Survivorship analysis and radiographic outcome following tantalum rod insertion for osteonecrosis of the femoral head.

BACKGROUND: For early stages of osteonecrosis, preservation of the femoral head is the primary objective; however, there has not been a consensus on how best to achieve this goal. Core decompression alone is associated with a lack of structural support with inconsistent outcomes, whereas vascularized fibular grafting requires an extensive surgical procedure with high donor-site morbidity and prolonged rehabilitation. The adjunctive use of a porous tantalum implant offers the advantages of core decompression, structural support, minimally invasive surgery, and no donor-site morbidity. The purpose of this study was to assess the survivorship and to evaluate the clinical results and radiographic outcomes of hips in which osteonecrosis of the femoral head was treated with core decompression and a porous tantalum implant.
METHODS: We evaluated fifty-four patients (sixty consecutive hips) in whom osteonecrosis of the femoral head was treated with core decompression and insertion of a porous tantalum implant. Fifty-two patients (fifty-eight hips) were available for follow-up at a mean of twenty-four months. All patients were sixty-five years of age or younger (mean age, thirty-five years). According to the classification system of Steinberg et al., one hip (2%) had stage-I disease, forty-nine hips (84%) had stage-II disease, and eight hips (14%) had stage-III disease. Outcome measures that were used included a limb-specific score (Harris hip score), radiographic outcome measures, and survivorship analysis with revision to total hip arthroplasty as the end point.
RESULTS: Overall, nine hips (15.5%) were converted to total hip arthroplasty, including six with stage-II disease and three with stage-III disease. The overall survival rates were 91.8% (95% confidence interval, 87.8% to 95.8%) at twelve months, 81.7% (95% confidence interval, 75.8% to 87.6%) at twenty-four months, and 68.1% (95% confidence interval, 54.7% to 81.5%) at forty-eight months. The absence of chronic systemic diseases resulted in a survival rate of 92% at forty-eight months (95% confidence interval, 87.4% to 96.4%).
CONCLUSIONS: Treatment of early stage osteonecrosis of the femoral head with core decompression and a porous tantalum implant can be accomplished with a minimally invasive technique and no donor-site morbidity. The early clinical results show encouraging survival rates in patients who do not have chronic systemic disease, especially in association with early stage disease. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions to Authors on jbjs.org for a complete description of levels of evidence.