*2.4.3. Comorbidities*

Patient factors such as diabetes mellitus, cigarette smoking and osteoporosis have been suggested to negatively affect the clinical outcomes and healing of RCTs [3, 14].

#### *2.4.4. Hand dominance*

There is no clear evidence to associate hand dominance with the development of RCTs [15]; however, one study demonstrated that in the dominant shoulders of 150 veteran competitive tennis players, there were more frequent RCTs, suggesting an association of high-energy activity [16].

#### *2.4.5. Contralateral shoulder*

Multiple authors have reported that those who have an established RCT, regardless whether partial or full-thickness and size, are at an increased risk of developing a contralateral RCT [17, 18]. Yamaguchi et al. [10] estimated the prevalence of full-thickness bilateral RCTs at 35%, increasing to as high as 50% in those over the age of 60 years.

#### *2.4.6. Smoking*

It is well recognised that smoking reduces microvascular perfusion, possibly reducing rotator cuff tendon vascular perfusion and healing [19]. Baumgarten et al. [20] conducted a study of 375 patients with RCTs confirmed by ultrasound (of all patients presenting with shoulder pain in general, of all demographics and characteristics). Of these 375 patients, 232 (62%) were smokers with a mean 23.4 years of smoking 1.25 packs per day and 30.1 mean packyears. This is confirmed by the systematic review by Bishop et al. [21] in which increased rates and sizes of rotator cuff degeneration and symptomatic RCTs were seen in smokers, which could consequently increased the number of surgical procedures in these patients. However, there is no case control in these studies, and therefore no strong dose- and timedependent association between smoking and the development of RCTs could be established.

#### *2.4.7. Family history*

likely to develop a tear that was likely to progress to full-thickness and larger tears (54% of tears in patients older than 60 years showed such progression compared to only 17% of tears in those younger than 60 years). A cohort of patients younger than 60 years who were treated non-operatively for FTTs was found to have a higher rate of tear progression than older patients. Of the 61 tears, 49% increased in size according to the findings of ultrasound

It has generally been reported that there are comparable incidence and characteristics of RCTs in both males and females [12], although only one study by Abate et al. [13] that specifically assessed menopausal women suggested that these women had an increased prevalence of

Patient factors such as diabetes mellitus, cigarette smoking and osteoporosis have been sug-

There is no clear evidence to associate hand dominance with the development of RCTs [15]; however, one study demonstrated that in the dominant shoulders of 150 veteran competitive tennis players, there were more frequent RCTs, suggesting an association of high-energy

Multiple authors have reported that those who have an established RCT, regardless whether partial or full-thickness and size, are at an increased risk of developing a contralateral RCT [17, 18]. Yamaguchi et al. [10] estimated the prevalence of full-thickness bilateral RCTs at 35%,

It is well recognised that smoking reduces microvascular perfusion, possibly reducing rotator cuff tendon vascular perfusion and healing [19]. Baumgarten et al. [20] conducted a study of 375 patients with RCTs confirmed by ultrasound (of all patients presenting with shoulder pain in general, of all demographics and characteristics). Of these 375 patients, 232 (62%) were smokers with a mean 23.4 years of smoking 1.25 packs per day and 30.1 mean packyears. This is confirmed by the systematic review by Bishop et al. [21] in which increased rates and sizes of rotator cuff degeneration and symptomatic RCTs were seen in smokers, which could consequently increased the number of surgical procedures in these patients. However, there is no case control in these studies, and therefore no strong dose- and timedependent association between smoking and the development of RCTs could be established.

gested to negatively affect the clinical outcomes and healing of RCTs [3, 14].

increasing to as high as 50% in those over the age of 60 years.

imaging [11].

18 Advances in Shoulder Surgery

*2.4.3. Comorbidities*

*2.4.4. Hand dominance*

*2.4.5. Contralateral shoulder*

activity [16].

*2.4.6. Smoking*

asymptomatic FTT in the postmenopausal period.

*2.4.2. Sex*

There is limited evidence regarding the genetic predisposition and hereditary component for RCTs; however, a study examining the genealogical database in Utah, USA by Tashjian et al. [22] a population-based controlled study of 3091 patients, with a subgroup analysis of 652 patients diagnosed before 40 years of age, showed a significant association between individuals with rotator cuff disease in close and distant relations (reportedly up to third cousin relations). This study was included in the systematic review conducted by Dabija et al. [23], which includes the study by Harvie et al. [24], concluding that siblings of patients diagnosed with RCTs were twice as likely to develop complete RCTs. In addition, they identified single-nucleotide polymorphisms (SNPs) associated with RCTs, indicating the future risk for development of RCTs to enable prophylactic rehabilitation techniques and to avoid the development of symptomatic RCTs [23].
