Failure of uncemented polyethylene acetabular components.

The authors describe the mode of failure of the Ring UPM (Downs Brothers, Surrey, United Kingdom) uncemented metal-on-plastic total hip arthroplasty. Erosion of the external surface of the uncemented acetabular cup led to early loosening in eight cases. The subsequent production of large quantities of polyethylene debris caused massive granulomata, resulting in osteolysis of the acetabulum and femur. Revision surgery was difficult because of the loss of bone stock. The serious consequences of failure of this design lead to the conclusion that uncemented, nonmetal-backed polyethylene acetabular components should not be used.