Complete replacement arthroplasty of the hip by the ring prosthesis.

fractures of the hip lies largely in the way in which the load is transferred through the femoral neck, the stem of the prosthesis serving to locate and maintain this relationship accurately. The results of using the Moore prosthesis in osteoarthritis, however, are relatively poor (Heywood-Waddington 1966) partly because of acetabular erosion. The matching of the arthritic acetabulum to the spherical implant is inaccurate, and can only be improved by some form of acetabular replacement. Progress in the development of the acetabular component has been limited by the difficulties of securing it in the pelvis, and by doubts about the most suitable material for completing the articulation.