Bone impaction grafting for corticosteroid-associated osteonecrosis of the knee.

ABSTRACT

BACKGROUND: Osteonecrosis of the distal portion of the femur produces a segment of dead bone in the weight-bearing portion of the femoral condyle, frequently associated with subchondral fracture and collapse and eventually resulting in secondary osteoarthritis. Treatment of these late stages of osteonecrosis in the knee can be problematic. The purpose of the present study was to evaluate a new surgical technique in which the subchondral osteonecrotic lesion is removed. The bone defect is then reconstructed with impacted bone grafts to prevent collapse and/or to regain distal femoral sphericity. METHODS: In this prospective, one-surgeon study, nine consecutive knees in six patients were studied, all of which had extensive corticosteroid-associated osteonecrotic lesions of the femoral condyles. Six knees had collapsed lesions when they were initially treated. The mean age of the patients was thirty-one years. Both the clinical and radiographic outcomes were assessed at a minimal follow-up time of two years. RESULTS: At a mean follow-up time of fifty-one months, none of the reconstructed knees had been converted to a total knee prosthesis. The objective Knee Society score improved from a mean of 63 to 89 points. The functional Knee Society score improved from a mean of 19 to 81 points. During the follow-up period, there was no progression of collapse observed; however, three knees showed early signs of osteoarthritis. Clinical success was achieved in six of eight knees, and radiographic success was achieved in seven of nine knees. CONCLUSIONS: At the time of writing (at the time of midterm follow-up), this method appears attractive as a joint-preserving procedure. It is a relatively simple procedure that is not likely to interfere with future knee procedures. It appears that this technique can be effective in knees with collapse of the femoral condyle, and it may delay the need for a total knee arthroplasty. LEVEL OF EVIDENCE Therapeutic Level IV. See Instructions to Authors on jbjs.org for a complete description of levels of evidence.