Core decompression in early stages of femoral head osteonecrosis--an MRI-controlled study.

We treated 45 hips with idiopathic necrosis of the femoral head stages I-III with core decompression. Average age of patients was 41 (27-68) years and average follow-up 68.9 (31-120) months. In 30 hip joints in stage I, 29 showed no radiographic progression and a complete remission of the changes consistent with necrosis on MRI at the last follow-up. In 27 patients the clinical result based on the Harris Hip Score (HHS) assessment--was excellent (average HHS 91.9 points). Of nine hips in stage II, four had received a total hip arthroplasty, one had deteriorated to stage IV, and four were still classified as stage II (average HHS 95 points). Of six hips in stage III, three had received a total hip arthroplasty and three had deteriorated to stage IV (average HHS 73 points).