Core decompression for early atraumatic osteonecrosis of the femoral head.

We performed 41 core decompressions in 32 patients for stage I or stage II osteonecrosis of the femoral head. The intra-osseous pressure at the intertrochanteric level was raised in 28 (68%) and there was histological confirmation of necrosis in 36 hips (88%). After a follow-up of 10 to 84 months (mean 31) nine of the 12 stage I hips (75%) showed significant clinical or radiological deterioration; no evidence of necrosis had been found in the core specimens of the other three hips. Of the 29 hips in stage II, 25 (86%) showed significant radiological deterioration, and only five (17%) had improved clinically. We believe that once necrosis has occurred, core decompression will not significantly influence the subsequent course of the disease.