Knee arthroplasty/replacement osteolysis

This chapter contains four main sections covering TKA and, where applicable, UKA. The first section reviews the biomechanical considerations of knee arthroplasty that distinguish it from hip replacement. The second section describes the survivorship of TKA and UKA, and outlines measures of clinical performance for UHMWPE in knee arthroplasty. The third section is devoted to wear and osteolysis in TKA. In the final section of this chapter, alternatives to metal-on-conventional UHMWPE articulation for knee arttiroplasty are described. 

Despite its successful track record, wear and damage of the UHMWPE insert compromises the longevity of knee arthroplasty. Osteolysis, a rare occurrence with all-UHMWPE tibial components, has been documented with increasing frequency in modular knee replacements. Clearly, improved wear behavior of the UHMWPE insert would be advantageous from the perspective of reducing the risk of osteolysis and aseptic loosening. 

One of the greatest concerns about the use of PE in joint replacement bearing surfaces is the wear of the material and the effect the wear debris has on the surrounding tissues. For many years, it has been demonstrated that this wear debris leads to osteolysis and loosening of the prosthetic components [21, 25]. Wear of the polyethylene or loosening of the implants, which may be related to wear debris, remains a common reason for revision surgery after total hip [26, 27] or total knee arthroplasty [28]. 

Based on the clinical experience of UHMWPE in total hip and knee replacements, the prodnction of wear debris from artificial discs, as well as from other motionpreserving spine implants, is a clinical concern. Wear debris indnced osteolysis has been implicated as a potential mechanism for late onset pain following the faUme of stainless steel and titanium instrumented fusions [65]. Osteolysis has also been observed around certain total disc replacement designs, such as the Acroflex artificial disc [66], and case smdies of osteolysis around CHARITE disc replacements have also been reported [67-69]. According to recent conference presentations, the UHMWPE particle load around long-term implanted artificial discs may be comparable to total hip arthroplasty [70], and the periprosthetic particle concentration appears to be correlated with a local inflammatory response [71]. Although the occurrence of osteolysis with metal-on- X)lyethylene total disc replacements has thus far been relatively rare, the long-term wear behavior of artificial discs remains of clinical importance [69]. 

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