LD hip arthroplasty. Design concepts and first clinical trials of a new modular system.

The new LD modular hip arthroplasty is made of Ti6A14V. The acetabular component has a hemispheric expansive metallic ring and a polyethylene nucleus in the shape of a cone segment. Since June 1988, when the clinical trials began, 352 arthroplasties have been performed with 112 total hip arthroplasties among them. Only 60 noncemented total hip arthroplasties, with the longest follow-up evaluation reaching 24 months, were analyzed. Patients with revision operations were excluded. The results have been evaluated using the Merle D'Aubigne scoring scale. Good results were found in 86% of cases. Pain improved markedly at three months in the postoperative period. At six months, the Trendelenburg sign was negative in 76% and positive in 12%. The Duchenne sign was positive in 11%. Major complications included three dislocations, two acetabular component revisions caused by initial malposition, one external popliteal nerve palsy, one deep infection, and two periprosthetic fractures. No acetabular migrations have been found. There are six femoral sinkings of less than 1 cm. Heterotopic ossifications Grade II-III appear in 24% of cases. The results to date are evaluated clinically and radiologically. The acetabular design has proved efficient, and the femoral components show a low incidence of stress shielding.