Tissue response to the failed Gerard double-cup. Histologic analysis of 40 uncemented hip arthroplasties.

Femoral head remnants, joint capsules and acetabular membranes were retrieved at revision of 40 failed uncemented, Gerard double-cup hip arthroplasties. All femoral heads were covered with a fibrous membrane containing polyethylene and metal particles, macrophages, and giant cells. The same histopathologic features were found in the joint capsules and acetabular membranes. There was a relationship between the amount of polyethylene particles in the fibrous membrane of the femoral head and the presence of osteonecrosis. Resorption of necrotic bone contributed to failure of the arthroplasty, aided by granulomatous reactions to the wear particles that appeared to induce osteolysis. The overall findings indicate that the severity of the foreign body reaction in periprosthetic tissues is related to the amount of wear particles. Future designs of resurfacing hip arthroplasties should be focused on wear-resistant material combinations.