Implant Bearings in Total Knee Arthroplasty

The enduring success of the low-friction arthroplasty, advanced by Sir John Charnley as a solution for hip arthrosis, may be appreciated by the fact that in 2022 almost 2.1 million primary and revision hip and knee arthroplasty procedures were performed in the United States, a number more than doubling on a global basis. Improvements in surgical technique and implant design over the last four decades have resulted in total knee arthroplasty (TKA) being deemed one of the most successful, contemporary orthopedic procedures to effectively relieve pain and allow patients to resume the activities of their daily lives. The prevalence of aseptic loosening attributed to ultra-high molecular weight polyethylene (UHMWPE) wear debris-induced osteolysis is in the single digits in most knee series, with some reports describing prosthesis survival beyond 20 years. Despite this obvious success, UHMWPE wear is an inescapable consequence of total joint articulation and is of contemporary concern particularly as our population grays and lifestyle demands increase. While UHMWPE has remained the tibial insert and patellar component-bearing material of choice over the last five decades, researchers are continually striving to increase its in-vivo longevity through alterations to processing and/or sterilization techniques. This chapter presents an overview of TKA-bearing materials and how they integrate into an orthopedic triad where patient outcomes are not only dictated by the implant but are highly dependent on patient factors and technical proficiency to assist the goal of avoiding revision arthroplasty.