBella et al., 2000b).

3. Freckling in the axillary or inguinal regions

5. Two or more Lisch nodules (iris hamartomas)

Table 1. The NIH diagnostic criteria for neurofibromatosis type 1

4. Optic glioma

criteria

individual both mutations must be acquire in intact alleles, so the chance for that is much lower. Cells that have lost both copies of the tumor suppressor gene have a growth advantage over so called wild cells. In a susceptible environment, this 'second hit' may result in tumor formation (Larizza et al., 2009; Upadhyaya, 2011). This helps to explain the development of neurofibromas and other malignancies occurring in Nf-1 patients, but currently does not fully explain the role of neurofibromin on the development of other ailments, and osseous abnormalities in particular. However the precise role of neurofibromin is not yet fully elucidated, although neurofibromin deficiency causes multiple clinical effects, suggesting that this gene product has diverse functions in a variety of tissues. Distorted process is responsible not only for tumorigenesis, but also for memory processing (intellectual disability) and bone remodeling (typical bone deformity seen in Nf-1 patients) (Radtke et al., 2007).

Phenotype expression of *NF1* gene mutation is extremely variable, so even individuals from one family with identical germline mutation may have dramatically different clinical manifestations. Observed complexity and the diversity of constitutional *NF1* mutations occurring in Nf-1 patients will continue to make genotype-phenotype correlation almost impossible. Clinical variability of Nf-1 results most probably from a combination of founder mutation effect of *NF1* gene influenced by further action of other genes engaged in signal transduction, as well as other genetic, non-genetic, and stochastic factors (Jouhilahti et al., 2011). Till now more than 500 different mutations of the *NF1* gene have been identified, and most of them are unique to a particular family. Different, mostly loss-of-function mutations, have been observed repeatedly, but none has been found in more than a few percent of studied families (Radtke et al., 2007). In consequence, there are not so called hot spots sequences manifest along the entire gene length, what significantly complicated not only molecular testing but genetic counseling as well. Till now, only two clear correlations have been observed between particular mutant *NF1* alleles and consistent clinical phenotypes. In one, the whole *NF1* gene deletion is associated with more prominent presentation of the disease (Mensink et al., 2006). In another, characterized by 3-bp in-frame deletion of exon 17 (c.2970-2972 delAAT), the typical pigmentary features, but no cutaneous or surface plexiform neurofibromas, exist (Upadhyaya et al., 2007). Data concerning *NF1* mutation have accumulated slowly owing to the variability of the mutation types and the size and complexity of the gene, belongs to the longest in human genome. This also reflects the lack of a simple, inexpensive, highly accurate DNA-based test for Nf-1 at present (Radtke et al., 2007).

Currently no treatments dedicated specifically to Nf-1 patients exist. Because of the increased risk of cancer and multiorgan involvement, Nf-1 patients required extensive medical surveillance, provided on the regular bases by the specific, highly specialized Nf-1 clinics (Karwacki & Wozniak, 2006). It obey a comprehensive standards, comprises of regular physical examination by a Nf-1 specialist, regular blood pressure and ophthalmologic monitoring, anthropometric and developmental assessment of children and periodical imaging, warrants follow-up of clinically suspected intracranial and other internal tumors, done by USG and/or MR imaging. CT scans are hardly recommended in NF-1 patients, but children in particular, as the imaging exerts the risk of irradiation and is of limited diagnostic value, especially in visualization of Nf-1 brain specific lesions, called undifferentiated bright objects [UBO](DeBella et al., 2000a). According to specific ailment, patients are referred by Nf-1 clinic to other specialists as well.

The Skeleton Abnormalities in Patients with

chemotherapy response of MPNST.

morbidity.

Neurofibromatosis Type 1: Important Consequences of Abnormal Gene Function 327

arising in Nf-1 patients, are considered high-grade sarcomas with the tendency to recur as well as to metastasize, typically to the lungs. It belongs to a group of malignancies of particularly worse prognosis and due to its rarity, there is a paucity of data concerning

As the overall understanding of bone growth, remodeling, and repair dependent on *NF1* gene function is critical to development of possible therapeutic interventions, in order to ensure continued collaboration and advancement toward better clinical management as well as effective drug therapies for Nf-1 related primary skeletal ailments, an International Nf-1 Bone Abnormalities Consortium have been convened in February 2008. The main goal of this Consortium is to identify barriers that might be impeding progression to future clinical trials for Nf-1 skeletal abnormalities and to highlights priorities for future research, based on

**2.1 Skeletal abnormalities in humans: Clinical presentation, diagnosis, complications**  The Nf-1 skeletal phenotypes might be either generalized or focal. Manifestation of generalized skeletal abnormalities, mostly osteopenia or osteoporosis and short stature, are common, but of mild clinical implications. Focal lesions, such as tibial dysplasia, short angle scoliosis, and sphenoid wing dysplasia, are less common, but usually cause significant

animal model of Nf-1 related bone disease (Elefteriou et al., 2009).

*Skeletal Deformities:*  - Short stature - Macrocephaly



*Bone Metabolism Disorders:* 








Table 2. Frequent manifestations of osseous abnormalities in patients suffering from Nf-1



> - short-angle dystrophic - idiopathic non-dystrophic


The skeletal manifestations of a disease itself and the post-surgical bony complications occurred in Nf-1 patients, are common and have a prominent place in the orthopedic literature. The orthopedic complications of Nf-1, which usually appear early, include spinal deformities such as dystrophic scoliosis and kyphoscoliosis, congenital bowing and pseudoarthrosis of the tibia and the forearm, overgrowth phenomenon of the extremity, and soft tissue tumors, both benign and malignant (Crawford & Schorry, 1999, 2006).

### **2. Primary and secondary bone abnormalities in neurofibromatosis type 1**

Although phenotype of Nf-1 patients is well described, the osseous manifestations are rarely emphasized in the clinical and genetic discussions concerning the diseases. In fact, one of the seventh diagnostic NIH criterion represents a distinctive osseous defect. Nf-1 is classically considers as a neurocutaneous disorder and clinical features of Nf-1 are classically thought of as neural crest in origin, but currently it is well accepted that mesodermally-derived abnormalities coexist as well. Restricted knowledge concerning the pathophysiology of Nf-1 skeletal abnormalities reflects the limited therapeutic modalities. Nf-1 is characterized by a multifaceted, polysystemic pathology. Among the other, bone involvement is representative for the majority of patients with Nf-1. The presentation of an ailment differs from patient to patient, but sometimes is extremely severe and appear from the birth or become evident either early in the childhood or further on and will accentuate with age. A number of skeletal involvements are highly morbid with a natural history distinct from that of the general population. A large proportion of patients with Nf-1 display primary skeletal involvement, including scoliosis and pseudoarthrosis, which are compounded by osteoporosis and poor bone healing (Crawford & Schorry, 1999). In considerable proportion of patients, these bone lesions can result in significant morbidity. The natural history and pathogenesis of the skeletal abnormalities, resulted from alter *NF1* gene function, are poorly understood. Consequently, therapeutic options for these ailments are currently limited. Corrective orthopedic intervention quite often fails necessitating multiple revision surgeries followed by prolonged recovery periods (Crawford & Schorry, 2006).

Besides true dysplasia of bone, some of the skeletal changes observed in these patients are secondary to a tumor, compressing the bone through expansive growth, or its metastases. The most frequently, such tumors are plexiform neurofibromas, and rarely other malignancies occurred in Nf-1 more frequently than in general population, such as soft tissue sarcomas, notably rhabdomyosarcoma, and especially, malignant peripheral nerve sheath tumor [MPNST]. These tumors infiltrate easily in surrounding tissue, eroding the neighborhood bone, and frequently give rise to metastases, mostly to bones. Malignant peripheral nerve sheath tumor is an uncommon soft-tissue sarcoma [STS] that occurs at a higher incidence in patients with prior radiation exposure and Nf-1. MPNST resulted almost exclusively from the malignant transformation of PMF. It is assessed that every Nf-1 patient presenting PMF has a life time risk of 8 to 13% to develop a MPNST out of a pre-existing benign plexiform neurofibroma. In comparison to intragenic mutation, in patients with a *NF1* microdeletion (5% of Nf-1 patients) this risk is twice as high. That risk is even greater in patients, in whom PMFs were incorporated into the field of therapeutic radiotherapy performed as an component of complex oncological treatment. Irradiation is linked with much higher risk of such a transformation, and in some STS therapeutic protocols introduced to the clinic by oncological treatment groups is either contraindicated or introduced with caution, when offered to children with Nf-1. Most of MPNST, especially

The skeletal manifestations of a disease itself and the post-surgical bony complications occurred in Nf-1 patients, are common and have a prominent place in the orthopedic literature. The orthopedic complications of Nf-1, which usually appear early, include spinal deformities such as dystrophic scoliosis and kyphoscoliosis, congenital bowing and pseudoarthrosis of the tibia and the forearm, overgrowth phenomenon of the extremity, and

soft tissue tumors, both benign and malignant (Crawford & Schorry, 1999, 2006).

periods (Crawford & Schorry, 2006).

**2. Primary and secondary bone abnormalities in neurofibromatosis type 1** 

Although phenotype of Nf-1 patients is well described, the osseous manifestations are rarely emphasized in the clinical and genetic discussions concerning the diseases. In fact, one of the seventh diagnostic NIH criterion represents a distinctive osseous defect. Nf-1 is classically considers as a neurocutaneous disorder and clinical features of Nf-1 are classically thought of as neural crest in origin, but currently it is well accepted that mesodermally-derived abnormalities coexist as well. Restricted knowledge concerning the pathophysiology of Nf-1 skeletal abnormalities reflects the limited therapeutic modalities. Nf-1 is characterized by a multifaceted, polysystemic pathology. Among the other, bone involvement is representative for the majority of patients with Nf-1. The presentation of an ailment differs from patient to patient, but sometimes is extremely severe and appear from the birth or become evident either early in the childhood or further on and will accentuate with age. A number of skeletal involvements are highly morbid with a natural history distinct from that of the general population. A large proportion of patients with Nf-1 display primary skeletal involvement, including scoliosis and pseudoarthrosis, which are compounded by osteoporosis and poor bone healing (Crawford & Schorry, 1999). In considerable proportion of patients, these bone lesions can result in significant morbidity. The natural history and pathogenesis of the skeletal abnormalities, resulted from alter *NF1* gene function, are poorly understood. Consequently, therapeutic options for these ailments are currently limited. Corrective orthopedic intervention quite often fails necessitating multiple revision surgeries followed by prolonged recovery

Besides true dysplasia of bone, some of the skeletal changes observed in these patients are secondary to a tumor, compressing the bone through expansive growth, or its metastases. The most frequently, such tumors are plexiform neurofibromas, and rarely other malignancies occurred in Nf-1 more frequently than in general population, such as soft tissue sarcomas, notably rhabdomyosarcoma, and especially, malignant peripheral nerve sheath tumor [MPNST]. These tumors infiltrate easily in surrounding tissue, eroding the neighborhood bone, and frequently give rise to metastases, mostly to bones. Malignant peripheral nerve sheath tumor is an uncommon soft-tissue sarcoma [STS] that occurs at a higher incidence in patients with prior radiation exposure and Nf-1. MPNST resulted almost exclusively from the malignant transformation of PMF. It is assessed that every Nf-1 patient presenting PMF has a life time risk of 8 to 13% to develop a MPNST out of a pre-existing benign plexiform neurofibroma. In comparison to intragenic mutation, in patients with a *NF1* microdeletion (5% of Nf-1 patients) this risk is twice as high. That risk is even greater in patients, in whom PMFs were incorporated into the field of therapeutic radiotherapy performed as an component of complex oncological treatment. Irradiation is linked with much higher risk of such a transformation, and in some STS therapeutic protocols introduced to the clinic by oncological treatment groups is either contraindicated or introduced with caution, when offered to children with Nf-1. Most of MPNST, especially arising in Nf-1 patients, are considered high-grade sarcomas with the tendency to recur as well as to metastasize, typically to the lungs. It belongs to a group of malignancies of particularly worse prognosis and due to its rarity, there is a paucity of data concerning chemotherapy response of MPNST.

As the overall understanding of bone growth, remodeling, and repair dependent on *NF1* gene function is critical to development of possible therapeutic interventions, in order to ensure continued collaboration and advancement toward better clinical management as well as effective drug therapies for Nf-1 related primary skeletal ailments, an International Nf-1 Bone Abnormalities Consortium have been convened in February 2008. The main goal of this Consortium is to identify barriers that might be impeding progression to future clinical trials for Nf-1 skeletal abnormalities and to highlights priorities for future research, based on animal model of Nf-1 related bone disease (Elefteriou et al., 2009).

### **2.1 Skeletal abnormalities in humans: Clinical presentation, diagnosis, complications**

The Nf-1 skeletal phenotypes might be either generalized or focal. Manifestation of generalized skeletal abnormalities, mostly osteopenia or osteoporosis and short stature, are common, but of mild clinical implications. Focal lesions, such as tibial dysplasia, short angle scoliosis, and sphenoid wing dysplasia, are less common, but usually cause significant morbidity.


Table 2. Frequent manifestations of osseous abnormalities in patients suffering from Nf-1

The Skeleton Abnormalities in Patients with

aggressive surgical stabilization very often.

of malignant transformation into MPNST.

**2.1.2 Focal lesions: Head and neck region** 

abnormalities has never been proof (Gutmann at al., 1997).

dystrophic form.

lesions development.

congenital deformities.

Neurofibromatosis Type 1: Important Consequences of Abnormal Gene Function 329

2002). However, dural ectasia may be a primary mesodermal dysplasia of the meninges as well (Casselman and Mandell, 1979). The vertebral column can further displace or erode, causing rib dislocation into the spinal canal, resulting in spinal cord injury. Weakening of spinal natural stabilizers, such as facets, pedicles, and ligaments, usually distorted in Nf-1, may lead to kyphosis. Kyphoscoliosis and humpback is a severe complication of advanced dystrophic scoliosis and finally can lead to cardiorespiratory insufficiency and failure. In this point, the best and well known touching description of Nf-1 patient's suffering, given by Victor Hugo in "The Hunchback of Notre Dame", is worth to be remembered. Dystrophic scoliosis in Nf-1 patients is particularly difficult to treat and necessitates early

The other, milder form of scoliosis occurring in Nf-1 children, is called non-dystrophic. It is diagnosed typically during adolescence and resembles idiopathic adolescent scoliosis in healthy population (Crawford & Herrera-Soto, 2007; Wang & Liu, 2010). This form usually involves 8-10 spinal segments. The deformity is most often convex to the right; however, this is not consistent. In rare instances, non-dystrophic scoliosis can progress to the

The presence of neurofibroma or abnormal pressure phenomena in and around the spinal canal neuraxis resulted in meningoceles, pseudomeningoceles, dural ectasia, and dumbbell

Kyphosis in individuals with Nf-1 might be distinguished by acute anteroposterior angulation. Severe deformity of vertebral bodies in Nf-1 might be confused even with

Chest wall deformities in patients with Nf-1 are observed even more frequently than scoliosis, and are thought to be present in as many as 50% of patients (Riccardi, 2010). The relationship between chest wall deformities and scoliosis is not clear, but its existence exacerbates the course of dysplastic scoliosis in particular. It could happened, that chest wall deformities constitute the first clinical sign of tumor arising within the chest and quite often penetrating throughout the intervertebral foramina or dura mater. It resembles an hourglass shape, and is called spinal dumbbell tumor. This kind of growth is usually form by multiple tumors arose in the intradural and epidural spaces from one nerve root, occurring at the same time in different regions, such as the paravertebral, epidural and intradural spaces. Histopathological diagnosis is usually plexiform neurofibroma, but it still comprises the risk

Increased head circumference is frequently observed in patients with Nf-1, and macrocephaly (head circumference >2 SD above the mean) occurs in about one-fourth of patients (Szudek et al., 2000). It is thought to be the consequence of brain enlargement (Greenwood et al., 2005). It is still not clear whether the skull growth contributes to macrocephaly. Contrariously, the association between macrocephaly and learning disabilities or underlying structural brain

Sphenoid Wing Dysplasia Cranial defects attributed to the clinical pathology in Nf-1 with relatively lower frequency (eg. 11% had a dysplastic sphenoid wing in an observational study of Friedman and Birch (1997)). Sphenoid dysplasia usually is asymptomatic but occasionally can be associated with herniation through the bony defect. It is still under debate whether these type of changes reveal a primary bone dysplasia related to *NF1*

### **2.1.1 Focal lesions: Spinal and chest wall deformations**

Spinal deformities frequently occur in individuals with Nf-1. These changes result from intra or perispinal pathology, such as tumors, or either meningoceles or dural ectasia. However, the deformities may be also present in persons with entirely normal intraspinal contents. In such patients, primary bone dysplasia accounts for the dystrophic vertebral changes.

The most frequent is scoliosis, and the most devastating form – kyphoscoliosis of progressive course regardless the intensive physiotherapy. In various series of Nf-1 patients reported in the literature, frequency of scoliosis is assumed for 10 to 33% (Crawford & Herrera-Soto, 2007; Wang & Liu, 2010). Vice versa, in general population, Nf-1 could be confirm in app. 2% of children suffering from scoliosis (Vitale et al., 2002). Orthopedic surgeons distinguished two types of spinal curvature disturbances in children with Nf-1: dystrophic and non-dystrophic. The cause of spinal deformity in Nf-1 is still a matter of debate, but some have suggested that it is secondary to endocrine disturbances observed in these patients, mesodermal dysplasia probably resulted from *NF1* mutations, and osteomalacia, caused by a localized neurofibromatous tumor eroding and infiltrating adjacent bone.

The dystrophic scoliosis, usually associated with paravertebral neurofibromas, has a progressive nature and is associated with vertebral scalloping and wedging. Almost always develops before 10th year of life (Crawford & Herrera-Soto, 2007). Dystrophic scoliosis is often early onsetting, the shortsegmented, sharply angulated type of this ailment that includes fewer than 6 spinal segments. It has a tendency to progress to a severe deformity. The term dystrophic is usually used to describe a dysplastic vertebrae observed within scoliotic spine. Although there is no formal diagnostic criterion for such a form of scoliosis, Durrani et al. (2000) described nine specific radiographic features associated with dystrophic scoliosis (Tabl. 3).


### Table 3. The radiologic appearance of the dystrophic scoliosis (Durrani et al., 2000)

Distinctive radiographic features of dystrophic scoliosis, usually presented in the preadolescent child, include a short-segment sharply angulated curve (involving four to six vertebrae), scalloping of vertebral margins, vertebral wedging, spinal canal widening, defective pedicles, and rib-penciling (Crawford et al., 2007). It is potentially debilitating and may rapidly progress to neurological impairment. This kind of scoliosis is frequently associated with paraspinal or other internal neurofibromas adjacent to the vertebrae, which could be seen in app. 70% of Nf-1 patients' MRI (Khong et al., 2003; Ramachandran et al., 2004). The complication of NFMs, or much frequently, PNFs penetrating into vertebral canal is dural ectasia, defined as widening of the dural sac surrounding the spinal cord, which might be seen in these patients (Khong et al., 2003; Schonauer et al., 2000; Tubbs and Oakes,

Spinal deformities frequently occur in individuals with Nf-1. These changes result from intra or perispinal pathology, such as tumors, or either meningoceles or dural ectasia. However, the deformities may be also present in persons with entirely normal intraspinal contents. In such

The most frequent is scoliosis, and the most devastating form – kyphoscoliosis of progressive course regardless the intensive physiotherapy. In various series of Nf-1 patients reported in the literature, frequency of scoliosis is assumed for 10 to 33% (Crawford & Herrera-Soto, 2007; Wang & Liu, 2010). Vice versa, in general population, Nf-1 could be confirm in app. 2% of children suffering from scoliosis (Vitale et al., 2002). Orthopedic surgeons distinguished two types of spinal curvature disturbances in children with Nf-1: dystrophic and non-dystrophic. The cause of spinal deformity in Nf-1 is still a matter of debate, but some have suggested that it is secondary to endocrine disturbances observed in these patients, mesodermal dysplasia probably resulted from *NF1* mutations, and osteomalacia, caused by a localized neurofibromatous tumor eroding and infiltrating

The dystrophic scoliosis, usually associated with paravertebral neurofibromas, has a progressive nature and is associated with vertebral scalloping and wedging. Almost always develops before 10th year of life (Crawford & Herrera-Soto, 2007). Dystrophic scoliosis is often early onsetting, the shortsegmented, sharply angulated type of this ailment that includes fewer than 6 spinal segments. It has a tendency to progress to a severe deformity. The term dystrophic is usually used to describe a dysplastic vertebrae observed within scoliotic spine. Although there is no formal diagnostic criterion for such a form of scoliosis, Durrani et al. (2000) described nine specific radiographic features associated with dystrophic

1. Scalloping of the posterior vertebral margins

8. Rotation of the ribs (the ribs resemble twisted ribbons)

Distinctive radiographic features of dystrophic scoliosis, usually presented in the preadolescent child, include a short-segment sharply angulated curve (involving four to six vertebrae), scalloping of vertebral margins, vertebral wedging, spinal canal widening, defective pedicles, and rib-penciling (Crawford et al., 2007). It is potentially debilitating and may rapidly progress to neurological impairment. This kind of scoliosis is frequently associated with paraspinal or other internal neurofibromas adjacent to the vertebrae, which could be seen in app. 70% of Nf-1 patients' MRI (Khong et al., 2003; Ramachandran et al., 2004). The complication of NFMs, or much frequently, PNFs penetrating into vertebral canal is dural ectasia, defined as widening of the dural sac surrounding the spinal cord, which might be seen in these patients (Khong et al., 2003; Schonauer et al., 2000; Tubbs and Oakes,

Table 3. The radiologic appearance of the dystrophic scoliosis (Durrani et al., 2000)

2. Severe rotation of the apical vertebra

7. Spindling of the transverse process

3. Widening of the spinal canal 4. Enlargement of the neural foramina

5. Defective pedicles 6. A paraspinal mass

patients, primary bone dysplasia accounts for the dystrophic vertebral changes.

**2.1.1 Focal lesions: Spinal and chest wall deformations** 

adjacent bone.

scoliosis (Tabl. 3).

2002). However, dural ectasia may be a primary mesodermal dysplasia of the meninges as well (Casselman and Mandell, 1979). The vertebral column can further displace or erode, causing rib dislocation into the spinal canal, resulting in spinal cord injury. Weakening of spinal natural stabilizers, such as facets, pedicles, and ligaments, usually distorted in Nf-1, may lead to kyphosis. Kyphoscoliosis and humpback is a severe complication of advanced dystrophic scoliosis and finally can lead to cardiorespiratory insufficiency and failure. In this point, the best and well known touching description of Nf-1 patient's suffering, given by Victor Hugo in "The Hunchback of Notre Dame", is worth to be remembered. Dystrophic scoliosis in Nf-1 patients is particularly difficult to treat and necessitates early aggressive surgical stabilization very often.

The other, milder form of scoliosis occurring in Nf-1 children, is called non-dystrophic. It is diagnosed typically during adolescence and resembles idiopathic adolescent scoliosis in healthy population (Crawford & Herrera-Soto, 2007; Wang & Liu, 2010). This form usually involves 8-10 spinal segments. The deformity is most often convex to the right; however, this is not consistent. In rare instances, non-dystrophic scoliosis can progress to the dystrophic form.

The presence of neurofibroma or abnormal pressure phenomena in and around the spinal canal neuraxis resulted in meningoceles, pseudomeningoceles, dural ectasia, and dumbbell lesions development.

Kyphosis in individuals with Nf-1 might be distinguished by acute anteroposterior angulation. Severe deformity of vertebral bodies in Nf-1 might be confused even with congenital deformities.

Chest wall deformities in patients with Nf-1 are observed even more frequently than scoliosis, and are thought to be present in as many as 50% of patients (Riccardi, 2010). The relationship between chest wall deformities and scoliosis is not clear, but its existence exacerbates the course of dysplastic scoliosis in particular. It could happened, that chest wall deformities constitute the first clinical sign of tumor arising within the chest and quite often penetrating throughout the intervertebral foramina or dura mater. It resembles an hourglass shape, and is called spinal dumbbell tumor. This kind of growth is usually form by multiple tumors arose in the intradural and epidural spaces from one nerve root, occurring at the same time in different regions, such as the paravertebral, epidural and intradural spaces. Histopathological diagnosis is usually plexiform neurofibroma, but it still comprises the risk of malignant transformation into MPNST.

### **2.1.2 Focal lesions: Head and neck region**

Increased head circumference is frequently observed in patients with Nf-1, and macrocephaly (head circumference >2 SD above the mean) occurs in about one-fourth of patients (Szudek et al., 2000). It is thought to be the consequence of brain enlargement (Greenwood et al., 2005). It is still not clear whether the skull growth contributes to macrocephaly. Contrariously, the association between macrocephaly and learning disabilities or underlying structural brain abnormalities has never been proof (Gutmann at al., 1997).

Sphenoid Wing Dysplasia Cranial defects attributed to the clinical pathology in Nf-1 with relatively lower frequency (eg. 11% had a dysplastic sphenoid wing in an observational study of Friedman and Birch (1997)). Sphenoid dysplasia usually is asymptomatic but occasionally can be associated with herniation through the bony defect. It is still under debate whether these type of changes reveal a primary bone dysplasia related to *NF1*

The Skeleton Abnormalities in Patients with

**2.1.4 Generalized skeletal abnormalities** 

other type pathology.

Illes et al. (2001).

Neurofibromatosis Type 1: Important Consequences of Abnormal Gene Function 331

physiological bowing, exemplary common in children as they begin to walk or from the

Various radiographic classification systems for tibia bowing have been proposed, but they are still not rigorous and several subtypes represent rather changes over time, than the real variety. Nevertheless, tibial bowing in Nf-1 patients prior to fracture represents in radiograph a cortical thickening and medullary canal narrowing at the apex of the convexity, typically

In general, every bone of whatever kind and at any localization may usually be affected by the adjacent tumors as well, with all the consequences resemble the ones described above.

Although focal skeletal abnormalities, such as dystrophic scoliosis or tibial pseudoarthrosis and the like, can be severely disabling, they are uncommon among individuals with Nf-1. In contrary, generalized skeletal abnormalities are less severe but much more frequent in these patients. The osseous dysplasia result from disturbed bone growth, perhaps secondary to a mineralization disturbance. Findings such as decreased bone mineral density (BMD) and short stature reflect a generalized alteration of bone. The Nf-1 patients tend to be below average in height for age (below -2SD), although heights less than -3SD below the mean is seen hardly ever. Decreased BMD in both sexes at an early age has been reported in up to 50% of individuals with Nf-1. Reduced BMD in Nf-1 patients was initially recognized by

The exact pathogenesis of these bony changes is not understood, but patients with Nf-1 present lower than expected serum 25-hydroxyvitamin D (25OHD) concentrations, elevated serum parathyroid hormone concentration, and evidence of increased bone resorption. Defects in vitamin D metabolism, osteoclastogenesis or bone cell response to systemic signals regulating bone remodeling are likely involved. An inadequate increase in bone remodeling is also indirectly confirm by both bone histomorphometry and changes in circulating bone markers (Stevenson et al., 2008; Seitz et al., 2010). However, an increased incidence of fractures has not been firmly established. Still, generalized osteopenia and frank osteoporosis are more common than expected in patients with Nf-1. The results of one of the biggest series, in which Nf-1 children became the subject of multivariant analysis, indicate that the mean lumbar and whole body BMD z-scores were in the range of osteopenia and osteoporosis in 48% and 25% of subjects, respectively. BMD was reduced at multiple bone sites, while the lumbar spine being more severely affected (Brunetti-Pierri et

al., 2008). A tumor inductive role has also been suggested (Ben-Baruch et al., 1994).

treatment of the patients is still poorly understood.

Several case reports from Nf-1 patients have identified histologically proven osteomalacia, which might be associated with hypophosphatemia due to renal phosphate wasting (Abdel-Wanis & Kawahara, 2002). Although the concentration of baseline vitamin D were in the normal range in these patients, researchers further found that the osteomalacia can be reversed independently of phosphate supplementation with oral treatment of 1-alpha-(OH) vitamin D3 (Konishi et al., 1991). Moreover, a recently published comparative study reported that 25OHD serum concentration were about twofold lower in the Nf-1 patients than in healthy population and were inversely correlated with the number of neurofibromas (Lammert et al., 2006). The exact underlying mechanism of vitamin D deficiency in Nf-1 patients still remains unclear as well as the value of vitamin D supplementation for the

near the junction of the middle and distal thirds of the tibia (Stevenson et al., 2007).

mutation, or occur as secondary response of bone to the adjacent soft tissue abnormality. Most cranial defects are associated with plexiform neurofibromas of the eyelid or temporal region induced ipsilateral infiltration and decalcification of cranial bones adjacent to tumors (Jacquemin et al., 2002, 2003). Other lesions, including arachnoid cysts, dural ectasia, or buphthalmos, usually associate sphenoid wing defects. The suggestion of a bone cellautonomous defect, accounted for the dysplastic sphenoid wing, is based on two meaningful observations: (1) Nf-1 sphenoid wing lesions have been associated with tibial and vertebral dysplasia (Alwan et al., 2007), and (2) formation of this skull structure proceeds through endochondral bone formation, which is defective in Nf-1 (Kolanczyk et al., 2007). Regardless the cause, a congenital malformation or secondary bony defect, the sphenoid wing dysplasia is not currently a primary target for therapeutic prevention. Nevertheless, it is imperious necessity to apply sensitive imaging techniques to screen patients with sphenoid wing dysplasia for adjacent tumors, which may be amenable to therapy (Jacquemin, 2002, 2003).

Increased caries and early primary tooth eruption as well as periapical cemental dysplasia have been quite often reported in patients with Nf-1 (Lammert et al., 2007; Tucker et al., 2007; Visnapuu et al., 2007). Dental abnormalities in Nf-1 patients still require more attention, yet everyday practice pointed unnecessary dental procedures performed in these patients, for instance when periapical cemental dysplasia is confused with chronic inflammation on radiographic analysis and precipitate dental surgery.

Cervical spine abnormalities are due to cervical spine instability or intraspinal pathology, caused mostly by benign tumor. These occur much more frequently when a scoliosis or kyphoscoliosis is present in the thoracolumbar region, but could be omitted as the examiner's attention is focused on the more obvious deformity. Severe cervical kyphosis is the most common abnormality, which itself is highly suggestive for Nf-1 diagnosis. Patients usually had either limited motion or pain in the neck, which were probably attributed to cervical instability. The numerous, minor to major neurologic deficits, such as paraplegia, are present.

#### **2.1.3 Focal lesions: Long bones and extremities**

Long bone dysplasia appears in a small percentage (3–4%) of patients with Nf-1 in clinicbased series (Friedman & Birch, 1997) and tibia is involved most often among other long bones, which can be affected sparsely. Infant with such an ailment usually presents with unilateral anterolateral bowing of the lower leg, notably tibial, although a child may be born with fracture and/or pseudarthrosis as well, or develop these shortly after birth. The deformity may appear before other protean manifestations of Nf-1, such as café-au-lait spots. The tibial bowing is usually evident within the first year of life, with a fracture not uncommonly occurring by age of 2-2.5 year. The tibial bowing associated with Nf-1 is always anterolateral. Affected bone is subject to pathologic fracture usually before age 3 years, often with minimal trauma. Subsequent healing may not occur normally, leading to consecutive non-union and pseudoarthrosis, sometimes requiring even amputation of affected extremity. As confirm histologically, the fibrous pseudarthrosis tissue seen at the fracture site is not a neurofibroma, but a fibrous overgrowth of unspecified cell origin. The ipsilateral fibula is often involved in association with tibial pseudoarthrosis and focal dysplasia of the ulna, radius, scapula, or vertebra may occur as well. The anterolateral bowing characterized patients with Nf-1 should be distinguished from the bilateral physiological bowing, exemplary common in children as they begin to walk or from the other type pathology.

Various radiographic classification systems for tibia bowing have been proposed, but they are still not rigorous and several subtypes represent rather changes over time, than the real variety. Nevertheless, tibial bowing in Nf-1 patients prior to fracture represents in radiograph a cortical thickening and medullary canal narrowing at the apex of the convexity, typically near the junction of the middle and distal thirds of the tibia (Stevenson et al., 2007).

In general, every bone of whatever kind and at any localization may usually be affected by the adjacent tumors as well, with all the consequences resemble the ones described above.

### **2.1.4 Generalized skeletal abnormalities**

330 Osteoporosis

mutation, or occur as secondary response of bone to the adjacent soft tissue abnormality. Most cranial defects are associated with plexiform neurofibromas of the eyelid or temporal region induced ipsilateral infiltration and decalcification of cranial bones adjacent to tumors (Jacquemin et al., 2002, 2003). Other lesions, including arachnoid cysts, dural ectasia, or buphthalmos, usually associate sphenoid wing defects. The suggestion of a bone cellautonomous defect, accounted for the dysplastic sphenoid wing, is based on two meaningful observations: (1) Nf-1 sphenoid wing lesions have been associated with tibial and vertebral dysplasia (Alwan et al., 2007), and (2) formation of this skull structure proceeds through endochondral bone formation, which is defective in Nf-1 (Kolanczyk et al., 2007). Regardless the cause, a congenital malformation or secondary bony defect, the sphenoid wing dysplasia is not currently a primary target for therapeutic prevention. Nevertheless, it is imperious necessity to apply sensitive imaging techniques to screen patients with sphenoid wing dysplasia for adjacent tumors, which may be amenable to

Increased caries and early primary tooth eruption as well as periapical cemental dysplasia have been quite often reported in patients with Nf-1 (Lammert et al., 2007; Tucker et al., 2007; Visnapuu et al., 2007). Dental abnormalities in Nf-1 patients still require more attention, yet everyday practice pointed unnecessary dental procedures performed in these patients, for instance when periapical cemental dysplasia is confused with chronic

Cervical spine abnormalities are due to cervical spine instability or intraspinal pathology, caused mostly by benign tumor. These occur much more frequently when a scoliosis or kyphoscoliosis is present in the thoracolumbar region, but could be omitted as the examiner's attention is focused on the more obvious deformity. Severe cervical kyphosis is the most common abnormality, which itself is highly suggestive for Nf-1 diagnosis. Patients usually had either limited motion or pain in the neck, which were probably attributed to cervical instability. The numerous, minor to major neurologic deficits, such as paraplegia,

Long bone dysplasia appears in a small percentage (3–4%) of patients with Nf-1 in clinicbased series (Friedman & Birch, 1997) and tibia is involved most often among other long bones, which can be affected sparsely. Infant with such an ailment usually presents with unilateral anterolateral bowing of the lower leg, notably tibial, although a child may be born with fracture and/or pseudarthrosis as well, or develop these shortly after birth. The deformity may appear before other protean manifestations of Nf-1, such as café-au-lait spots. The tibial bowing is usually evident within the first year of life, with a fracture not uncommonly occurring by age of 2-2.5 year. The tibial bowing associated with Nf-1 is always anterolateral. Affected bone is subject to pathologic fracture usually before age 3 years, often with minimal trauma. Subsequent healing may not occur normally, leading to consecutive non-union and pseudoarthrosis, sometimes requiring even amputation of affected extremity. As confirm histologically, the fibrous pseudarthrosis tissue seen at the fracture site is not a neurofibroma, but a fibrous overgrowth of unspecified cell origin. The ipsilateral fibula is often involved in association with tibial pseudoarthrosis and focal dysplasia of the ulna, radius, scapula, or vertebra may occur as well. The anterolateral bowing characterized patients with Nf-1 should be distinguished from the bilateral

inflammation on radiographic analysis and precipitate dental surgery.

**2.1.3 Focal lesions: Long bones and extremities** 

therapy (Jacquemin, 2002, 2003).

are present.

Although focal skeletal abnormalities, such as dystrophic scoliosis or tibial pseudoarthrosis and the like, can be severely disabling, they are uncommon among individuals with Nf-1. In contrary, generalized skeletal abnormalities are less severe but much more frequent in these patients. The osseous dysplasia result from disturbed bone growth, perhaps secondary to a mineralization disturbance. Findings such as decreased bone mineral density (BMD) and short stature reflect a generalized alteration of bone. The Nf-1 patients tend to be below average in height for age (below -2SD), although heights less than -3SD below the mean is seen hardly ever. Decreased BMD in both sexes at an early age has been reported in up to 50% of individuals with Nf-1. Reduced BMD in Nf-1 patients was initially recognized by Illes et al. (2001).

The exact pathogenesis of these bony changes is not understood, but patients with Nf-1 present lower than expected serum 25-hydroxyvitamin D (25OHD) concentrations, elevated serum parathyroid hormone concentration, and evidence of increased bone resorption. Defects in vitamin D metabolism, osteoclastogenesis or bone cell response to systemic signals regulating bone remodeling are likely involved. An inadequate increase in bone remodeling is also indirectly confirm by both bone histomorphometry and changes in circulating bone markers (Stevenson et al., 2008; Seitz et al., 2010). However, an increased incidence of fractures has not been firmly established. Still, generalized osteopenia and frank osteoporosis are more common than expected in patients with Nf-1. The results of one of the biggest series, in which Nf-1 children became the subject of multivariant analysis, indicate that the mean lumbar and whole body BMD z-scores were in the range of osteopenia and osteoporosis in 48% and 25% of subjects, respectively. BMD was reduced at multiple bone sites, while the lumbar spine being more severely affected (Brunetti-Pierri et al., 2008). A tumor inductive role has also been suggested (Ben-Baruch et al., 1994).

Several case reports from Nf-1 patients have identified histologically proven osteomalacia, which might be associated with hypophosphatemia due to renal phosphate wasting (Abdel-Wanis & Kawahara, 2002). Although the concentration of baseline vitamin D were in the normal range in these patients, researchers further found that the osteomalacia can be reversed independently of phosphate supplementation with oral treatment of 1-alpha-(OH) vitamin D3 (Konishi et al., 1991). Moreover, a recently published comparative study reported that 25OHD serum concentration were about twofold lower in the Nf-1 patients than in healthy population and were inversely correlated with the number of neurofibromas (Lammert et al., 2006). The exact underlying mechanism of vitamin D deficiency in Nf-1 patients still remains unclear as well as the value of vitamin D supplementation for the treatment of the patients is still poorly understood.

The Skeleton Abnormalities in Patients with

than bone resorption.

Neurofibromatosis Type 1: Important Consequences of Abnormal Gene Function 333

clinically proven osseous abnormalities (Stevenson et al., 2005). Muscle mass is important in the development of bone strength, as voluntary muscle forces (the largest physiological load) impact skeletal response. Combinations of extrinsic forces including decreased muscle

It is well known that *NF1* gene is widely expressed in chondrocytes, osteoblasts, osteoclast, and osteocytes (Kuorilehto et al., 2004). Kuorilehto et al. (2004) reported as well that neurofibromin is expressed in growing cartilage in areas where proliferation has ceased and the chondrocytes are undergoing differentiation, and in periostealosteoblasts of embryonic and mature mice and rats. However, mechanism of various skeletal deformities and bone metabolism defects in Nf-1 patients are not clearly understood. Experimental work done on animal models suggest that patients with Nf-1 suffers from a bone formation defect rather

Individuals with Nf-1 tend to be shorter than expected for their families (Szudek et al., 2000; Virdis et al., 2003), with 20–30% of adults with NF1 estimated to have a height below the 3rd centile. Growth velocity in these individuals is typically normal or near normal before puberty, then declines. Short stature in patients with NF1 is usually proportional. Scoliosis, growth hormone deficiency, and other Nf-1 related complications can contribute to short

Bony abnormalities may be clinically silent, with radiographic evidence of long bone intramedullary fibrosis, cortical thinning, or vertebral dural ectasias often found incidentally. Among the other bone abnormalities observed Nf-1 patients rarely, but with frequency a bit higher than in general populations, are cystic osseous lesions. They are usually identified incidentally during ongoing process of repeated imaging, reflecting the international recommendations. Found during radiographic knee exam, these cystic lesions are occasionally seen in the absence of tumors or long bone dysplasia (Colby & Saul, 2003; Lee & Cho, 2006). The lesions rarely fracture or show progressive deformity, and biopsy generally shows non-ossifying fibroma bone tumors. The association of multiple nonossifying fibromas with cafe au lait skin patches are the fundamental signs of Jaffee-Campanacci syndrome (JCS) (Campanacci et al., 1983). The long bones affected more often are the femur, the humerus, and the tibia as well as the bones of the jaw. Other bones can be involved less frequently, especially the pelvis, the fibula, the radius, and the ulna. The lesions may be large enough to cause pathological fracture of the involved bone. Recent

mass could compromise potentially abnormal osseous matrix as well.

**2.1.5 Other skeletal manifestations of neurofibromatosis type 1** 

stature, but the cause of this in most patients with Nf-1 is unknown.

findings suggest that JCS may be a form of Nf-1 (Colby & Saul, 2003).

**Experience from transgenic mouse models** 

**2.2 Pathophysiology of skeletal abnormalities in neurofibromatosis type 1:** 

Studies assessing the role of *NF1* gene not only in tumor formation and development, but also in pathogenesis of other multiple abnormalities, are to be a matter of numerous experimental work, which cannot be apply neither on living individuals, nor cell lines. These restrictions led to the development of transgenic mouse models allowing determination of the role of *NF1* gene and its product in affected systems and facilitate preclinical studies. Unfortunately, mice's embryos with inactivated both *NF1* alleles exhibit severe neural closure defect, namely exencephaly, and cardiovascular abnormalities including structural malformations of the outflow tract of the heart and enlarged

Selected genetic disease populations, including Nf-1, display increased risks for osteoporosis, which is an emerging complication of utmost importance. Early diagnosis in the pediatric population is essential, since the highest contribution to peak bone mass is attained in the first three decades. Osteopenia or decreased bone mass accrual in the pediatric period can lead to frank osteoporosis and fractures in adulthood in the general population, as peak bone density is generally reached by late adolescence. Emerging evidence shows that vitamin D deficiency combined with a higher than normal bone turnover contributes to decreased bone mineral density in patients with Nf-1. The results of currently published studies suggest that the population of Nf-1 patient is at an increased risk for the development of clinical complications related to osteoporosis.

Seldom but yet published data revealed that significantly lower blood concentration of osteocalcin was observed in Nf-1 patients with, in comparison with patients without, skeletal abnormalities. Osteocalcin is secreted by osteoblasts, plays a role in mineralization and calcium ion homeostasis and its level reflects the rate of bone formation. Reduced blood concentration of osteocalcin in Nf-1 patients with skeletal deformity may indicate defect in osteoblasts functioning. Other biochemical markers of bone turnover usually do not exhibit any difference between these groups (Duman et al., 2008). When compared to healthy subjects, in Nf-1 patients BMD of the lumbar spine and femoral neck is significantly decreased. The same significant decrease apply to pubertal patients when compared to pubertal controls and in prepubertal patients when compared to prepubertal controls. The decrease in BMD is still more pronounced in Nf-1 patients with severe scoliosis, than those without spinal deformities. Duman et al. (2008) suggests that relevant predictors of skeletal abnormalities among Nf-1 patients are bone formation markers (exclusively osteocalcin) rather than imaging (conventional radiography, CT, MRI or quantitative ultrasonometry of the calcaneal bone) and densitometry techniques, especially dual-energy X-ray absorptiometry (DXA). In opposite to this report, the other published data suggest that both DXA and quantitative ultrasonometry of the calcaneal or other bones may prove useful to identify individuals with NF1 who are at risk for clinical osseous complications. These techniques and the logistics, introduced into pediatric practice quite recently, may also be appropriate for monitoring of therapeutic trials concerning skeletal ailments in Nf-1 children. However, many significant heterogeneities among the reports in the literature, such as patient groups (ages, variability of skeletal involvements, etc.) and methods (BMD assaying, comparison criteria such as T-score, Z-score, their cutoff points, etc.) make the comparisons amongst the studies very difficult. The densitometric criterion commonly used as a predictor of fracture risk for osteoporotic adults, called T-scores, derived from reference populations of young-adult women. While useful for evaluation of fracture risk in adults, but especially in postmenopausal women, is not applicable to the diagnosis of osteoporosis in children. In this age period the evaluation of osteoporotic risk of fracture is much more difficult. Densitometric data in children must be compared with age-matched control populations (z-scores). Currently, it is generally accepted that z-scores below −1.5 indicate low bone mass or osteopenia, and that osteoporosis is suspected strongly with z-scores below −2, especially followed by the episodes of fracturing. According to Writing Group for the ISCD Position Development Conference, z-score less than −2 define low bone density in children (2004).

According to unique published papers, children with Nf-1 had also statistically significant decreases in muscle mass compared to healthy controls regardless the presence or not of

Selected genetic disease populations, including Nf-1, display increased risks for osteoporosis, which is an emerging complication of utmost importance. Early diagnosis in the pediatric population is essential, since the highest contribution to peak bone mass is attained in the first three decades. Osteopenia or decreased bone mass accrual in the pediatric period can lead to frank osteoporosis and fractures in adulthood in the general population, as peak bone density is generally reached by late adolescence. Emerging evidence shows that vitamin D deficiency combined with a higher than normal bone turnover contributes to decreased bone mineral density in patients with Nf-1. The results of currently published studies suggest that the population of Nf-1 patient is at an increased

Seldom but yet published data revealed that significantly lower blood concentration of osteocalcin was observed in Nf-1 patients with, in comparison with patients without, skeletal abnormalities. Osteocalcin is secreted by osteoblasts, plays a role in mineralization and calcium ion homeostasis and its level reflects the rate of bone formation. Reduced blood concentration of osteocalcin in Nf-1 patients with skeletal deformity may indicate defect in osteoblasts functioning. Other biochemical markers of bone turnover usually do not exhibit any difference between these groups (Duman et al., 2008). When compared to healthy subjects, in Nf-1 patients BMD of the lumbar spine and femoral neck is significantly decreased. The same significant decrease apply to pubertal patients when compared to pubertal controls and in prepubertal patients when compared to prepubertal controls. The decrease in BMD is still more pronounced in Nf-1 patients with severe scoliosis, than those without spinal deformities. Duman et al. (2008) suggests that relevant predictors of skeletal abnormalities among Nf-1 patients are bone formation markers (exclusively osteocalcin) rather than imaging (conventional radiography, CT, MRI or quantitative ultrasonometry of the calcaneal bone) and densitometry techniques, especially dual-energy X-ray absorptiometry (DXA). In opposite to this report, the other published data suggest that both DXA and quantitative ultrasonometry of the calcaneal or other bones may prove useful to identify individuals with NF1 who are at risk for clinical osseous complications. These techniques and the logistics, introduced into pediatric practice quite recently, may also be appropriate for monitoring of therapeutic trials concerning skeletal ailments in Nf-1 children. However, many significant heterogeneities among the reports in the literature, such as patient groups (ages, variability of skeletal involvements, etc.) and methods (BMD assaying, comparison criteria such as T-score, Z-score, their cutoff points, etc.) make the comparisons amongst the studies very difficult. The densitometric criterion commonly used as a predictor of fracture risk for osteoporotic adults, called T-scores, derived from reference populations of young-adult women. While useful for evaluation of fracture risk in adults, but especially in postmenopausal women, is not applicable to the diagnosis of osteoporosis in children. In this age period the evaluation of osteoporotic risk of fracture is much more difficult. Densitometric data in children must be compared with age-matched control populations (z-scores). Currently, it is generally accepted that z-scores below −1.5 indicate low bone mass or osteopenia, and that osteoporosis is suspected strongly with z-scores below −2, especially followed by the episodes of fracturing. According to Writing Group for the ISCD Position Development Conference, z-score less than −2 define low bone density in

According to unique published papers, children with Nf-1 had also statistically significant decreases in muscle mass compared to healthy controls regardless the presence or not of

risk for the development of clinical complications related to osteoporosis.

children (2004).

clinically proven osseous abnormalities (Stevenson et al., 2005). Muscle mass is important in the development of bone strength, as voluntary muscle forces (the largest physiological load) impact skeletal response. Combinations of extrinsic forces including decreased muscle mass could compromise potentially abnormal osseous matrix as well.

It is well known that *NF1* gene is widely expressed in chondrocytes, osteoblasts, osteoclast, and osteocytes (Kuorilehto et al., 2004). Kuorilehto et al. (2004) reported as well that neurofibromin is expressed in growing cartilage in areas where proliferation has ceased and the chondrocytes are undergoing differentiation, and in periostealosteoblasts of embryonic and mature mice and rats. However, mechanism of various skeletal deformities and bone metabolism defects in Nf-1 patients are not clearly understood. Experimental work done on animal models suggest that patients with Nf-1 suffers from a bone formation defect rather than bone resorption.

### **2.1.5 Other skeletal manifestations of neurofibromatosis type 1**

Individuals with Nf-1 tend to be shorter than expected for their families (Szudek et al., 2000; Virdis et al., 2003), with 20–30% of adults with NF1 estimated to have a height below the 3rd centile. Growth velocity in these individuals is typically normal or near normal before puberty, then declines. Short stature in patients with NF1 is usually proportional. Scoliosis, growth hormone deficiency, and other Nf-1 related complications can contribute to short stature, but the cause of this in most patients with Nf-1 is unknown.

Bony abnormalities may be clinically silent, with radiographic evidence of long bone intramedullary fibrosis, cortical thinning, or vertebral dural ectasias often found incidentally.

Among the other bone abnormalities observed Nf-1 patients rarely, but with frequency a bit higher than in general populations, are cystic osseous lesions. They are usually identified incidentally during ongoing process of repeated imaging, reflecting the international recommendations. Found during radiographic knee exam, these cystic lesions are occasionally seen in the absence of tumors or long bone dysplasia (Colby & Saul, 2003; Lee & Cho, 2006). The lesions rarely fracture or show progressive deformity, and biopsy generally shows non-ossifying fibroma bone tumors. The association of multiple nonossifying fibromas with cafe au lait skin patches are the fundamental signs of Jaffee-Campanacci syndrome (JCS) (Campanacci et al., 1983). The long bones affected more often are the femur, the humerus, and the tibia as well as the bones of the jaw. Other bones can be involved less frequently, especially the pelvis, the fibula, the radius, and the ulna. The lesions may be large enough to cause pathological fracture of the involved bone. Recent findings suggest that JCS may be a form of Nf-1 (Colby & Saul, 2003).

### **2.2 Pathophysiology of skeletal abnormalities in neurofibromatosis type 1: Experience from transgenic mouse models**

Studies assessing the role of *NF1* gene not only in tumor formation and development, but also in pathogenesis of other multiple abnormalities, are to be a matter of numerous experimental work, which cannot be apply neither on living individuals, nor cell lines. These restrictions led to the development of transgenic mouse models allowing determination of the role of *NF1* gene and its product in affected systems and facilitate preclinical studies. Unfortunately, mice's embryos with inactivated both *NF1* alleles exhibit severe neural closure defect, namely exencephaly, and cardiovascular abnormalities including structural malformations of the outflow tract of the heart and enlarged

The Skeleton Abnormalities in Patients with

osteoporosis.

consequences if neglected.

Neurofibromatosis Type 1: Important Consequences of Abnormal Gene Function 335

At present, there are either no clinical trials to support the use of osteoporotic drugs in a population of Nf-1 patients or treatment guidelines. Thus, conservative therapy to promote bone health, such as treatment with calcium and vitamin D, and weight-bearing exercise forms the first line of therapy in children with Nf-1 and low bone mass. Correction of measured deficiencies in hormones (vitamin D, thyroid, estrogen, etc.) that are known to regulate skeletal growth and maturation is inevitable. Judicious vitamin D supplementation may prove beneficial for patients with Nf-1 who have vitamin D deficiency or evidence of osteopenia. Similarly, until further information is obtained, treatment of osteoporosis in adults with Nf-1 follow the recommendations developed for general population. Because low serum 25-OH-D and osteomalacia has been reported in patients with Nf-1 and low bone mass, osteoporotic adult patients over age 50 years should take supplemental 1,200 mg calcium and 800–1,000 IU vitamin D per day, and reduce clinical risk factors by regular weight bearing and muscle strengthening exercises and avoidance of smoking and excessive alcohol. Selection of approved anabolic or anti-resorptive drugs to prevent or treat osteoporotic fractures should follow the standard practice with exception of children. Children should be treated as well, as soon as fracture complicates the osteopenic/osteoporotic bone dysplasia (Elefteriou, 2009). Unfortunately, anabolic substances available currently upon two forms of parathyroid hormone pose the increased risk of osteosarcoma development, proven in rats, and are contraindicated in children (Tashjian & Gagel, 2006). Bisphosphonates and monoclonal antibodies that target osteoclasts, belonging to anti-resorptive drugs, have been used to reduce osteoporotic fractures in adults, but their effect on BMD and fracture risk in children with Nf-1 is unknown. Clinical trials are necessary to determine which of currently available therapies are most effective to treat patients with Nf-1 and reduces BMD, but especially frank

In patients with Nf-1, the morbidity associated with either dystrophic scoliosis or tibial dysplasia is much greater than that of osteopenia and osteoporosis or even non-dystrophic scoliosis. This helps define priorities for current and future trials. Some of the ailments, particularly dystrophic scoliosis or tibial bowing, can lead to clinically significant

Children with dystrophic scoliosis require the extensive medical attention. In children who do not complete skeletal maturation, typically presented dystrophic form of scoliosis, bracing is routinely used when the spine curvature exceeded 25 up to 45 degrees. While the curvature progresses to more than 45 degrees before maturity or 55 degrees after maturity, surgery is commonly employed. Unique management approach due to progression is necessary in skeletally immature patients with dystrophic scoliosis in whom a curvature exciding 30 degrees. Exclusion of paravertebral tumors and dystrophic changes required MR or, less sensitive, CT imagings, as those finding may be missed on plain radiographs. Regarding possible complications of surgery, careful presurgical assessment is critical, as the lamina may be thin, the canal affected by dural ectasia or intraspinal tumors, and a rib may have displaced into the spinal canal, all of which express an increased risk of poor postsurgical outcome. Variables such as age, gender, associated neurofibromas, location and degree of the curve, and associated radiographic dystrophic features make the operation design difficult. Surgical treatment with fusion and growing rods is complex. Occasionally, intraspinal elements may directly compromise the cord when instrumentation and stabilization are attempted, or they may cause erosive changes in the bone, preventing

endocardial cushions. These *NF1*-deficient embryos die between embryonic days 12.5 and 13.5, presumably due to the cardiac vessel defect. In contrast to completely defective organism, inactivation of only one allele of *NF1* gene locally, in the neural crest only, does not cause cardiac defects but results in tumors of neural crest origin, resembling those seen in Nf-1 patients. Following this early experiments the another models of an experimental animal has been developed to determine the role of *NF1* in bone cells and resolve difficulties in understanding the human pathophysiology of Nf-1 skeletal defects (Kolanczyk, 2007, 2008).

It has been well known that neurofibromin is a cytoplasmic protein that is predominantly expressed in neurons, Schwann cells, oligodendrocytes, astrocytes, and leukocytes. Due to early studies based on transgenic animal models of skeletal defective mice it is obvious currently that *NF1*-mRNA and neurofibromin are expressed in mouse bone and cartilage during development and adulthood (Kuorilehto et al., 2004), and more specifically in mesenchymal stem cells, chondrocytes, osteoblasts (Elefteriou et al., 2006; Kolanczyk et al., 2007), and osteoclasts (Yang et al., 2006a). Kuorilehto et al. (2004) reported the expression of neurofibromin in growth plate, periosteum, and tracebular bone of mice, and the expression in growth plate was mainly located in chondrocytes of the hypertrophic layer. Yu et al (2005) showed that upon the activation of *ras* signals, *NF1*+/- murine osteoprogenitor cells show increased proliferation and premature apoptosis; the osteoprogenitor cells also exhibit a lower rate of differentiation to osteoblasts. He considered neurofibromin and its role as *ras* signal regulator to be necessary for osteoblast function. Kolanczyk et al (2007) found that osteoblasts from *NF1*Prx1(*NF1*+/-) mice show increased proliferation and decreased abilities to differentiate and mineralize, whereas chondrocytes demonstrate a lower proliferation rate and defective differentiation. These results indicate that *NF1* has multiple roles in skeletal development including joint formation, growth plate function, osteoblast differentiation, and control of vessel growth, and proved that *NF1* is an important regulator of development and growth of the skeleton. The pattern of expression suggests that *NF1* related skeletal abnormalities stem in part from primary osseous defects caused by bone cellular dysfunctions related to generalized *NF1* heterozygosity, and/or to *NF1* loss of function in specific bone cell types.

Investigations of affected skeletal tissue in tibial pseudarthrosis model created by inactivation of one of *NF1* alleles during early mouse limb development, confirm that further mutation of the second *NF1* allele, thus the homozygous loss of *NF1* function, was detrimental for normal bone development. Thus, like in *NF1*-mediated tumorigenicity, a loss of both *NF1* alleles is likely to be required to cause the skeletal abnormality phenotype.

Available mouse models recapitulate some, but not all, of the bone abnormalities in patients with Nf-1. Mouse data helped clarify that *NF1* haploinsufficiency is likely related to the generalized Nf-1 bone remodeling defects, whereas total loss of *NF1* function is likely related to the focal dysplastic events. Identifying neurofibromin cellular functions, target genes and downstream signaling pathways remains a priority to understand the etiology of the Nf-1 skeletal manifestations.

### **3. Present day and future treatment of skeletal dysplasia in neurofibromatosis type 1**

Consensus guidelines for the treatment of the specific orthopedic manifestations in patients with Nf-1 do not exist and clinical management practices for each Nf-1 skeletal abnormality varied considerably.

endocardial cushions. These *NF1*-deficient embryos die between embryonic days 12.5 and 13.5, presumably due to the cardiac vessel defect. In contrast to completely defective organism, inactivation of only one allele of *NF1* gene locally, in the neural crest only, does not cause cardiac defects but results in tumors of neural crest origin, resembling those seen in Nf-1 patients. Following this early experiments the another models of an experimental animal has been developed to determine the role of *NF1* in bone cells and resolve difficulties in understanding the human pathophysiology of Nf-1 skeletal defects (Kolanczyk, 2007, 2008). It has been well known that neurofibromin is a cytoplasmic protein that is predominantly expressed in neurons, Schwann cells, oligodendrocytes, astrocytes, and leukocytes. Due to early studies based on transgenic animal models of skeletal defective mice it is obvious currently that *NF1*-mRNA and neurofibromin are expressed in mouse bone and cartilage during development and adulthood (Kuorilehto et al., 2004), and more specifically in mesenchymal stem cells, chondrocytes, osteoblasts (Elefteriou et al., 2006; Kolanczyk et al., 2007), and osteoclasts (Yang et al., 2006a). Kuorilehto et al. (2004) reported the expression of neurofibromin in growth plate, periosteum, and tracebular bone of mice, and the expression in growth plate was mainly located in chondrocytes of the hypertrophic layer. Yu et al (2005) showed that upon the activation of *ras* signals, *NF1*+/- murine osteoprogenitor cells show increased proliferation and premature apoptosis; the osteoprogenitor cells also exhibit a lower rate of differentiation to osteoblasts. He considered neurofibromin and its role as *ras* signal regulator to be necessary for osteoblast function. Kolanczyk et al (2007) found that osteoblasts from *NF1*Prx1(*NF1*+/-) mice show increased proliferation and decreased abilities to differentiate and mineralize, whereas chondrocytes demonstrate a lower proliferation rate and defective differentiation. These results indicate that *NF1* has multiple roles in skeletal development including joint formation, growth plate function, osteoblast differentiation, and control of vessel growth, and proved that *NF1* is an important regulator of development and growth of the skeleton. The pattern of expression suggests that *NF1* related skeletal abnormalities stem in part from primary osseous defects caused by bone cellular dysfunctions related to generalized *NF1* heterozygosity, and/or to *NF1* loss of

Investigations of affected skeletal tissue in tibial pseudarthrosis model created by inactivation of one of *NF1* alleles during early mouse limb development, confirm that further mutation of the second *NF1* allele, thus the homozygous loss of *NF1* function, was detrimental for normal bone development. Thus, like in *NF1*-mediated tumorigenicity, a loss of both *NF1* alleles is likely to be required to cause the skeletal abnormality phenotype. Available mouse models recapitulate some, but not all, of the bone abnormalities in patients with Nf-1. Mouse data helped clarify that *NF1* haploinsufficiency is likely related to the generalized Nf-1 bone remodeling defects, whereas total loss of *NF1* function is likely related to the focal dysplastic events. Identifying neurofibromin cellular functions, target genes and downstream signaling pathways remains a priority to understand the etiology of

Consensus guidelines for the treatment of the specific orthopedic manifestations in patients with Nf-1 do not exist and clinical management practices for each Nf-1 skeletal abnormality

**3. Present day and future treatment of skeletal dysplasia in** 

function in specific bone cell types.

the Nf-1 skeletal manifestations.

**neurofibromatosis type 1** 

varied considerably.

At present, there are either no clinical trials to support the use of osteoporotic drugs in a population of Nf-1 patients or treatment guidelines. Thus, conservative therapy to promote bone health, such as treatment with calcium and vitamin D, and weight-bearing exercise forms the first line of therapy in children with Nf-1 and low bone mass. Correction of measured deficiencies in hormones (vitamin D, thyroid, estrogen, etc.) that are known to regulate skeletal growth and maturation is inevitable. Judicious vitamin D supplementation may prove beneficial for patients with Nf-1 who have vitamin D deficiency or evidence of osteopenia. Similarly, until further information is obtained, treatment of osteoporosis in adults with Nf-1 follow the recommendations developed for general population. Because low serum 25-OH-D and osteomalacia has been reported in patients with Nf-1 and low bone mass, osteoporotic adult patients over age 50 years should take supplemental 1,200 mg calcium and 800–1,000 IU vitamin D per day, and reduce clinical risk factors by regular weight bearing and muscle strengthening exercises and avoidance of smoking and excessive alcohol. Selection of approved anabolic or anti-resorptive drugs to prevent or treat osteoporotic fractures should follow the standard practice with exception of children. Children should be treated as well, as soon as fracture complicates the osteopenic/osteoporotic bone dysplasia (Elefteriou, 2009). Unfortunately, anabolic substances available currently upon two forms of parathyroid hormone pose the increased risk of osteosarcoma development, proven in rats, and are contraindicated in children (Tashjian & Gagel, 2006). Bisphosphonates and monoclonal antibodies that target osteoclasts, belonging to anti-resorptive drugs, have been used to reduce osteoporotic fractures in adults, but their effect on BMD and fracture risk in children with Nf-1 is unknown. Clinical trials are necessary to determine which of currently available therapies are most effective to treat patients with Nf-1 and reduces BMD, but especially frank osteoporosis.

In patients with Nf-1, the morbidity associated with either dystrophic scoliosis or tibial dysplasia is much greater than that of osteopenia and osteoporosis or even non-dystrophic scoliosis. This helps define priorities for current and future trials. Some of the ailments, particularly dystrophic scoliosis or tibial bowing, can lead to clinically significant consequences if neglected.

Children with dystrophic scoliosis require the extensive medical attention. In children who do not complete skeletal maturation, typically presented dystrophic form of scoliosis, bracing is routinely used when the spine curvature exceeded 25 up to 45 degrees. While the curvature progresses to more than 45 degrees before maturity or 55 degrees after maturity, surgery is commonly employed. Unique management approach due to progression is necessary in skeletally immature patients with dystrophic scoliosis in whom a curvature exciding 30 degrees. Exclusion of paravertebral tumors and dystrophic changes required MR or, less sensitive, CT imagings, as those finding may be missed on plain radiographs. Regarding possible complications of surgery, careful presurgical assessment is critical, as the lamina may be thin, the canal affected by dural ectasia or intraspinal tumors, and a rib may have displaced into the spinal canal, all of which express an increased risk of poor postsurgical outcome. Variables such as age, gender, associated neurofibromas, location and degree of the curve, and associated radiographic dystrophic features make the operation design difficult. Surgical treatment with fusion and growing rods is complex. Occasionally, intraspinal elements may directly compromise the cord when instrumentation and stabilization are attempted, or they may cause erosive changes in the bone, preventing

The Skeleton Abnormalities in Patients with

Neurofibromatosis Type 1: Important Consequences of Abnormal Gene Function 337

belief that bracing after pathological fracture should continue, delaying surgery until midchildhood, in fifth - eight year of age at earliest. Among the surgical procedures the most often applied are resection of the pseudarthrotic region and bone bridging with fixation via intramedullary stabilization devices, or free vascularized fibular grafting (contralateral or ipsilateral), or external fixation (e.g., Ilizarov technique), either alone or in combination with transankle fixation. Residual angular deformity, ankle stiffness, limb length discrepancy, refracture, and chronic pain are amongst the most severe complications of long bone pseudarthrosis. Attempts must been made to promote bone healing, always impaired in children with Nf-1 affected bones. Thus, electrical stimulation, varying periods of postoperative immobilization, supplemental bone grafting, and more sophisticated techniques, such as application of bone morphogenetic proteins and monocytic progenitors stem cells are under the routine or experimental options. Summarizing, tibial dysplasia with pseudarthrosis is still challenging Nf-1 skeletal manifestation required further extensive

Established transgenic mouse models of *NF1* gene and its protein dysfunctions opens up new vistas for a better understanding of the natural history and the development of new therapies and long-term orthopedic management essential to improve patient care. Based on data from these models, a variety of cell types and signaling pathways are likely to be involved in Nf-1 patients with bone manifestations. Therefore, combination therapies, using both anabolic and anti-catabolic medications, will likely give optimal results. For example, use of locally applied biological mediators (e.g., bone morphogenetic protein) at the time of surgery in patients with pseudarthrosis is an attractive option in order to avoid complications of systemic administration of pharmacologic agents. Unfortunately, no mouse model, even closely resembles the human skeletal manifestations, is fully identical, despite similarities with the human condition, in part due to the limitations of the genetic manipulations. Nevertheless, *NF1*-deficient mice are currently the only and highly valuable

Various studies have been initiated until now in preclinical mouse models to assess the potential efficacy of selected drugs on bone formation, repair and remodeling. Even when they represent just an initial approach, the most promising demonstrated potential of bisphosphonates (such as zolendronic acid) and recombinant human bone morphogenetic proteins (rhBMPs), which induces bone and cartilage formation, for improved net bone production in an in vivo model of heterotopic bone formation (Schindeler et al., 2008, Schindeler et al., 2011). Bisphosphonates are currently approved for other applications, so they could transition rapidly to Nf-1 clinical trials. Kolanczyk et al. (2008) quite recently published data concerning lovastatin, which improves cortical bone injury healing defects observed in the *NF1*-deficient mice. The inhibition of Ras/Erk signaling by lovastatin and other statins in mouse model counteracts the Ras/Erk constitutive activation occurred in *NF1*-deficient osteoblasts (as in Schwann cells), and improves bone healing defects. His work established the base for future experiments aimed at the treatment of the focal Nf-1

Although neurofibromatosis type 1 is associated with marked clinical variability, most affected children do well from the standpoint of their growth and development. Some features of Nf-1 are present at birth, and others are age related abnormalities of tissue

elaboration, on both scientific and everyday practice fields (Elefteriou, 2009).

project in preclinical testing of candidate therapies for Nf-1 skeletal defects.

bone changes with local statin's delivery (Weixi et al., 2010).

**4. Final remarks and conclusions for the future** 

primary fusion. The local condition may exclude the possibility of radical excision of tumor not infrequently, additionally worsen the postsurgical outcome. A lack of animal models of dystrophic scoliosis and consequently poor understanding of the natural history of this ailment, additionally hinder progress. As the pathogenesis of Nf-1 dystrophic scoliosis is still poorly understood, there are no clear pharmacologic adjunctive options. It is postulated, that prospective studies to determine the relationship of spinal neurofibromas in patients with dystrophic scoliosis may help to determine if early treatment of spinal tumors could prevent dystrophic scoliosis. Currently there is no effective treatment for Nf-1 related dural ectasia. If microfractures and vertebral wedging with subsequent development of scoliosis is diagnosed, then pharmacologic agents to increase vertebral strength may be appropriate (Elefteriou, 2009).

The dumbbell tumors, most of which are located unilaterally in the spinal canal and paravertebral space, are excised through a hemilaminectomy and a facetectomy, because these techniques provide large space for tumors excision. In addition, the spinal stability can be reconstructed by Rogers wiring and contralateral facet fusion, because the hemilaminectomy and facetectomy can minimize damage to spinal stability by leaving the spinous process, supra- and intraspinous ligaments, and contralateral facet joint.

Some dermal and most often internal plexiform neurofibromas, generally larger, more diffuse, and locally invasive to adjacent tissue and bone are seen in more than one fourth of patients with Nf-1 and can present a surgical or medical management conundrum. Besides pain, disfigurement, neurological and other clinical deficits complicated its growth, the wisdom of watchful waiting versus aggressive intervention is often debated (Wozniak & Karwacki, 2008). Complete resection of a PNF, radicalism of which is always controversial, without residual functional deficits is rarely possible, on the other hand, it must be remembered that app. 10% of them undergo malignant transformation. Thus debulking or partial resection of PNF may be undertaken not only for cosmetic purposes, but especially when progressive functional consequences are anticipated.

Surgical treatment of the chest wall deformities is usually not required, and the ailment, as well as short but proportional stature and not prominent macrocephaly, are assumed as principally cosmetic.

Sphenoid wing dysplasia, comprising a congenital malformation or a secondary bony defect, is not a primary target for therapeutic prevention. Although, it requires sensitive imaging techniques, particularly MRI, to screen patient for adjacent tumor, which may be amenable to therapy.

The management of anterolateral bowing deformity, characteristic for Nf-1, is most frustrating. Unlike scoliosis, treatment of congenital pseudarthrosis of the tibia does not appear to be more successful when it is initiated early. Anecdotally, early surgical intervention in children with Nf-1 and tibial pseudarthrosis results in poorer outcomes compared to later surgical management. The Consortium orthopedists recommended routine bracing of the dysplastic long bone upon diagnosis of bowing and agreed that prophylactic surgery should be avoided (Elefteriou, 2009). So, the current standard for treatment of long bone bowing in children is bracing to prevent fracture. The majority of members of the Consortium advocated early bracing until the child achieves maturity and, in some cases, continued even into adulthood. Evaluations of brace type, duration of use, or long-term benefits have not been obvious. Treatment of long bone pseudarthrosis is often unsatisfactory and very often require multiple surgeries or ultimate amputation. It is general

primary fusion. The local condition may exclude the possibility of radical excision of tumor not infrequently, additionally worsen the postsurgical outcome. A lack of animal models of dystrophic scoliosis and consequently poor understanding of the natural history of this ailment, additionally hinder progress. As the pathogenesis of Nf-1 dystrophic scoliosis is still poorly understood, there are no clear pharmacologic adjunctive options. It is postulated, that prospective studies to determine the relationship of spinal neurofibromas in patients with dystrophic scoliosis may help to determine if early treatment of spinal tumors could prevent dystrophic scoliosis. Currently there is no effective treatment for Nf-1 related dural ectasia. If microfractures and vertebral wedging with subsequent development of scoliosis is diagnosed, then pharmacologic agents to increase vertebral strength may be appropriate

The dumbbell tumors, most of which are located unilaterally in the spinal canal and paravertebral space, are excised through a hemilaminectomy and a facetectomy, because these techniques provide large space for tumors excision. In addition, the spinal stability can be reconstructed by Rogers wiring and contralateral facet fusion, because the hemilaminectomy and facetectomy can minimize damage to spinal stability by leaving the

Some dermal and most often internal plexiform neurofibromas, generally larger, more diffuse, and locally invasive to adjacent tissue and bone are seen in more than one fourth of patients with Nf-1 and can present a surgical or medical management conundrum. Besides pain, disfigurement, neurological and other clinical deficits complicated its growth, the wisdom of watchful waiting versus aggressive intervention is often debated (Wozniak & Karwacki, 2008). Complete resection of a PNF, radicalism of which is always controversial, without residual functional deficits is rarely possible, on the other hand, it must be remembered that app. 10% of them undergo malignant transformation. Thus debulking or partial resection of PNF may be undertaken not only for cosmetic purposes, but especially

Surgical treatment of the chest wall deformities is usually not required, and the ailment, as well as short but proportional stature and not prominent macrocephaly, are assumed as

Sphenoid wing dysplasia, comprising a congenital malformation or a secondary bony defect, is not a primary target for therapeutic prevention. Although, it requires sensitive imaging techniques, particularly MRI, to screen patient for adjacent tumor, which may be

The management of anterolateral bowing deformity, characteristic for Nf-1, is most frustrating. Unlike scoliosis, treatment of congenital pseudarthrosis of the tibia does not appear to be more successful when it is initiated early. Anecdotally, early surgical intervention in children with Nf-1 and tibial pseudarthrosis results in poorer outcomes compared to later surgical management. The Consortium orthopedists recommended routine bracing of the dysplastic long bone upon diagnosis of bowing and agreed that prophylactic surgery should be avoided (Elefteriou, 2009). So, the current standard for treatment of long bone bowing in children is bracing to prevent fracture. The majority of members of the Consortium advocated early bracing until the child achieves maturity and, in some cases, continued even into adulthood. Evaluations of brace type, duration of use, or long-term benefits have not been obvious. Treatment of long bone pseudarthrosis is often unsatisfactory and very often require multiple surgeries or ultimate amputation. It is general

spinous process, supra- and intraspinous ligaments, and contralateral facet joint.

when progressive functional consequences are anticipated.

(Elefteriou, 2009).

principally cosmetic.

amenable to therapy.

belief that bracing after pathological fracture should continue, delaying surgery until midchildhood, in fifth - eight year of age at earliest. Among the surgical procedures the most often applied are resection of the pseudarthrotic region and bone bridging with fixation via intramedullary stabilization devices, or free vascularized fibular grafting (contralateral or ipsilateral), or external fixation (e.g., Ilizarov technique), either alone or in combination with transankle fixation. Residual angular deformity, ankle stiffness, limb length discrepancy, refracture, and chronic pain are amongst the most severe complications of long bone pseudarthrosis. Attempts must been made to promote bone healing, always impaired in children with Nf-1 affected bones. Thus, electrical stimulation, varying periods of postoperative immobilization, supplemental bone grafting, and more sophisticated techniques, such as application of bone morphogenetic proteins and monocytic progenitors stem cells are under the routine or experimental options. Summarizing, tibial dysplasia with pseudarthrosis is still challenging Nf-1 skeletal manifestation required further extensive elaboration, on both scientific and everyday practice fields (Elefteriou, 2009).

Established transgenic mouse models of *NF1* gene and its protein dysfunctions opens up new vistas for a better understanding of the natural history and the development of new therapies and long-term orthopedic management essential to improve patient care. Based on data from these models, a variety of cell types and signaling pathways are likely to be involved in Nf-1 patients with bone manifestations. Therefore, combination therapies, using both anabolic and anti-catabolic medications, will likely give optimal results. For example, use of locally applied biological mediators (e.g., bone morphogenetic protein) at the time of surgery in patients with pseudarthrosis is an attractive option in order to avoid complications of systemic administration of pharmacologic agents. Unfortunately, no mouse model, even closely resembles the human skeletal manifestations, is fully identical, despite similarities with the human condition, in part due to the limitations of the genetic manipulations. Nevertheless, *NF1*-deficient mice are currently the only and highly valuable project in preclinical testing of candidate therapies for Nf-1 skeletal defects.

Various studies have been initiated until now in preclinical mouse models to assess the potential efficacy of selected drugs on bone formation, repair and remodeling. Even when they represent just an initial approach, the most promising demonstrated potential of bisphosphonates (such as zolendronic acid) and recombinant human bone morphogenetic proteins (rhBMPs), which induces bone and cartilage formation, for improved net bone production in an in vivo model of heterotopic bone formation (Schindeler et al., 2008, Schindeler et al., 2011). Bisphosphonates are currently approved for other applications, so they could transition rapidly to Nf-1 clinical trials. Kolanczyk et al. (2008) quite recently published data concerning lovastatin, which improves cortical bone injury healing defects observed in the *NF1*-deficient mice. The inhibition of Ras/Erk signaling by lovastatin and other statins in mouse model counteracts the Ras/Erk constitutive activation occurred in *NF1*-deficient osteoblasts (as in Schwann cells), and improves bone healing defects. His work established the base for future experiments aimed at the treatment of the focal Nf-1 bone changes with local statin's delivery (Weixi et al., 2010).

### **4. Final remarks and conclusions for the future**

Although neurofibromatosis type 1 is associated with marked clinical variability, most affected children do well from the standpoint of their growth and development. Some features of Nf-1 are present at birth, and others are age related abnormalities of tissue

The Skeleton Abnormalities in Patients with

54, No. 8, pp. 1646 –1651

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proliferation, which necessitate periodic monitoring to address ongoing health and developmental needs and to minimize the risk of serious medical complications. Among the most important and often debilitating are skeletal abnormalities. The skeleton is frequently affected in individuals with Nf-1, and some of these bone manifestations can result in significant morbidity and even profound invalidism. The natural history and pathogenesis of these skeletal abnormalities are still poorly understood and consequently therapeutic options for these manifestations are currently limited. Lately established transgenic mouse models as well as continuously developing new and improved imaging techniques warrants further achievements either in basic science concerning the complications of *NF1* mutation or clinical availability of diagnostic tools. The ongoing investigational trials, both preclinical and clinical as well as observational, gather significant number of participants, strengthen patient's belief for future improved care and therapy potentially freed them from often burdensome complications of disease course.

### **5. References**


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(discussion p 198)

634-53


**18** 

*Slovak Republic* 

**Studies of Osteoporosis in Cancer Patients** 

Beata Spanikova and Stanislav Spanik *St. Elisabeth Cancer Institute, Bratislava* 

**in Slovakia – Experience from Single Institute** 

Osteoporosis is a metabolic skeletal disease characterized by low bone mineral density (BMD), damage of bone microstructure, bone fragility resulting in increase risk of bone fractures. Epidemiologic data are continuously showing rising number of newly diagnostic patients with osteoporosis. The expected number of bone fractures due to osteoporosis is to be 6. 26 million in 2050, growth from 1. 56 million in 1990 (Payer et al., 2007). The fractures are usually localized in lumbar spine (or other vertebra), hip and forearm (wrist), The most serious is the fracture of proximal femur (hip), beacuse approximately 20% of these pateints die within one year after the fracture and almost 80% become dependent on some kind of care (Cooper, 1997). The precise number of vertebral pathological fractures is difficult to assess, because many of these fractures are asymptomatic. Despite this they increase mortality by 23% (Cooper, 2007). The wrist fracture do not increase the mortality. The incidence is much more frequent in women than in men (4 : 1). The increased frequency of osteoporosis is partly due to increase in absolute number of new patients and partly due to continualy improving diagnostic procedures. The new generation of equipments and laboratory technics more precisely identify patients with bone loss. In the same time improvement in public information leads to increasing number of densitometric

Bone tissue is highly active metabolic organ. The bone tissue remodelation (formation of new bone tissue and its degradation) is active and continual process. Very important role in regulation of this process have hormones (estrogens and androgens). The mostly understood and resolved is postmenopausal osteoporosis and the most important risk

Cancer patients, especially those with "hormone dependent" disease (breast cancer, prostate cancer) or those with treatment interfering in hormonal metabolism (breast cancer, prostate cancer, thyroid cancer, ovarian cancer, germ cell tumor and others) are in inceased risk of disease or therapy induced osteoporosis. There are increased numbers of information and

The most advanced are data on patients with breast cancer, particularly those with early

Women with breast cancer, especially those receiving aromatase inhibitors are at higher risk for bone loss and fracture. Postmenopausal women may already have multiple risk factors

groups and factors were identified (Rizzoli et al., 2005).

breast cancer (EBC) on adjuvant aromatase inhibitors (AI) therapy.

**1. Introduction** 

examinations.

references on this topic.

delAAT): evidence of a clinically significant NF1 genotype-phenotype correlation. Am J Hum Genet. Vol. 80, No. 1, pp. 140 –151.


## **Studies of Osteoporosis in Cancer Patients in Slovakia – Experience from Single Institute**

Beata Spanikova and Stanislav Spanik *St. Elisabeth Cancer Institute, Bratislava Slovak Republic* 

### **1. Introduction**

342 Osteoporosis

Virdis, R., Street, M.E., Bandello, M.A., Tripodi, C., Donadio, A., Villani, A.R., Cagozzi, L.,

Visnapuu, V., Peltonen, S., Ellila, T., Kerosuo, E., Vaananen, K., Happonen, R.P. & Peltonen,

Vitale, M.G., Guha A. & Skaggs D.L. (2002). Orthopaedic manifestations of

Walker, L., Thompson, D., Easton, D., Ponder, B., Ponder, M., Frayling, I. & Baralle, D.

Wang, Z. & Liu, Y. (2010). Research update and recent developments in the management of scoliosis in neurofibromatosis type 1. Orthopedics. Vol. 33, No. 5, pp. 335-41 Weixi, W., Nyman, J.S., Moss H., E., Gutierrez G., Mundy G.R., Xiangli Y. & Elefteriou F.

Williams, V.C., Lucas, J., Babcock, M.A., Gutmann., DH, Korf, B. & Maria, B.L. (2009). Neurofibromatosis type 1 revisited. Pediatrics; Vol. 123, No. 1, pp. 124 –133 Wozniak, W. & Karwacki, M.W. (2008). Is "watchful waiting" superior to surgery in children

Yang, F.C., Chen, S., Clegg, T., Li, X., Morgan, T., Estwick, S.A., Yuan, J., Khalaf, W., Burgin,

Yu, X., Chen, S., Potter, O.L., Murthy, S.M., Li, J., Pulcini, J.M., Ohashi, N., Winata, T.,

tumor mass at diagnosis? Childs Nerv Syst. Vol. 24, No. 12, pp. 1431-6 Writing Group for the ISCD Position Development Conference: Diagnosis of osteoporosis in

Am J Hum Genet. Vol. 80, No. 1, pp. 140 –151.

Genet. Vol. 50, No. 4, pp. 274–280

Br J Cancer. Vol. 95, No. 2, pp. 233-8

Mol Genet. Vol. 15, No. 16, pp. 2421–2437

Vol. 25, No 7, pp. 1658-1667

18

pp. 17–26

pp. 793–802

delAAT): evidence of a clinically significant NF1 genotype-phenotype correlation.

Garavelli, L. & Bernasconi, S. (2003). Growth and pubertal disorders in neurofibromatosis type 1. J Pediatr Endocrinol Metab. Vol. 16, Suppl. 2, pp. 289–292

J. (2007). Periapical cemental dysplasia is common in women with NF1. Eur J Med

neurofibromatosis in children: an update. Clin Orthop Relat Res. No. 401, pp. 107-

(2006). A prospective study of neurofibromatosis type 1 cancer incidence in the UK.

(2010) Local Low-Dose Lovastatin Delivery Improves the Bone-Healing Defect Caused by Loss of Function in Osteoblasts. Journal of Bone and Mineral Research.

with neurofibromatosis type 1 presenting with extracranial and extramedullary

men, premenopausal women, and children. (2004). J Clin Densitom. Vol. 7, No. 1,

S., Travers, J., Parada, L.F., Ingram, D.A., Clapp, D.W. (2006). Nf1+/- mast cells induce neurofibroma like phenotypes through secreted TGF-beta signaling. Hum

Everett, E.T., Ingram, D., Clapp, W.D. & Hock, J.M. (2005). Neurofibromin and its inactivation of Ras are prerequisites for osteoblast functioning. Bone. Vol. 36, No. , Osteoporosis is a metabolic skeletal disease characterized by low bone mineral density (BMD), damage of bone microstructure, bone fragility resulting in increase risk of bone fractures. Epidemiologic data are continuously showing rising number of newly diagnostic patients with osteoporosis. The expected number of bone fractures due to osteoporosis is to be 6. 26 million in 2050, growth from 1. 56 million in 1990 (Payer et al., 2007). The fractures are usually localized in lumbar spine (or other vertebra), hip and forearm (wrist), The most serious is the fracture of proximal femur (hip), beacuse approximately 20% of these pateints die within one year after the fracture and almost 80% become dependent on some kind of care (Cooper, 1997). The precise number of vertebral pathological fractures is difficult to assess, because many of these fractures are asymptomatic. Despite this they increase mortality by 23% (Cooper, 2007). The wrist fracture do not increase the mortality. The incidence is much more frequent in women than in men (4 : 1). The increased frequency of osteoporosis is partly due to increase in absolute number of new patients and partly due to continualy improving diagnostic procedures. The new generation of equipments and laboratory technics more precisely identify patients with bone loss. In the same time improvement in public information leads to increasing number of densitometric examinations.

Bone tissue is highly active metabolic organ. The bone tissue remodelation (formation of new bone tissue and its degradation) is active and continual process. Very important role in regulation of this process have hormones (estrogens and androgens). The mostly understood and resolved is postmenopausal osteoporosis and the most important risk groups and factors were identified (Rizzoli et al., 2005).

Cancer patients, especially those with "hormone dependent" disease (breast cancer, prostate cancer) or those with treatment interfering in hormonal metabolism (breast cancer, prostate cancer, thyroid cancer, ovarian cancer, germ cell tumor and others) are in inceased risk of disease or therapy induced osteoporosis. There are increased numbers of information and references on this topic.

The most advanced are data on patients with breast cancer, particularly those with early breast cancer (EBC) on adjuvant aromatase inhibitors (AI) therapy.

Women with breast cancer, especially those receiving aromatase inhibitors are at higher risk for bone loss and fracture. Postmenopausal women may already have multiple risk factors

Studies of Osteoporosis in Cancer Patients in Slovakia – Experience from Single Institute 345

published results of large international multicenter clinical studies (including more than 15 000 pacients) such as ATAC (Howell et al., 2005) and BIG (Coates et al., 2007) have shown that adjuvant hormonal therapy using AIs and lasting 5 years is more effective than adjuvant therapy using selective estrogen receptor modulators (SERMs), mainly tamoxifen. Substudies of these and many other similar studies dealing with bone mineral density (BMD) in early breast cancer patients on adjuvant hormonal therapy are consistently showing higher decrease of BMD during treatment with AIs than that with tamoxifen. This is the reason why regular BMD measurements at the beginning and during AIs adjuvant therapy were implemented into new recommendations for early breast cancer therapy published in July 2007 as results of consensus of panel of most important international

We started regular bone mineral density (BMD) measurement of postmenopausal early breast cancer patients treated either with aromatase inhibitors (AIs) or tamoxifen in St. Elisabeth Cancer Institute on September 2005. The most important goal of our study was to determine bone mineral density decrease in early breast cancer patients treated with (AIs). We measured BMD at the begining of treatment and during therapy (after one year or two depending on initial results) with AIs and a group of patients who have their hormonal therapy switched from tamoxifen do AIs for different reasons (intolerance or toxicity). As an comparative groups we measured BMD in group of early breast cancer patients treated with tamoxifen and patients after finished hormonal therapy without any anticaner therapy, only on regular follow-up. The study is sitll active, in this preliminary evaluation we analysed group of 263 consecutive patients with early breast cancer, 42 on active AIs therapy - 22 on letrozole on oral daily dose 2,5 mg, 20 on anastrozole on oral daily dose 1 mg, 72 patients with "switched" therapy from tamoxifen to AIs, 69 on active tamoxife therapy on oral daily dose 20 mg and 80 patients just on follow-up after finishing active

In all our patients the BMD measurement was performed on total body densitometer Hologic Explorer. We measured and evaluated region of proximal femur and L spine. In cases of degenerative changes which overestimated results we measured and evaluated the region of forearm. For comparisons we evaluated T score. All patients included in our study have measured height, weight, assessed age, duration of menopause, hormonal replacement therapy and history of other risk factors and previous fractures. All patients have measured calcium blood level. We also measured markers of bone turnover, CTX (CrossLaps - C telopeptide of alfa chain 2(I) colagen) as marker of osteoporosis measured by ELISA method and isoensyme of ALP as marker of osteoproduction. In patients with BMD results on levels of osteoporosis we made differential diagnostic examinations to exclude secondary osteoporosis. This is important especially in patients with breast cancer to exclude bone marrow metastases, which are most frequent sites of generalised disease. We used cancer

For the statistical analysis we used standard methods of descriptive statistics, test of data independence and multiple regression was used to verify influence of separate factors especially to exclude possible secondary influences in case of interactive correlation among

markers, RTG, CT, MRI or bone scan - sceletal gamagraphy

leaders in the field during 10th St Gallen Conference (Goldhirsch et al., 2007).

**2.2 Patients and methods** 

hormonal treatment.

parameters.

for fracture, and breast cancer therapies compound these risk (Hadji & Bundred, 2007). Fractures can have serious clinical consequences including need for major surgery, increased morbidity and mortality, increased cost of disease management, and reduced quality of the life for patients (Body, 2011).

Additional group of patients in risk are those with prostate cancer on hormonal therapy, thyroid cancer (TC) after total or nearly total thyroidectomy on whole-life substitution therapy by oral thyroxine (T4) and patients with germ cell tumors (GCT) after surgery and radiotherapy and/or chemotherapy.

We have started to measure BMD in patients with breast cancer (BC), prostate cancer, thyroid cancer (TC) and germ cell tumors few years ago. Some of the results are nearly mature and ready to be publish (EBC, TC, GCT) others need more patients and time of follow-up (PC).

### **2. Breast cancer**

#### **2.1 Introduction**

Postmenopausal breast cancer patients are in high risk of osteoporosis in many reasons – primary diagnosis of breast cancer, then side-effects of anticancer therapy, postmenopausal status. These factors mean not just elevated risk of bone loss, osteoporosis, but especially risk of patological fractures. Many of postmenopausal breast cancer patients, especially those with early stage, with aromatase inhibitors (AI) adjuvant therapy have very good prognosis. The elevated risk of osteoporosis can lead to patological fractures which may markedly worsen their quality of life (Coleman et al., 2008).

Antagonizing estrogen in hormone-dependent breast cancer is well-known method of reducing tumor growth. Five years of treatment with tamoxifen, an antiestrogen or selective estrogen-receptor modulator (SERM), has been shown to reduce the risk of recurrence and breast cancer mortality by 41% and 34% respectively and is still recommended as one of several options for early-stage hormone receptor-positive breast cancer.

New data from clinical trials comparing third-generation aromatase inhibitors (AI) with tamoxifen have confirmed that AI offer significant efficacy and tolerability advantage over tamoxifen. Aromatase inhibitors are recommended as adjuvant treatmen for postmenopausal women with hormone-receptor positive early breast cancer. The group of clinicaly used AI contains non-steroidal AI letrozole and anastrozole and steroidal-AI exemestane. The primary mechanism of action of AI is inhibition of aromatase activity. Aromatase is the most important enzyme responsible for conversion of androgens to estrogens, mainly in tissues outside endocrine system. This is the most important mechanism of estrogen production in postmenopausal women. Estrogen production blockade influences bone metabolism directly via osteoclastogenesis stimulation. Survival extension of osteoclasts is the main mechanism. Cytokines, interleukines 1 and 6, osteoprotegerin, bone resorption potentiation, osteocytes and osteoblasts apoptosis are other important mechanisms resulting in osteosynthesis inhibiton. AIs also play key role in calcium metabolism. Their action influence calcium absorption in small bowel and renal elimination. It is very similar to estrogens level decrease after menopause leading to postmenopausal osteoporosis (Rizzoli, 2005).

AIs in breast cancer treatment are used as adjuvant therapy – it means after radical surgery in early breast cancer, stages I - III or as palliative therapy of locally advanced or metastatic disease. Standard duration of adjuvant hormonal therapy is now 5 years. Recently published results of large international multicenter clinical studies (including more than 15 000 pacients) such as ATAC (Howell et al., 2005) and BIG (Coates et al., 2007) have shown that adjuvant hormonal therapy using AIs and lasting 5 years is more effective than adjuvant therapy using selective estrogen receptor modulators (SERMs), mainly tamoxifen. Substudies of these and many other similar studies dealing with bone mineral density (BMD) in early breast cancer patients on adjuvant hormonal therapy are consistently showing higher decrease of BMD during treatment with AIs than that with tamoxifen. This is the reason why regular BMD measurements at the beginning and during AIs adjuvant therapy were implemented into new recommendations for early breast cancer therapy published in July 2007 as results of consensus of panel of most important international leaders in the field during 10th St Gallen Conference (Goldhirsch et al., 2007).

### **2.2 Patients and methods**

344 Osteoporosis

for fracture, and breast cancer therapies compound these risk (Hadji & Bundred, 2007). Fractures can have serious clinical consequences including need for major surgery, increased morbidity and mortality, increased cost of disease management, and reduced

Additional group of patients in risk are those with prostate cancer on hormonal therapy, thyroid cancer (TC) after total or nearly total thyroidectomy on whole-life substitution therapy by oral thyroxine (T4) and patients with germ cell tumors (GCT) after surgery and

We have started to measure BMD in patients with breast cancer (BC), prostate cancer, thyroid cancer (TC) and germ cell tumors few years ago. Some of the results are nearly mature and ready to be publish (EBC, TC, GCT) others need more patients and time of

Postmenopausal breast cancer patients are in high risk of osteoporosis in many reasons – primary diagnosis of breast cancer, then side-effects of anticancer therapy, postmenopausal status. These factors mean not just elevated risk of bone loss, osteoporosis, but especially risk of patological fractures. Many of postmenopausal breast cancer patients, especially those with early stage, with aromatase inhibitors (AI) adjuvant therapy have very good prognosis. The elevated risk of osteoporosis can lead to patological fractures which may

Antagonizing estrogen in hormone-dependent breast cancer is well-known method of reducing tumor growth. Five years of treatment with tamoxifen, an antiestrogen or selective estrogen-receptor modulator (SERM), has been shown to reduce the risk of recurrence and breast cancer mortality by 41% and 34% respectively and is still recommended as one of

New data from clinical trials comparing third-generation aromatase inhibitors (AI) with tamoxifen have confirmed that AI offer significant efficacy and tolerability advantage over tamoxifen. Aromatase inhibitors are recommended as adjuvant treatmen for postmenopausal women with hormone-receptor positive early breast cancer. The group of clinicaly used AI contains non-steroidal AI letrozole and anastrozole and steroidal-AI exemestane. The primary mechanism of action of AI is inhibition of aromatase activity. Aromatase is the most important enzyme responsible for conversion of androgens to estrogens, mainly in tissues outside endocrine system. This is the most important mechanism of estrogen production in postmenopausal women. Estrogen production blockade influences bone metabolism directly via osteoclastogenesis stimulation. Survival extension of osteoclasts is the main mechanism. Cytokines, interleukines 1 and 6, osteoprotegerin, bone resorption potentiation, osteocytes and osteoblasts apoptosis are other important mechanisms resulting in osteosynthesis inhibiton. AIs also play key role in calcium metabolism. Their action influence calcium absorption in small bowel and renal elimination. It is very similar to estrogens level decrease after menopause leading to

AIs in breast cancer treatment are used as adjuvant therapy – it means after radical surgery in early breast cancer, stages I - III or as palliative therapy of locally advanced or metastatic disease. Standard duration of adjuvant hormonal therapy is now 5 years. Recently

quality of the life for patients (Body, 2011).

markedly worsen their quality of life (Coleman et al., 2008).

postmenopausal osteoporosis (Rizzoli, 2005).

several options for early-stage hormone receptor-positive breast cancer.

radiotherapy and/or chemotherapy.

follow-up (PC).

**2. Breast cancer 2.1 Introduction** 

We started regular bone mineral density (BMD) measurement of postmenopausal early breast cancer patients treated either with aromatase inhibitors (AIs) or tamoxifen in St. Elisabeth Cancer Institute on September 2005. The most important goal of our study was to determine bone mineral density decrease in early breast cancer patients treated with (AIs). We measured BMD at the begining of treatment and during therapy (after one year or two depending on initial results) with AIs and a group of patients who have their hormonal therapy switched from tamoxifen do AIs for different reasons (intolerance or toxicity).

As an comparative groups we measured BMD in group of early breast cancer patients treated with tamoxifen and patients after finished hormonal therapy without any anticaner therapy, only on regular follow-up. The study is sitll active, in this preliminary evaluation we analysed group of 263 consecutive patients with early breast cancer, 42 on active AIs therapy - 22 on letrozole on oral daily dose 2,5 mg, 20 on anastrozole on oral daily dose 1 mg, 72 patients with "switched" therapy from tamoxifen to AIs, 69 on active tamoxife therapy on oral daily dose 20 mg and 80 patients just on follow-up after finishing active hormonal treatment.

In all our patients the BMD measurement was performed on total body densitometer Hologic Explorer. We measured and evaluated region of proximal femur and L spine. In cases of degenerative changes which overestimated results we measured and evaluated the region of forearm. For comparisons we evaluated T score. All patients included in our study have measured height, weight, assessed age, duration of menopause, hormonal replacement therapy and history of other risk factors and previous fractures. All patients have measured calcium blood level. We also measured markers of bone turnover, CTX (CrossLaps - C telopeptide of alfa chain 2(I) colagen) as marker of osteoporosis measured by ELISA method and isoensyme of ALP as marker of osteoproduction. In patients with BMD results on levels of osteoporosis we made differential diagnostic examinations to exclude secondary osteoporosis. This is important especially in patients with breast cancer to exclude bone marrow metastases, which are most frequent sites of generalised disease. We used cancer markers, RTG, CT, MRI or bone scan - sceletal gamagraphy

For the statistical analysis we used standard methods of descriptive statistics, test of data independence and multiple regression was used to verify influence of separate factors especially to exclude possible secondary influences in case of interactive correlation among parameters.

Studies of Osteoporosis in Cancer Patients in Slovakia – Experience from Single Institute 347

Median of age of the whole group of patients was 61 years. The BMD loss to levels of osteoporosis was found in group of patients under 50 years of age in 26%, where 50% of them had osteoporosis in region of L spine, 38% in region of proximal femur and only 13% in region of forearm. The rate of osteoporosis was higher in the group of patients older than 70 years - 73% and most of them had osteoporosis in the region of forearm – 49%. The region of L spine was overestimated by degenerative and deformative changes in this age group of patients. Group of patients in age between 50 to 70 years had BMD levels of osteoporosis in 34%, most frequently in region of L spine – 80%. These findings are in correlation with many clinical studies confirming rising incidence of osteoporosis with rising age. We confirm influence of menopause duration on osteoporosis as well as negative correlation of weight and osteoporosis in our study. All this findings are in consensus with

We also analysed impact of therapy on BMD loss. In the group of patients with AI therapy BMD loss to level of osteoporosis was diagnosed in 43,86% and normal BMD had 13,16% of patients, in the group with tamoxifen therapy the rate of osteoporosis was 30,43% and normal BMD had 18,84% of patients, in the group on follow-up without hormonal therapy the rate of osteoporosis was 53,75% and normal BMD had 8,7% of patients. The correlation between BMD loss and hormonal therapy was not proven statistically significant despite trend of tamoxifen protective effect on BMD maintenance. This was not statistically significant - (p=0,0610). In subanalysis, where we correlate BMD loss only in subgroup of patients treated by AIs at least one year and patients treated less than 1 year or just on follow-up without hormonal therapy (figure 3), the difference was statistically significant. The rate of BMD loss to level of osteoporosis was 53,13% in the first group and only 40,2% in the letter and normal BMD rate was only 3,13% in the first group versus 16,58% in second

Fig. 3. BMD in Patients with Aromatase Inhibitors Therapy and Others

literature data.

one - (p=0,0150).

### **2.3 Results**

From the whole study group of 263 postmenopausal early breast cancer patients, 114 patients in the group treated with AIs (72 of them switched from previous tamoxifen to AIs), 69 on tamoxifen therapy and 80 patients without hormonal therapy only on follow-up after finishing hormonal treatment (figure 1).

### Fig. 1. Patients Characteristics

We found normal BMD only in 13,31% among all evaluated patients, 43,35% of the whole analysed patients had BMD rate in levels of osteoporosis. Analysing the localisations of measured osteoporosis we found this in 5,25% in proximal femur, 63,1% in L spine and 31,58% in region of the forearm (figure 2) – those were patients with deformations or degenerative changes in region of spine, which overestimated the results.

Fig. 2. BMD in Patients with Breast Cancer

From the whole study group of 263 postmenopausal early breast cancer patients, 114 patients in the group treated with AIs (72 of them switched from previous tamoxifen to AIs), 69 on tamoxifen therapy and 80 patients without hormonal therapy only on follow-up

We found normal BMD only in 13,31% among all evaluated patients, 43,35% of the whole analysed patients had BMD rate in levels of osteoporosis. Analysing the localisations of measured osteoporosis we found this in 5,25% in proximal femur, 63,1% in L spine and 31,58% in region of the forearm (figure 2) – those were patients with deformations or

> **Osteoporosis 43.35 %**

**HIP 5,26%**

**L -spine 63.16 %**

**Forearm 31.58 %**

degenerative changes in region of spine, which overestimated the results.

**2.3 Results** 

after finishing hormonal treatment (figure 1).

Fig. 1. Patients Characteristics

**Normal BMD 13,31%**

Fig. 2. BMD in Patients with Breast Cancer

**osteopenia 43,35%**

Median of age of the whole group of patients was 61 years. The BMD loss to levels of osteoporosis was found in group of patients under 50 years of age in 26%, where 50% of them had osteoporosis in region of L spine, 38% in region of proximal femur and only 13% in region of forearm. The rate of osteoporosis was higher in the group of patients older than 70 years - 73% and most of them had osteoporosis in the region of forearm – 49%. The region of L spine was overestimated by degenerative and deformative changes in this age group of patients. Group of patients in age between 50 to 70 years had BMD levels of osteoporosis in 34%, most frequently in region of L spine – 80%. These findings are in correlation with many clinical studies confirming rising incidence of osteoporosis with rising age. We confirm influence of menopause duration on osteoporosis as well as negative correlation of weight and osteoporosis in our study. All this findings are in consensus with literature data.

We also analysed impact of therapy on BMD loss. In the group of patients with AI therapy BMD loss to level of osteoporosis was diagnosed in 43,86% and normal BMD had 13,16% of patients, in the group with tamoxifen therapy the rate of osteoporosis was 30,43% and normal BMD had 18,84% of patients, in the group on follow-up without hormonal therapy the rate of osteoporosis was 53,75% and normal BMD had 8,7% of patients. The correlation between BMD loss and hormonal therapy was not proven statistically significant despite trend of tamoxifen protective effect on BMD maintenance. This was not statistically significant - (p=0,0610). In subanalysis, where we correlate BMD loss only in subgroup of patients treated by AIs at least one year and patients treated less than 1 year or just on follow-up without hormonal therapy (figure 3), the difference was statistically significant. The rate of BMD loss to level of osteoporosis was 53,13% in the first group and only 40,2% in the letter and normal BMD rate was only 3,13% in the first group versus 16,58% in second one - (p=0,0150).

Fig. 3. BMD in Patients with Aromatase Inhibitors Therapy and Others

Studies of Osteoporosis in Cancer Patients in Slovakia – Experience from Single Institute 349

The rate of pathological fractures was analysed also (figure 5). The most frequent incidence was in group of patients with osteoporosis. Wrist fracture was found in 10 patients and 5 had fractures in region of L spine. In the group of patients with BMD on level of osteopenia, 5 patients had pathological fractures, 3 of them were wrist fractures and 2 in region of L spine. There were only 2 pathological fractures in patients with normal BMD levels, both were wrist fractures. The whole group of patients we considered to be too small to make

The last was the analysis of influence of antiresorptive therapy on BMD changes (figure 6). The analysis seemed to be preliminary as in the control group (control BMD measurement after 1 year of duration of antiresorptive therapy) were only 53 patients. This did not allow us to make relevant statistical analysis, although we found trend toward protective effect of

Fig. 6. Impact of Antiresorptive Therapy on BMD in patients with Breast Cancer

statistical analysis of risk factors of pathological fractures.

antiresorptive therapy in this group of patients.

Fig. 5. Patological Fractures Rate

We analysed other risk factors and we found highest rate of patients with diabetes mellitus among those risk factors (33 patients) but we did not confirm statistical significant influence of diabetes mellitus on BMD loss - (p=0,816).

Correlation of BMD loss and increase levels of CTX as a marker of bone resorption was not confirmed in our study.

We tested all above mentioned risk factors statistically also (figure 4) using method of multiple linear regression to eliminate potential secondary influences in cross interactions among factors. Correlations BMD level to age (p0,0001 and weight (p0,0001) were confirmed by multiple linear regression. Borderline statistical significance was shown in correlation to AIs therapy (=0,0476). The influence of time from menopause (p=0,3410) seemed to be secondary regarding to high correlation to age of patients (r=0,89, p 0,0001).

The rate of pathological fractures was analysed also (figure 5). The most frequent incidence was in group of patients with osteoporosis. Wrist fracture was found in 10 patients and 5 had fractures in region of L spine. In the group of patients with BMD on level of osteopenia, 5 patients had pathological fractures, 3 of them were wrist fractures and 2 in region of L spine. There were only 2 pathological fractures in patients with normal BMD levels, both were wrist fractures. The whole group of patients we considered to be too small to make statistical analysis of risk factors of pathological fractures.

The last was the analysis of influence of antiresorptive therapy on BMD changes (figure 6). The analysis seemed to be preliminary as in the control group (control BMD measurement after 1 year of duration of antiresorptive therapy) were only 53 patients. This did not allow us to make relevant statistical analysis, although we found trend toward protective effect of antiresorptive therapy in this group of patients.

Fig. 5. Patological Fractures Rate

348 Osteoporosis

We analysed other risk factors and we found highest rate of patients with diabetes mellitus among those risk factors (33 patients) but we did not confirm statistical significant influence

Correlation of BMD loss and increase levels of CTX as a marker of bone resorption was not

We tested all above mentioned risk factors statistically also (figure 4) using method of multiple linear regression to eliminate potential secondary influences in cross interactions among factors. Correlations BMD level to age (p0,0001 and weight (p0,0001) were confirmed by multiple linear regression. Borderline statistical significance was shown in correlation to AIs therapy (=0,0476). The influence of time from menopause (p=0,3410) seemed to be secondary regarding to high correlation to age of patients (r=0,89, p 0,0001).

Fig. 4. Correlation of BMD with Age, Weight and Time from Menopause

of diabetes mellitus on BMD loss - (p=0,816).

confirmed in our study.

Fig. 6. Impact of Antiresorptive Therapy on BMD in patients with Breast Cancer

Studies of Osteoporosis in Cancer Patients in Slovakia – Experience from Single Institute 351

hormonal treatment. With median of follow-up of 30 months (Goss et al., 2005), there were more patients with newly diagnostic osteoporosis on arm A (8. 1% versus 6. 0% p = 0. 003), and more bone fractures (5. 6% versus 4. 6%, this difference was however not

In comparison of patients on AI anastrozole (A) therapy from the clinical study "ATAC" to their healthy counterparts matched in age, postmenopausal status, with osteopenia, the

We confirmed the prognostic importance of age, duration of menopause, AIs treatment in comparison to tamoxifen treatment or no therapy in follow-up group in our clinical

According to WHO and NOF (National Osteoporotic Foundation) guidelines is the value of T-score in BMD measurement critical in distribution to normal BMD (T-score - 1. 0), osteopenia (T-score between – 1. 0 and – 2. 5) and osteoporosis (T-score ≤ - 2.5) (Kanis et al., 2008). According to international general guidelines is this classification universally accepted and it is recognised that with decreasing BMD level the risk of pathological bone fractures is rising. That is why the results and observations of the clinical study NORA (National Osteoporosis Risk Assessment) are so interesting. They observed 200 000 healthy postmenopausal women and found that 82% pathological bone fractures happened in women with T-score - 2. 5, which means that they did no have osteoporosis and 52%

All these results and findings confirm the importance of BMD measurement before AIs therapy initiation and importance of preventive measurements as components of adjuvant AIs therapy as well. Calcium and vitamin D supplementation and appropriate physical activity are standard components of these recommendations (Goldhirsch et al., 2007). Preventive bisphosphonates application is being evaluated in many running clinical studies. Especially zoledronic acid is showing excellent results and it seems to be incorporated into standard combination with AIs in adjuvant therapy of postmenopausal early breast cancer patients very soon as osteoporosis and bone fracture prevention

There was observed protective effect against bone loss, longer period to bone metastases occurence and suspected direct anticancer effect as well. These results will probably lead very soon to change today ´s standards and bisphosphonates will be used together with AIs

The influence of antiresorptive therapy on BMD was part of our study as well. This analysis is difficult to interpret as our control group (control BMD measurement after 1 year of duration of antiresorptive therapy) was very small (only 53 patients) and median of followup very short. This did not allow us to make relevant statistical analysis but we found trend

We did not confirm correlation of BMD decrease and CTX elevation. Probably the reason was small analysed group of patients and low specificity of CTX as osteoporosis marker

The most important goal of our study was to confirm the importance of BMD measurement and evaluation in group of postmenopausal early breast cancer patients on AIs therapy. Even the study group is not very large, all the patients are from single

observation. All these results are in concordance with world scientific literature.

fractures were in women with osteopenia (T-score – 1. 0 to – 2.5).

in adjuvant therapy of early breast cancer patients (Gnant et al., 2007).

toward protective effect of antiresorptive therapy in this group of patients.

statistically significant p = 0. 25).

(Gnant et al., 2007).

(S.Špánik & B. Špániková, 2010).

**2.5 Conclusions and future directions** 

incidence of bone fractures were nearly doubled.

#### **2.4 Discussion**

The AIs are new standard in adjuvant hormonal therapy of early breast cancer postmenopausal patients. As the results of many large international multicentre clinical trials are more mature and results of substudies focused on BMD loss more and more consistant, new standards for BMD examination are evolving. The prognosis of early breast cancer patients is continually improving. BMD loss means increasing risk of osteoporosis and it means increasing risk of pathological fractures. There are many risks factors for this group of patients - age, postmenopausal status, breast cancer, AIs therapy. Adjuvant hormonal therapy is one of the most important factors leading to significant improvement in patient survival and the same important is quality of life which may be markedly decreased by pathological fractures from osteoporosis.

Identification of all risk factors of origin and progression of osteoporosis as well as exact examination procedures to find them is as important as prevention and therapy of BMD loss. Generally confirmed risk factors for pathological fractures of osteoporosis in breast cancer patients are:


Table 1. Risk factors for pathological fractures of osteoporosis in breast cancer patients

In multicenter international clinical trial "ATAC", where the postmenopausal early breast cancer patients were randomised (final design) to AI anastrozole (A) versus tamoxifen (T) showed that after 5 years of therapy (Howell et al., 2005) there were significantly more bone fractures on arm A (11% versus 7% p 0. 001). In clinical trial "BIG 1-98" the same postmenopausal early breast cancer patients were randomised to AI letrozole (L) versus tamoxifen (T). With median of follow-up of 26 months (Thurliman et al., 2005) there were significantly more bone fractures on arm L (5.7% versus 4.0% p 0. 001). Very similar results were reached in the clinical study "IES" where the postmenopausal early breast cancer patients were randomised to AI exemestane (E) versus tamoxifen (T) and with median of follow-up 56 months (Coombes et al., 2007) there were significantly more bone fractures on arm E (7% versus 4. 9% p = 0. 003). In combined clinical study "ABCSG-8 and ARNO 95" the patients were "switched" after anastrozole (A) therapy to tamoxifen (T) vs continuing T therapy. With median of follow-up of 28 months (Jakesz et al., 2005) there was similar significant difference against arm A (2% versus 1% p = 0. 015). In the clinical study "MA.17" were the patients after 5 years on tamoxifen (T) therapy randomised to "switch" to anastrozole (A) versus only follow-up without

The AIs are new standard in adjuvant hormonal therapy of early breast cancer postmenopausal patients. As the results of many large international multicentre clinical trials are more mature and results of substudies focused on BMD loss more and more consistant, new standards for BMD examination are evolving. The prognosis of early breast cancer patients is continually improving. BMD loss means increasing risk of osteoporosis and it means increasing risk of pathological fractures. There are many risks factors for this group of patients - age, postmenopausal status, breast cancer, AIs therapy. Adjuvant hormonal therapy is one of the most important factors leading to significant improvement in patient survival and the same important is quality of life which may be markedly decreased

Identification of all risk factors of origin and progression of osteoporosis as well as exact examination procedures to find them is as important as prevention and therapy of BMD loss. Generally confirmed risk factors for pathological fractures of osteoporosis in breast

Table 1. Risk factors for pathological fractures of osteoporosis in breast cancer patients

In multicenter international clinical trial "ATAC", where the postmenopausal early breast cancer patients were randomised (final design) to AI anastrozole (A) versus tamoxifen (T) showed that after 5 years of therapy (Howell et al., 2005) there were significantly more bone fractures on arm A (11% versus 7% p 0. 001). In clinical trial "BIG 1-98" the same postmenopausal early breast cancer patients were randomised to AI letrozole (L) versus tamoxifen (T). With median of follow-up of 26 months (Thurliman et al., 2005) there were significantly more bone fractures on arm L (5.7% versus 4.0% p 0. 001). Very similar results were reached in the clinical study "IES" where the postmenopausal early breast cancer patients were randomised to AI exemestane (E) versus tamoxifen (T) and with median of follow-up 56 months (Coombes et al., 2007) there were significantly more bone fractures on arm E (7% versus 4. 9% p = 0. 003). In combined clinical study "ABCSG-8 and ARNO 95" the patients were "switched" after anastrozole (A) therapy to tamoxifen (T) vs continuing T therapy. With median of follow-up of 28 months (Jakesz et al., 2005) there was similar significant difference against arm A (2% versus 1% p = 0. 015). In the clinical study "MA.17" were the patients after 5 years on tamoxifen (T) therapy randomised to "switch" to anastrozole (A) versus only follow-up without

**2.4 Discussion** 

cancer patients are:

AIs therapy T-score 1. 5 Age 65 years

by pathological fractures from osteoporosis.

Low body mass index (BMI 20 kg/m2)

Oral corticosteroid therapy lasting 6 months

Personal history of fracture from osteoporosis after age of 50

Family history of hip fracture

Smoking (in present or in past)

hormonal treatment. With median of follow-up of 30 months (Goss et al., 2005), there were more patients with newly diagnostic osteoporosis on arm A (8. 1% versus 6. 0% p = 0. 003), and more bone fractures (5. 6% versus 4. 6%, this difference was however not statistically significant p = 0. 25).

In comparison of patients on AI anastrozole (A) therapy from the clinical study "ATAC" to their healthy counterparts matched in age, postmenopausal status, with osteopenia, the incidence of bone fractures were nearly doubled.

We confirmed the prognostic importance of age, duration of menopause, AIs treatment in comparison to tamoxifen treatment or no therapy in follow-up group in our clinical observation. All these results are in concordance with world scientific literature.

According to WHO and NOF (National Osteoporotic Foundation) guidelines is the value of T-score in BMD measurement critical in distribution to normal BMD (T-score - 1. 0), osteopenia (T-score between – 1. 0 and – 2. 5) and osteoporosis (T-score ≤ - 2.5) (Kanis et al., 2008). According to international general guidelines is this classification universally accepted and it is recognised that with decreasing BMD level the risk of pathological bone fractures is rising. That is why the results and observations of the clinical study NORA (National Osteoporosis Risk Assessment) are so interesting. They observed 200 000 healthy postmenopausal women and found that 82% pathological bone fractures happened in women with T-score - 2. 5, which means that they did no have osteoporosis and 52% fractures were in women with osteopenia (T-score – 1. 0 to – 2.5).

All these results and findings confirm the importance of BMD measurement before AIs therapy initiation and importance of preventive measurements as components of adjuvant AIs therapy as well. Calcium and vitamin D supplementation and appropriate physical activity are standard components of these recommendations (Goldhirsch et al., 2007). Preventive bisphosphonates application is being evaluated in many running clinical studies. Especially zoledronic acid is showing excellent results and it seems to be incorporated into standard combination with AIs in adjuvant therapy of postmenopausal early breast cancer patients very soon as osteoporosis and bone fracture prevention (Gnant et al., 2007).

There was observed protective effect against bone loss, longer period to bone metastases occurence and suspected direct anticancer effect as well. These results will probably lead very soon to change today ´s standards and bisphosphonates will be used together with AIs in adjuvant therapy of early breast cancer patients (Gnant et al., 2007).

The influence of antiresorptive therapy on BMD was part of our study as well. This analysis is difficult to interpret as our control group (control BMD measurement after 1 year of duration of antiresorptive therapy) was very small (only 53 patients) and median of followup very short. This did not allow us to make relevant statistical analysis but we found trend toward protective effect of antiresorptive therapy in this group of patients.

We did not confirm correlation of BMD decrease and CTX elevation. Probably the reason was small analysed group of patients and low specificity of CTX as osteoporosis marker (S.Špánik & B. Špániková, 2010).

### **2.5 Conclusions and future directions**

The most important goal of our study was to confirm the importance of BMD measurement and evaluation in group of postmenopausal early breast cancer patients on AIs therapy. Even the study group is not very large, all the patients are from single

Studies of Osteoporosis in Cancer Patients in Slovakia – Experience from Single Institute 353

androgens influence bone modelling and remodelling acting on osteoblasts, osteocytes and pluripotent stem cells through androgen receptors. They also act indirectly via estrogen receptors. The combined influence of androgens and estrogens is even stronger. We suppose that patients after unilateral orchiectomy (OE) or bilateral orchiectomy and consecutive radiotherapy and/or chemotherapy should have lower levels of testosterone. Literature sources on this issue are scarce and conflicting. There are numerous animal studies proving the effect of androgens on bone and also proving much stronger effect of androgen and

Our aim was to determine BMD and serum bone turnover markers in survivors from GCT. We included 719 patients with GCT into the study. We measured BMD in GCT patients

BMD was measured by dual-energy X-ray absorptiometry using osteodenzitometer Holgic Discovery in the lumbar spine and hips. BMD was classified as osteopenia (T score ranging from –2, 5 to –1.0) and osteoporosis (T score less than –2. 5). Latter according to WHO recommendation for men under 50 years of age we use Z score (comparison of detected

C-terminal cross-linked telopeptides of type I collagen (CTX) were measured using Enzyme-Linked Immunoabsorbent Assay (ELISA). Additionally serum total testosterone was

Comparison was made with matched healthy control group from Ministery of health registry. Relationships between baseline characteristics (age, treatment type and time from orchiectomy) and BMD were assessed using univariate and multivariate analysis

The data was evaluated using Microsoft Excel 2003 software and its built-in statistical functions and data analysis tools. We used standard uni-, bi- and multivariate statistical methods as appropriate throughout data analysis. Association between two nominal variables was tested using the Chi-squared test of independence. Association between an interval variable and a nominal one was tested using ANOVA or Kruskal-Wallis test, depending on the distribution of the interval variable; in case of a dichotomous variable, ttest was applied instead of ANOVA and Mann-Whitney test instead of Kruskal-Wallis test. A multiple linear regression was performed to test for association between an dependent

We included 719 patients into the study (21 – 76 yrs old, median: 39 yrs) who were treated for GCT since 1982. In this group, 663 pts (92%) were treated by unilateral orchiectomy (OE) and 56 pts (8%) by bilateral OE. The further treatment was radiotherapy of retroperitoneal lymph nodes (RPLND) in 124 pts (17%), chemotherapy in 405 pts (57%), radiotherapy and chemotherapy in in 16 pts (2%), the rest 174 pts (24%) did not receive any adjuvant therapy

We have proved a significant difference between BMD patients with GCT compared to the healthy population (p<0.0001) with more osteopenia and osteoporosis in GCT

interval variable and several predicting interval variables (Mardiak et al., 2007)

(fig. 7). Median time since OE was 6. 5 yrs, average time was 8. 1 yrs.

estrogen combination (Ondruš et al., 2007).

BMD to healthy bone of comparable age group).

**3.2 Patients and methods** 

from 2005.

measured.

**3.3 Results** 

patients.

tools.

institute and we have planned to follow-up them throughout the AIs therapy and thereafter. Preliminary analysis of our data confirmed significant BMD loss in this group of patients. The AIs therapy influence on BMD loss was statistically significant after one year of therapy. For more valid data we need more patients and longer time of follow-up. Our plan is to continue in evaluation of influence of antiresorptive therapy on BMD as we observed trend of protection of BMD. Evaluation of importance of BMD loss for increase risk of pathological bone fractures also needs more patients and longer time of follow-up (Hadji et al., 2011).

Our observational study confirmed importance of BMD measurement and evaluation in postmenopausal early breast cancer patients on AIs therapy. This is in concordance with new recommendations for early breast cancer therapy published in July 2007 as a result of consensus conference (10th St Gallen Conference) and other important international guidelines.

### **3. Testicular cancer**

### **3.1 Introduction**

Testicular cancer (TC) is still being serious disease although when the patients are correctly diagnosed and treated the cure rate is about 90%. Testicular cancer make about 1% of malignant tumors in men, the incidence in recent years is going up. The incidence in Slovak Republic in 2003 was 7,3/100000 men and during last 30 years has increased almost 5 times.TC appear mostly in men from 20 to 40 years of lilfe. (D. Ondruš & M. Ondrušová, 2008). According to international classification more than 95% of TC are germ cell tumors (GCT), which are classified into two major subgroups: seminoma and non-seminoma GCT. Nonseminomatous GCT comprises approximately 50% of all GCT. Most tumors are mixed, consisting of two or more cell types (embryonal carcinoma, choriocarcinoma, yolk sac tumor, teratoma or their mixtures). The rest of testicular tumors are rare - Leydig cell tumors, Sertoli cell tumors, granulosa cell tumors, gonadoblastoma, sarcomas, lymphomas and others).

The diagnosis of GCT is based on clinical picture – painless testicular mass, symptoms of epididymitis or orchitis, less frequently occurs testicular pain.

For pretreatment staging we use ultrasound, computed tomography (CT) of chest, abdomen and pelvis and serum tumor markers (alfa-fetoprotein, human chorionic gonadotropin, lactate dehydrogenase).

The standard therapeutic procedure is surgery, radical orchciectomy and retroperitoneal lymph node dissection (according to histological type and stage of the disease). Other therapeutic options are radiotherapy and chemotherapy (again according to histological type and stage of the disease).

During recent decades the survival rate of patients with testicular cancer or germ cell tumors (GCT) has substantially improved. Consequently the long-term side effects of treatment of GCT have gained attention, including accelerated bone loss leading to increased risk of osteoporosis. Treatment-related bone loss is well recognized in breast and prostate cancer, but there has been little information in long-term survivors from other tumors (Marcus et al., 2008).

We have a large group of GCT patients in our registry at the Department of Urology of St. Elisabeth Cancer Institute with a long duration follow-up. It is already known that androgens influence bone modelling and remodelling acting on osteoblasts, osteocytes and pluripotent stem cells through androgen receptors. They also act indirectly via estrogen receptors. The combined influence of androgens and estrogens is even stronger. We suppose that patients after unilateral orchiectomy (OE) or bilateral orchiectomy and consecutive radiotherapy and/or chemotherapy should have lower levels of testosterone. Literature sources on this issue are scarce and conflicting. There are numerous animal studies proving the effect of androgens on bone and also proving much stronger effect of androgen and estrogen combination (Ondruš et al., 2007).

### **3.2 Patients and methods**

352 Osteoporosis

institute and we have planned to follow-up them throughout the AIs therapy and thereafter. Preliminary analysis of our data confirmed significant BMD loss in this group of patients. The AIs therapy influence on BMD loss was statistically significant after one year of therapy. For more valid data we need more patients and longer time of follow-up. Our plan is to continue in evaluation of influence of antiresorptive therapy on BMD as we observed trend of protection of BMD. Evaluation of importance of BMD loss for increase risk of pathological bone fractures also needs more patients and longer time of follow-up

Our observational study confirmed importance of BMD measurement and evaluation in postmenopausal early breast cancer patients on AIs therapy. This is in concordance with new recommendations for early breast cancer therapy published in July 2007 as a result of consensus conference (10th St Gallen Conference) and other important international

Testicular cancer (TC) is still being serious disease although when the patients are correctly diagnosed and treated the cure rate is about 90%. Testicular cancer make about 1% of malignant tumors in men, the incidence in recent years is going up. The incidence in Slovak Republic in 2003 was 7,3/100000 men and during last 30 years has increased almost 5 times.TC appear mostly in men from 20 to 40 years of lilfe. (D. Ondruš & M. Ondrušová, 2008). According to international classification more than 95% of TC are germ cell tumors (GCT), which are classified into two major subgroups: seminoma and non-seminoma GCT. Nonseminomatous GCT comprises approximately 50% of all GCT. Most tumors are mixed, consisting of two or more cell types (embryonal carcinoma, choriocarcinoma, yolk sac tumor, teratoma or their mixtures). The rest of testicular tumors are rare - Leydig cell tumors, Sertoli cell tumors, granulosa cell tumors, gonadoblastoma, sarcomas, lymphomas

The diagnosis of GCT is based on clinical picture – painless testicular mass, symptoms of

For pretreatment staging we use ultrasound, computed tomography (CT) of chest, abdomen and pelvis and serum tumor markers (alfa-fetoprotein, human chorionic gonadotropin,

The standard therapeutic procedure is surgery, radical orchciectomy and retroperitoneal lymph node dissection (according to histological type and stage of the disease). Other therapeutic options are radiotherapy and chemotherapy (again according to histological

During recent decades the survival rate of patients with testicular cancer or germ cell tumors (GCT) has substantially improved. Consequently the long-term side effects of treatment of GCT have gained attention, including accelerated bone loss leading to increased risk of osteoporosis. Treatment-related bone loss is well recognized in breast and prostate cancer, but there has been little information in long-term survivors from other

We have a large group of GCT patients in our registry at the Department of Urology of St. Elisabeth Cancer Institute with a long duration follow-up. It is already known that

epididymitis or orchitis, less frequently occurs testicular pain.

(Hadji et al., 2011).

**3. Testicular cancer** 

**3.1 Introduction** 

and others).

lactate dehydrogenase).

type and stage of the disease).

tumors (Marcus et al., 2008).

guidelines.

Our aim was to determine BMD and serum bone turnover markers in survivors from GCT. We included 719 patients with GCT into the study. We measured BMD in GCT patients from 2005.

BMD was measured by dual-energy X-ray absorptiometry using osteodenzitometer Holgic Discovery in the lumbar spine and hips. BMD was classified as osteopenia (T score ranging from –2, 5 to –1.0) and osteoporosis (T score less than –2. 5). Latter according to WHO recommendation for men under 50 years of age we use Z score (comparison of detected BMD to healthy bone of comparable age group).

C-terminal cross-linked telopeptides of type I collagen (CTX) were measured using Enzyme-Linked Immunoabsorbent Assay (ELISA). Additionally serum total testosterone was measured.

Comparison was made with matched healthy control group from Ministery of health registry. Relationships between baseline characteristics (age, treatment type and time from orchiectomy) and BMD were assessed using univariate and multivariate analysis tools.

The data was evaluated using Microsoft Excel 2003 software and its built-in statistical functions and data analysis tools. We used standard uni-, bi- and multivariate statistical methods as appropriate throughout data analysis. Association between two nominal variables was tested using the Chi-squared test of independence. Association between an interval variable and a nominal one was tested using ANOVA or Kruskal-Wallis test, depending on the distribution of the interval variable; in case of a dichotomous variable, ttest was applied instead of ANOVA and Mann-Whitney test instead of Kruskal-Wallis test. A multiple linear regression was performed to test for association between an dependent interval variable and several predicting interval variables (Mardiak et al., 2007)

### **3.3 Results**

We included 719 patients into the study (21 – 76 yrs old, median: 39 yrs) who were treated for GCT since 1982. In this group, 663 pts (92%) were treated by unilateral orchiectomy (OE) and 56 pts (8%) by bilateral OE. The further treatment was radiotherapy of retroperitoneal lymph nodes (RPLND) in 124 pts (17%), chemotherapy in 405 pts (57%), radiotherapy and chemotherapy in in 16 pts (2%), the rest 174 pts (24%) did not receive any adjuvant therapy (fig. 7). Median time since OE was 6. 5 yrs, average time was 8. 1 yrs.

We have proved a significant difference between BMD patients with GCT compared to the healthy population (p<0.0001) with more osteopenia and osteoporosis in GCT patients.

Studies of Osteoporosis in Cancer Patients in Slovakia – Experience from Single Institute 355

Comparison was made between the subgroup of patients with unilateral orchiectomy and a the subgroup of those treated with bilateral orchiectomy. While the incidence of osteoporosis has not proved to be significantly different in the two subgroups (p=0.1725), patients treated with bilateral OE have significantly higher incidence of osteopenia

Fig. 8. Comparison of GCT group to healthy match control group We made comparison of BMD and the type of orchiectomy (fg. 9)

Fig. 9. Comparison of BMD and type of OE

(p=0.0116).

#### Fig. 7. Patients characteristics

We have made comparisons between the group of GCT patients and the healthy match control group according to type of surgery and subsequent therapy (fig. 8)

**Patients with GCT: Sample Distribution According to Type of Orchiectomy**

663; 92%

**Patients with GCT: Sample Distribution According to Therapy**

405; 57%

Unilateral Bilateral

Chemotherapy Radiotherapy CHT/RAT Observation

56; 8%

We have made comparisons between the group of GCT patients and the healthy match

control group according to type of surgery and subsequent therapy (fig. 8)

Fig. 7. Patients characteristics

124; 17%

16; 2%

174; 24%

We made comparison of BMD and the type of orchiectomy (fg. 9)

Comparison was made between the subgroup of patients with unilateral orchiectomy and a the subgroup of those treated with bilateral orchiectomy. While the incidence of osteoporosis has not proved to be significantly different in the two subgroups (p=0.1725), patients treated with bilateral OE have significantly higher incidence of osteopenia (p=0.0116).

Studies of Osteoporosis in Cancer Patients in Slovakia – Experience from Single Institute 357

Total Osteoporosis Osteopenia Normal BMD P value

Number of patients: 719 98 / 14% 296 / 41% 325 / 45%

 Unilateral OE 663 87 / 13% 264 / 40% 312 / 47% Bilateral OE 56 11 / 20% 32 / 57% 13 / 23% Chemotherapy 405 48 / 12% 172 / 42% 185 / 46% Radiotherapy 124 19 / 15% 48 / 39% 57 / 46% Chemo- and Radiotherapy 16 3 / 19% 10 / 63% 3 / 19%

Characteristics (Risk Factors): Fractures 98 10 / 10% 47 / 48% 41 / 42%

Baseline Characteristics (medians):

Table 2. Patients with GST – characteristics and results

 Median age 43,0 39,0 37,0 (<0.0001) Average age 43,8 39,5 37,7 (<0.0001)

 Time since OE 702 9,0 6,0 5,0 (0.0049) Testosterone (nmol/l) 478 16,8 16,6 16,3 (0.6887) Free Testosterone (pg/ml) 132 7,0 8,3 8,3 (0.3526) CTX (scale 1: ng/ml) 137 0,4 0,5 0,4 (0.5545) CTX (scale 2: pM) 287 3341,0 4175,5 3941,5 (0.2101) LH 4,6 4,6 4,6 (0.3602)

Fig. 11. BMD and median time since OE

 

 

 

Demographics:

Treatment:

All the most important results are summarized in table 2.

We also made comparisons of BMD of patients with GCT and different types of OE to healthy match control group (fig. 10)

Fig. 10. Comparisons of BMD of patients with GCT and different types of OE to the healthy match control group

In a separate comparison of the subgroup of patients treated with bilateral orchiectomy to the healthy population we have concluded not only a significantly higher incidence of osteoporosis in the former (p<0.0001), but also a significantly higher incidence of osteopenia in those patients treated with bilateral OE (p=0.0114). Patients treated with unilateral OE compared to the healthy population have a significantly higher incidence of osteoporosis (p<0.0001) We also made comparisons of BMD according to time from primary therapy

### Fig. 11. BMD and median time since OE

356 Osteoporosis

We also made comparisons of BMD of patients with GCT and different types of OE to

Fig. 10. Comparisons of BMD of patients with GCT and different types of OE to the healthy

In a separate comparison of the subgroup of patients treated with bilateral orchiectomy to the healthy population we have concluded not only a significantly higher incidence of osteoporosis in the former (p<0.0001), but also a significantly higher incidence of osteopenia in those patients treated with bilateral OE (p=0.0114). Patients treated with unilateral OE compared to the healthy population have a significantly higher incidence of osteoporosis (p<0.0001) We also made comparisons of BMD according to time from primary therapy

healthy match control group (fig. 10)

match control group



Table 2. Patients with GST – characteristics and results

Studies of Osteoporosis in Cancer Patients in Slovakia – Experience from Single Institute 359

increased bone turnover and decreased bone mineral density (BMD). The aim of the study

Bone mineral density (BMD) was measured by dual energy photon x-ray absorptiometry BMD using osteodenzitometer Holgic Discovery in the lumbar spine and hips. In cases with arteficialy increased bone density caused by degenerative bone changes we measured BMD also in forearm. BMD was classified using T score in postmenopausal women and more than 50 years old men . We classified Z score in premenopausal women and younger than 50 years men. C-terminal cross -linked telopeptides of type I collagen (CTX) were measured using ELISA. Additionally serum TSH and fT4 (free T4) were measured. Relationships between baseline characteristics (age, menopausal status in women, TSH levels and duration of substitutional therapy) and BMD were assessed using univariate and

Association between two nominal variables was tested using the Chi-squared test of independence. Association between an interval variable and a nominal one was tested using ANOVA or Kruskal-Wallis test, depending on the distribution of the interval variable; in case of a dichotomous variable, t-test was applied instead of ANOVA and Mann-Whitney test instead of Kruskal-Wallis test. A multiple linear regression was performed to test for association between an dependent interval variable and several predicting interval

We analysed BMD data from 165 TC patients after total tyroidectomy on supportive therapy in our study. There were 13 men and 152 women, 94 were postmenpausal (postMP), 44 premenopausal (preMP), in 14 the menopausal sattus was unknown. The mean age was 51

Age characteristics:

We included 165 TC patients in the study. There were 13 men a 152 women, the mean duration of thyroid suppressive therapy was 7. 2 years (0 – 24 years). The patients exhibit

osteporosis in 31%, 39% had osteopenia, whereas 30% had normal BMD (fig. 12).

Min 21 29 34 21 Max 78 77 78 55 Mean 53 49 59 39 Median 54 50 58 41 Standard deviation 12.65 14.21 8.25 8.45

All Men PostMP women PreMP women

was to assign the damage of bone metabolism in TC patients.

**4.2 Patients and methods** 

multivariate analysis tools.

years. Age characteristics are in table 3.

Table 3. Age characteristics

**4.3 Results** 

variables.

### **3.4 Conclusions and future directions**


We did not find any significant differences between GCT and matched control data regarding the incidence of osteopenia and bone turnover marker, but the incidence of osteoporosis was considerably higher in GCT patients. The incidence of osteopororsis appeared to increase with age and to slightly correlate with time since OE, particularly after 10 years following OE. Type of therapy did not prove to have significant impact on the appearance of osteoporosis. Serum testosterone level did not correlate with BMD. We recommend BMD measurement and evaluation in GCT patients after therapy (Ondrušová et al., 2009).

### **4. Bone mineral density in thyroid cancer (TC) patients on suppresive therapy after total thyroidectomy**

### **4.1 Introduction**

Thyroid cancer (TC) is another type of cancer which should be associated with decrease of BMD after total thyreoidectomy and subsequent suppressive therapy. Although TC comprises only 1. 1 – 1. 9% of all cancers it is the most frequent endocrine tumor making around 90% of them. It is 3-times more frequent in women than in men. The most frequent types are well-differentiated cancers – papillary (80 – 85%) and less frequent follicular (5 – 10%) thyroid carcinoma.

The standard therapy of thyroid carcinomas (TC) consists of total or nearly total thyroidectomy. Then the whole-life substitution therapy by oral thyroxine (T4) is given. Another goal of this therapy is to suppress serum thyroid stimulating hormone (TSH) to prevent the growth factor-like effect of TSH on well-differentiated TC cells. The recommendation is to administer supraphysiologic amounts of oral T4. This leads to hyperthyroidism, which is subclinical. The influence of thyroid hormones on bone tissue is well known (Altabas et al., 2007). In hyperthyreosis the acitivty of osteoblasts and osteoclasts is increased, but the influence of osteoclasts is dominating leading to bone resorption and osteoporosis. The longstanding subclinical hyperthyroidism may result in increased bone turnover and decreased bone mineral density (BMD). The aim of the study was to assign the damage of bone metabolism in TC patients.

### **4.2 Patients and methods**

358 Osteoporosis

We have proved a significant difference between BMD patients with GCT and healthy

The incidence of osteoporosis is significantly higher in patients with GCT compared to

 While the incidence of osteoporosis has not proved to be significantly different in the two subgroups (p=0.1725), patients treated with bilateral OE have significantly higher

 Comparing the minimum T-score between the two subgroups, we have concluded significantly lower median T-score in patients with bilateral OE compared to those

We have come to the conclusion of no significant association between BMD and type of

 Correlation between T-score and testosterone also free testosterone level in patients with GCT, the correlation coefficient of 0.0881, did not prove as significant

We did not find any significant differences between GCT and matched control data regarding the incidence of osteopenia and bone turnover marker, but the incidence of osteoporosis was considerably higher in GCT patients. The incidence of osteopororsis appeared to increase with age and to slightly correlate with time since OE, particularly after 10 years following OE. Type of therapy did not prove to have significant impact on the appearance of osteoporosis. Serum testosterone level did not correlate with BMD. We recommend BMD measurement and evaluation in GCT patients after therapy (Ondrušová et

There is no significant association between BMD and CTX level (p=0.1600).

**4. Bone mineral density in thyroid cancer (TC) patients on suppresive** 

Thyroid cancer (TC) is another type of cancer which should be associated with decrease of BMD after total thyreoidectomy and subsequent suppressive therapy. Although TC comprises only 1. 1 – 1. 9% of all cancers it is the most frequent endocrine tumor making around 90% of them. It is 3-times more frequent in women than in men. The most frequent types are well-differentiated cancers – papillary (80 – 85%) and less frequent follicular (5 –

The standard therapy of thyroid carcinomas (TC) consists of total or nearly total thyroidectomy. Then the whole-life substitution therapy by oral thyroxine (T4) is given. Another goal of this therapy is to suppress serum thyroid stimulating hormone (TSH) to prevent the growth factor-like effect of TSH on well-differentiated TC cells. The recommendation is to administer supraphysiologic amounts of oral T4. This leads to hyperthyroidism, which is subclinical. The influence of thyroid hormones on bone tissue is well known (Altabas et al., 2007). In hyperthyreosis the acitivty of osteoblasts and osteoclasts is increased, but the influence of osteoclasts is dominating leading to bone resorption and osteoporosis. The longstanding subclinical hyperthyroidism may result in

**3.4 Conclusions and future directions** 

the healthy population (p<0.0001).

incidence of osteopenia (p=0.0116).

treated with unilateral OE (p=0.0148).

therapy in patients with GCT (p=0.287).

**therapy after total thyroidectomy** 

population (p<0.0001).

(p=0.3263).

al., 2009).

**4.1 Introduction** 

10%) thyroid carcinoma.

Bone mineral density (BMD) was measured by dual energy photon x-ray absorptiometry BMD using osteodenzitometer Holgic Discovery in the lumbar spine and hips. In cases with arteficialy increased bone density caused by degenerative bone changes we measured BMD also in forearm. BMD was classified using T score in postmenopausal women and more than 50 years old men . We classified Z score in premenopausal women and younger than 50 years men. C-terminal cross -linked telopeptides of type I collagen (CTX) were measured using ELISA. Additionally serum TSH and fT4 (free T4) were measured. Relationships between baseline characteristics (age, menopausal status in women, TSH levels and duration of substitutional therapy) and BMD were assessed using univariate and multivariate analysis tools.

Association between two nominal variables was tested using the Chi-squared test of independence. Association between an interval variable and a nominal one was tested using ANOVA or Kruskal-Wallis test, depending on the distribution of the interval variable; in case of a dichotomous variable, t-test was applied instead of ANOVA and Mann-Whitney test instead of Kruskal-Wallis test. A multiple linear regression was performed to test for association between an dependent interval variable and several predicting interval variables.

We analysed BMD data from 165 TC patients after total tyroidectomy on supportive therapy in our study. There were 13 men and 152 women, 94 were postmenpausal (postMP), 44 premenopausal (preMP), in 14 the menopausal sattus was unknown. The mean age was 51 years. Age characteristics are in table 3.


Table 3. Age characteristics

### **4.3 Results**

We included 165 TC patients in the study. There were 13 men a 152 women, the mean duration of thyroid suppressive therapy was 7. 2 years (0 – 24 years). The patients exhibit osteporosis in 31%, 39% had osteopenia, whereas 30% had normal BMD (fig. 12).

Studies of Osteoporosis in Cancer Patients in Slovakia – Experience from Single Institute 361

Fig. 14. Duration of suppressive therapy and BMD

The BMD changes were localised in different sites (fig. 13)

Fig. 13. Localisations of BMD decresae in TC paients

The incidence of osteoporosis appeared to increase with age but did not correlated with duration of thyroid suppressive therapy (fig. 14)

31%

**29%**

**49%**

**22%**

osteoporosis

osteopenia

normal BMD

Forearm L-spine Prox.femur

**BMD in patients with thyroid cancer** 

**k i ó ší jžľ**

30%

Fig. 12. BMD in TC patients

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

39%

The BMD changes were localised in different sites (fig. 13)

**10%**

Fig. 13. Localisations of BMD decresae in TC paients

duration of thyroid suppressive therapy (fig. 14)

Osteoporosis Osteopenia

The incidence of osteoporosis appeared to increase with age but did not correlated with

**Localisations of decrease BMD in thyroid cancer patients**

**75%**

**16%**

Fig. 14. Duration of suppressive therapy and BMD

Studies of Osteoporosis in Cancer Patients in Slovakia – Experience from Single Institute 363

BMD (T-score) and compressive fractures CF) in TC pacients (p=0.048)

CF No CF

Published data on this topic are scarce and conflicting. Some of them did not prove correlation between subclinical hyperthyreosis and decrease in BMD (S. I. Greenspan & F. S. Greenspan, 2005). Others have found, that if suppressive therapy does not suppress the TSH below normal value it does not decrease BMD and does not worsen the prognosis of TC (Biondi & Cooper, 2010). Similar results were published also in the past (Shomon, 1995). Some on the other hand has confirmed that long term suppressive therapy affects bone turnover and bone mineral density in pre and postmenopausal women with TC (Heijekmann et al., 2005). Decrese in BMD as a result of suppressive therapy in TC was confirmed but this effect was ameliorated by preventive substitution of calcium and calcitonin (Mikosch et al., 2006). In this metaanalysis of 8 studies the influence of thyreoidal suppression on BMD in postmenopausal women was confirmed. It was not confirmed in men and premenopausal women. The limitation was a substantial inhomogeneity of

The long term survivors from TC after total thyroidectomy on thyroid suppressive therapy have higher risk of osteoporosis and therefore we recommend BMD testing and appropriate measures according to results. The BMD decrease may be a risk factor for pathological fractures and as the TC has very good prognosis, it does matter (B. Špániková.& S. Špánik,

Normal BMD Osteopenia Osteoporosis

25%

41%

34%

60%

Fig. 16. BMD and compressive fractures in TC patients

patients groups and uneveness in calcium supplementation.

**4.5 Conclusions and future directions** 

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

**4.4 Discussion** 

2011)

30%

10%

We confiirmed higher incidence of osteoporosis in postMP women and in the small subgroup of postMP women on antiporotic therapy we confirmed efficacy of this therapy (fig.15). But the gorup was very small and we cannot make any conclusuions.

## **Comparison of BMD changes in controlled group of patients with/without antiresorptive therapy (p=0.062)**

Fig. 15. Comparison of BMD changes in controlled group with/without antiresorpitve therapy

We confirmed 10 pathological fractures in our study (tab. 4)

#### Fractures

10 pathological fractures

Site


Table 4. Pathological fractures in TC patients

The pathological fractures were in correlation with decreased BMD to osteopenia or osteoporosis (fig. 16)

BMD (T-score) and compressive fractures CF) in TC pacients (p=0.048)

Fig. 16. BMD and compressive fractures in TC patients

#### **4.4 Discussion**

362 Osteoporosis

We confiirmed higher incidence of osteoporosis in postMP women and in the small subgroup of postMP women on antiporotic therapy we confirmed efficacy of this therapy

**Comparison of BMD changes in controlled group of patients** 

Fig. 15. Comparison of BMD changes in controlled group with/without antiresorpitve

The pathological fractures were in correlation with decreased BMD to osteopenia or

**with/without antiresorptive therapy (p=0.062)**

7

Without antiresorptive therapy

Normal BMD Osteopenia Osteoporosis

(fig.15). But the gorup was very small and we cannot make any conclusuions.

5 5 5 5

0

We confirmed 10 pathological fractures in our study (tab. 4)

10 pathological fractures

Fractures

Table 4. Pathological fractures in TC patients

osteoporosis (fig. 16)

Site wrist 3 spine 3 others 4

Antiresorptive therapy

therapy

Published data on this topic are scarce and conflicting. Some of them did not prove correlation between subclinical hyperthyreosis and decrease in BMD (S. I. Greenspan & F. S. Greenspan, 2005). Others have found, that if suppressive therapy does not suppress the TSH below normal value it does not decrease BMD and does not worsen the prognosis of TC (Biondi & Cooper, 2010). Similar results were published also in the past (Shomon, 1995). Some on the other hand has confirmed that long term suppressive therapy affects bone turnover and bone mineral density in pre and postmenopausal women with TC (Heijekmann et al., 2005). Decrese in BMD as a result of suppressive therapy in TC was confirmed but this effect was ameliorated by preventive substitution of calcium and calcitonin (Mikosch et al., 2006). In this metaanalysis of 8 studies the influence of thyreoidal suppression on BMD in postmenopausal women was confirmed. It was not confirmed in men and premenopausal women. The limitation was a substantial inhomogeneity of patients groups and uneveness in calcium supplementation.

#### **4.5 Conclusions and future directions**

The long term survivors from TC after total thyroidectomy on thyroid suppressive therapy have higher risk of osteoporosis and therefore we recommend BMD testing and appropriate measures according to results. The BMD decrease may be a risk factor for pathological fractures and as the TC has very good prognosis, it does matter (B. Špániková.& S. Špánik, 2011)

Studies of Osteoporosis in Cancer Patients in Slovakia – Experience from Single Institute 365

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Howell, A., & Cuzick, J., & Baum, M., & Buzdar, A., & Dowsett, M., & Forbes, J.F., & Hoctin-

adjuvant treatment for breast cancer. Lancet. 2005 Jan 1-7;365 (9453), 60-2. Jakesz, R., et al: Switching of postmenopausal women with endocrine-responsive early beast

Kanis, J. A., & Johnell, O., & Oden,.A., & Johansson, H., & Closkey, E.Mc.: Frax™ and the

Marcus, R., & Feldman, D., & Nelson, D.A., & Rosen, C.J.: Osteoporosis, Elsevier AP,

Mardiak, J., & Ondrus, D., & Spanikova, B., & Ostatnikova, B.: Damage of bone metabolism

Mikosch, P., & Igerc, I., & Kudlacek, S., & Woloszczuk, W., & Kresnik, H., et al: Receptor

Ondruš, D., & Ondrušová, M.: Testicular cancer – diagnostic and therapy. Onkológia 2008 3

Ondruš, D., & Špániková, B., & Ondrušová, M., & Mardiak, J.: Damage of hormonal

Ondruš, D., & Špániková, B., & Ondrušová, M., & Mardiak, J.: Testosteron deficiency and bone metabolism damage in testicular cancer survivors. Urology 2007 70, 3A, 166 Ondrušová, M., & Ondruš, D., & Dušek, L., & Špániková, B.: Damage of hormonal function

Payer, J., & Rovensky, J., & Killinger, Z. Lexikon of osteoporosis. Slovak Academic Press

Rizzoli, R, & el. Atlas of postmenopausal osteoporosis. 2nd ed. London: Current Medicine

Shomon, M.: The tyroid treatement osteoporosis Controversy. Does the tyroid treatement

Špánik, S., & Špániková, B.: Bone mineral density in early brest cancer patients. Bratisl Lek

Špániková, B., & Špánik, S.: Changes in bone mineral density in breast cancer patients.

contribute to los soft bone density? Thyroid 1995 5(1):13-7

ABCSG trial 8 and ARNO 95 trial. Lancet 2005;366: 455 – 462

carcinoma Eur J Endocrinol 2005 153, 23-29

2008 19, s. 385–397

(3): 170–174

Burlington MA, 2008: 1939

2007 vol. 25 no. 18\_suppl 5052

Andrology, 2007; 1,1, 36-37

2007 Bratislava, 75 pp., ISBN: 80809

Osteolog bulletin 2010; 15,3,127-8

2009 56, 6 473-479

Group, 2005:25-46.

Listy 2010 111(1) 27-32

cancer. Eur J Clin Invest 2006 36, 8, 566-73

Wolffenbuttel, B.: Hip bone mineral density, bone turnover and risk of fracture in patiens on long-term suúúressive L-thyroxine therapy for differentiared toroid

Boes, G., & Houghton, J., & Locker, G.Y., & Tobias, J.: Results of the ATAC (Arimidex, Tamoxifen, Alone or in Combination) trial after completion of 5 years'

cancer to anastrozole after two years adjuvant tamoxifen: Combine results of

assessment of fracture probability in men and women from the UK. Osteoporos Int.

and osteoporosis in testicular cancer patients. J Clin Oncol (Meeting Abstracts) June

activator of nuclear factor kappa B ligand and osteoprotegerin in men with thyroid

function and bone metabolism in long term survivors of testicular cancer. European

and bone metabolism in long –terma survivors of testicular cancer. Neoplasma

#### **5. References**


Altabas, V., & Berkovič, M., & Bečejac, B., & Solter, M.: Bone Remodeling and Thyroid

Biondi, B., & Cooper, D.S.: Benefits of thyreotropin suppresion versus the risk of adverse

Body, J. J. Increased Fracture Rate in Women With Breast Cancer: a Review of the Hidden

Coates, A.S., & Keshaviah, A., & Thurlimann, B., et al.: Five years of letrozole compared

Coleman, R.E., & Banks, L.M,, & Girgis, S.I., & Kilburn, L.S., & Vrdoljak, E., & Fox, J., &

(IES): a randomised controlled study, Lancet Oncol 2007 Feb:8(2),119-27 Coleman, R.E., & Body, J. J., & Gralow, Jr, Lipton A: Bone loss in patients with breast cancer

Coombes, R.C., & Kilburn, L.S., & Snowdon, C.F., et al. Survival and safety of exemestane

Cooper, C. The crippling consequences of fractures and their impact on quality of life. Am J

Gnant M, et al.: Adjuvant ovarian suppression combined with tamoxifen or anastrozole,

Goldhirsch, A., & Wood, W.C., & Gelber, R.D., & Coates, A.S., & Thurlimann, B., & Senn,

Goos, P.E., & Ingle, J.N., & Martino, S., et al: Random.trial of letrozol tamoxifen as extended

Greenspan, S.I., & Greenspan, F.S.: The effect of tyroid hormone on skeletal integrity. Horm

Hadji, P., & Aapro, M.S., & Body, J.J.: Management of aromatase inhibitor-associated bone

Study): a randomized controled trial. Lancet 2007 369: 559 – 570.

Med 1997 Aug 18;103(2A):12S-17S; discussion 17S-19S.

ABCSG-12. ASCO 2008. Abstract LBA4

J.Nat.Cancer Inst 2005; 97:1262-1271

Risk. BMC Cancer. 2011 Aug 29 11 (1): 384. http://www.biomedcentral.com/1471-

with tamoxifen as initial adjuvant therapy for postmenopausal women with endocrine-responsive early breast cancer: update of study BIG 1-98, J Clin Oncol

Cawthorn, S.J., & Patel, A., & Snowdon, C.F., & Hall, E., & Bliss, J.M., & Coombes, R.C.: Intergroup Exemestane Study group.Skeletal effects of exemestane on bonemineral density, bone biomarkers, and fracture incidence in postmenopausal women with early breast cancer participating in the Intergroup Exemestane Study

receiving aromatase inhibitors and associated treatment strategies. Cancer Treat

versus tamoxifen after 2 – 3 years tamoxifen treatment (Inergroup Exmestane

alone or in combination with zoledronic acid, in premenopausal women with hormone-responsive, stage I and II breast cancer: First efficacy results from

H.J, - Panel Members: Progress and promise: highlights of the internqational expert consensus on the primary therapy of early breast cancer 2007. Ann Oncol 2007 18:

adjuvant therapy in receptor-positive breast cancer. Update findings from MA 17.

loss in postmenopausal women with breast cancer: practical guidance for prevention and treatement Annals of Oncol. Advance Access; 2011,

effects in differentiated thyroid cancer, Thyroid 2010 20, 135-146.

Function, Acta Clin Croat 2007 46: 41-47

**5. References** 

2407/11/384

2007; 25, 486-492

1133 – 1144

Res 2005; 64(6), 293-8

doi:10.1093/annonc/mdr017

Rev 2008;34:S1–S18. July 2008


**Part 5** 

**Pediatric Issues in Osteoporosis** 


**Part 5** 

**Pediatric Issues in Osteoporosis** 

366 Osteoporosis

Špániková, B., & Špánik, S.: Bone mineral density in patients with thyroid cancer on

Thürlimann, B., & Keshaviah, A., & Coates, A.S., & Mouridsen, H., & Mauriac, L., & Forbes,

19739)

353(26), 2747-57

suppressive therapy after total thyroidectomy. J Clin Oncol 29:2011 (suppl; abstr e

J.F., & Paridaens, R., & Castiglione-Gertsch, M., & Gelber, R.D., & Rabaglio, M., & Smith, I., & Wardley, A., & Price, K.N., & Goldhirsch, A.: Breast International Group (BIG) 1-98 Collaborative Group, A comparison of letrozole and tamoxifen in postmenopausal women with early breast cancer .N Engl J Med. 2005; Dec 29,

**19** 

*España* 

**Osteoporosis in Pediatric** 

Emilio González Jiménez *Departamento de Enfermería,* 

**Patients and Its Clinical Management** 

The increase in longevity achieved at present, the population has determined a striking increase in the prevalence of certain diseases and in other cases, the emergence of new forms

Osteoporosis is defined as a decrease in bone mass associated with the deterioration of bone tissue architecture and increased fracture risk, has become a serious public health problem in our society that affects a wide strata of the population age variable, though increasingly common among younger (2). There are two types of osteoporosis, primary and secondary. Primary osteoporosis is rare affecting one case per 100,000 subjects. For high school, its frequency is higher, being secondary to diseases or drug therapies. Table 1 shows the main

The bone will undergo changes during growth reaching its peak during the second decade. After the fourth decade, there is progressive increase in bone loss that mainly affects trabecular tissue at both the peripheral and axial. Accordingly, it is during childhood when determining events occur in the development of adequate bone mineralization and bone

It is now accepted that osteoporosis in the adult subject has its origins in childhood. Accordingly, the prevention of it would begin with the empowerment of those factors that promote the acquisition of optimal bone mass development. Now if we take into account the dietary habits and sedentary marking between the current youth population, we can

During the first decade of life, the appendicular skeleton is growing faster than the axial. Also, the bone mineralization process starts in utero found strongly influenced by calcium intake during growth. However, calcium requirements vary throughout life, being greatest during the first years of life and in times such as puberty, pregnancy and lactation. Moreover, the loss of bone mass increases with age and accelerates with menopause. In this

For pediatric patients, there is a relationship between bone mass and size. However, in periods like puberty and after the pubertal growth spurt can be established called an imbalance between the rate of bone growth rate and increased bone mass resulting from this

glimpse the high risk of developing the disorder to an increasingly early age (3).

sense, it is advisable to increase the intake of calcium from the perimenopause.

**1. Introduction** 

mass final (3).

of illness and during different life stages (1).

transient increase in bone fragility (4).

causes that can lead to a primary or secondary osteoporosis.

*Facultad de Ciencias de la Salud, Universidad de Granada,* 

## **Osteoporosis in Pediatric Patients and Its Clinical Management**

Emilio González Jiménez *Departamento de Enfermería, Facultad de Ciencias de la Salud, Universidad de Granada, España* 

### **1. Introduction**

The increase in longevity achieved at present, the population has determined a striking increase in the prevalence of certain diseases and in other cases, the emergence of new forms of illness and during different life stages (1).

Osteoporosis is defined as a decrease in bone mass associated with the deterioration of bone tissue architecture and increased fracture risk, has become a serious public health problem in our society that affects a wide strata of the population age variable, though increasingly common among younger (2). There are two types of osteoporosis, primary and secondary. Primary osteoporosis is rare affecting one case per 100,000 subjects. For high school, its frequency is higher, being secondary to diseases or drug therapies. Table 1 shows the main causes that can lead to a primary or secondary osteoporosis.

The bone will undergo changes during growth reaching its peak during the second decade. After the fourth decade, there is progressive increase in bone loss that mainly affects trabecular tissue at both the peripheral and axial. Accordingly, it is during childhood when determining events occur in the development of adequate bone mineralization and bone mass final (3).

It is now accepted that osteoporosis in the adult subject has its origins in childhood. Accordingly, the prevention of it would begin with the empowerment of those factors that promote the acquisition of optimal bone mass development. Now if we take into account the dietary habits and sedentary marking between the current youth population, we can glimpse the high risk of developing the disorder to an increasingly early age (3).

During the first decade of life, the appendicular skeleton is growing faster than the axial. Also, the bone mineralization process starts in utero found strongly influenced by calcium intake during growth. However, calcium requirements vary throughout life, being greatest during the first years of life and in times such as puberty, pregnancy and lactation. Moreover, the loss of bone mass increases with age and accelerates with menopause. In this sense, it is advisable to increase the intake of calcium from the perimenopause.

For pediatric patients, there is a relationship between bone mass and size. However, in periods like puberty and after the pubertal growth spurt can be established called an imbalance between the rate of bone growth rate and increased bone mass resulting from this transient increase in bone fragility (4).

Osteoporosis in Pediatric Patients and Its Clinical Management 371

development as well as any conditions that cause increased bone loss. Finally, prolonged

Given the above should be considered the early diagnosis of osteoporosis in pediatric patients who have had one or more fractures are not preceded by trauma or as a result of minor trauma. Moreover, the development of significant angular deformities in the extremities and the presence of a marked kyphosis should guide the clinician to the

This review aims to provide guidance on the characteristics of the process of normal and abnormal bone mineralization in the pediatric patient, the main factors involved and the

Bone mass is defined as the total amount of bone tissue in the organism including the extracellular matrix ossified. At present, it is accepted that the acquisition of appropriate peak bone mass is essential to prevent osteoporosis later in life. Since this formation and accumulation of bone mass occurs during the first decades of life, control of bone mineralization during childhood is a significant aspect to assess interest. This monitoring should aim to identify children at risk of developing osteopenia. Also, in the general population should implement measures to prevent the onset of the disease promoting

The development of an adequate level of bone mass is partly dependent on nutritional factors, so it is necessary to maintain an adequate nutrient supply during the growing season. Another aspect to consider genetic factors, accounting for 60% of total factors. In adulthood decreases

Puberty brings the largest increase in bone mineral density in both sexes, however, as in any period may generate changes to diet and exercise as much as 20% (9). Bone mass is increased from birth to be reduced by calcium deposition significantly as we approach the third decade or so. To three years increases to 30% after 20% and reach puberty about 40%. From the end of growth and to reach adulthood is increasing by 15%. Even 10 years ago mineralization at the same rate in both sexes. From this age is accelerated significantly in the

The diagnosis and even prevention evaluation and therapy of osteoporosis may be jeopardized in a special way in the child all because of the need to use techniques which, although sensitive, reproducible and precise, resulting quick, painless, safe and non

Of all the methods proposed by the National Osteoporosis Foundation to assess the quality of bone, the most used technique is dual x-ray absorptiometry (DEXA). The basis of this technique in the study of attenuation is subjected to a dual X-ray beam through bone tissue (11). Although it can be done at different levels, the benchmarks for determining the criteria of normality, osteopenia or osteoporosis referred to data obtained at the height of the femoral neck or lumbar vertebrae (L2-L4) of the reference population. The interpretation of this technique has some difficulties in the child (12). There are already benchmarks (13-15),

The measures are available in axial regions (hip, spine) or peripheral (calcaneus, tibia, knee, radio and phalanges), but it has shown that measurements in predicting spinal fracture risk at that level, but not others, and so does the rest of the locations where BMD is measured.

the neo-bone formation after a period in which bone mass remains stable (8).

exposure to certain drugs that induce the development of osteoporosis.

**2. Bone mass concept and assessment of their status** 

lifestyles and measures to increase bone mass (7).

although obtained in cross-sectional studies.

presence of impaired bone quality.

existing prevention strategies.

girls (10).

invasive.


Table 1. Causes of primary and secondary osteoporosis in children

On the other hand, it is normal that there is a correlation between the stage of pubertal development and BMD at both the peripheral and axial. Among girls after menarche has been a significant increase in BMD. BMD in boys increases after puberty, with a more extended in time because their pubertal development is slower (5).

Genetic factors in turn, are equally important in the development of an adequate peak bone mass. Thus, a correlation in BMD between twins. For their part, black women have greater BMD and thus a lower incidence of osteoporosis when compared to white women. Also found lower BMD among women whose mothers had a post-menopausal status with osteoporosis compared to those other women the same age but without such a history. Accordingly, it should raise the transmission of genetic information is carried out mainly through the mother (6).

Analyzing the etiology of osteoporosis in children are significantly different from those in adulthood. Accordingly, the diagnostic approach would be completely different in children compared to adults. Among the risk factors associated with the occurrence of bone metabolism during childhood are processes that interfere with proper bone mineralization, the absence of positive stimulus of calcium and vitamin D from diet or exercise to obtain adequate bone mass. Other causes are disorders that cause interference in pubertal

**Primary Osteoporosis** 

**Secundary Osteoporosis** 

Trasplantes Infección por VIH

**Yatrogenia Corticosteroids**

Cyclosporine Heparin

On the other hand, it is normal that there is a correlation between the stage of pubertal development and BMD at both the peripheral and axial. Among girls after menarche has been a significant increase in BMD. BMD in boys increases after puberty, with a more

Genetic factors in turn, are equally important in the development of an adequate peak bone mass. Thus, a correlation in BMD between twins. For their part, black women have greater BMD and thus a lower incidence of osteoporosis when compared to white women. Also found lower BMD among women whose mothers had a post-menopausal status with osteoporosis compared to those other women the same age but without such a history. Accordingly, it should raise the transmission of genetic information is carried out mainly

Analyzing the etiology of osteoporosis in children are significantly different from those in adulthood. Accordingly, the diagnostic approach would be completely different in children compared to adults. Among the risk factors associated with the occurrence of bone metabolism during childhood are processes that interfere with proper bone mineralization, the absence of positive stimulus of calcium and vitamin D from diet or exercise to obtain adequate bone mass. Other causes are disorders that cause interference in pubertal

Anticonvulsivants Radiotherapy

Idiopathic juvenile osteoporosis Marfan syndrome Osteogenesis imperfecta Homocystinuria

**Neuromuscular Disease Procesos Crónicos** 

Duchenne Muscular Dystrophy Fibrosis Quística

Prolonged Immobilization Malabsorción intestinal

Hypogonadism Cirrosis Biliar Primaria

Growth hormone deficiency Anorexia Nerviosa

Cerebral Palsy Leucemia

**Endocrine Diseases** Talasemia

Turner Syndrome Nefropatías

Gaucher Disease Metotrexate

Table 1. Causes of primary and secondary osteoporosis in children

extended in time because their pubertal development is slower (5).

Ehler Danlos syndrome

Bruck syndrome

Hyperthyroidism hyperprolactinemia

Cushing Syndrome

through the mother (6).

Congenital Metabolic Disorders

development as well as any conditions that cause increased bone loss. Finally, prolonged exposure to certain drugs that induce the development of osteoporosis.

Given the above should be considered the early diagnosis of osteoporosis in pediatric patients who have had one or more fractures are not preceded by trauma or as a result of minor trauma. Moreover, the development of significant angular deformities in the extremities and the presence of a marked kyphosis should guide the clinician to the presence of impaired bone quality.

This review aims to provide guidance on the characteristics of the process of normal and abnormal bone mineralization in the pediatric patient, the main factors involved and the existing prevention strategies.

### **2. Bone mass concept and assessment of their status**

Bone mass is defined as the total amount of bone tissue in the organism including the extracellular matrix ossified. At present, it is accepted that the acquisition of appropriate peak bone mass is essential to prevent osteoporosis later in life. Since this formation and accumulation of bone mass occurs during the first decades of life, control of bone mineralization during childhood is a significant aspect to assess interest. This monitoring should aim to identify children at risk of developing osteopenia. Also, in the general population should implement measures to prevent the onset of the disease promoting lifestyles and measures to increase bone mass (7).

The development of an adequate level of bone mass is partly dependent on nutritional factors, so it is necessary to maintain an adequate nutrient supply during the growing season. Another aspect to consider genetic factors, accounting for 60% of total factors. In adulthood decreases the neo-bone formation after a period in which bone mass remains stable (8).

Puberty brings the largest increase in bone mineral density in both sexes, however, as in any period may generate changes to diet and exercise as much as 20% (9). Bone mass is increased from birth to be reduced by calcium deposition significantly as we approach the third decade or so. To three years increases to 30% after 20% and reach puberty about 40%. From the end of growth and to reach adulthood is increasing by 15%. Even 10 years ago mineralization at the same rate in both sexes. From this age is accelerated significantly in the girls (10).

The diagnosis and even prevention evaluation and therapy of osteoporosis may be jeopardized in a special way in the child all because of the need to use techniques which, although sensitive, reproducible and precise, resulting quick, painless, safe and non invasive.

Of all the methods proposed by the National Osteoporosis Foundation to assess the quality of bone, the most used technique is dual x-ray absorptiometry (DEXA). The basis of this technique in the study of attenuation is subjected to a dual X-ray beam through bone tissue (11). Although it can be done at different levels, the benchmarks for determining the criteria of normality, osteopenia or osteoporosis referred to data obtained at the height of the femoral neck or lumbar vertebrae (L2-L4) of the reference population. The interpretation of this technique has some difficulties in the child (12). There are already benchmarks (13-15), although obtained in cross-sectional studies.

The measures are available in axial regions (hip, spine) or peripheral (calcaneus, tibia, knee, radio and phalanges), but it has shown that measurements in predicting spinal fracture risk at that level, but not others, and so does the rest of the locations where BMD is measured.

Osteoporosis in Pediatric Patients and Its Clinical Management 373

to cow's milk proteins and inflammatory bowel disease. Other processes potentially involved in the development of osteopenia will neuropathy and liver disease that present with an impairment of the synthesis of active metabolites of vitamin D. Other processes involved will be the states of metabolic acidosis, prolonged administration of certain drugs

Proper nutrition is a key factor in maintaining adequate skeletal mineralization. In this process of bone mineralization energy and nutrients intervene in various ways, either by encouraging the development of cell mitosis, participating as visual elements, to be a source of vitamins which will involve regulating the synthesis of bone matrix and promoting the absorption level intestinal calcium or contributing to the synthesis of various hormones and

By feeding the body receives visual elements, vitamins intervene by regulating the synthesis of bone matrix and intestinal absorption of calcium and other minerals whose primary function is to act in the formation and consolidation of mineralized bone. Another essential aspect of bone remodeling in the child will be energy intake. This is an essential as the volume decreases in energy intake induce delays in growth, maturation and hence bone mineralization (24). Then in children with malnutrition by default is necessary to control the

The bone mineralization process will necessarily regulated by protein intake through the diet. Its role essentially plastic makes these elements are essential for the synthesis of bone matrix. In this sense, the child, situations of inadequate intake may induce default to the emergence of problems of mineralization. On the contrary, when its contribution in the diet is excessive can cause hypercalciuria boxes, this is due to increased excretion of acid produced during protein catabolism. At present it is possible that the protein diet consumed in most developed countries it is closely linked with the increase in osteoporosis in the

Another aspect to consider is the ratio of sodium ingested with the level of calcium excretion by the kidney. Sodium and calcium share the same carrier at the proximal renal tubule. Although and yet there is no need to adjust the contribution of calcium to sodium intake through the diet in children (26). Calcium is an essential pillar in the prevention of osteoporosis. In our body and especially in the bones is deposited as hydroxyapatite crystals. Your deposit varies throughout life from 30 grams at birth to about 1.300 grams in

Given the above will be necessary to modulate calcium intake during periods of increased growth and, especially during adolescence. During adolescence tends to accumulate 40% of total bone mass produced throughout life. Several studies have shown that calcium supplementation during adolescence increases bone mineral density (28). After administering 500 ml of milk per day during childhood will ensure intake of about 400mg of

Moreover, we have to take into account the bioavailability of calcium in food. The presence of phytates inhibit absorption and therefore vegetables, legumes and cereals despite containing high levels of calcium, it is not as comparable as that of milk. Similarly oxalates, alcohol, caffeine and phosphates hinder calcium absorption even when present in the diet (29, 30). Finally, pictures of obesity and overweight in children have been associated with

calcium, equivalent to 60% of the recommended daily amount.

such as anticonvulsants or corticosteroids and pictures of hypogonadism (22).

**5. Nutritional factors** 

factors crecimiento (23).

state of bone mineralization.

population (25).

adulthood (27).

In children, the area selection is further complicated because the timing and rate of mineralization depends on the biological age (13). Should be selected sufficiently vascularized bone, with good motility and under some pressure. In this regard, the determination in the calcaneus could induce excessive bias to withstand pressure, although some authors is the preferred (14).

Other recent application techniques are ultrasound imaging and computed tomography. It is noninvasive, excellent acceptance of any age which have been effective as bone assessment procedures in both the adult and the child (15). However, in the case of computed tomography to excessive cost limits their use as a technique for the prevention of osteoporosis.

### **3. Bone mineralization process**

Bone mineralization is a complex process regulated by both genetic and hormonal factors, environmental and nutritional (16). From a genetic standpoint, the mineralization is controlled by a large group of genes. Among the most studied is the gene that controls vitamin D receptor, which depends on calcium absorption in the intestine. Hormonal level, there are several hormones involved in bone mineralization. These include parathyroid hormone which balances the mechanisms of formation and resorption of bone at the same time enhances the action of vitamin D. Calcitonin, which inhibits the action of osteoclasts, and growth hormone, HGH and IGF-1 that acts in the formation of cartilage and promotes the synthesis of the active metabolite of vitamin D (17).

Other molecules with activity on bone mass are the corticosteroids. They only act on bone mineralization when increased above normal levels, decreasing bone mass and bone growth. This is an important consideration in those children treated with corticosteroids. Thyroid hormones, in turn, are also involved in mineralization diminishing with increasing concentration. But all of these factors may also act on the environmental factors that can intervene by modifying diet and lifestyle (18).

### **4. Concept of osteopenia and osteoporosis**

Osteopenia is defined by decreased bone mineral density between -1 and -2.5 SD for age, sex, height and pubertal stage. In cases where the decrease in bone mineral density is below 2 SD is considered osteoporosis (19).

Osteoporosis was defined in 1991 as a systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, which leads to increased bone fragility with a consequent increase in fracture risk. This definition implies a qualitative concept of altered bone architecture and a quantity related to bone density (20). Both osteoporosis and osteopenia may be primary as in aging or menopause but may also result from inadequate nutrition, and hormonal disorders or diseases of the bone.

However, there are childhood diseases that may present with osteopenia thereby increasing the risk of osteoporosis in adulthood. Among the mechanisms of production of osteopenia could cite many, though, could be divided into three main groups. Those processes that occur with an inadequate intake of nutrients such as anorexia nervosa, bulimia, proteincalorie malnutrition or poorly controlled diets (21). A second group would be composed of those disorders with intestinal malabsorption boxes. Within this section as possible symptoms of osteopenia generators could include celiac disease, cystic fibrosis, intolerance to cow's milk proteins and inflammatory bowel disease. Other processes potentially involved in the development of osteopenia will neuropathy and liver disease that present with an impairment of the synthesis of active metabolites of vitamin D. Other processes involved will be the states of metabolic acidosis, prolonged administration of certain drugs such as anticonvulsants or corticosteroids and pictures of hypogonadism (22).

### **5. Nutritional factors**

372 Osteoporosis

In children, the area selection is further complicated because the timing and rate of mineralization depends on the biological age (13). Should be selected sufficiently vascularized bone, with good motility and under some pressure. In this regard, the determination in the calcaneus could induce excessive bias to withstand pressure, although

Other recent application techniques are ultrasound imaging and computed tomography. It is noninvasive, excellent acceptance of any age which have been effective as bone assessment procedures in both the adult and the child (15). However, in the case of computed tomography to excessive cost limits their use as a technique for the prevention of

Bone mineralization is a complex process regulated by both genetic and hormonal factors, environmental and nutritional (16). From a genetic standpoint, the mineralization is controlled by a large group of genes. Among the most studied is the gene that controls vitamin D receptor, which depends on calcium absorption in the intestine. Hormonal level, there are several hormones involved in bone mineralization. These include parathyroid hormone which balances the mechanisms of formation and resorption of bone at the same time enhances the action of vitamin D. Calcitonin, which inhibits the action of osteoclasts, and growth hormone, HGH and IGF-1 that acts in the formation of cartilage and

Other molecules with activity on bone mass are the corticosteroids. They only act on bone mineralization when increased above normal levels, decreasing bone mass and bone growth. This is an important consideration in those children treated with corticosteroids. Thyroid hormones, in turn, are also involved in mineralization diminishing with increasing concentration. But all of these factors may also act on the environmental factors that can

Osteopenia is defined by decreased bone mineral density between -1 and -2.5 SD for age, sex, height and pubertal stage. In cases where the decrease in bone mineral density is below

Osteoporosis was defined in 1991 as a systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, which leads to increased bone fragility with a consequent increase in fracture risk. This definition implies a qualitative concept of altered bone architecture and a quantity related to bone density (20). Both osteoporosis and osteopenia may be primary as in aging or menopause but may also result

However, there are childhood diseases that may present with osteopenia thereby increasing the risk of osteoporosis in adulthood. Among the mechanisms of production of osteopenia could cite many, though, could be divided into three main groups. Those processes that occur with an inadequate intake of nutrients such as anorexia nervosa, bulimia, proteincalorie malnutrition or poorly controlled diets (21). A second group would be composed of those disorders with intestinal malabsorption boxes. Within this section as possible symptoms of osteopenia generators could include celiac disease, cystic fibrosis, intolerance

from inadequate nutrition, and hormonal disorders or diseases of the bone.

promotes the synthesis of the active metabolite of vitamin D (17).

intervene by modifying diet and lifestyle (18).

2 SD is considered osteoporosis (19).

**4. Concept of osteopenia and osteoporosis** 

some authors is the preferred (14).

**3. Bone mineralization process** 

osteoporosis.

Proper nutrition is a key factor in maintaining adequate skeletal mineralization. In this process of bone mineralization energy and nutrients intervene in various ways, either by encouraging the development of cell mitosis, participating as visual elements, to be a source of vitamins which will involve regulating the synthesis of bone matrix and promoting the absorption level intestinal calcium or contributing to the synthesis of various hormones and factors crecimiento (23).

By feeding the body receives visual elements, vitamins intervene by regulating the synthesis of bone matrix and intestinal absorption of calcium and other minerals whose primary function is to act in the formation and consolidation of mineralized bone. Another essential aspect of bone remodeling in the child will be energy intake. This is an essential as the volume decreases in energy intake induce delays in growth, maturation and hence bone mineralization (24). Then in children with malnutrition by default is necessary to control the state of bone mineralization.

The bone mineralization process will necessarily regulated by protein intake through the diet. Its role essentially plastic makes these elements are essential for the synthesis of bone matrix. In this sense, the child, situations of inadequate intake may induce default to the emergence of problems of mineralization. On the contrary, when its contribution in the diet is excessive can cause hypercalciuria boxes, this is due to increased excretion of acid produced during protein catabolism. At present it is possible that the protein diet consumed in most developed countries it is closely linked with the increase in osteoporosis in the population (25).

Another aspect to consider is the ratio of sodium ingested with the level of calcium excretion by the kidney. Sodium and calcium share the same carrier at the proximal renal tubule. Although and yet there is no need to adjust the contribution of calcium to sodium intake through the diet in children (26). Calcium is an essential pillar in the prevention of osteoporosis. In our body and especially in the bones is deposited as hydroxyapatite crystals. Your deposit varies throughout life from 30 grams at birth to about 1.300 grams in adulthood (27).

Given the above will be necessary to modulate calcium intake during periods of increased growth and, especially during adolescence. During adolescence tends to accumulate 40% of total bone mass produced throughout life. Several studies have shown that calcium supplementation during adolescence increases bone mineral density (28). After administering 500 ml of milk per day during childhood will ensure intake of about 400mg of calcium, equivalent to 60% of the recommended daily amount.

Moreover, we have to take into account the bioavailability of calcium in food. The presence of phytates inhibit absorption and therefore vegetables, legumes and cereals despite containing high levels of calcium, it is not as comparable as that of milk. Similarly oxalates, alcohol, caffeine and phosphates hinder calcium absorption even when present in the diet (29, 30). Finally, pictures of obesity and overweight in children have been associated with

Osteoporosis in Pediatric Patients and Its Clinical Management 375

reabsorption of calcium and induce a secondary hyperparathyroidism. They also inhibit pituitary gonadotropin secretion and decrease the response of estrogen/testosterone to the follicle stimulating hormone (FSH). A level of osteoblasts caused a decrease in their ability to replicate, in turn stimulating the expression of collagenase by the osteoblast and thereby inducing the increase in bone matrix degradation with a decrease in the synthesis of growth

Appropriate strategies to prevent osteoporosis from childhood: The prevention of osteoporosis to necessarily an assessment of bone mineralization status since early infancy, particularly in subjects at risk. In this sense, preterm infants, patients with malabsorption syndromes and corticosteroid therapy patients constitute the population most at risk of poor

The bioavailability of calcium in milk is far superior to commercial formulas, making it the leading source for calcium during breastfeeding. Only in the case of infants it should increase their calcium intake to the recommended supplementary with commercial formulas

In children aged 1 to 8 years there is no explicit consensus on the specific requirements of calcium. In any case, we recommend an intake of 500 mg per day for ages 1 and 3 years (40). This figure should be increased as they age and approach puberty. Thus, for ages 4 to 8 years the requirements will amount up to 800mg calcium per day. But have found no overt health benefits by increasing the daily amount (41). And at puberty, it is estimated that for

Given the above, eating disorders, inflammatory bowel disease or the use of corticosteroids and prolonged rest in the minors are situations that require an attitude of monitoring and

It is estimated that the highest positive balance is achieved with an average daily intake of 1300mg. By contrast, those exposed to lower levels will have a negative impact on bone mineralization process (42). This corresponds to measurements made on white teens. In the case of blacks and adolescents have shown a better efficiency for the absorption of dietary calcium, can reach the same peak bone mass even with lower contributions of calcium (43). Excess calcium in the diet, in turn, can cause a deficiency of iron and zinc, while favoring the formation of kidney stones (44). Similarly as phosphates present in carbonated drinks can

In cases of subjects with lactose intolerance, the simple addition of commercial lactase or

The existence of toxic habits such as snuff or alcohol consumption can also interfere with the process of bone mineralization (47). But if there is a successful strategy to prevent osteoporosis from childhood this is the regular practice of exercise (48). The physical exercise from an early age not only ensure optimal weight status but also a formidable mineralization of our skeleton, reason is of great importance when the subject population are children and adolescents (49, 50). The continued practice of physical activity helps to acquire peak bone mass genetically determined (51). Although, to achieve these benefits, the current recommendations set out the need to practice a minimum of three days a week (52). Moreover, at present it is unknown whether calcium intake through diet may or may not

With regard to drug-induced osteoporosis, the most important preventive factor is the wise

ingestion of fermented dairy products like yogurt can remedy this situation (46).

factors (IGF1, IGF-2) (36).

bone mineralization (37, 38).

supervision by health staff (41).

alter the beneficial effect of exercise (52).

use and dosage of the same (53).

that have a higher calcium content (39).

every inch of growth are required calcio 20g (41).

also act by inhibiting the absorption of calcium in the intestine (45).

increased bone density. However there is evidence linking these situations with a higher incidence of fractures (31).

Vitamin D is another factor regulating the homeostasis calcium / phosphorus. Its main sources are dairy products. Exposure to sunlight or UV light promotes the metabolism of it. However, alterations in intestinal absorption mechanism and factors affecting their metabolism at the level of the skin should be considered as processes that alter bone formation and thus risk factors for developing osteoporosis (32).

### **6. Idiopathic juvenile osteoporosis**

In some pediatric patients (usually young) are not able to establish any risk factors for osteoporosis. In these cases must be considered the possibility of presenting idiopathic juvenile osteoporosis. Its etiology is unknown, manifesting itself in some cases for an accidental radiological finding which may also require a significant osteopenia, short stature and kyphosis (secondary to vertebral crush fractures) (32). Generally do not exhibit any endocrine abnormality nor metabolism of calcium/ phosphorus. The levels of vitamin D and calcitonin are variable in these patients. For bone biopsy, this is not conclusive proof but often shows an increase of osteocytes in trabecular bone as well as signs of increased bone resorption. In general, treatment consists of substitution of calcium and calcitriol, tending to improve spontaneously in the post pubertal period by several authors due to the effect of gonadal hormones (33).

### **7. Osteogenesis imperfecta**

Osteogenesis imperfecta is a genetic disease, autosomal dominant, in which there is an abnormality in the formation of collagen type 1 (34). This disorder causes weakness and bone fragility of varying degrees of severity and subsequent pathological fractures, as well as affecting other tissues. The etiology of this disease lies in the mutation of genes that encode both qualitative and quantitative production of collagen fibers. In terms of prevalence in the world, this ranges from about 1 case per 30,000 live births (34). The continuous advances in diagnosis have created new expectations for subjects with the disease, greatly improving their quality of life. At present there is no effective treatment, healing, since it can not act directly on the formation of collagen type I (34). Throughout history have used various medical treatments (calcitonin, anabolic steroids, etc.) to try to increase bone mass, to no avail. Currently, treatment is symptomatic and should be approached in a multidisciplinary manner. The best results were achieved with growth hormone (GH) and bisphosphonates (34).

#### **8. Osteopathy associated with use of drugs**

Another group of pediatric patients at high risk for osteoporosis are those subjects taking medications which interfere with the normal process of bone mineralization. The drugs most commonly associated with the development of bone disease or iatrogenic demineralizantes include steroids, anticonvulsants, cyclosporine, anthracyclines, methotrexate, warfarin and agonists of gonadotropin-releasing hormone (35).

In the case of steroids, these lead to the development of osteoporosis secondary to increased bone resorption. In addition, they inhibit intestinal absorption of calcium, decreased tubular

increased bone density. However there is evidence linking these situations with a higher

Vitamin D is another factor regulating the homeostasis calcium / phosphorus. Its main sources are dairy products. Exposure to sunlight or UV light promotes the metabolism of it. However, alterations in intestinal absorption mechanism and factors affecting their metabolism at the level of the skin should be considered as processes that alter bone

In some pediatric patients (usually young) are not able to establish any risk factors for osteoporosis. In these cases must be considered the possibility of presenting idiopathic juvenile osteoporosis. Its etiology is unknown, manifesting itself in some cases for an accidental radiological finding which may also require a significant osteopenia, short stature and kyphosis (secondary to vertebral crush fractures) (32). Generally do not exhibit any endocrine abnormality nor metabolism of calcium/ phosphorus. The levels of vitamin D and calcitonin are variable in these patients. For bone biopsy, this is not conclusive proof but often shows an increase of osteocytes in trabecular bone as well as signs of increased bone resorption. In general, treatment consists of substitution of calcium and calcitriol, tending to improve spontaneously in the post pubertal period by several authors due to the effect of

Osteogenesis imperfecta is a genetic disease, autosomal dominant, in which there is an abnormality in the formation of collagen type 1 (34). This disorder causes weakness and bone fragility of varying degrees of severity and subsequent pathological fractures, as well as affecting other tissues. The etiology of this disease lies in the mutation of genes that encode both qualitative and quantitative production of collagen fibers. In terms of prevalence in the world, this ranges from about 1 case per 30,000 live births (34). The continuous advances in diagnosis have created new expectations for subjects with the disease, greatly improving their quality of life. At present there is no effective treatment, healing, since it can not act directly on the formation of collagen type I (34). Throughout history have used various medical treatments (calcitonin, anabolic steroids, etc.) to try to increase bone mass, to no avail. Currently, treatment is symptomatic and should be approached in a multidisciplinary manner. The best results were achieved with growth

Another group of pediatric patients at high risk for osteoporosis are those subjects taking medications which interfere with the normal process of bone mineralization. The drugs most commonly associated with the development of bone disease or iatrogenic demineralizantes include steroids, anticonvulsants, cyclosporine, anthracyclines,

In the case of steroids, these lead to the development of osteoporosis secondary to increased bone resorption. In addition, they inhibit intestinal absorption of calcium, decreased tubular

methotrexate, warfarin and agonists of gonadotropin-releasing hormone (35).

formation and thus risk factors for developing osteoporosis (32).

incidence of fractures (31).

gonadal hormones (33).

**7. Osteogenesis imperfecta** 

hormone (GH) and bisphosphonates (34).

**8. Osteopathy associated with use of drugs** 

**6. Idiopathic juvenile osteoporosis** 

reabsorption of calcium and induce a secondary hyperparathyroidism. They also inhibit pituitary gonadotropin secretion and decrease the response of estrogen/testosterone to the follicle stimulating hormone (FSH). A level of osteoblasts caused a decrease in their ability to replicate, in turn stimulating the expression of collagenase by the osteoblast and thereby inducing the increase in bone matrix degradation with a decrease in the synthesis of growth factors (IGF1, IGF-2) (36).

Appropriate strategies to prevent osteoporosis from childhood: The prevention of osteoporosis to necessarily an assessment of bone mineralization status since early infancy, particularly in subjects at risk. In this sense, preterm infants, patients with malabsorption syndromes and corticosteroid therapy patients constitute the population most at risk of poor bone mineralization (37, 38).

The bioavailability of calcium in milk is far superior to commercial formulas, making it the leading source for calcium during breastfeeding. Only in the case of infants it should increase their calcium intake to the recommended supplementary with commercial formulas that have a higher calcium content (39).

In children aged 1 to 8 years there is no explicit consensus on the specific requirements of calcium. In any case, we recommend an intake of 500 mg per day for ages 1 and 3 years (40). This figure should be increased as they age and approach puberty. Thus, for ages 4 to 8 years the requirements will amount up to 800mg calcium per day. But have found no overt health benefits by increasing the daily amount (41). And at puberty, it is estimated that for every inch of growth are required calcio 20g (41).

Given the above, eating disorders, inflammatory bowel disease or the use of corticosteroids and prolonged rest in the minors are situations that require an attitude of monitoring and supervision by health staff (41).

It is estimated that the highest positive balance is achieved with an average daily intake of 1300mg. By contrast, those exposed to lower levels will have a negative impact on bone mineralization process (42). This corresponds to measurements made on white teens. In the case of blacks and adolescents have shown a better efficiency for the absorption of dietary calcium, can reach the same peak bone mass even with lower contributions of calcium (43).

Excess calcium in the diet, in turn, can cause a deficiency of iron and zinc, while favoring the formation of kidney stones (44). Similarly as phosphates present in carbonated drinks can also act by inhibiting the absorption of calcium in the intestine (45).

In cases of subjects with lactose intolerance, the simple addition of commercial lactase or ingestion of fermented dairy products like yogurt can remedy this situation (46).

The existence of toxic habits such as snuff or alcohol consumption can also interfere with the process of bone mineralization (47). But if there is a successful strategy to prevent osteoporosis from childhood this is the regular practice of exercise (48). The physical exercise from an early age not only ensure optimal weight status but also a formidable mineralization of our skeleton, reason is of great importance when the subject population are children and adolescents (49, 50). The continued practice of physical activity helps to acquire peak bone mass genetically determined (51). Although, to achieve these benefits, the current recommendations set out the need to practice a minimum of three days a week (52). Moreover, at present it is unknown whether calcium intake through diet may or may not alter the beneficial effect of exercise (52).

With regard to drug-induced osteoporosis, the most important preventive factor is the wise use and dosage of the same (53).

Osteoporosis in Pediatric Patients and Its Clinical Management 377

[16] Bos S, Delmas PD, Pearce D. The differing tempo of grow thin bone size, mass and

[17] Gregg EW, Kriska AM, Salamone LM. The epidemiology of quantitative ultrasound:

[18] Polanco I, Hernández J, Scherer JI, Prieto G, Molina M, Sarria J. Curva de normalidad

[19] Alonso Franch M, Redondo del Río MP. Nutrición y patología ósea en la infancia. En Ángel Gil Hernández (editor) Tratado de Nutrición. Acción Médica. Madrid 2005 [20] Creer FR, Krebs NF, Comité on Nutrition, Optimizing bone health and calcium intakes

[21] Morris RC, Frassetto LA, SchmidlinO, Forman A, Sebastián A. Expression of

[22] Winzenberg TM, Oldenburg B, Frendin S, De Wit L, Jones G. A mother-based intervention trial for osteoporosis prevention in children. Prev Med 2006; 42: 21 [23] Welten DC, Kemper HC, Post GB, et al. Weight-bearing activity during youth is a more

[24] Weaver CM, Hauney RP, Prouly WR, Choices for achieving adequate dietary calcium

[27] Hernández Rodriguez M. Alimentación y problemas nutricionales en la adolescencia.

[28] Bryant RJ, Wastney ME, Martin BR, Wood O, McCabe GP, Morshidi M, Smith DL,

[30] Díaz M, Riobo P, Esteban J, Rodríguez G. Nutrición en las enfermedades del tejido

[31] Fernández I, Alobera MA, Del Canto M, Blanco L. Physiological bases of bone regeneration II. The remodeling process. Med Oral Patol Oral Cir Bucal. 11: E151 – E157 [32] Krall EA, Dawson-Hughes B. Osteoporosis. En: Shils ME, Olson JA, Ross AC (editores). Nutricion en Salud y Enfermedad. México: Interamericana. Pp: 1563 – 576 [33] Saggese G, Bertelloni S, Baroncelli GI, Perri G , Calderazzi A. Mineral metabolism and

[25] Stalling VA. Calcium and bone health in children: a review. Am J Ther. 1997; 4: 259 [26] Bishop NJ, King FJ, Lucas A. Increased bone mineral content of preterm infants fed

Are view of the relations hip with bone mass, osteoporosis and fracture risk.

en población española de 4 a 22 años para un densitómetro óseo por ultrasonidos

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important factor for peak bone mass than calcium intake. J Bone Miner Res 1994; 9:

with a nutrient enriched formula after discharge from hospital. Arch Dis Child.

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(edditors) Nutrition in Pediatrics. Basic Science and Clinical Applications. 3th ed.

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In summary, we conclude that the onset osteoporosis in children differs in its clinical management of osteoporosis in adults. In this sense, the early identification of risk grpos be a priority. Therefore it should be emphasized that during the first and second decade of life, events occur which are essential for the proper development of bone metabolism. On this basis, the prevention of osteoporosis in adults should begin as early as the early childhood.

#### **9. References**


In summary, we conclude that the onset osteoporosis in children differs in its clinical management of osteoporosis in adults. In this sense, the early identification of risk grpos be a priority. Therefore it should be emphasized that during the first and second decade of life, events occur which are essential for the proper development of bone metabolism. On this basis, the prevention of osteoporosis in adults should begin as early as the early childhood.

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**20** 

*Brock University,* 

*Canada* 

**Physical Activity Interactions with** 

Izabella A. Ludwa and Panagiota Klentrou

**Bone Accrual in Children and Adolescents** 

Osteoporosis is a skeletal disease characterized by low bone mass and the deterioration of the micro architecture of bone tissue resulting in bone fragility and susceptibility to fractures (Gordon, 2003). According to the World Health Organization, osteoporosis is estimated to affect approximately 200 million women worldwide (Kanis, 2007) with the burden of osteoporosis being felt both personally and economically. Although the prevalence of fractures is higher is women, the mortality rate related to fragility fractures is higher in men (Center et al. 1999; Hasserius et al., 2003). Moreover, the annual cost of treating fractures in the United States is projected to increase to \$25 billion in 2025 from \$17 billion in 2005

Achieving peak bone mass (PBM) during adolescence and the subsequent rate of bone loss are major determinants of bone mass later in life (Hansen et al., 1991). The amount of bone mass achieved early in life has been shown to predict the level of bone mass and the incidence of fracture later in life suggesting that a primary risk factor for the development of osteoporosis is the inability to attain high PBM (Hansen et al., 1991; Heaney et al., 2000). PBM is generally defined as the highest level of bone mass achieved as a result of normal growth and seems to be established, for most sites of the skeleton, by late adolescence (Matkovic et al., 1994). Previous studies (Bonjour et al., 1991; Bailey et al., 1996) have demonstrated the period between 9-20 years of age to be critical in building peak bone mass as 90% of total body bone mineral content (BMC) is accrued by the age of 16 (Elgan et al., 2003; Stager et al., 2006), with the remaining 5-10% of total body bone mass achieved in the third decade (Cadogan et al, 1998). In fact, the most rapid bone mineral accumulation occurs approximately 1 year after the age of peak linear growth (Bailey et al., 1996); around the time of menarche for females (Cadogan et al., 1998). With considerable increases in bone mass occurring during puberty, maximizing PBM during this time is often advocated as the best way to delay age-related bone loss and prevent osteoporotic fractures (Fulkerson et al.,

It appears, therefore, as though there is a critical period, a 'window of opportunity' (MacKelvie et al., 2002), in which we can influence the amount of bone mass we attain. However, bone development is the product of complex interactions between genetic and environmental factors including diet, hormonal influences, and mechanical stimuli (Gordon, 2003; Steelman & Zeitler, 2001). Permanent deficits in PBM are the result of any process that

**1. Introduction** 

(Burge et al., 2005).

**1.1 Osteoporosis and peak bone mass** 

2004; Molgaard et al., 1999; Valimaki et al., 1994).



## **Physical Activity Interactions with Bone Accrual in Children and Adolescents**

Izabella A. Ludwa and Panagiota Klentrou *Brock University, Canada* 

### **1. Introduction**

378 Osteoporosis

[34] Espallargues M, Sampietro-Colom L, Estrada MD. Osteoporosis: factores de riesgo y

[35] Huth PJ, Dirienzo DB, Miller GD. Major scientific advances with dairy foods in

[36] Hathcock JN, Shao A, Vieth R, Heaney R. Risk assessment for vitamin D. Am J Clin

[37] Papierska L, Rabijewski M. Glucocorticoid induced osteoporosis. Pol Arch Med Wewn

[38] Guéguen L, Pointillart A. The bioavailability of dietary calcium. J Am Coll Nutr 2000;

[39] Food and Nutrition Board, Institute of Medicine. Dietary reference intakes for Arsenic,

[40] Stevenson JC. Pathogenesis, prevention, and treatment of osteoporosis. Obstet Gynecol

[43] Bacciottini L, Brandi ML. Foods and new foods: the role of nutrition in skeletal health. J

[46] Macdonald HM, Cooper DM, McKay HA: Anterior-posterior bending strength at the

[47] Valimaki M, Karkkainen M, Lamberg-Allert C. Exercise, smoking and calcium intake

[48] Macdonald HM, Kontulainen SA, Khan KM, McKay HA: Is a school-based physical

[49] Weeks BK, Young CM, Beck BR: Eight months of regular in-school dumping improves

[50] González I, Gracia R. Osteoporosis en la edad pediátrica. An Pediatr 2006; 64 (2): 85-91

[52] Vainionpaa A, Korpelainen R, Sievanen H, Vihriala E, Leppaluoto J, Jamsa T: Effect of

[53] Alonso Franch M, Redondo Del río MP, Suárez Cortina L. Nutrición infantil y salud

[51] Bianchi ML. Osteoporosis in children and adolescents. Bone 2007; 41: 486-495

ósea. Anales de Pediatría (Barc) 2010; 72 (1): 1 - 11

exercise against osteoporosis: A systematic review and meta-analysis for

tibial shaft increases with physical activity in boys: evidence for non-uniform

during adolescence and early adulhood as determinants of peak bone mass. British

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indices of bone strength in adolescent boys and Girls: the POWER PE study. J Bone

impact exercise and its intensity on bone geometry at weightbearing tibia and

zinc. Washington D.C.: National Academy Press: 2004 .p. 290 – 393

[41] Krassas GE. Idiopathic juvenile osteoporosis. Ann N Y Acad Sci 2000; 900: 409 - 12. [42] Smith R. Idiopathic juvenile osteoporosis: Experience of twenty-one patients. Br J

[44] Ahmed SF, Elmantaser M. Secondary osteoporosis. Endocr Dev 2009; 16: 170 – 90 [45] Nikander R, Sievänen H, Heinonen A, Daly RM, Uusi-Rasi K, Kannus P. Targeted

optimising bone strength throughout life. BMC Med 21 (8): 1 - 16

geometric adaptation. Osteoporos Int 2009; 20: 61 – 70

Boron, Calcium, Chromium, Copper, Fluoride , Ioride, Iron, Magnesium, Manganese, Molybdenum, Nickel, phosphorus, selenium, silicon, vanadium and

densitometría. Med Clin (Barc) 2002; 118: 319.

Nutr 2007; 85: 6 – 18

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Clin Gastroenterol. 38 (6): 115 – 17

19: 119 – 136

nutrition and health. J Dairy Sci 2006; 89: 1207 – 221

### **1.1 Osteoporosis and peak bone mass**

Osteoporosis is a skeletal disease characterized by low bone mass and the deterioration of the micro architecture of bone tissue resulting in bone fragility and susceptibility to fractures (Gordon, 2003). According to the World Health Organization, osteoporosis is estimated to affect approximately 200 million women worldwide (Kanis, 2007) with the burden of osteoporosis being felt both personally and economically. Although the prevalence of fractures is higher is women, the mortality rate related to fragility fractures is higher in men (Center et al. 1999; Hasserius et al., 2003). Moreover, the annual cost of treating fractures in the United States is projected to increase to \$25 billion in 2025 from \$17 billion in 2005 (Burge et al., 2005).

Achieving peak bone mass (PBM) during adolescence and the subsequent rate of bone loss are major determinants of bone mass later in life (Hansen et al., 1991). The amount of bone mass achieved early in life has been shown to predict the level of bone mass and the incidence of fracture later in life suggesting that a primary risk factor for the development of osteoporosis is the inability to attain high PBM (Hansen et al., 1991; Heaney et al., 2000). PBM is generally defined as the highest level of bone mass achieved as a result of normal growth and seems to be established, for most sites of the skeleton, by late adolescence (Matkovic et al., 1994). Previous studies (Bonjour et al., 1991; Bailey et al., 1996) have demonstrated the period between 9-20 years of age to be critical in building peak bone mass as 90% of total body bone mineral content (BMC) is accrued by the age of 16 (Elgan et al., 2003; Stager et al., 2006), with the remaining 5-10% of total body bone mass achieved in the third decade (Cadogan et al, 1998). In fact, the most rapid bone mineral accumulation occurs approximately 1 year after the age of peak linear growth (Bailey et al., 1996); around the time of menarche for females (Cadogan et al., 1998). With considerable increases in bone mass occurring during puberty, maximizing PBM during this time is often advocated as the best way to delay age-related bone loss and prevent osteoporotic fractures (Fulkerson et al., 2004; Molgaard et al., 1999; Valimaki et al., 1994).

It appears, therefore, as though there is a critical period, a 'window of opportunity' (MacKelvie et al., 2002), in which we can influence the amount of bone mass we attain. However, bone development is the product of complex interactions between genetic and environmental factors including diet, hormonal influences, and mechanical stimuli (Gordon, 2003; Steelman & Zeitler, 2001). Permanent deficits in PBM are the result of any process that

Physical Activity Interactions with Bone Accrual in Children and Adolescents 381

2008) and controls. Therefore, research investigating the relationship regarding bone markers and different PA types is limited and ambiguous, but even more so in children and adolescents, making it difficult to ascertain the effect of sport on bone. The examination of biochemical measurements of bone turnover, in addition to static measures of bone, is advantageous in the study of skeletal metabolism and growth as they provide an understanding of the dynamic course of bone remodelling. To date, the use of biochemical marks of bone turnover in PA interventions on bone in youth has been extremely limited. Difficulties in comparing and assessing the benefits of PA on bone during growth reflect the varying methodologies used between studies. PA interventions aimed at improving bone health in youth have been subject to limited maturational comparisons as the majority of interventions have been conducted in one distinct pubertal group. Furthermore, the types of PA interventions that have been applied have varied greatly between studies. Discrepancies in results are due in part to the varying bone assessment techniques that are used across cross-sectional and intervention studies. Many of the aforementioned studies measured improvements in BMD using dual-energy x-ray absorptiometry (DXA). The use of DXA to interpret and evaluate BMD in the growing years can be difficult as there are considerable changes to the size and shape of bone (Bailey et al., 1996; Gordon, 2003; Schoenau et al., 2004), making comparisons between youth problematic. Furthermore, the measurements provided by DXA fail to account for the architecture, organization of tissues, mechanical properties and other factors known to impart bone strength. In addition, the bone assessment techniques used in majority of these studies have provided a static rather than dynamic picture of bone, which could in fact allow for more comparisons across studies. Evidence supporting the role of PA on bone health has been accumulated from a wide range of studies investigating different activity methods using athletes, non-athletes and inactive individuals. Although these studies contribute to the literature they do not provide us with causality that PA does impart benefits to bone health. In response, there has been an increase in the number of intervention studies conducted, particularly in the school setting. PA interventions in schools are in many ways ideal places to intervene as they allow for a large population of children and adolescents to be targeted in a somewhat controlled environment, regardless of socioeconomic status, in a location where youth already spend a majority of their day during their most skeletally responsive years (Hughes et al. 2007).

Therefore, the primary objective of this chapter is to conduct a systematic review on the effectiveness of exercise and PA interventions to improve bone accrual in children and adolescents. Key finding from controlled intervention trials using various techniques to assess bone mineral density, content and strength changes will be discussed and be grouped according to maturity status. This will hopefully help to shed light on the best time during growth and development to influence bone health and to ascertain if there is indeed a

We will also discuss and compare the different types of interventions used to affect changes in bone properties in youth, to determine if there is a modality that is best suited to improving bone development and to what degree these interventions influence changes in bone. Furthermore, we will address the characteristics of loading that have been shown to be best associated with particular structural improvements as interventions can be designed to impart mechanical loading on bone by jumping or by resistance training

**2. Methods** 

window of opportunity for bone response.

interferes with normal bone mineral accretion during adolescence, such as inadequate calcium intake, physical inactivity, and poor lifestyle choices (related to smoking, alcohol consumption, carbonated beverages) (Javaid & Cooper, 2002). As a result, research in bone growth and development in youth has endeavoured to ascertain the factors important to increasing bone mineral accretion.

#### **1.2 Physical activity**

The use of physical activity (PA) in maintaining bone health throughout the lifespan and ultimately preventing osteoporosis has been the focus of considerable research in improving PBM in order to minimize later bone loss (Beck & Snow, 2003). It is generally accepted that engaging in PA during growth enhances bone development (Boot et al., 1997; Janz et al., 2001; Janz et al., 2006). Habitual PA has been shown to enhance lean mass (Baxter-Jones et al., 2008) and bone accrual (Baxter-Jones et al., 2003) in youth, both of which are believed to promote bone health and muscle function in older age (Lefevre et al., 1990). Furthermore, 'when' activity occurs during the lifespan is important as PA at a young age can account up to 17% of the variance in bone mineral density (BMD) seen in individuals in their late 20s (Davies et al., 2005).

In addition to the timing of PA, the method by which PA imparts its benefits on bone is also important. Mechanical loading of sufficient intensity to promote increases in skeletal mass during growth require maximal strains to be greater than those of normal everyday living. If the bone is properly overloaded the load will elicit a modeling response making the bone susceptible to new levels of mechanical demand (Bailey et al., 1996). Some of the largest loads placed on the skeleton are physiological ones resulting from muscle contractions (Rauch et al., 2004; Scheonau & Frost, 2002). Furthermore, gravitational or ground reaction forces are also capable of generating the loads necessary to elicit a favourable response in bone. These two loading methods have lead to investigations of bone responses to different forms of PA with comparisons between athletes and non-athletes. Studies have demonstrated athletes involved in high-impact weight-bearing activities such as gymnastics and running have higher BMD (Lehtonen-Veromaa et al., 2000b, 2000c) than athletes participating in low-impact sports such as swimming; with such athletes exhibiting lower or normal bone densities than non-active youth (Bellew & Gehrig, 2006; Cassell et al., 1996; Courteix et al., 1998). Resistance training and simple jumping exercises have also been shown to have positive effects on femoral BMD in adolescent females and as such can be useful in promoting bone growth and maintaining acquired gains (Fuchs & Snow, 2002; Kato et al., 2006; Nichols et al., 2001). Therefore, different forms of PA, such as resistance training (Nichols et al., 2001) and weight-bearing exercise (Fuchs & Snow, 2002; Lehtonen-Veromaa et al., 2000c) have been shown to have positive effects on the developing skeleton through ground reaction forces and muscle contraction.

Various studies have examined the relationship between PA and markers of bone metabolism (Creighton et al., 2001; Lehtonen-Veromaa et al., 2000a), with little research conducted on markers of bone formation and resorption in relation to different types of sports, particularly in children and adolescents. In female athletes between the ages of 18-26, Creighton et al. (2001) found bone formation to be lower and resorption similar in swimmers compared to basketball, volleyball, and soccer players. In a younger population of boys and girls, ages 9-16 years, no differences were found in any markers of bone metabolism between gymnasts (Lehtonen-Veromaa et al., 2000a), swimmers (Derman et al., 2008) and controls. Therefore, research investigating the relationship regarding bone markers and different PA types is limited and ambiguous, but even more so in children and adolescents, making it difficult to ascertain the effect of sport on bone. The examination of biochemical measurements of bone turnover, in addition to static measures of bone, is advantageous in the study of skeletal metabolism and growth as they provide an understanding of the dynamic course of bone remodelling. To date, the use of biochemical marks of bone turnover in PA interventions on bone in youth has been extremely limited.

Difficulties in comparing and assessing the benefits of PA on bone during growth reflect the varying methodologies used between studies. PA interventions aimed at improving bone health in youth have been subject to limited maturational comparisons as the majority of interventions have been conducted in one distinct pubertal group. Furthermore, the types of PA interventions that have been applied have varied greatly between studies. Discrepancies in results are due in part to the varying bone assessment techniques that are used across cross-sectional and intervention studies. Many of the aforementioned studies measured improvements in BMD using dual-energy x-ray absorptiometry (DXA). The use of DXA to interpret and evaluate BMD in the growing years can be difficult as there are considerable changes to the size and shape of bone (Bailey et al., 1996; Gordon, 2003; Schoenau et al., 2004), making comparisons between youth problematic. Furthermore, the measurements provided by DXA fail to account for the architecture, organization of tissues, mechanical properties and other factors known to impart bone strength. In addition, the bone assessment techniques used in majority of these studies have provided a static rather than dynamic picture of bone, which could in fact allow for more comparisons across studies.

Evidence supporting the role of PA on bone health has been accumulated from a wide range of studies investigating different activity methods using athletes, non-athletes and inactive individuals. Although these studies contribute to the literature they do not provide us with causality that PA does impart benefits to bone health. In response, there has been an increase in the number of intervention studies conducted, particularly in the school setting. PA interventions in schools are in many ways ideal places to intervene as they allow for a large population of children and adolescents to be targeted in a somewhat controlled environment, regardless of socioeconomic status, in a location where youth already spend a majority of their day during their most skeletally responsive years (Hughes et al. 2007).

### **2. Methods**

380 Osteoporosis

interferes with normal bone mineral accretion during adolescence, such as inadequate calcium intake, physical inactivity, and poor lifestyle choices (related to smoking, alcohol consumption, carbonated beverages) (Javaid & Cooper, 2002). As a result, research in bone growth and development in youth has endeavoured to ascertain the factors important to

The use of physical activity (PA) in maintaining bone health throughout the lifespan and ultimately preventing osteoporosis has been the focus of considerable research in improving PBM in order to minimize later bone loss (Beck & Snow, 2003). It is generally accepted that engaging in PA during growth enhances bone development (Boot et al., 1997; Janz et al., 2001; Janz et al., 2006). Habitual PA has been shown to enhance lean mass (Baxter-Jones et al., 2008) and bone accrual (Baxter-Jones et al., 2003) in youth, both of which are believed to promote bone health and muscle function in older age (Lefevre et al., 1990). Furthermore, 'when' activity occurs during the lifespan is important as PA at a young age can account up to 17% of the variance in bone mineral density (BMD) seen in individuals in their late 20s

In addition to the timing of PA, the method by which PA imparts its benefits on bone is also important. Mechanical loading of sufficient intensity to promote increases in skeletal mass during growth require maximal strains to be greater than those of normal everyday living. If the bone is properly overloaded the load will elicit a modeling response making the bone susceptible to new levels of mechanical demand (Bailey et al., 1996). Some of the largest loads placed on the skeleton are physiological ones resulting from muscle contractions (Rauch et al., 2004; Scheonau & Frost, 2002). Furthermore, gravitational or ground reaction forces are also capable of generating the loads necessary to elicit a favourable response in bone. These two loading methods have lead to investigations of bone responses to different forms of PA with comparisons between athletes and non-athletes. Studies have demonstrated athletes involved in high-impact weight-bearing activities such as gymnastics and running have higher BMD (Lehtonen-Veromaa et al., 2000b, 2000c) than athletes participating in low-impact sports such as swimming; with such athletes exhibiting lower or normal bone densities than non-active youth (Bellew & Gehrig, 2006; Cassell et al., 1996; Courteix et al., 1998). Resistance training and simple jumping exercises have also been shown to have positive effects on femoral BMD in adolescent females and as such can be useful in promoting bone growth and maintaining acquired gains (Fuchs & Snow, 2002; Kato et al., 2006; Nichols et al., 2001). Therefore, different forms of PA, such as resistance training (Nichols et al., 2001) and weight-bearing exercise (Fuchs & Snow, 2002; Lehtonen-Veromaa et al., 2000c) have been shown to have positive effects on the developing skeleton

Various studies have examined the relationship between PA and markers of bone metabolism (Creighton et al., 2001; Lehtonen-Veromaa et al., 2000a), with little research conducted on markers of bone formation and resorption in relation to different types of sports, particularly in children and adolescents. In female athletes between the ages of 18-26, Creighton et al. (2001) found bone formation to be lower and resorption similar in swimmers compared to basketball, volleyball, and soccer players. In a younger population of boys and girls, ages 9-16 years, no differences were found in any markers of bone metabolism between gymnasts (Lehtonen-Veromaa et al., 2000a), swimmers (Derman et al.,

increasing bone mineral accretion.

through ground reaction forces and muscle contraction.

**1.2 Physical activity** 

(Davies et al., 2005).

Therefore, the primary objective of this chapter is to conduct a systematic review on the effectiveness of exercise and PA interventions to improve bone accrual in children and adolescents. Key finding from controlled intervention trials using various techniques to assess bone mineral density, content and strength changes will be discussed and be grouped according to maturity status. This will hopefully help to shed light on the best time during growth and development to influence bone health and to ascertain if there is indeed a window of opportunity for bone response.

We will also discuss and compare the different types of interventions used to affect changes in bone properties in youth, to determine if there is a modality that is best suited to improving bone development and to what degree these interventions influence changes in bone. Furthermore, we will address the characteristics of loading that have been shown to be best associated with particular structural improvements as interventions can be designed to impart mechanical loading on bone by jumping or by resistance training

Physical Activity Interactions with Bone Accrual in Children and Adolescents 383

comparison to controls. The results presented in the Table 2 are the final finding after any

Maturational Status Gender

*School Based* SXA 1 Prepubertal 16 Boys 12 Part of PE Class 23 DPA 1 Early Pubertal 16 Girls 24 At the School 5 DXA 33 Pubertal 7 Boys + Girls 7

Table 1. Numerical Breakdown by Category of Exercise Interventions for Bone in Youth

Prepubertal corresponds to Tanner Stage 1, early pubertal Tanner Stages 2-3, and pubertal Tanner Stages 4-5. Multi pubertal *separate* are studies with results separated by maturity, with *together* being studies that averaged data for more than one maturity group. Boys + girls reflect studies that did not separate results by sex. PE: physical education; WBPA: weight-bearing physical activity; SXA: single energy x-ray absorptiometry; DXA: dual energy x-ray absorptiometry; DPA: dual photon absorptiometry; pQCT; peripheral QCT;

Majority of the intervention studies were school based with 23 of the studies being conducted as part of a regular physical education class and 5 at some point within the school day. Approximately half (51%) of the studies utilized specific jumping interventions that relied on ground reaction forces in order to elicit a positive response on bone. Fourteen studies consisted of general weight bearing types of activities such as running, volleyball, aerobics etc., with only 3 studies specifically using resistance training with free or machine assisted weights. Significant increases in primary bone outcomes were found in 16 jumping interventions, 14 WBPA interventions, and 1 resistance training study. This translated into 79.5% of physical activity interventions positively influencing some form of bone strength parameter in children and adolescents. Furthermore, 5 studies also included calcium

interventions which demonstrated benefits to bone in addition to physical activity.

Of the 35 studies reviewed 24 presented results separately for girls, 12 for boys, with 7 studies presenting data for boys and girls together. Moreover, 16 studies conducted interventions in prepubertal and early pubertal children. The smallest number of studies was performed in pubertal youth with a total of 7. All the pubertal interventions were completed on a population of girls, with 1 study (Weeks et al., 2008) including boys in their sample. Based on pubertal groups, an even number of boys and girls were represented in the results of prepubertal youth with 8 studies separately reporting results for boy and girls and 2 grouping results together. In early pubertal children, a larger number of studies were conducted on and included girls. Ten studies reported results separately for girls, 3 for boys

DXA was the measurement technique predominantly used (94%) to assess bone, followed by pQCT (14%) and then QUS (8.5%). In total, 5 studies used more than one technique to determine changes in bone and these were all done in conjunction with DXA measurements. Four studies using DXA also performed hip structural analysis (HSA), which is a new

 Outside School 7 HSA 4 Multi Pubertalseparate 4 Jumping 18 pQCT 5 Multi Pubertaltogether 5

Technique

statistical adjustments have been made.

General WBPA 14 QUS 3 Resistance Training 3 Bone Markers 1

HSA: hip structural analysis; QUS: quantitative ultrasound.

and 5 did not distinguish results between genders.

Type of Intervention Measurement

where the weight-bearing load on bone is applied through muscle. As majority of interventions measure only static properties of bone, this chapter will also be used to discuss bone remodelling parameters influenced by such exercise interventions. To our knowledge there has not been any studies examining the effects of PA interventions on bone remodelling.

#### **2.1 Eligibility criteria and search strategy**

The aim of the literature search was to find all available randomized control trials and controlled studies that examined the effects of any type of exercise or PA intervention trial on bone status in healthy (non-clinical, non-athletes) children and adolescents between 6 and 17 years of age. For this review we included all types of bone parameters from various bone assessment techniques (DXA, pQCT, QUS etc.) to be used as primary outcome measures as long as there were at least two measurement time points. Primary outcome measures included areal bone mineral density (aBMD), volumetric bone mineral density (vBMD), bone mineral content (BMC), bone area (BA), cortical thickness, bone strength index (BSI), stress-strain index (SSI), maximal moment of inertia (Imas), section modulus (SM), speed of sound (SOS), broadband ultrasound attenuation (BUA), and markers of bone metabolism.

A computerised search of the MEDLINE and PubMed databases was performed on articles up till 2011 using a comprehensive combination of keywords to describe exercise, bone and participant parameters. The keywords used to describe exercise included: intervention and intervention studies, training, exercise, resistance training, physical education and physical education training, physical activity and motor activity. Bone parameter keywords included: bone mineral, bone density, bone and bones, bone strength, bone accrual and development, bone turnover, resorption, modelling and metabolism. For the participants, keywords such as children, adolescents, boys and girls were used. A total of 2728 were found, their titles and abstracts reviewed to determine if they met the inclusion criteria. Papers from all journals were considered and retrieved electronically or by interlibrary loan.

After screening the articles a total of 35 studies met the criteria and were used for the current review. Studies were grouped according to the maturity status of their participants based on Tanner Staging of development (Tanner, 1962). Participants were grouped as either prepubertal (Tanner 1), early pubertal (Tanner 2 and 3), and pubertal (Tanner 4 and 5) to maintain consistency with other literature review groupings. Studies in which authors provided results for more than one maturity group were divided into two parts (A and B).

#### **3. Results**

Table 1 represents the numerical breakdown of all the intervention studies reviewed into particular categories based on the type of intervention that was used, the method in which bone parameters were assessed, the maturity and sex of the population measured. Studies were included more than once if more than one measurement technique was used and if results were separated by sex or maturity group. Table 2 is a detailed summary of the design and outcomes of all the PA intervention studies reviewed, and are grouped according to the participants' maturity status. The results presented in Table 2 express the percentage difference in gain between the experimental groups participating in the intervention in

where the weight-bearing load on bone is applied through muscle. As majority of interventions measure only static properties of bone, this chapter will also be used to discuss bone remodelling parameters influenced by such exercise interventions. To our knowledge there has not been any studies examining the effects of PA interventions on

The aim of the literature search was to find all available randomized control trials and controlled studies that examined the effects of any type of exercise or PA intervention trial on bone status in healthy (non-clinical, non-athletes) children and adolescents between 6 and 17 years of age. For this review we included all types of bone parameters from various bone assessment techniques (DXA, pQCT, QUS etc.) to be used as primary outcome measures as long as there were at least two measurement time points. Primary outcome measures included areal bone mineral density (aBMD), volumetric bone mineral density (vBMD), bone mineral content (BMC), bone area (BA), cortical thickness, bone strength index (BSI), stress-strain index (SSI), maximal moment of inertia (Imas), section modulus (SM), speed of sound (SOS), broadband ultrasound attenuation (BUA), and

A computerised search of the MEDLINE and PubMed databases was performed on articles up till 2011 using a comprehensive combination of keywords to describe exercise, bone and participant parameters. The keywords used to describe exercise included: intervention and intervention studies, training, exercise, resistance training, physical education and physical education training, physical activity and motor activity. Bone parameter keywords included: bone mineral, bone density, bone and bones, bone strength, bone accrual and development, bone turnover, resorption, modelling and metabolism. For the participants, keywords such as children, adolescents, boys and girls were used. A total of 2728 were found, their titles and abstracts reviewed to determine if they met the inclusion criteria. Papers from all

After screening the articles a total of 35 studies met the criteria and were used for the current review. Studies were grouped according to the maturity status of their participants based on Tanner Staging of development (Tanner, 1962). Participants were grouped as either prepubertal (Tanner 1), early pubertal (Tanner 2 and 3), and pubertal (Tanner 4 and 5) to maintain consistency with other literature review groupings. Studies in which authors provided results for more than one maturity group were divided into

Table 1 represents the numerical breakdown of all the intervention studies reviewed into particular categories based on the type of intervention that was used, the method in which bone parameters were assessed, the maturity and sex of the population measured. Studies were included more than once if more than one measurement technique was used and if results were separated by sex or maturity group. Table 2 is a detailed summary of the design and outcomes of all the PA intervention studies reviewed, and are grouped according to the participants' maturity status. The results presented in Table 2 express the percentage difference in gain between the experimental groups participating in the intervention in

journals were considered and retrieved electronically or by interlibrary loan.

bone remodelling.

markers of bone metabolism.

two parts (A and B).

**3. Results** 

**2.1 Eligibility criteria and search strategy** 


comparison to controls. The results presented in the Table 2 are the final finding after any statistical adjustments have been made.

Table 1. Numerical Breakdown by Category of Exercise Interventions for Bone in Youth

Prepubertal corresponds to Tanner Stage 1, early pubertal Tanner Stages 2-3, and pubertal Tanner Stages 4-5. Multi pubertal *separate* are studies with results separated by maturity, with *together* being studies that averaged data for more than one maturity group. Boys + girls reflect studies that did not separate results by sex. PE: physical education; WBPA: weight-bearing physical activity; SXA: single energy x-ray absorptiometry; DXA: dual energy x-ray absorptiometry; DPA: dual photon absorptiometry; pQCT; peripheral QCT; HSA: hip structural analysis; QUS: quantitative ultrasound.

Majority of the intervention studies were school based with 23 of the studies being conducted as part of a regular physical education class and 5 at some point within the school day. Approximately half (51%) of the studies utilized specific jumping interventions that relied on ground reaction forces in order to elicit a positive response on bone. Fourteen studies consisted of general weight bearing types of activities such as running, volleyball, aerobics etc., with only 3 studies specifically using resistance training with free or machine assisted weights. Significant increases in primary bone outcomes were found in 16 jumping interventions, 14 WBPA interventions, and 1 resistance training study. This translated into 79.5% of physical activity interventions positively influencing some form of bone strength parameter in children and adolescents. Furthermore, 5 studies also included calcium interventions which demonstrated benefits to bone in addition to physical activity.

Of the 35 studies reviewed 24 presented results separately for girls, 12 for boys, with 7 studies presenting data for boys and girls together. Moreover, 16 studies conducted interventions in prepubertal and early pubertal children. The smallest number of studies was performed in pubertal youth with a total of 7. All the pubertal interventions were completed on a population of girls, with 1 study (Weeks et al., 2008) including boys in their sample. Based on pubertal groups, an even number of boys and girls were represented in the results of prepubertal youth with 8 studies separately reporting results for boy and girls and 2 grouping results together. In early pubertal children, a larger number of studies were conducted on and included girls. Ten studies reported results separately for girls, 3 for boys and 5 did not distinguish results between genders.

DXA was the measurement technique predominantly used (94%) to assess bone, followed by pQCT (14%) and then QUS (8.5%). In total, 5 studies used more than one technique to determine changes in bone and these were all done in conjunction with DXA measurements. Four studies using DXA also performed hip structural analysis (HSA), which is a new

Physical Activity Interactions with Bone Accrual in Children and Adolescents 385

Table 2. Randomized and Non-Randomized Controlled Studies on the Effects of Exercise on

Bone Indices in Youth

Alwis

et al.

(2008a)

Age range: 6.7-9 yrs

Ex: n=80, Con: n=57

Randomized by Con: 60min/wk

school: 1 Ex + 3 Con.

Alwis

et al.

(2008b)

Age range: 6.7-9 yrs

Ex: n=53, Con: n=50

All remained TS 1 Ex: 40min/day (200min/wk)

Randomized by Con: 60min/wk

school: 1Ex + 3 Con.

Bass et al.

(2007)

Total n=88, 7-11 yrs

Ex Placebo: n=21

Ex Ca: n=20 No Ex Ca: n=21

No Ex Placebo: n=26

Randomized groups

Ca: double blind

Bradney Boys, White

et al.

(1998)

Age range: 8.4-11.8

N=20 Ex, m=20 Con

Randomized by weight training

school: 1 Ex + 1 Con

Fuchs

et al.

(2001)

Age range: 5.9-9.8 yrs

n=45 Ex., n=41 Con

Randomized 1 school

Asian and White

All remained TS 1 90% Compliance

50-100 high box jumps, 2 footed

Ground rx forces = 8.8 x BW

BA: femoral neck

BA FN: +2.9%

femoral neck

aBMD FN: NS

Boys and Girls, 7 Months

30 minutes, 3 x week

Program outside of school:

aerobics, soccer, volleyball,

All remained TS 1 dance, gymnastics, basketball, Femoral Midshaft BMC,

8 Months

Compliance 86%

DXA

lumbar spine, femur,

aBMD: total body and

aBMD and vBMD, and

cortical thickness

DXA Activities added to PE classes: BMC and aBMD: BMC FN: +4.5%

10 min 3x week jumping lumbar spine and aBMD LS: +2%

BMC LS: +3%

cannot distinguish results

between boys and girls

femoral midshaft: +5.6%

cortical thickness: +6.4%

were derived/estimated

aBMD LS: +2.8%

Ca: 800mg Ca/day

Boys, White + Asian

 8.5 Months

moderate or low impact

Ex: Ground rx forces 2-8 x BW

No Ex: Ground rx forces 1 x BW

Compliance: Con 76%, Ex 95%

 CSA of FN

DXA Part of PE class: 20min 3x week BMC: total body, Ex+Ca > all other grps

Hopping jumping, skipping lumbar spine, femur,

 radius-ulna

tibia-fibula, humerus,

+2% ExCa>Ex Placebo

+3% Ex Ca> No ExCa

Femur BMC: +2%

 the groups Tibia-fibula BMC: Control grp participated in

and No Ex Pl groups smaller

NS for BMC in arms

aBMD TB: +1.2%

 the groups BMC and aBMD volumetric bone densities

Low sample sizes in each of

Population not all TS1

61% TS 1, 39% TS 2

low impact exercise making

possible differences between

Low sample sizes in each of

running jumping, climbing

Typical PE class: ball games, BMC, aBMD, periosteal

and endosteal diameter,

cortical thickness, CSMI

section modulus, and

Girls, White

12 Months

Compliance: Con 84%, Ex 95%

running jumping, climbing

 L3 vertebra Accelerometers captured only All remained TS 1 Ex: 40min/day (200min/wk)

L3 vertebral width

HSA of femoral neck

DXA and HSA No significant

 found

between group Higher spare time activities

differences were in control group.

Follow up periods varied

Boys, White

24 Months

DXA Typical PE class: ball games, BMC: total body and

BMC L3: +3%

L3 width: +1.3% Ex and Con.

**Reference**

 **Population** *Pre Pubertal (Tanner Stage 1)*

**Intervention**

**Measures**

**Results Limitations**

Uneven sample size between

4 days of 2-yr intervention

Compliance not reported

application for DXA allowing for the estimation of geometric contributions to bone strength in the proximal femur and may potentially provide a better representation of bone strength (Bonnick, 2007). It is surprising that such a large percentage of studies utilized DXA given the known methodological issues with assessing changes in bone during growth. Until recently, we had thought no intervention studies had used biochemical markers of bone metabolism. Our extensive literature search found 1 study (Schneider et al., 2007) that measured serum markers of bone formation and resorption in adolescents. As static measures require longer durations for differences to be found, measuring biochemical markers of bone turnover to assess dynamic properties of bone could be advantageous in detecting changes sooner and allow for better comparisons of results between studies.

#### **3.1 Prepubertal interventions**

Positive effects of exercise on bone indices were found in 13 of 16 studies (81%), with overall effects ranging from 0.6% to 9.5% depending on the skeletal location and the type of measure (BMC, BMD, etc) taken for studies 7-36 months in duration. The average percent improvements for BMC included 4.5%, 4%, 2%and 1.5% at the lumbar spine (LS), femoral neck (FN), femur and total body (TB) respectively. BMD gains across studies were between 0.6-3% for the LS, FN and TB. The largest gains in girls was in BMC and area of the forearm (12.5% and 13.2% respectively) using peripheral DXA after 36 months of increased physical education class time (Hasselstrom et al., 2008). The one study that used pQCT in this group (Macdonald et al., 2007) was also the study that exhibited the largest bone gains in boys after 16 months of jump training, finding an increase of approximately 25% in BSI (an index of bone structural strength) of the distal tibia. MacKelvie et al. (2004) also presented large gains using HSA, with boys seeing a 12% increase in FN cross-sectional moment of inertia.

Despite the bone gains being similar between boys and girls, the number of studies that reported significant findings differed (4 vs. 7 out of 8 for girls vs. boys respectively). These discrepancies can largely be explained by the differences in the length and type PA intervention employed. MacKelvie et al. (2001) and (2002) were studies that utilized 7 months of school based physical education classes to employ a jump circuit intervention eliciting ground reaction forces 3-5 times one's body weight and demonstrated favourable gains in bone in boys but not girls. Fuchs et al. (2001) also found 7 months of jump training to be favourable to improvements in LS and FN BMC and BMD in prepubertal boys and girls. In fact the gains demonstrated in Fuchs et al. (2001) were greater than those in the MacKelvie et al. (2001, 2001) studies, most likely due to the larger ground reaction forces generated (8.8 vs. 3.5-5 x body weight). Studies at 12 months (Alwis et al., 2008b; Linden et al., 2007) utilizing a weight bearing physical education intervention follow a similar trend with improvements being seen in boys but not girls. The extra intervention time has not helped to elicit a significant positive bone response in the young girls. It is not till 24 months of the same type of weight bearing PA intervention that positive gains are found in girls (Linden et al., 2006). It would therefore appear that improvements in bone as a result of a PA intervention would more likely occur in prepubertal boys than girls. This is particularly true after 7 months of jumping training (MacKelvie et al., 2001, 2002) and 12 months of weight bearing PA (Alwis et al., 2008b; Linden et al., 2007). Improvements in prepubertal girls were seen in studies lasting 24 months in duration (Linden et al. 2006) and any studies demonstrating bone gains in a mixed gendered population (Fuchs et al., 2001; McKay et al., 2000) could be due to greater changes in the boys than the girls.


Table 2. Randomized and Non-Randomized Controlled Studies on the Effects of Exercise on Bone Indices in Youth

application for DXA allowing for the estimation of geometric contributions to bone strength in the proximal femur and may potentially provide a better representation of bone strength (Bonnick, 2007). It is surprising that such a large percentage of studies utilized DXA given the known methodological issues with assessing changes in bone during growth. Until recently, we had thought no intervention studies had used biochemical markers of bone metabolism. Our extensive literature search found 1 study (Schneider et al., 2007) that measured serum markers of bone formation and resorption in adolescents. As static measures require longer durations for differences to be found, measuring biochemical markers of bone turnover to assess dynamic properties of bone could be advantageous in detecting changes sooner and allow for better comparisons of results between studies.

Positive effects of exercise on bone indices were found in 13 of 16 studies (81%), with overall effects ranging from 0.6% to 9.5% depending on the skeletal location and the type of measure (BMC, BMD, etc) taken for studies 7-36 months in duration. The average percent improvements for BMC included 4.5%, 4%, 2%and 1.5% at the lumbar spine (LS), femoral neck (FN), femur and total body (TB) respectively. BMD gains across studies were between 0.6-3% for the LS, FN and TB. The largest gains in girls was in BMC and area of the forearm (12.5% and 13.2% respectively) using peripheral DXA after 36 months of increased physical education class time (Hasselstrom et al., 2008). The one study that used pQCT in this group (Macdonald et al., 2007) was also the study that exhibited the largest bone gains in boys after 16 months of jump training, finding an increase of approximately 25% in BSI (an index of bone structural strength) of the distal tibia. MacKelvie et al. (2004) also presented large gains

using HSA, with boys seeing a 12% increase in FN cross-sectional moment of inertia.

2000) could be due to greater changes in the boys than the girls.

Despite the bone gains being similar between boys and girls, the number of studies that reported significant findings differed (4 vs. 7 out of 8 for girls vs. boys respectively). These discrepancies can largely be explained by the differences in the length and type PA intervention employed. MacKelvie et al. (2001) and (2002) were studies that utilized 7 months of school based physical education classes to employ a jump circuit intervention eliciting ground reaction forces 3-5 times one's body weight and demonstrated favourable gains in bone in boys but not girls. Fuchs et al. (2001) also found 7 months of jump training to be favourable to improvements in LS and FN BMC and BMD in prepubertal boys and girls. In fact the gains demonstrated in Fuchs et al. (2001) were greater than those in the MacKelvie et al. (2001, 2001) studies, most likely due to the larger ground reaction forces generated (8.8 vs. 3.5-5 x body weight). Studies at 12 months (Alwis et al., 2008b; Linden et al., 2007) utilizing a weight bearing physical education intervention follow a similar trend with improvements being seen in boys but not girls. The extra intervention time has not helped to elicit a significant positive bone response in the young girls. It is not till 24 months of the same type of weight bearing PA intervention that positive gains are found in girls (Linden et al., 2006). It would therefore appear that improvements in bone as a result of a PA intervention would more likely occur in prepubertal boys than girls. This is particularly true after 7 months of jumping training (MacKelvie et al., 2001, 2002) and 12 months of weight bearing PA (Alwis et al., 2008b; Linden et al., 2007). Improvements in prepubertal girls were seen in studies lasting 24 months in duration (Linden et al. 2006) and any studies demonstrating bone gains in a mixed gendered population (Fuchs et al., 2001; McKay et al.,

**3.1 Prepubertal interventions** 


Table 2. Continued – Studies on the Effects of Exercise on Bone in Youth

Physical Activity Interactions with Bone Accrual in Children and Adolescents 387

Table 2. Continued – Studies on the Effects of Exercise on Bone in Youth

(2004)

schools: 7 Ex + 7 Con

McKay

et al.

(2000)

Ex: n=63, C: n=81

White and Asian

Boys and Girls

 8 Months

Age range: 6.9-10.2 3 x week 10 tuck jumps

School randomized

Petit Girls, Asian + White

et al.

(2002)

(Part a)

Ex: n=43, Con: n=25

Randomized by exercise stations

schools: 14 schools Con: regular PE classes

ethnic stratification

Valdimar-

sson

et al.

(2006)

one school

Ex group come from

Age range: 7-9 yrs

Ex: n=53, Con: n=50

Ex: 40min/day (200min/wk)

Con: 60min/wk. 90% Attendance

running jumping, climbing

vBMD: L3 and FN

LS (L2-L4), L3, FN, leg

Girls, White

12 Months

DXA Typical PE class: ball games, BMC and aBMD: TB,

BMC LS: +4.7%

aBMD L3: 3.1%

Bone width L3: +2.9%

aBMD LS: 2.8%

BMC L3: +9.5%

were derived/estimated

Compliance low in controls

volumetric bone densities

No randomization

Ground rx forces=3.5-5 x BW

 7 Months Age range: 9.4-10.6 Part of PE classes: 10-12 min abed: TB, LS, TR, PF

3x week: 5 x diverse jumping cortical thickness, area

and SM: PF

Con: regular PE classes

DXA and HSA NS differences in any

 measured

of the bone variables

measurement

Compliance not reported

Errors related to method of

Part of PE classes: jumping,

hopping, skipping 2 x week

MacKelvie

et al.

Ex: n=31, Con: n= 33

Boys, White + Asian

 20 Months

Age range: 9.6-10.7 class: 10min, 3 x week

Randomized by 50-100 jumps and circuit HAS: PF, NN, TR , FN

training, progressing w/jumps

Jumping = 3.5-5 x BW

DXA

and trochanter (TR)

aBMD: TB, LS, PF, FN,

aBMD TR: +1.2%

All boys remained TS 1, with

some girls maturing to TS 2

Compliance not reported

 SM: FN

Activity added to regular PE

BMC and BA: TB, LB,

PF, FN, and TR

 SM: +7.4%

of inertia: +12.35%

Cross-sectional moment

**Reference**

 **Population** *Pre Pubertal (Tanner Stage 1)*

MacKelvie

et al.

(2002)

Ex: n=61, Con: n=60

Boys White + Asian

 7 Months

Age range: 9.7-10.9 class: 10min, 3 x week

Randomized by 50-100 jumps and circuit vBMD: FN

schools: 7 Ex + 7 Con

training, progressing w/jumps

Jumping = 3.5-5 x BW

 Compliance 80% across schools

DXA and HSA BMC FN: +4.3%

 Con 42%

More Con remained TS 1 and

more Ex's advanced to TS 3

Study compliance: Ex 39% and

Activity added to regular PE

TB, LS, PF, FN

BMC and aBMD: aBMD PF: +1%

DXA

BMC TB: +1.6%

vBMD measurements were

derived/estimated

**Intervention**

**Measures**

**Results Limitations**


Table 2. Continued – Studies on the Effects of Exercise on Bone in Youth

Table 2. Continued – Studies on the Effects of Exercise on Bone in Youth

**Reference**

 **Population** *Pre Pubertal (Tanner Stage 1)*

Hassel-

strom (Ex: n= 135 and 108)

et al. (Con: n= 62 and 76)

(2008)

Age Range: 6-8

No Randomization

TS 1 and 2

Linden

Girls, White et al. Ex: n=49, Con: n=50

(2006)

Age range: 7-9 running jumping, climbing

Randomized by Con: 60min/wk

school: 1 Ex + 3 Con.

Linden Boys, White

et al.

(2007)

Ex: n=81, Con: n=57

Age range: 7-9 running jumping, climbing

All remained TS 1 Ex: 40min/day (200min/wk)

Randomized by Con: 60min/wk

school: 1 Ex + 3 Con.

Macdonald

et al. Asian and White

(Part A)

Ex: n=140, Con: n=72

Boys and Girls

 16 Months

Randomized by Compliance 74%

MacKelvie

et al.

(2001)

(Part A)

schools: 7 Ex + 7 Con

training, progressing w/jumps

Jumping = 3.5-5 x BW

Compliance 80% across schools

Ex: n=44, Con: n=26

Girls, White + Asian

 7 Months

Age range: 9.4-10.6 class: 10min, 3 x week

Activity added to regular PE

Randomized by 50-100 jumps and circuit vBMD: FN

Uneven sample sizes and school: 7 Ex. + 3 Con.

DXA

TB, LS, PF, FN

NS differences in any

BMC and aBMD: of the bone variables

measured

derived/estimated

Uneven sample size between

Ex and Con.

More Ex's advances from

TS 1 to TS2

vBMD measurements were

5-36 jumps/day 4 x week

Ex. Attendance: 90%

pQCT Ex: 15 min/day PA 5 x week, BSI distal tibia increased ~+25%

Potential bias for school (2007)

SSI tibial midshaft

Girls: NS changes in

Age range: 9.6-10.8 Con: regular school curriculum all measures

12 Months

Ex. Attendance: 90% and FN

24 Months

DXA Typical PE class: ball games, BMC and aBMD: L3 +7.2%, Leg +3.0%

FN, and Leg vBMD, bone size: L3

DXA Typical PE class: ball games, BMC and aBMD: width L3: +5.9%, +2.1%

Bone Width: L3 and FN

TB, L3 vertebra, FN

 and +2.3%

 Leg +1.2% Bone Size: L3 +1.8%,

and FN +0.3%

BMC, aBMD, bone Uneven sample size between

Ex and Con. Compliance in Con Low

Only assessed duration of PA,

not intensity or effort

Boys: BSI distal tibia Low Compliance

 selection

Low Compliance

distribution of sexes

L2-L4 +1.2%, L3 +1.6%,

TB, LS L2-L4 and L3, aBMD: TB +0.6%, All remained TS 1 Ex: 40min/day (200min/wk)

Boys and Girls, White

 36 Months

90min/wk Activities conducted in classes

School based curriculum, time

increased: 4 classes 180 min/wk

Con: regular school curriculum

 forearm

Calcaneus and distal

BMC and BMD:

**Intervention**

**Measures**

Peripheral DXA

forearm BMD BMC forearm: +12.5%

forearm area: +13.2%

Boys: NS changes in

anatomical region measured not mentioned all measures

 studied

BMC: L2-L4 +3.8%, Differences in leisure time PA

Compliance not reported

due to growth

Possible differences in standard

Girls: NS changes in

calcaneal and distal allowing for selection bias

Non-randomized study design

DXA locations measured less

**Results Limitations**


Table 2. Continued – Studies on the Effects of Exercise on Bone in Youth

Physical Activity Interactions with Bone Accrual in Children and Adolescents 389

Table 2. Continued - Studies on the Effects of Exercise on Bone in Youth

Macdonald

et al. Asian and White

(Part B)

Age range: 9.6-10.8 yrs

school: 7 Ex. + 3 Con.

Macdonald

et al.

Ex: n=140, Con: n=72

Age range: 9-11 yrs

Asian and White

Boys and Girls

 16 Months

Randomized by Compliance 74%

school: 7 Ex. + 3 Con.

TS 1-3

Macdonald

et al.

(2009)

Age range: 9-11 yrs

Ex: m=139, Con: n=63

Boys, Asian + White

 16 Months

Randomized by Con: regular school curriculum

school: 7 Ex. + 3 Con.

Compliance 74

%

5-36 jumps/day 4 x week

tibia

cortical thickness of

in cortical area and

thickness, but NS

pQCT Ex: 15 min/day PA 5 x week, Second moments of

5-36 jumps/day 4 x week

Con: regular school curriculum

Ex: n=135, Con: n=57

Boys and Girls

 16 Months

5-36 jumps/day 4 x week

Con: regular school curriculum

Uneven sample sizes and Randomized by Compliance 74%

Ex: 15 min/day PA 5 x week, BSI distal tibia

Potential bias for school (2007)

SSI tibial midshaft

**Reference**

*Early Pubertal (Tanner Stage 2-3)*

MacKelvie

et al.

(2001)

(Part B)

MacKelvie

et al. Ex: n=33, C: n=43

(2003)

Age range: 9.3-10.7

Randomized by

schools: 7 Ex + 7 Con

Girls, Asian + White

 20 Months

Jumping = 3.5-5 x BW

 Compliance 42% over 20 Mos.

pQCT

NS changes in any

of the measures

selection distribution of sexes between

groups

of FN: +5.4% More boys prepubertal and

(only in girls with girls early pubertal

80% compliance)

Max second moment

area, cortical area, Trends for increase

of area: +3%

 more TS1

Uneven sample sizes

Higher percentage of TS2 in

Ex Group compared to Con

at baseline, with Con having

maturity status

Results not separated by

distribution of sexes btw grps

Low teacher compliance

DXA and HSA Boys: BMC LS: +2.7%

Ex: 15 min/day PA 5 x week, FN bone strength, BMC TB: +1.7%

Uneven sample sizes and (2008)

BMC: TB, PF, LS

geometry, and BMC

Girls: section modulus

Low Compliance

training, progressing w/jumps

Part of PE class: 10min 3x week

50-100 jumps and circuit BMC: LS and FN

Randomized by

schools: 7 Ex + 7 Con

Age range: 9.9-11.1 yr

Jumping = 3.5-5 x BW

Compliance 80% across schools

DX

BMC LS: +3.7%

BMC FN: +4.6%

 mature Compliance not reported for

Ex. Group

Con group older and more

training, progressing w/jumps

Ex: n=43, Con: n=64

Girls, White + Asian

 7 Months

Part of PE class: 10min 3x week

50-100 jumps and circuit TB, LS, PF, FN

Volumetric BMD: FN

aBMD FN: +1.6%

vBMD FN: +3.1%

Ex and Con.

BMC FN: NS

BMC and aBMD: aBMD LS +1.7%

DXA

BMC LS +1.8%

were derived/estimated

Uneven sample size between

Volumetric bone densities

**Population**

**Intervention**

**Measures**

**Results**

**Limitations**


Table 2. Continued - Studies on the Effects of Exercise on Bone in Youth

Table 2. Continued – Studies on the Effects of Exercise on Bone in Youth

Courteix

et al.

(2005)

Ex Ca: n=12 Ex Placebo: n=42

9 Months

bearing physical activity

DXA and pQCT

BMC FN: +4.0%

Cortical area: tibial to teachers selecting groups

BMC LS: +3.3%

Compliance low

Potential selection bias due

No Ex Placebo: n=21

Randomized, Blinded

Heinonen

et al.

(2000)

(Part A)

Iuliano-

Burns

 Total n=64 et al. Age range: 8-9 yrs

(2003)

Mod Ex. Ca: n=16

Mod Ex. Pl: n=16

Low Ex. Ca: n=16

Low Ex. Pl: n=16

Randomized groups

Low Ex. Impact: stretching

Ca: average of 434 mg/day

Compliance: Ex 93%, Study 88%

weights in final 8 weeks

Girls, White + Asian

 8.5 Months Ex: 20 min 3 x week

Mod Ex. Impact: skipping, Tibia-Fibula

decided by teachers

box (two and one footed)

Ground rx forces not measured

Compliance: Ex 73%, Study 92%

DXA BMC: LS, Femur,

hopping, jumping. Used hand Low Ex. No Pl.

+3% Mod ex>Low Ex.

+7.1% Mod Ex Ca >

BMC tibia-fibula:

Low sample sizes

Age range: 10-12yrs

Ex: n=25, Con:, n=33

Selection to groups exercises: 100-200 jumps from

Step aerobic program: 50 min

2 x week: 20 min of jumping

 midshaft

BMC: LS, FN, and TR

Girls, White

Compliance 75%

Ex: Participated in weight

Ca: 800 mg/day

Age range: 8-13 yrs

Girls, White (n=85)

 12 Months

Ex: 7.2h/week

No Ex: 1.2h/week

**Reference**

 **Population** *Pre Pubertal (Tanner Stage 1)*

Van Lang-

endonck

et al.

(2003)

21 pairs of monozy-

Age range: 8-9yrs

*Early Pubertal (Tanner Stage 2-3)*

Barbeau Girls, Black

et al.

(2007)

Age range: 8-12 yrs

n=77 Ex., n=83 Con.

Recruited from 8 25min skills, 35min MVPA,

elementary schools 20min toning + stretching

5 days/week, 80 min PA:

DXA aBMD: TB, LS, FN, WT

aBMD LS: +11%

aBMD FN: +8.2%

aBMD WT: 9.3%

(all Ex Ca > No Ex Pl)

NS differences between

other groups

Exercise based on habitual No Ex Ca: n=10

aBMD TB: +6.3%

 activity

Uneven sample size

distribution between groups

Type of exercise not controlled

10 Months

DXA After school intervention Total body BMD, BMC

BMC TB: +4.0%

BMD TB: +2%

Examined girls who attended

40% of classes 2d/wk

Main focus was to improve

cardiovascular fitness

Low compliance

Compliance: Ex 91%

Ex: n=21, Con: n=21

Ethnicity not reported

gotic twins Ground rx forces not measured

different stimulus

Ex: 3x week: hopping/jumping

Progression: removal of shoes

 Girls

9 Months

DXA

 FN and PF

BMC, aBMD, BA:

aBMD PF: +1.3%

BMC FN: +2.0%

aBMD FN: +2.4%

BMC PF: +2.5%

analysis conducted

Some of the girls participated

in high impact sports during

their leisure time - separate

**Intervention**

**Measures**

**Results Limitations**


Table 2. Continued - Studies on the Effects of Exercise on Bone in Youth

Physical Activity Interactions with Bone Accrual in Children and Adolescents 391

Table 2. Continued - Studies on the Effects of Exercise on Bone in Youth

**Reference**

*Early Pubertal (Tanner Stage 2-3)*

Nichols

et al.

(2008)

Age range: 9-10yrs

Ex only: n=61

Nutrition only: n=9

Ex + nutrition: n=14

Con: n=28 4 schools randomized

85% TS1 at baseline

Petit

et al.

(2002)

(Part B)

stratified by ethnic

composition

Sundberg

et al.

(2001)

Ex Girls: n=40

Con Boys: n=82

Con Girls: n=66

Age range: 12-16 yrs

2 Schools (1 Ex, 1 Con)

Recruited grade 6,7

(12-13yrs), follow up

grade 9 (15-16yrs)

TS 2,3 start TS 4,5 end

*Pubertal (Tanner Stage 4-5)*

Blimkie

et al.

(1996)

Ex: n=16, Con: n=16

Age range: 15.9-16.3

All postmenarcheal

Ethnicity not reported

training 3 x week

4 sets of 12 reps each, with

progression every 6 weeks

Machine assisted weight

 Girls

6.5 Months

DPA

BMC: TB and LS

aBMD: TB and LS

 measured

Ex Boys: n=40

Boys and Girls, White

 3-4 Years

60 min 2 x week

Compliance: Ex 93%, Con 91%

gymnastics, ball games

1 of 4 classes: swimming

Con: regular PE classes of

3 of 4 classes: weight bearing

activities, jumping, running,

calcaneus (heel)

QUS: BUA, SOS, and SI:

ultradistal radius

Additional time in PE classes

Ex: 40min 4 x week TB, LS, FN

vBMD, and bone size:

SXA: BMC and aBMD:

distal radius and ulna

SI Heel: +7% / +2%

3-4 Years Girls:

aBMD distal/ultra-

distal radius: -6-7%

NS differences in any

of the bone variables

Compliance was no clear

The duration/length of each

session was not clear

SOS Heel: +1% / +11%

aBMD LS: 0% / +10%

BMC LS: +9% / 0%

vBMD FN: 9% / +15%

Con: regular PE classes

Ground rx forces=3.5-5 x BW

DXA: BMC, aBMD,

BMC FN: +8% / 0%

aBMD FN: +9% / +14%

3/4 Years Boys:

same school

Control group not from the

building bone

Ex program not specific to

vBMD and BA was derived

Con girls had high levels of

leisure PA, bone mass, Ca

intake and earlier menarche

than Ex girls, which may have

masked effects of intervention

Ex: n=43, Con: n=63

Age range: 9.9-11.1yrs

Girls, Asian + White

 7 Months

Randomized by Activities done in addition to

jumping exercise stations

10-12 min 3x week 5 x diverse

 SM: FN

schools: 14 schools regular PE classes FN: : +3.2%

cortical thickness: FN

cortical thickness

aBMD: TR and FN

aBMD FN: +2.6%

SM FN: +4.0%

73% at 20 months

clasees to improve Ca intake

Compliance: 80% at 8 months,

8 and 20 months

DXA and HSA aBMD TR: +1.7%

measurement

Compliance not reported

Errors related to method of

Ground Rx forces 2-3 x BW

Nutrition: 45min biweely Measures taken twice:

and skipping

Total n=112

Boys and Girls, White

 20 Months Activity added to PE classes:

8-12min 2 x week: of jumping

DX

 PF, and FN BMC: TB, LS, FN, PF

measurements taken

at 8 and 20 months

BMD: TB, LS (L2-L4),

between groups for

any of the bone

Leisure PA not controlled:

59% reported participating

in organized sports/activities

Ground rx forces estimated

height velocity

TS estimated based on

distribution between groups

A

**Population**

**Intervention**

**Measures**

**Results** NS differences Uneven sample size

**Limitations**


Table 2. Continued - Studies on the Effects of Exercise on Bone in Youth

Table 2. Continued - Studies on the Effects of Exercise on Bone in Youth

**Reference**

*Early Pubertal (Tanner Stage 2-3)*

McKay Girls and Boys

et al.

Ex: n=51, Con: n=73

Asian and White

 8 Months

Age Range: 9.5-10.5 3 min 3 x day each school day

No Randomization

Meyer

et al.

(2011)

Age range: 6.6-11.7 yrs

Randomized by PE classes that include 10 min

classes: Ex: 16 classes/

classes/6 schools

TS 1-3

Morris

et al.

(1997)

to ethnicity Ex: n=38, Con: n=33

No randomization

Grouped by teachers

Nemet

et al.

(2006)

Ex: n=12, Con: n=12

Age range: 6-16 yrs

Obese participants

Randomized groups

Ethnicity not given

Boys and Girls,

 3 Months

Received nutrition counseling

games: 1 hour 2 x week

50% sports, 50% running and

Structured activities to mimic

weight training

Ground rx forces not measured

Compliance: Ex 92%, Study 97%

QUS

SOS of left tibia

PE classes. Mainly endurance: significant SOS range

Difference due to

decrease (-2.6%) in Compliance not reported

Con, and NS increase

in Ex. (+0.6%)

Population spans a large age

ball games, progressing to

could contribute to the Age range: 8.6-10.4 yrs

stratified according

given, but schools

Girls, Ethnicity not

 10 Months

class: 30 min 3 x week

Aerobics, skipping, dance,

BMAD: LS, FN

Activity added to regular PE

BMC: TB, LS, FN, PF

aBMD: TB, LS, PF

Con: regular PE classes

DXA and BMAD

BMC PF: +8.3%

aBMD TB: +2.3%

aBMD LS: +3.6%

BMC FN: +4.5%

Ex: regular PE class + 2 extra

 FN, L2-L4

jumping activities. aBMD LS:+7.3%

9 schools, Con: 12 2-5min jumping/balancing Pubertal stage\*group

tasks through out day interaction favored Compliance not reported

prepubertal children

BMC TB and LS: +5.5% Potential selection bias as

aBMD FN: +10.3% greater gains seen

aBMD pF: +3.2%

BMAD LS: +2.9%

SOS: +2.9%

Small sample size

control (due to drop outs) and

Maturity greater in Ex than

teachers selected groups

Ex: n=297, Con: n=205

School based program

Boys and Girls, White

 12 Mos

Ground Rx forces: 5 x BW

Compliance: Ex 60%, study 100%

DXA BMC and aBMD: TB,

BMC FN: +5.4%

BMC LS: +4.7%

aBMD TB: +8.4%

10 counter movement jumps

Program: Bounce at the Bell

Ex group participated in (2005)

BA: PF and TR

Cortical thickness and

BA TB BMC TB: +5.5%

pubertal Con grp (loss of data)

Small sample size of pre

adjust for variables

maturity. Maturity used to

but results not separated by

Has distinct pubertal groups

BA TR: +2.0%

Con > Ex: BMC and BMC and BA

Con greater increase in TB

 area: PF

BMC: PF and TR

BMC TR: +2.7%

BA PF: +1.3%

**Population**

**Intervention**

**Measures** DXA and HSA BMC PF: +2.0%

greater PA at baseline

Compliance Low

**Results**

**Limitations**


Table 2. Continued - Studies on the Effects of Exercise on Bone in Youth

**Reference**

*Pubertal (Tanner Stage 4-5)*

Weeks

et al.

(2008)

Con Boys: n=15

Ex Girls: n=21

Compliance Ex 80%

Study dropout rate 18%

9 Months

DXA

BMC: TB, LS, FN, TR

between groups

However, increases

TR ranged +0.1-2.1%

in Ex group

Randomized 1 school

Witzke

& Snow.

(2002)

Age range: 14-15 yrs

All postmenarcheal

No randomization

intensity over 9 months

Ground rx forces not measured

Table 2. Randomized and Non-Randomized Controlled Studies on the Effects of Exercise

Ex: exercise group; Con: control group; BMC: bone mineral content; aBMD: areal bone mineral density; vBMD: volumetric

BMD; BA: bone area; BMAD: bone mineral apparent density (BMD adjusted for BA); TB: total body; LS: lumbar spine; FN:

femoral neck; NN: narrow neck; PF: proximal femur;, WT: wards triangle; TR: trochanter; SXA: single energy x-ray

absorptiometry; DXA: dual energy x-ray absorptiometry; DPA: dual photon absorptiometry; QCT: qualitative computed

tomography, pQCT; peripheral QCT; HSA: hip structural analysis; QUS: quantitative ultrasound; SOS: speed of sound; SM:

section modulus; CSMI: cross-sectional moment of inertia; IBS/BSI: index of bone structural strength; SSI: strength strain

index; BUA: broadband ultrasound attenuations; OC: osteocalcin; BSAP: bone-specific alkaline phosphatise; CICP: c-terminal

procollagen peptide; PYD: deoxypyridinoline; Ca: calcium; Rx: reaction; BW: body weight; PE: physical education; TS: Tanner

sta

ge; Pl: Placebo; Gr

ps: Grou

ps; NS: no si

gnificant.

**o**n Bone Indices in Youth

resistance and plyometrics

training with increasing in BMC for TB, LS, FN,

Ex: n=25, Con:, n=28

Ex: 30-45 min 3 x week of

Girls, White

Con: 10min 2x week of regular

1-3 Hz, height 0.2-0.4m

worked up to ~300 jumps at

Ex Boys: n=22 activities as warmup in PE class

 Total n=81

Boys and Girls

 8 Months

**Population**

**Intervention**

**Measures**

DXA and QUS

Ex: 10 min 2x week jumping BMC, BMD, and BA: TB, NS increases Ex boys:

NS increases Ex girls: Age range: 13.5-14.5

PE class warmup calcaneus

BUA: nondominant

Girls: NS differences Ex Girls: n=23

cortical wall thickness

BMAD, CSMI, IBS, and

BMC FN: +9% BMAD LS: +3.7%

LS area: +2.9%

NS differences in BMC

Potential selection bias

Compliance not reported

FN area: +1.1%

FN, LS, TR BUA calcaneus: +3.6%

Boys: BMC TB: +4.3%

group sex differences

Small sample size for between

were derived/estimated

Volumetric bone densities

**Results**

**Limitations**

Physical Activity Interactions with Bone Accrual in Children and Adolescents 393


Table 2. Randomized and Non-Randomized Controlled Studies on the Effects of Exercise **o**n Bone Indices in Youth Ex: exercise group; Con: control group; BMC: bone mineral content; aBMD: areal bone mineral density; vBMD: volumetric BMD; BA: bone area; BMAD: bone mineral apparent density (BMD adjusted for BA); TB: total body; LS: lumbar spine; FN: femoral neck; NN: narrow neck; PF: proximal femur;, WT: wards triangle; TR: trochanter; SXA: single energy x-ray absorptiometry; DXA: dual energy x-ray absorptiometry; DPA: dual photon absorptiometry; QCT: qualitative computed tomography, pQCT; peripheral QCT; HSA: hip structural analysis; QUS: quantitative ultrasound; SOS: speed of sound; SM: section modulus; CSMI: cross-sectional moment of inertia; IBS/BSI: index of bone structural strength; SSI: strength strain index; BUA: broadband ultrasound attenuations; OC: osteocalcin; BSAP: bone-specific alkaline phosphatise; CICP: c-terminal procollagen peptide; PYD: deoxypyridinoline; Ca: calcium; Rx: reaction; BW: body weight; PE: physical education; TS: Tanner sta ge; Pl: Placebo; Gr ps: Grou ps; NS: no si gnificant.

392 Osteoporosis

Table 2. Continued - Studies on the Effects of Exercise on Bone in Youth

Nichols

et al.

Ex: n=5, Con: 11

Age range: 14-17 yrs

All postmenarcheal

Randomized groups

Schneider

et al.

(2007)

Age range:

Ex: n=63, Con: n=59

Hispanic, Asian

schools: 1 Ex + 1 Con

All given 500mg Ca/d

Stear

et al.

Age range: 16-18 yrs

Ca No Ex: n=28

Placebo Ex: n=38

Placebo No Ex: n=28

All postmenarcheal

Randomized, double

Ca: 1000mg/day

high impact movements

45min 3 x week of aerobic to

music: moderate to vigorous

Girls, White

15.5 Months Total n=144 Lunch + after school program

strength building (1 x week),

educational (1 x week) activities

5 x week (~40min activity time)

Variety of aerobic (3 x week), and TR

BSAP, and CICP

Bone resorption: PYD

DXA

Decreased BA in the hip (2003)

Ground rx forces not measured BMC TR: +4.8%

Ex attendance: 36% BA LS: +0.7%

Ca compliance: 70% BMC Hip: +1.4%

blinded 2 schools BMC TR: +2.6%

distal third radius

which may suggest Ca Ex: n=37

total, ultradistal and

TR, hip, nondominant

BMC and BA: TB, LS, FN

BMC Hip: +2.7%

BMC FN: +2.2%

BMC LS: +1.9%

BMC TB: +0.8%

Ca Ex > Placebo No Ex

Ex > No Ex or alternation in bone-edge

compliance (smaller sample)

Results based on good

detection of DXA

redistribution of mineral,

with increasing age,

reorientation of the hip

Poor Ex attendance

approach to attrition taken Randomized two

Bone formation: OC,

 turnover

Hip, thoracic spine, FN

Ethnicity not reported

Girls, White, 10 Months, 2 school semesters

Progression: weight increase

Compliance: Ex. 73%, Study 15%

School based program: 60 min BMC and BMD: TB, LS,

DXA + bone turnover

or markers of bone

Thoracic BMC: +4.9%

NS differences in Population may not be

BMD measurements generalizable as proactive

and terminated participation

Duration of study time points

is unclear

Compliance not reported

30-45 min, 3 x week of 15

BMAD: LS and FN

Resistance training program

 Girls

**Reference**

*Pubertal (Tanner Stage 4-5)*

Heinonen

et al.

(2000)

(Part B)

decided by teachers

box (two and one footed)

Ground rx forces not measured

Compliance: Ex 65%, Study 92%

15 Months

DXA

in small sample size (2001)

weights and machines: FN, WT, and TR

BMC and aBMD: TB, LS,

aBMD FN: +2.3%

aBMD WT: +3.2%

(originally Ex=46, Con=21)

Large dropout rate resulting

Age range: 12.8-15yrs

Selection to groups exercises: 100-200 jumps from

Ex: n=39, Con:, n=29

Step aerobic program: 50 min

2 x week with 20 min of jump

 midshaft

BMC: LS and FN

Girls, White

9 Months

DXA and pQCT

Cortical area: tibial measured

of the bone variables

NS differences in any

Compliance low

Potential selection bias due

to teachers selecting groups

**Population**

**Intervention**

**Measures**

**Results**

**Limitations**

Physical Activity Interactions with Bone Accrual in Children and Adolescents 395

sufficient to instigate bone responses (Heinonen et al., 2000; MacKelvie et al., 2001; McKay et al. 2005, Meyer et al., 2011; Petit et al., 2002). Unlike the studies conducted in prepubertal youth, interventions prescribing weight bearing activities do not need to be conducted over long periods of time to see similar responses in bone. Barbeau et al. (2007), Courteix et al. (2005), and Morris et al. (1997) demonstrated such improvements in 7-12 months time. Interventions in which there were no improvements in bone parameters attributed this to higher levels of leisure PA in the non-experimental groups, increased bone mass at baseline, and earlier menarcheal status (Petit et al., 2002; Sundberg et al., 2001). All of these factors would contribute to bone indices being elevated prior to the intervention allowing for only

small changes to occur and in turn masking any effects of the intervention program.

The fewest PA interventions were conducted in pubertal youth, with all 7 involving girls and 1 including boys. The types of interventions included resistance training (Blimkie et al., 1996; Nichols et al., 2001; Witzke & Snow, 2002), jumping trials (Weeks et al., 2008), and those with a variety of different weight-bearing activities (Heinonen et al., 2000, Schneider et al., 2007, Stear et al., 2003). DXA was the predominant method used to asses bone in this population, with one study using DPA (Blimkie et al., 1996). Three of the studies that used DXA also used an alternate method such as pQCT (Heinonen et al. 2000), QUS (Weeks et al., 2008) and serum biochemical markers of bone turnover (Schneider et al., 2007). Half of the trials demonstrated significant changes (0.7-4.9%) in bone following their interventions, with 3 of the studies demonstrating non-significant trends (Schneider et al., 2007; Weeks et al., 2008, Witzke & Snow, 2002). Of those studies that reported significant trends, one included both an exercise and calcium intervention and observed bone mineral advantages at the femoral neck, lumbar spine and total body in adolescent girls receiving both interventions (Stear et al., 2003). Albeit the combination of calcium and exercise generated greater improvements, those girls receiving just the exercise also demonstrated significant changes at the hip. Schneider et al. (2007) provided all pubertal girls with 500mg of calcium per day and unlike Stear et al. (2003) only observed significant changes in thoracic BMC despite improved trends in BMD and markers of bone turnover. It is possible that these results failed to reach significance as the intervention by Schneider et al. (2007) was shorter in duration than Stear et al. (2003), 10 vs. 15.5 months respectively. Moreover, as everyone in Schneider et al.'s (2007) study was taking calcium the room for improvements may have been smaller than Stear et al.'s (2003) who observed the greatest differences between exercising calcium takers and non- exercising non-calcium consuming controls. Regardless of these discrepancies, the one thing that is clear from these two studies and those described in the early pubertal section (Courteix et al., 2005; Iuliano-Burns et al., 2003), is that calcium is important to bone health and its use during PA interventions will greatly affect results. Three investigations of the effects of resistance training on bone mineral accrual in pubertal girls were completed, with only 1 reporting significant changes in bone indices (Nichols et al., 2001). A major difference between the studies that did not find significant changes (Blimkie et al., 1996; Witzke & Snow, 2002) and the one that did (Nichols et al., 2001) was the duration of the intervention trial. It appears that with resistance training a longer trial of approximately 15 months is necessary to demonstrate significant improvements in bone, similarly to the 15.5 months of WBPA in Stear et al. (2003). In addition to resistance training Witzke & Snow (2002) used plyometric training and the utilization of this may have resulted

**3.3 Pubertal interventions** 

#### **3.2 Early pubertal interventions**

Eighty-three percent of the PA interventions were capable of creating a positive effect on bone strength parameters in pubertal boys and girls. Study durations ranged from 3 months to 4 years, with both the average and median duration being 12 months. The percent gains in bone ranged anywhere between 1.3-15%; again depending on the measurement location and the technique employed. Of the 16 studies conducted in this group 12 utilized DXA, 3 pQCT, 2 QUS, and 1 SXA. Three of the DXA studies also conducted HSA with 2 of the overall studies employing more than one technique to assess experimental effects on bone. The largest improvements in bone for girls was a 10.3% change in aBMD at the FN following 10 months of a mixed program using jumping, weight bearing exercise and weight training (Morris et al, 1997). This large improvement, however, could be the result of a potential selection bias. In boys, the greatest improvements were in the double digits at 10%, 11%, 14% and 15% for LS aBMD, calcaneal SOS, FN aBMD and vBMD, respectively (Sundberg et al., 2001). These finding in boys were demonstrated after 4 years of increased physical education classes that involved a mixed program of weight bearing and jumping activities. In addition to a PA intervention, 2 of the studies also employed a calcium intervention (Courteix et al., 2005; Iuliano-Burns et al., 2003). These studies (Courteix et al., 2005; Iuliano-Burns et al., 2003) demonstrated calcium supplementation in addition to PA can elicit greater responses in bone than with exercise alone, highlighting the importance of monitoring calcium intake during intervention studies particularly during puberty.

The number of interventions conducted in boys and girls was not equal as it was in the prepubertal group making the discussion on gender differences and effects of PA on bone in this group problematic. Three studies in early pubertal children by the same author (Macdonald et al., 2007, 2008, 2009) incorporated 16 months of 60 minute weekly classroom PA including a bone building program of 5-36 jumps per day 4 times a week. Using pQCT, DXA and HSA these studies demonstrated no significant changes in bone strength in the tibia, but improvements in tibial geometry and bending resistance in boys (Macdonald et al., 2007, 2009). Boys also experienced improvements in lumbar spine BMC and whole body BMC, with girls seeing increases in section modulus (a measure of bending resistance) of the femoral neck (Macdonald et al., 2008). These results imply there may be gender differences in the properties of bone that improve following an exercise intervention. There are 3 reasons why the trends shown by Macdonald et al. (2007, 2009) failed to reach significance. Firstly, there was an uneven distribution of sample size, maturity status and gender between groups making some of the groups underpowered. Secondly, as ground reaction forces were not reported it is possible that external loads applied during the intervention was not high enough to instigate a loading response in bone. Third and most likely, the benefits of the jumping intervention could have been attenuated due to the low compliance to the program. In fact, Macdonald et al. (2008) reported significant findings for individuals with 80% compliance. This notion is supported by 3 studies that (MacKelvie et al., 2001, 2003; Petit et al., 2002) demonstrated improvements in BMC, aBMD and vBMD in girls following a shorter jumping program (7 months) eliciting larger ground reaction forces (3.5- 5 x body weight) and for whom study compliance was 80% (MacKelvie et al., 2001).

Not only does it appear that larger loading responses are needed to elicit positive changes in bone, but also the way in which that load is applied to bone matters. A large number of studies (69%) employed specific jumping exercises as part of their intervention demonstrating that short, irregular, diverse large loads at varying times of the day are sufficient to instigate bone responses (Heinonen et al., 2000; MacKelvie et al., 2001; McKay et al. 2005, Meyer et al., 2011; Petit et al., 2002). Unlike the studies conducted in prepubertal youth, interventions prescribing weight bearing activities do not need to be conducted over long periods of time to see similar responses in bone. Barbeau et al. (2007), Courteix et al. (2005), and Morris et al. (1997) demonstrated such improvements in 7-12 months time. Interventions in which there were no improvements in bone parameters attributed this to higher levels of leisure PA in the non-experimental groups, increased bone mass at baseline, and earlier menarcheal status (Petit et al., 2002; Sundberg et al., 2001). All of these factors would contribute to bone indices being elevated prior to the intervention allowing for only small changes to occur and in turn masking any effects of the intervention program.

#### **3.3 Pubertal interventions**

394 Osteoporosis

Eighty-three percent of the PA interventions were capable of creating a positive effect on bone strength parameters in pubertal boys and girls. Study durations ranged from 3 months to 4 years, with both the average and median duration being 12 months. The percent gains in bone ranged anywhere between 1.3-15%; again depending on the measurement location and the technique employed. Of the 16 studies conducted in this group 12 utilized DXA, 3 pQCT, 2 QUS, and 1 SXA. Three of the DXA studies also conducted HSA with 2 of the overall studies employing more than one technique to assess experimental effects on bone. The largest improvements in bone for girls was a 10.3% change in aBMD at the FN following 10 months of a mixed program using jumping, weight bearing exercise and weight training (Morris et al, 1997). This large improvement, however, could be the result of a potential selection bias. In boys, the greatest improvements were in the double digits at 10%, 11%, 14% and 15% for LS aBMD, calcaneal SOS, FN aBMD and vBMD, respectively (Sundberg et al., 2001). These finding in boys were demonstrated after 4 years of increased physical education classes that involved a mixed program of weight bearing and jumping activities. In addition to a PA intervention, 2 of the studies also employed a calcium intervention (Courteix et al., 2005; Iuliano-Burns et al., 2003). These studies (Courteix et al., 2005; Iuliano-Burns et al., 2003) demonstrated calcium supplementation in addition to PA can elicit greater responses in bone than with exercise alone, highlighting the importance of

monitoring calcium intake during intervention studies particularly during puberty.

5 x body weight) and for whom study compliance was 80% (MacKelvie et al., 2001).

Not only does it appear that larger loading responses are needed to elicit positive changes in bone, but also the way in which that load is applied to bone matters. A large number of studies (69%) employed specific jumping exercises as part of their intervention demonstrating that short, irregular, diverse large loads at varying times of the day are

The number of interventions conducted in boys and girls was not equal as it was in the prepubertal group making the discussion on gender differences and effects of PA on bone in this group problematic. Three studies in early pubertal children by the same author (Macdonald et al., 2007, 2008, 2009) incorporated 16 months of 60 minute weekly classroom PA including a bone building program of 5-36 jumps per day 4 times a week. Using pQCT, DXA and HSA these studies demonstrated no significant changes in bone strength in the tibia, but improvements in tibial geometry and bending resistance in boys (Macdonald et al., 2007, 2009). Boys also experienced improvements in lumbar spine BMC and whole body BMC, with girls seeing increases in section modulus (a measure of bending resistance) of the femoral neck (Macdonald et al., 2008). These results imply there may be gender differences in the properties of bone that improve following an exercise intervention. There are 3 reasons why the trends shown by Macdonald et al. (2007, 2009) failed to reach significance. Firstly, there was an uneven distribution of sample size, maturity status and gender between groups making some of the groups underpowered. Secondly, as ground reaction forces were not reported it is possible that external loads applied during the intervention was not high enough to instigate a loading response in bone. Third and most likely, the benefits of the jumping intervention could have been attenuated due to the low compliance to the program. In fact, Macdonald et al. (2008) reported significant findings for individuals with 80% compliance. This notion is supported by 3 studies that (MacKelvie et al., 2001, 2003; Petit et al., 2002) demonstrated improvements in BMC, aBMD and vBMD in girls following a shorter jumping program (7 months) eliciting larger ground reaction forces (3.5-

**3.2 Early pubertal interventions** 

The fewest PA interventions were conducted in pubertal youth, with all 7 involving girls and 1 including boys. The types of interventions included resistance training (Blimkie et al., 1996; Nichols et al., 2001; Witzke & Snow, 2002), jumping trials (Weeks et al., 2008), and those with a variety of different weight-bearing activities (Heinonen et al., 2000, Schneider et al., 2007, Stear et al., 2003). DXA was the predominant method used to asses bone in this population, with one study using DPA (Blimkie et al., 1996). Three of the studies that used DXA also used an alternate method such as pQCT (Heinonen et al. 2000), QUS (Weeks et al., 2008) and serum biochemical markers of bone turnover (Schneider et al., 2007). Half of the trials demonstrated significant changes (0.7-4.9%) in bone following their interventions, with 3 of the studies demonstrating non-significant trends (Schneider et al., 2007; Weeks et al., 2008, Witzke & Snow, 2002). Of those studies that reported significant trends, one included both an exercise and calcium intervention and observed bone mineral advantages at the femoral neck, lumbar spine and total body in adolescent girls receiving both interventions (Stear et al., 2003). Albeit the combination of calcium and exercise generated greater improvements, those girls receiving just the exercise also demonstrated significant changes at the hip. Schneider et al. (2007) provided all pubertal girls with 500mg of calcium per day and unlike Stear et al. (2003) only observed significant changes in thoracic BMC despite improved trends in BMD and markers of bone turnover. It is possible that these results failed to reach significance as the intervention by Schneider et al. (2007) was shorter in duration than Stear et al. (2003), 10 vs. 15.5 months respectively. Moreover, as everyone in Schneider et al.'s (2007) study was taking calcium the room for improvements may have been smaller than Stear et al.'s (2003) who observed the greatest differences between exercising calcium takers and non- exercising non-calcium consuming controls. Regardless of these discrepancies, the one thing that is clear from these two studies and those described in the early pubertal section (Courteix et al., 2005; Iuliano-Burns et al., 2003), is that calcium is important to bone health and its use during PA interventions will greatly affect results. Three investigations of the effects of resistance training on bone mineral accrual in pubertal girls were completed, with only 1 reporting significant changes in bone indices (Nichols et al., 2001). A major difference between the studies that did not find significant changes (Blimkie et al., 1996; Witzke & Snow, 2002) and the one that did (Nichols et al., 2001) was the duration of the intervention trial. It appears that with resistance training a longer trial of approximately 15 months is necessary to demonstrate significant improvements in bone, similarly to the 15.5 months of WBPA in Stear et al. (2003). In addition to resistance training

Witzke & Snow (2002) used plyometric training and the utilization of this may have resulted

Physical Activity Interactions with Bone Accrual in Children and Adolescents 397

(Schneider et al., 2007; Stear et al., 2003) stages. Moreover, the velocity for BMC accrual is highest in early puberty prior to menarche (in girls) (Bailey et al., 1996, 1997; Cadogan et al., 1998, after which accrual rates decrease with age plateauing in late adolescence upon achieving PBM (Davies et al., 2005). Therefore, the 'window of opportunity' to impart the

Based on our systematic review of the literature we can deduce that regular exercise can be an effective way to improve bone density, size, and shape; in turn improving the mechanical strength of bone. With the variability in the types of interventions used and how they were employed there is no clear consensus on exactly how we should prescribe exercise in order to see the greatest returns in terms of bone health. However, in reviewing the literature, regardless of pubertal stage, the duration of the trial and the intensity in which it was employed appeared to matter. If interventions were short in duration (8-10 months) those that utilized jumping activities with high ground reaction forces received the most positive results (Bass et al. 2007; Fuchs et al., 2001; MacKelvie et al., 2001, 2002; McKay et al., 2005; Petit et al., 2002; Weeks et al., 2008). If weight bearing PA or resistance training was utilized the length of the intervention needed to be longer (10-24 months depending on maturity), in order to see significant gains in bone (Alwis et al., 2008a; Courteix et al., 2005; Linden et al., 2006, 2007; Morris et al., 1997; Nichols et al., 2001; Stear et al., 2003; Valdimarsson et al., 2006). In terms of frequency of exercise, Turner & Robling (2003) suggest it is better to shorten each individual exercise session than to reduce the number of sessions, as jump training has been shown to improve BMC when performed at least 3 time per week but not when reduced to 2 time per week, with gains increasing up to 5 days a week with 2 shorter session in one day. This is reflected in the interventions reviewed with significant gains in bone indices being observed in trials occurring 3-5 times per week. The most recent intervention study reviewed (Meyer et al., 2011) is a good example of these last two concepts by demonstrating that a variety of different activities in one intervention at random times of the day can be effective in eliciting bone gains. Therefore, PA is beneficial for bone health and irregular activities utilizing jump and resisting training to weight bearing activities are some of the best ways to elicit an adaptive response in bone. Not only is the variety beneficial for bone but it can also help to alleviate the boredom that accompanies exercise

largest influences on bone development may be during early puberty.

**4.2 Optimal physical activity interventions for bone adaptations** 

regimens. Remember that in terms of bone change really is good!

DXA was the technique most often used in the PA intervention trials reviewed, and was used to measure BMC and BMD in various skeletal regions of the body. However, BMD assessed using DXA is an estimation of 'true' bone density and the areal density that is expressed is affected by bone size making it difficult to interpret, evaluate and compare BMD in the growing years when there are considerable changes to the size and shape of bone in children (Bailey et al., 1996; Fulkerson et al., 2004; Gordon, 2003; Schoenau et al., 2004). Moreover aBMD is a surrogate measure for bone strength and even though BMC and BMD are related to bone strength inferring information regarding strength from studies using these measures can be misleading. This fact is represented in the many studies citing increases in BMD and BMC that were not always significant. It is possible that DXA may not be sensitive enough to detect small changes in bone particularly at a time in development

**4.3 Methodological issues** 

in the strong non-significant trends, demonstrating that perhaps shorter trials that include ground reaction forces can be efficacious at improving bone. Results from studies examining jumping trials (Heinonen et al., 2000; Weeks et al., 2008) 8-9 months in duration have been ambiguous. Heinonen et al. (2000) failed to measure significant changes in bone; however, Weeks et al. (2008) did observe improved total body BMC in pubertal boys but not girls. Interestingly, Weeks et al. (2008) did measure large percent changes, albeit non-significant trends, in many different parameters of bone strength in both boys and girls. These trends could be the result of the greater ground reaction forces used in this study compared to that of Heinonen et al. (2000) and could possibly have reached significant if the length of the trial were longer. A common theme in all of these studies not having significant findings or 'almost' measuring differences is poor compliance. If it were not for the issues with compliance, there is a large probability these studies would have found significant results. Another important factor as to why very few studies reported changes in pubertal youth is due to how bone is accrued in this maturity group. According to Bailey et al. (1996, 1999) peak velocity of BMC accrual for the whole body occurs approximately 0.7-1 year after peak linear growth around the time of menarche, which corresponds to approximately 12-13 years of age in girls. The pubertal girls in the 7 studies reviewed were between the ages of 13 and 18, putting them after the point of peak BMC velocity accrual where the velocity at which they are accruing bone is actually decreasing. The schematic representation of PBM and the rate at which bone mass is accrued over time resembles a dose response curve. It would appear that the pubertal girls in these studies are nearing their PBM, putting them near the plateau of the accrual process, and therefore both the rate and amount of BMC that can be accrued during this time is less. As a result, detecting significant changes will be difficult. Just because these percent gains are small and non-significant statistically does not mean that they are not meaningful. Turner and Robling (2003) demonstrated that a 5.4% and 6.9% gain in aBMD and BMC respectively, translated into a 64% and 94% increase in the amount of force and energy a bone could absorb before failure. This suggests that even small changes in bone mass, which are marginally detectable by DXA can significantly improve bone strength. Therefore a little bone goes a long way.

### **4. Discussion**

#### **4.1 The window of opportunity for bone adaptations**

The early pubertal period may be the best time to generate skeletal adaptations to PA. Studies conducted in more than one maturity group demonstrated positive bone gains in early pubertal girls with no significant increases in prepubertal (MacKelvie et al., 2001; MacKelvie et al., 2003; Petite et al., 2002) or pubertal (Heinonen et al., 2000) girls. When reviewing all of the intervention studies the greatest gains in bone on average, regardless of sex, skeletal location and type of activity used, was during the early pubertal years. These results are more definitive in girls as a larger proportion of intervention studies have been conducted on females across puberty, with the sample of boys decreasing with maturity. Despite this trend, longer duration intervention studies where boys most likely transitioned from pre- to early puberty also demonstrate larger gains in bone than in just prepubertal boys (MacKelvie et al., 2004). Larger skeletal gains were also observed in interventions trials that supplemented with calcium during early puberty (Courteix et al., 2005; Iuliano-Burns et al., 2003) compared to those supplementing in prepubertal (Bass et al., 2007) and pubertal

in the strong non-significant trends, demonstrating that perhaps shorter trials that include ground reaction forces can be efficacious at improving bone. Results from studies examining jumping trials (Heinonen et al., 2000; Weeks et al., 2008) 8-9 months in duration have been ambiguous. Heinonen et al. (2000) failed to measure significant changes in bone; however, Weeks et al. (2008) did observe improved total body BMC in pubertal boys but not girls. Interestingly, Weeks et al. (2008) did measure large percent changes, albeit non-significant trends, in many different parameters of bone strength in both boys and girls. These trends could be the result of the greater ground reaction forces used in this study compared to that of Heinonen et al. (2000) and could possibly have reached significant if the length of the trial were longer. A common theme in all of these studies not having significant findings or 'almost' measuring differences is poor compliance. If it were not for the issues with compliance, there is a large probability these studies would have found significant results. Another important factor as to why very few studies reported changes in pubertal youth is due to how bone is accrued in this maturity group. According to Bailey et al. (1996, 1999) peak velocity of BMC accrual for the whole body occurs approximately 0.7-1 year after peak linear growth around the time of menarche, which corresponds to approximately 12-13 years of age in girls. The pubertal girls in the 7 studies reviewed were between the ages of 13 and 18, putting them after the point of peak BMC velocity accrual where the velocity at which they are accruing bone is actually decreasing. The schematic representation of PBM and the rate at which bone mass is accrued over time resembles a dose response curve. It would appear that the pubertal girls in these studies are nearing their PBM, putting them near the plateau of the accrual process, and therefore both the rate and amount of BMC that can be accrued during this time is less. As a result, detecting significant changes will be difficult. Just because these percent gains are small and non-significant statistically does not mean that they are not meaningful. Turner and Robling (2003) demonstrated that a 5.4% and 6.9% gain in aBMD and BMC respectively, translated into a 64% and 94% increase in the amount of force and energy a bone could absorb before failure. This suggests that even small changes in bone mass, which are marginally detectable by DXA can significantly

improve bone strength. Therefore a little bone goes a long way.

The early pubertal period may be the best time to generate skeletal adaptations to PA. Studies conducted in more than one maturity group demonstrated positive bone gains in early pubertal girls with no significant increases in prepubertal (MacKelvie et al., 2001; MacKelvie et al., 2003; Petite et al., 2002) or pubertal (Heinonen et al., 2000) girls. When reviewing all of the intervention studies the greatest gains in bone on average, regardless of sex, skeletal location and type of activity used, was during the early pubertal years. These results are more definitive in girls as a larger proportion of intervention studies have been conducted on females across puberty, with the sample of boys decreasing with maturity. Despite this trend, longer duration intervention studies where boys most likely transitioned from pre- to early puberty also demonstrate larger gains in bone than in just prepubertal boys (MacKelvie et al., 2004). Larger skeletal gains were also observed in interventions trials that supplemented with calcium during early puberty (Courteix et al., 2005; Iuliano-Burns et al., 2003) compared to those supplementing in prepubertal (Bass et al., 2007) and pubertal

**4.1 The window of opportunity for bone adaptations** 

**4. Discussion** 

(Schneider et al., 2007; Stear et al., 2003) stages. Moreover, the velocity for BMC accrual is highest in early puberty prior to menarche (in girls) (Bailey et al., 1996, 1997; Cadogan et al., 1998, after which accrual rates decrease with age plateauing in late adolescence upon achieving PBM (Davies et al., 2005). Therefore, the 'window of opportunity' to impart the largest influences on bone development may be during early puberty.

### **4.2 Optimal physical activity interventions for bone adaptations**

Based on our systematic review of the literature we can deduce that regular exercise can be an effective way to improve bone density, size, and shape; in turn improving the mechanical strength of bone. With the variability in the types of interventions used and how they were employed there is no clear consensus on exactly how we should prescribe exercise in order to see the greatest returns in terms of bone health. However, in reviewing the literature, regardless of pubertal stage, the duration of the trial and the intensity in which it was employed appeared to matter. If interventions were short in duration (8-10 months) those that utilized jumping activities with high ground reaction forces received the most positive results (Bass et al. 2007; Fuchs et al., 2001; MacKelvie et al., 2001, 2002; McKay et al., 2005; Petit et al., 2002; Weeks et al., 2008). If weight bearing PA or resistance training was utilized the length of the intervention needed to be longer (10-24 months depending on maturity), in order to see significant gains in bone (Alwis et al., 2008a; Courteix et al., 2005; Linden et al., 2006, 2007; Morris et al., 1997; Nichols et al., 2001; Stear et al., 2003; Valdimarsson et al., 2006). In terms of frequency of exercise, Turner & Robling (2003) suggest it is better to shorten each individual exercise session than to reduce the number of sessions, as jump training has been shown to improve BMC when performed at least 3 time per week but not when reduced to 2 time per week, with gains increasing up to 5 days a week with 2 shorter session in one day. This is reflected in the interventions reviewed with significant gains in bone indices being observed in trials occurring 3-5 times per week. The most recent intervention study reviewed (Meyer et al., 2011) is a good example of these last two concepts by demonstrating that a variety of different activities in one intervention at random times of the day can be effective in eliciting bone gains. Therefore, PA is beneficial for bone health and irregular activities utilizing jump and resisting training to weight bearing activities are some of the best ways to elicit an adaptive response in bone. Not only is the variety beneficial for bone but it can also help to alleviate the boredom that accompanies exercise regimens. Remember that in terms of bone change really is good!

### **4.3 Methodological issues**

DXA was the technique most often used in the PA intervention trials reviewed, and was used to measure BMC and BMD in various skeletal regions of the body. However, BMD assessed using DXA is an estimation of 'true' bone density and the areal density that is expressed is affected by bone size making it difficult to interpret, evaluate and compare BMD in the growing years when there are considerable changes to the size and shape of bone in children (Bailey et al., 1996; Fulkerson et al., 2004; Gordon, 2003; Schoenau et al., 2004). Moreover aBMD is a surrogate measure for bone strength and even though BMC and BMD are related to bone strength inferring information regarding strength from studies using these measures can be misleading. This fact is represented in the many studies citing increases in BMD and BMC that were not always significant. It is possible that DXA may not be sensitive enough to detect small changes in bone particularly at a time in development

Physical Activity Interactions with Bone Accrual in Children and Adolescents 399

exercise self-efficacy and barriers to exercise are the best predictors of weight bearing exercise and dietary intake (Wallace, 2002), with educational interventions targeting youth demonstrating improvements in bone health knowledge, increases in intake of calcium rich foods and calcium self-efficacy (Schrader et al., 2005; Sharma et al., 2010). Therefore, knowing which factors will help children and adolescents adopt healthy 'bone' behaviors is

Based on our literature review we know that structured and controlled PA interventions are effective in eliciting bone gains in youth. In order for youth to get involved in osteoporosis preventative behaviors such as PA they need to be able intervene in their daily lives on their own. McWannell et al. (2008) conducted a study to determine whether a structured high impact exercise program would be more effective in improving BMC and BMD than a lifestyle intervention program promoting PA in middle school children 10-11 years of age. This study demonstrated that the structured high impact PA program significantly improved total body BMC and BMD compared to controls after 9 weeks, with the lifestyle intervention seeing insignificant trends for bone gains. Moreover, a health plan-based lifestyle intervention designed at improving both diet and PA in adolescent girls outside of school demonstrated significant improvements in BMD and bone metabolism due to greater consumption of calcium and vitamin D (DeBar et al., 2006). However, when a larger focus was placed on PA and the adolescent girls taught how to properly conduct exercises a selfled PA program proved to be just as significant in improving bone strength parameters as a structured teacher-led PA program (Murphy et al., 2006). More importantly, those girls involved in the self-led PA program continued to exercise after the intervention had ceased, whereas the teach-led group did not. Therefore, it is not only important to get youth physically active in order to improve bone health, it is just as important to develop the

With the current growing inactivity and unhealthy dietary habits, the body composition of youth is changing making this systemic review regarding the different types of exercise interventions, those utilizing resistance training vs. ground reaction forces, relevant. For long-term gains, it appears that short-term high-impact exercises undertaken early in childhood (pre and early puberty) if sustained into adulthood has a persistent effect over and beyond that of normal growth and development. Benefits in total body, lumbar spine, thoracic and femoral neck BMC (2.3-4.4%) as well as BMC at the hip (1.4%) have respectively been observed 3 (Gunter et al., 2008b) and 5 years (Gunter et al., 2008) following the jumping intervention by Fuchs et al. (2001). It is therefore redundant in some respect to conduct more PA interventions, unless more advanced techniques of measuring bone are used, as it is apparent from this review that PA in a structured controlled environment is effective in creating positive gains in bone. The next step is to influence change by schools either adopting these activities into their physical education curriculums or providing youth with the tools to administer this change on their own. Therefore, the examination of behavioral, social-psychological variables in addition to physical determinants of skeletal development provides a holistic multi-faceted conceptual framework of bone health that will provide the tools to better disseminate knowledge on positive bone building activities

important to making the exercise interventions we reviewed a reality.

personal skills necessary to direct their own activity.

in hopes of creating life-long PA practices.

**5. Conclusions** 

when small changes are difficult to come by, like later in puberty when the rate of BMC accrual is decreasing. However, even these small detectable changes in bone mass using DXA can signify improvements in bone strength most likely by favourably altering bone geometry (Turner & Robling, 2003). Therefore the best parameter for assessing the effectiveness of PA interventions on bone would be to use a technique that includes measures of bone strength but also bone shape and size.

pQCT is a method that can be used to detect true vBMD, bone strength, shape and size. Unfortunately, only 5 of the studies that we reviewed utilized this method. An advantage of using pQCT to compare bone structural differences is that it has the capability to demonstrate bone strength adaptations in bone size via changes in cortical thickness or area through investigation of periosteal or endocortical expansion (Haapasalo et al., 2000; Kontulainen et al., 2002; Nikander et al., 2009). Moreover, these measurements indirectly provide an idea of the dynamic course of bone and how bone is metabolized to infer strength. However, to date only 1 study has directly measured biochemical markers of bone turnover in response to a PA intervention (Schneider et al., 2007). Measuring bone turnover would allow for detection of potential exercise effects sooner, as gains in bone markers have been demonstrated after 8 weeks of resistance training in women 20 years of age (Lester et al., 2009). Moreover, reference values for many of the markers have been set within the literature allowing for comparison across studies; something that is difficult to do for static measures of bone as the standards and definitions defining low bone mass are available only for postmenopausal women and not youth.

One way of avoiding this issue is to cease relating bone mass and strength to age, and relate it instead to muscle function (Schoenau & Fricke, 2008). This new methodological concept is based on the thought that the critical property of bone is strength rather than weight and that what influences bone strength are the mechanical loads it must endure either through PA or muscle contraction. Regardless of the mode of mechanical load the stability of the bone must be adapted to muscle strength, in a sense creating a functional muscle-bone unit (Schoenau & Fricke, 2008). Such an analysis removes the concept of a 'peak bone mass', which in fact is something we are not capable of measuring for an individual. Instead this approach allows for determination and comparison of bone deficits irrespective of age as bone strength is related to the strength and function of muscle (Schoenau & Fricke, 2008). Moreover, this approach moves away from looking at bone as a separate entity but as functionally linked system.

#### **4.4 Psycho-social factors**

It is also important to consider the psycho-social factors that are believed to affect bone health; these include osteoporosis beliefs, knowledge and practises. Women's willingness to adopt healthy behaviors depends on their level of knowledge of osteoporosis (Cook et al., 1991; Jamal et al., 1999). Majority of research examining calcium intake and PA with respect to osteoporosis knowledge and beliefs, and as preventative behaviours have been investigated in post menopausal women (Tudor-Locke & McColl, 2000). A few researchers have examined these criteria in younger women (Kasper et al., 1994, 2001; Wallace, 2002), let alone in adolescents (Anderson et al., 2005; Schrader et al., 2005). A lack of knowledge about osteoporosis risk factors (insufficient calcium intake and daily PA), as well as perceptions of low risk for developing osteoporosis, has been reported among college women (Kasper et al., 2001) and adolescent females (Anderson et al., 2005). Moreover, studies have suggested exercise self-efficacy and barriers to exercise are the best predictors of weight bearing exercise and dietary intake (Wallace, 2002), with educational interventions targeting youth demonstrating improvements in bone health knowledge, increases in intake of calcium rich foods and calcium self-efficacy (Schrader et al., 2005; Sharma et al., 2010). Therefore, knowing which factors will help children and adolescents adopt healthy 'bone' behaviors is important to making the exercise interventions we reviewed a reality.

Based on our literature review we know that structured and controlled PA interventions are effective in eliciting bone gains in youth. In order for youth to get involved in osteoporosis preventative behaviors such as PA they need to be able intervene in their daily lives on their own. McWannell et al. (2008) conducted a study to determine whether a structured high impact exercise program would be more effective in improving BMC and BMD than a lifestyle intervention program promoting PA in middle school children 10-11 years of age. This study demonstrated that the structured high impact PA program significantly improved total body BMC and BMD compared to controls after 9 weeks, with the lifestyle intervention seeing insignificant trends for bone gains. Moreover, a health plan-based lifestyle intervention designed at improving both diet and PA in adolescent girls outside of school demonstrated significant improvements in BMD and bone metabolism due to greater consumption of calcium and vitamin D (DeBar et al., 2006). However, when a larger focus was placed on PA and the adolescent girls taught how to properly conduct exercises a selfled PA program proved to be just as significant in improving bone strength parameters as a structured teacher-led PA program (Murphy et al., 2006). More importantly, those girls involved in the self-led PA program continued to exercise after the intervention had ceased, whereas the teach-led group did not. Therefore, it is not only important to get youth physically active in order to improve bone health, it is just as important to develop the personal skills necessary to direct their own activity.

### **5. Conclusions**

398 Osteoporosis

when small changes are difficult to come by, like later in puberty when the rate of BMC accrual is decreasing. However, even these small detectable changes in bone mass using DXA can signify improvements in bone strength most likely by favourably altering bone geometry (Turner & Robling, 2003). Therefore the best parameter for assessing the effectiveness of PA interventions on bone would be to use a technique that includes

pQCT is a method that can be used to detect true vBMD, bone strength, shape and size. Unfortunately, only 5 of the studies that we reviewed utilized this method. An advantage of using pQCT to compare bone structural differences is that it has the capability to demonstrate bone strength adaptations in bone size via changes in cortical thickness or area through investigation of periosteal or endocortical expansion (Haapasalo et al., 2000; Kontulainen et al., 2002; Nikander et al., 2009). Moreover, these measurements indirectly provide an idea of the dynamic course of bone and how bone is metabolized to infer strength. However, to date only 1 study has directly measured biochemical markers of bone turnover in response to a PA intervention (Schneider et al., 2007). Measuring bone turnover would allow for detection of potential exercise effects sooner, as gains in bone markers have been demonstrated after 8 weeks of resistance training in women 20 years of age (Lester et al., 2009). Moreover, reference values for many of the markers have been set within the literature allowing for comparison across studies; something that is difficult to do for static measures of bone as the standards and definitions defining low bone mass are available

One way of avoiding this issue is to cease relating bone mass and strength to age, and relate it instead to muscle function (Schoenau & Fricke, 2008). This new methodological concept is based on the thought that the critical property of bone is strength rather than weight and that what influences bone strength are the mechanical loads it must endure either through PA or muscle contraction. Regardless of the mode of mechanical load the stability of the bone must be adapted to muscle strength, in a sense creating a functional muscle-bone unit (Schoenau & Fricke, 2008). Such an analysis removes the concept of a 'peak bone mass', which in fact is something we are not capable of measuring for an individual. Instead this approach allows for determination and comparison of bone deficits irrespective of age as bone strength is related to the strength and function of muscle (Schoenau & Fricke, 2008). Moreover, this approach moves away from looking at bone as a separate entity but as

It is also important to consider the psycho-social factors that are believed to affect bone health; these include osteoporosis beliefs, knowledge and practises. Women's willingness to adopt healthy behaviors depends on their level of knowledge of osteoporosis (Cook et al., 1991; Jamal et al., 1999). Majority of research examining calcium intake and PA with respect to osteoporosis knowledge and beliefs, and as preventative behaviours have been investigated in post menopausal women (Tudor-Locke & McColl, 2000). A few researchers have examined these criteria in younger women (Kasper et al., 1994, 2001; Wallace, 2002), let alone in adolescents (Anderson et al., 2005; Schrader et al., 2005). A lack of knowledge about osteoporosis risk factors (insufficient calcium intake and daily PA), as well as perceptions of low risk for developing osteoporosis, has been reported among college women (Kasper et al., 2001) and adolescent females (Anderson et al., 2005). Moreover, studies have suggested

measures of bone strength but also bone shape and size.

only for postmenopausal women and not youth.

functionally linked system.

**4.4 Psycho-social factors** 

With the current growing inactivity and unhealthy dietary habits, the body composition of youth is changing making this systemic review regarding the different types of exercise interventions, those utilizing resistance training vs. ground reaction forces, relevant. For long-term gains, it appears that short-term high-impact exercises undertaken early in childhood (pre and early puberty) if sustained into adulthood has a persistent effect over and beyond that of normal growth and development. Benefits in total body, lumbar spine, thoracic and femoral neck BMC (2.3-4.4%) as well as BMC at the hip (1.4%) have respectively been observed 3 (Gunter et al., 2008b) and 5 years (Gunter et al., 2008) following the jumping intervention by Fuchs et al. (2001). It is therefore redundant in some respect to conduct more PA interventions, unless more advanced techniques of measuring bone are used, as it is apparent from this review that PA in a structured controlled environment is effective in creating positive gains in bone. The next step is to influence change by schools either adopting these activities into their physical education curriculums or providing youth with the tools to administer this change on their own. Therefore, the examination of behavioral, social-psychological variables in addition to physical determinants of skeletal development provides a holistic multi-faceted conceptual framework of bone health that will provide the tools to better disseminate knowledge on positive bone building activities in hopes of creating life-long PA practices.

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**Part 6** 

**Prevention and Management of Osteoporosis** 

