This article presents an unreported case of a 64-year-old woman who sustained a subtrochanteric fracture of the femur 4 weeks after implantation of a trabecular metal osteonecrosis intervention implant for osteonecrosis of the femoral head. Traditional treatments for femoral head avascular necrosis include observation, core decompression, bone grafting, vascularized fibular grafting, osteotomy, hemi-arthroplasty, and total hip arthroplasty (THA). With the recent development of trabecular metal, a new implant system has been developed using the properties of trabecular metal for treatment of osteonecrosis. Trabecular metal is a relatively new and unique material that physically and mechanically more closely resembles bone than any other prosthesis. Its use in osteonecrosis of the femoral head has shown promising results with few if any short-term complications. To the best of our knowledge, besides normal progression of the disease, no major complications of this implant system have been reported. The case we present is the first reported case of a subtrochanteric fracture of the femur following implantation of a trabecular metal osteonecrosis implant.
In our patient, care was taken in placement of the implant, and no intraoperative or immediate postoperative complications occurred. Four weeks later she sustained a fall that resulted in a subtrochanteric fracture. Based on the location of the fracture we believe this implant acted as a stress riser that predisposed her to fracture. The high friction and bony in-growth of the implant made removal difficult. Instead of routine removal, it was necessary to make a femoral neck cut with the implant still in place sawing it into 2 pieces. The femoral head with proximal implant was disposed of and the distal portion of the implant was removed with a trephine. The hip was then converted to a THA with cable plate fixation.