Granulomatous pseudotumors in total joint replacement.

Fourteen patients (15 joints) developed a foreign body reaction to methylmethacrylate, polyethylene, or metal adjacent to a total joint implant, a condition we would like to term granulomatous pseudotumors. There were eight male and six female patients. Their average age was 61 years. The hip was involved in 14 joints (femoral component 11 times, acetabulum 7, and greater trochanter once). One patient presented with granulomatous pseudotumors of the knee. The principal findings included increasing pain and radiographic evidence of loosening occurring on average 2.7 years following the implant. This was followed by a characteristic and gradually developing radiographic pattern of discrete rounded lucencies. These developed into large ovoid lytic areas, destroying both methylmethacrylate and bone. Histologically, the appearances were characterized by histiocytic infiltration and the presence of multiple foreign body giant cells. Foreign material was identified in 9 of 11 cases. The pathogenesis is unknown but appears related to micromovement or loosening of the implant.