Arthroplasty of the knee.

A stable polycentric knee mechanism which allows axial rotation as well as simulating other knee movements was introduced into clinical use in 1971. The surgical and mechanical problems that presented over the past 7 1/2 years have greatly helped in improving our understanding of knee reconstruction and design. A patient satisfaction rate of 95% compares favorably with the results achieved with hip arthroplasty but the complexity of knee reconstruction far outweights that of the hip.