**7.4 Cementing techniques**

Improvements in prosthesis survival have accompanied advances in cementation technique100. First generation cementing techniques involved finger packing of the cement without bone preparation, pressurization or use of a medullary plug. In the mid-seventies second generation techniques were adopted which involved improved canal preparation by pulsatile lavage that increased cement penetration and interdigitation, retrograde insertion of cement using a gun to reduce blood lamination, and the use of an intramedullary plug to limit the size of the cement column. Studies with 10 year follow up have shown that 2nd generation techniques were associated with a reduced the incidence in femoral loosening with rates of 3 to 7%101,102 compared with rates of approximately 30% at 10 years in first generation reports103,104. Third generation techniques included vacuum mixing of cement to reduce cement porosity and increase fatigue strength105, and cement pressurization to

Risk Factors for Aseptic Loosening Following Total Hip Arthroplasty 289

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further improve cement interdigitation. Subsequently 4th generation cementation techniques have added distal and proximal prosthesis centralizers to improve the stem position allowing for an optimal and even cement mantle. Herbert, in a review of the Swedish THA Register examining 160,000 cases, reported that the evolution from 1st to 3rd generation cementing techniques over a 20 year period was associated with a reduced incidence of revision for aseptic loosening100.

### **8. Summary and future directions**

Aseptic loosening is the end result of a complex interaction of variables leading to development of osteolysis. Although the last 30 years has seen many advances in the understanding of these factors, osteolysis will remain a problem for the foreseeable future. Newer bearing surfaces have shown potential in wear rate reduction. However, wear particles from all materials have the potential to trigger an inflammatory response. The local and systemic consequences of metal release also need to be more clearly defined and quantitated. Further studies looking at prosthesis bone anchorage in conjuction with particle and pressure effects need to be explored, and the factors that influence loosening membrane formation.

Currently the only effective treatment for aseptic loosening is revision surgery. Future advances in our understanding of the biological response to wear particles may lead to the development of biological markers for better prediction and early detection of osteolysis, and the development of non-surgical solutions for prophylaxis and therapy. Advances in genomic and bioinformatics technology have provided us with the opportunity to identify investigational targets for prophylaxis or treatment. Pharmocological and biological agents used in the treatment of osteolysis in metastatic disease and metabolic bone disease may have potential in osteolysis following THA.

### **9. References**


further improve cement interdigitation. Subsequently 4th generation cementation techniques have added distal and proximal prosthesis centralizers to improve the stem position allowing for an optimal and even cement mantle. Herbert, in a review of the Swedish THA Register examining 160,000 cases, reported that the evolution from 1st to 3rd generation cementing techniques over a 20 year period was associated with a reduced incidence of

Aseptic loosening is the end result of a complex interaction of variables leading to development of osteolysis. Although the last 30 years has seen many advances in the understanding of these factors, osteolysis will remain a problem for the foreseeable future. Newer bearing surfaces have shown potential in wear rate reduction. However, wear particles from all materials have the potential to trigger an inflammatory response. The local and systemic consequences of metal release also need to be more clearly defined and quantitated. Further studies looking at prosthesis bone anchorage in conjuction with particle and pressure effects need to be explored, and the factors that influence loosening membrane formation. Currently the only effective treatment for aseptic loosening is revision surgery. Future advances in our understanding of the biological response to wear particles may lead to the development of biological markers for better prediction and early detection of osteolysis, and the development of non-surgical solutions for prophylaxis and therapy. Advances in genomic and bioinformatics technology have provided us with the opportunity to identify investigational targets for prophylaxis or treatment. Pharmocological and biological agents used in the treatment of osteolysis in metastatic disease and metabolic bone disease may

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**15** 

*Bulgaria* 

**Evidence Linking Elevated Oxidative** 

**Stress and Aseptic Loosening** 

*Queen Giovanna – ISUL University Hospital, Department of Orthopedics and Traumatology, Medical University of Sofia* 

Aseptic loosening is still the most common late complication after total hip arthroplasty (THA) and one of the main reasons for its failure. Artificial joints are made of metallic, polymeric and ceramic components. In the process of prosthesis functioning in the recipient's body implant materials are subject to wear and fretting as well as of influence of aggressive biological fluids. Wear debris particles, corrosion products and metal ions from the bearing and contact surfaces of the implant are released in the periprosthetic tissues. As a result of the processes taking part at the implant-bone interface osteolysis develops with

Today, the most widely used bearing surface is a metal femoral head made of cobalt chromium molybdenum alloy coupled with a polymeric inlay fabricated from ultra-high molecular weight polyethylene (UHMWPE). For decades in clinical use, metal on polyethylene (MoPE) bearings in total hip arthroplasty provided consistent results. Despite the widespread use of UHMWPE as a bearing surface its wear is the main obstacle restricting the longevity of the artificial joint. With an average rate of polyethylene (PE) wear of 0.1mm per year, 100 million UHMWPE particles (assumed diameter of 1 μm) are liberated into the joint space on a daily basis (Muratoglu & Kurtz, 2002). It is now well established that cyclic mechanical loading, production of wear particles, and the ensuing cascade of adverse tissue response are all significant contributors to local osteolysis at the prosthesis–bone interface and in certain cases loosening of the prosthesis (Aspenberg & Herbertsson, 1996, Goldring et al., 1986, Schmalzried et al., 1992, Willert & Semtlitsch, 1977). Deterioration of clinical results with time and eventually revision of the arthroplasty were a very strong impetus for the search for the "ideal bearing" (Muratoglu & Kurtz, 2002). Improving longevity of the total hip arthroplasty by engineering of new bearing couples with improved biomechanical characteristics and lower rate of wear has been the main line of ongoing research in the orthopedic community. Today, orthopedic surgeons have a wide choice of implants and bearing couples for a particular patient. The new generation of joint bearings provides significantly lower wear rates and is anticipated to diminish the incidence

**1. Introduction** 

subsequent loosening of the implant.

of osteolysis and subsequent revisions.

 **of Hip Arthroplasty** 

Plamen Kinov and Peter Tivchev

