Chapter 5 - The Clinical Performance of UHMWPE in Hip Replacements

Abstract

This chapter reviews the historical development of concepts related to quantifying clinical wear performance of gamma sterilized ultra-high molecular weight polyethylene (UHMWPE) in hip replacements. Wear of conventional UHMWPE is historically recognized as the primary culprit responsible for inflammatory bone loss and late revision of hip replacements. Researchers have estimated that for each day of patient activity, around 100 million microscopic UHMWPE wear particles are released into the tissues surrounding the hip joint. This particulate wear debris can initiate a cascade of adverse tissue responses leading to osteolysis (bone death) and ultimately aseptic loosening of the components. Therefore, understanding the natural history of UHMWPE wear in a clinical setting is an important first step to improving the longevity of total hip arthroplasty (THA). The absolute amount of wear observed in a group of patients depends on the time interval between radiographic examinations. It has been suggested that the volumetric wear rate, as opposed to the linear wear rate, may also be a clinically relevant metric for wear because the biological stimulus may be related to the volume of wear debris.