[Experimental and clinical studies concerned with the Jikei femoral head prosthesis (author's transl)]

For experimental purposes, femoral head prostheses for dogs, using both high density polyethylene (HDP) or titanium as the material for the head, were developed. Periodic observations of the acetabular cartilage influenced by the prosthetic head were done. The results showed that HDP was not suitable as a material for the artificial head because of rapid degeneration of the acetabular cartilage and marked wear and deformity of the HDP femoral head as soon as the surgery was done. On the other hand, the titanium femoral head was seen as causing much less damage to the acetabular cartilage in those cases where the diameter of the prosthetic head was quite adequate in its size. These findings indicated that the metal prosthetic head was useful for clinical cases. It was also clarified that the fixing of the stem to the bone could be achieved with our self-locking design instead of the use of bone cement. In follow-up studies of clinical cases used by the Jikei titanium femoral head prosthesis based upon our experimental results, it was found that better results could be expected when care is taken to use a femoral head which is not larger against the acetabulum. In addition, it was proved the procedure with the femoral head prosthesis is not indicated in cases where degeneration in acetabular cartilage has already occurred.