Core decompression for osteonecrosis of the femoral head at pre-collapse stage

Twenty-five patients (27 hips) were retrospectively studied for core decompression in the treatment of osteonecrosis of the femoral heads at pre-collapse stage, Ficat and Alert stages I and II, from Apr. 1984 to Jun. 1998 with follow-up period at least 1 yr (mean 28 months). Eleven hips (10 patients) were considered to have failed due to progressive collapsed more than 2 mm, severe pain or reoperation. We further analyzed the results with regard to the stages, the size of the necrotic area according to the Ohzono classification, the lateral head index (LHI) and the Kerboul combined necrotic angle. The survival rate according to the Ohzono classification was type 1B: 100%, 1C: 44%, 2: 25%, and 3B: 0%. Hips with Kerboul angle less than 250 degrees revealed satisfactory results in all except one hip. All hips with Kerboul angle more than 250 degrees collapsed. Fourteen of the 15 hips (93%) with lateral head index more than 20% did not collapse and all hips except one (7/8) with LHI less than 12% collapsed. We conclude core decompression yields satisfactory results in osteonecrotic femoral heads at pre-collapse stage and with small necrotic area or good lateral buttress.