A painful metal-on-metal total hip arthroplasty: a diagnostic dilemma.

Infection, loosening, osteolysis, or other causes can lead to the development of pain about a previously well-functioning total hip arthroplasty. An inflammatory reaction unique to metal on metal arthroplasty can lead to a painful total hip. A synovial biopsy is needed to make this specific diagnosis, and included in the differential diagnosis is infection. The workup of infection includes obtaining a C-reactive protein and erythrocyte sedimentation rate. Elevations of both the C-reactive protein and erythrocyte sedimentation rate are felt to indicate possible infection. This case report describes both of these findings and the treatment rendered in a painful subluxing metal-on-metal total hip arthroplasty presenting with ongoing pain and a large effusion.