Radiographic predictors of outcome of core decompression for hips with osteonecrosis stage III.

Various investigators have studied the prognostic influence of various demographic, laboratory, and radiographic parameters on outcome for different treatment methods for osteonecrosis of the femoral head. A cross sectional study was done of 52 patients (68 hips) who had a core decompression for Ficat and Arlet Stage III osteonecrosis of the femoral head. The purpose of this study was to evaluate the prognostic significance of various radiographic factors for risk of disease progression after treatment with core decompression. Radiographic parameters included Steinberg stages (III or IV), Ohzono stage (central or lateral location), amount of head depression, extent of crescent sign arc, and extent of lesion by Kerboul combined necrotic angle measurements. Patient outcome assessment was at a followup mean of 12 years (range, 4-18 years) after core decompression. Overall, 20 of the 68 hips (29%) had satisfactory outcomes. Of the 44 hips with Steinberg Stage III disease, 18 (41%) underwent total hip arthroplasty. In comparison, in the Steinberg Stage IV hips, 22 of 24 hips (92%) underwent arthroplasty. Ohzono Stage B lesions had 50% survival (eight of 16 hips) compared with 23% survival (12 of 52 hips) for Ohzono Stage C. Hips with combined necrotic angles greater than 250 degrees had 16% survival (seven of 45) which can be compared with 57% survival (13 of 23) for hips with angles less than 250 degrees. The best multiple regression model for a satisfactory outcome was a Steinberg Stage III hip (no head depression), a central lesion (Ohzono Stage B), and a small lesion (< 250 degrees combined necrotic angle). With this combination, there were 89% satisfactory outcomes (8 of 9 hips). Conversely, the best generalized linear model for unsatisfactory outcomes (0 hips surviving of 14) was Steinberg Stage IV disease (head depression), lateral location (Ohzono Stage C lesion), and a large extent of the lesion (> 250 degrees combined necrotic angle).