The results of 157 consecutive Vitallium mold arthroplasties and 107 consecutive prosthetic replacements performed for osteo-arthritis of the hip were analyzed and compared. The conclusions drawn from this study were:
1. Relief of pain in osteo-arthritis of the hip was greater and more lasting after mold arthroplasty than after insertion of a prosthesis.
2. When a prosthesis was used, the incidence of good and excellent results was 11 per cent higher in the group in which the acetabulum was remodeled and reamed than in the patients in whom the acetabulum was not reamed.
3. The best long-term results were obtained when a Vitallium mold was inserted after removal of hard sclerotic bone from both the head and the acetabulum.