After the Austin Moore prosthesis had been in use at the Massachusetts General Hospital for nine years, a clinical study of the 164 patients operated on between March 1952 and March 1955 was undertaken, first during 1956 and again during 1959. The results were thus evaluated in eighty patients one to five years after operation and in forty-five of these same patients four to eight years after operation.

The results were satisfactory or better to the surgeon in 84 per cent of the patients and to the patients in an equal percentage. For fresh fractures of the femoral neck that could not be adequately reduced by internal fixation, replacement of the femoral head by an Austin Moore prothesis gave results superior to any other method of reconstruction with which we are familiar. We believe that ununited fractures of the femoral neck and post-traumatic avascular necrosis of the femoral head are also best treated by prosthetic arthroplasty. Satisfactory results with this procedure in other conditions, such as degenerative arthritis, postinfectious arthritis, and congenital dysplasia or dislocation of the hip, were much less frequent, especially when complete acetabular reconstruction was required. However, severe pain was usually relieved and a useful range of motion achieved. The long-term results in rheumatoid arthritis were disappointing. Mold arthroplasty appears to be preferable to prosthetic replacement in rheumatoid arthritis and in burned-out pyogenic infections. Reconstructive surgery for neurotrophic hip disease, in our limited experience, was unsuccessful.

The surgeon must be aware of the many factors which contribute to success or failure of prosthetic arthroplasty. The patient must be selected with care and informed of the need for his cooperation and of the vital role he must play in the postoperative program. The surgical technique must be meticulous. The procedure should not be undertaken by the occasional surgeon. The prosthesis must be of adequate design. The after-care must be carefully supervised.

Mold arthroplasty and prosthetic arthroplasty have their limitations and indications. Both procedures yield satisfactory results or better in an acceptable proportion of cases when properly used. In our opinion, prosthetic arthroplasty is firmly established as a useful procedure for hip reconstruction.