Biomechanics of Total Knee Replacement

Abstract

Metal-plastic Total Knee Placement (TKR) was first introduced in the late 1960’s. Among the first designs were the Polycentric, the Freeman-Swanson, the Geomedic and the DuoCondylar (1). During the 1970’s, many other designs were introduced, some being adaptions to address the problems with the early designs, and others being new concepts. During the decade, frequent clinical problems were due to inadequate instrumentation, inaccurate component alignment, poor cement technique, excessive device constraint, absence of patello-femoral replacement, and lack of ligament balancing. However, institutional reviews published in the early 1980’s, suggested that some designs at least, problems occurred in only a few percent of cases at up to 10 years follow-up. To optimise the design for performance and durability, the designer, manufacturer, and surgeon are faced with a variety of requirements. Some of these requirements will be discussed in this article. The first stage is to identify and quantify the present status, particularly the strong and weak points. This is done by a review from our own institutional data on retrieved total knees and clinical follow-ups (2,3,4,5).