This study evaluated patients with heterotopic ossification after implantation of a free vascularized fibular graft for the treatment of femoral head osteonecrosis. We hypothesized that the osteogenic tendency of these patients might enhance the graft-host union and new bone formation in the femoral head, although the presence of heterotopic ossification might influence adversely the clinical result. Of patients with femoral head osteonecrosis, 32% developed heterotopic ossification after treatment with free vascularized fibular graft. Heterotopic bone formation did not influence the efficacy of the procedure to preserve the hip joint. The radiographic and clinical results and the rate of subsequent total hip arthroplasty were not affected by the heterotopic bone, but local trochanteric tenderness was associated with large heterotopic lesions.
