Chapter 8 - The Clinical Performance of UHMWPE in Knee Replacements

Abstract

The knee is one of the most complex joints in the body. Unlike the hip in which the joint surfaces are highly conforming, in the knee the articulating surfaces are more nonconforming. This chapter describes total and unicondylar knee arthroplasties (TKA and UKA), which are highly successful surgical procedures. It reviews the biomechanical considerations of knee arthroplasty that distinguish it from hip replacement and also describes the survivorship of TKA and UKA and outlines measures of clinical performance for ultra-high molecular weight polyethylene (UHMWPE) in knee arthroplasty. It is devoted to wear and osteolysis in TKA. This study describes alternatives to metal-on-conventional UHMWPE articulation for knee arthroplasty. Fixed bearing and mobile bearing total knee designs both share the clinical spotlight as safe and effective treatment options for patients requiring total knee replacement. Knee arthroplasty enjoys a remarkable clinical track record. Problems with wear and fatigue damage of UHMWPE continue to limit the longevity of both unicondylar and bicondylar knee replacement components. Unlike in the hip, where radiographic techniques are developed to quantify in vivo wear rates, there currently exists no standard and widely accepted techniques for tracking the clinical performance of UHMWPE in patients with knee replacement. Thus, today the most effective way to evaluate the in vivo performance of UHMWPE continues to be the analysis of retrieved components from revision surgery or from autopsy donations.