Failure of a properly positioned tantalum rod for treatment of early femoral head necrosis and conversion to total hip arthroplasty

Abstract

Conventional core decompression (CD) is a well-known procedure for treatment of avascular necrosis of the femoral head. Weight bearing is usually restricted in the early postoperative weeks to avoid the risk of fracture. Theoretically, a properly positioned implantation of the new tantalum rod after reaming of the necrotic area has the advantages of decompression, supports the remaining bone to avoid collapse, lowers the risk of subtrochanteric fracture, and allows for early weight bearing. The objective of this study was to evaluate the role of the tantalum rod in the management of early avascular necrosis. Twenty patients with a mean age of 30.4 years were treated with CD and implantation of a tantalum rod. The cases were evaluated radiologically by x-rays, CT, and MRI. Sixteen cases were idiopathic while four patients were corticosteroid induced. Using the Steinberg classification system, Fifteen hips were stage II and five hips stage III. Postoperative CT was done in all cases to ensure proper position of the cases. Clinical and radiographic evaluation was carried out preoperatively then at 3, 12, and 24 months postoperatively. The average preoperative Harris Hip Score (HHS) was 42.5 and improved to 80.7 at 3 months with two cases of persistent pain and unsatisfactory results with conversion to total hip arthroplasty (THA) in the first 6 months. At 1 year, the average HHS was deteriorated to 76.1 of the remaining 18 cases. At 2 years endpoint follow-up, five cases already converted to THA, another seven cases had a deterioration of the HHS score, and only 40 % of the cases had satisfactory results. Implantation of a porous tantalum metal rod for early-stage osteonecrosis of the femoral head did not add a significant advantage to core decompression alone even with the proper position in relation to the necrotic area. We had to convert to total hip arthroplasty in 60 % of the cases.