Abstract
Purpose: A porous tantalum cylindrical shaped implant (Osteonecrosis Intervention Implant, Zimmer, Warsaw, IN) has been designed to provide subchondral bony support of the subchondral plate, be osteoconductive and allow revascularization of an osteonecrotic femoral head. This study evaluates retrieved implants obtained at the time of conversion to total hip arthroplasty to determine the ability of this device to fulfill its objectives. |
Methods: Eighteen femoral heads with the tantalum implant still in situ were evaluated with contact radiographs and scanning electron microscopy to assess femoral head and bony anatomy, bone growth into the implant and femoral head revascularization. Retrievals from 12 males and 6 females with an average age of 46 years old (range, 31–61) and Stage I or II osteonecrosis were evaluated. |
Results: At a mean of 13.4 months (range, 3–36) postoperatively, all femoral heads demonstrated subchondral collapse. The bone surrounding the implant remained necrotic with no evidence of revascularization or healing. Ingrowth was marginal and averaged less than 5%.
Conclusions: This tantalum implant in its present design and surgical technique does not appear to uniformly provide structural support and promote healing of early osteonecrosis of the femoral head. This retrieval study suggests that successful results with this implant in certain cases of early osteonecrosis may be more attributable to the surgical technique requiring a core decompression, rather than the implant itself. |
Correspondence should be addressed to Cynthia Vezina, Communications Manager, COA, 4150-360 Ste. Catherine St. West, Westmount, QC H3Z 2Y5, Canada
