Protrusion of the ceramic head through the acetabular shell in total hip replacement

Total hip replacement (THR) is one of the most successful elective operations currently being performed. However, increased implant wear in the femoral head-acetabulum articulation has been found to limit the long-term survivorship of the procedure. Clinical complications of this wear process include mechanical failure of the polyethylene insert as well as a biologic foreign-body response to wear debris. Factors that have been implicated in the pathogenesis of this phenomenon include implant design and positioning, patient age, and time from the operation. Pain and sound originating from the joint are among the most common clinical manifestations. Radiographic signs present in the form of progressive radiolucent zones or an eccentrically displaced femoral head. The true extent of bone damage usually is greater than that appreciated originally. A high index of suspicion is essential for an early and successful surgical intervention. We report a rare case of a 72-year-old woman who presented with excessive wear of both the acetabular polyethylene socket and metal backing 3 years after the initial cementless THR. This resulted in protrusion of the femoral head through both the polyethylene cup and the acetabular shell, and subsequent subluxation of the femoral head. Marked periacetabular osteolysis and loosening had developed progressively. No definite signs of infection were identified, either by bone scintigraphy, preoperatively, or by repeated cultures of the excised tissues. The THR was revised, in a 2-stage operation, using bone autografts and a cemented acetabular socket, with a good postoperative outcome.