Introduction

Abstract

The first artificial knees using metal-on-plastic components were invented in England in the late 1960s and early 1970s, based on the success of the artificial hip designed by Sir John Charnley in England. While design and research on artificial knees quickly spread to other countries, designing a successful artificial knee was not easy due to the complex structure and mechanics of the joint. However, during the 1970s, as a result of the efforts of pioneering surgeons and engineers working together, several designs were invented which provided satisfactory functional results with few short-term problems. By 1980, the field had narrowed to a few basic design types but with two types dominating the market, the cruciate retaining (CR) and the posterior stabilized (PS). The author, who was involved as a designer from 1969 to the present, reviews the history of this development and asks why the CR and PS designs still dominate. He then identifies the design principles that led to the successful performance and suggests parameters for the way in which further advances can be made.