Total Hip Replacement and the Law of Diminishing Returns

Total hip replacement was introduced primarily to relieve pain and restore function in patients crippled with arthritis of the hip. Secondary objectives included optimized durability of implant fixation and the bearing surfaces, as well as a combination of optimized mobility and stability of the articular couple. Early attempts at replacement of the hip joint were condemned as a result of poor materials and poor design. Charnley1 made three major contributions to the evolution of contemporary hip replacement: the concept of low-friction torque arthroplasty, the introduction of high-density polyethylene, and the use of acrylic bone cement to secure implant fixation to bone. In studies of total hip arthroplasty with use of the first-generation Charnley stem, Berry et al.2 and Callaghan et al.3 reported a twenty-five-year survival rate of 81% and 77%, respectively, with revision of any component as the end point. Similar results have been reported by other authors4-6.