Prophylactic decompression and bone grafting for small asymptomatic osteonecrotic lesions of the femoral head.

Core decompression and grafting has been shown to relieve pain and possibly prevent disease progression in patients with symptomatic osteonecrosis (ON) of the hip. However, there is a lack of evidence regarding the management of the asymptomatic hip with femoral head ON. The purpose of this study was to evaluate the outcome of core decompression in the asymptomatic hip with ON. We prospectively followed 37 consecutive patients with MRI confirmed ON of the hips that underwent simultaneous bilateral core decompression and bone grafting. Prior to surgery, only one of the hips was symptomatic, and the main indication for surgical decompression of the asymptomatic side was to prevent disease progression. No hip on the asymptomatic side was staged greater than Steinberg IIB classification. Serial radiographs were followed for evidence of disease progression. Six patients were lost to follow-up prior to two years. The remaining 31 patients were followed for an average of 32.6 months. There were 20 men and 11 women with an average age of 40.6 years. Ten patients with asymptomatic hips at the time of surgical decompression had disease progression requiring THA. The mean time to arthroplasty in this group was 15.1 months. Meanwhile, 13 symptomatic hips at the initial surgery progressed to THA at an average of 12.9 months following core decompression. The proportion of hips requiring conversion to THA was similar between the two groups (p=0.30), and the rate of progression to THA was not significantly faster compared to patients with symptomatic hips who subsequently required THA (p=0.18). Core decompression for asymptomatic ON of the femoral head is unpredictable. Based on our results, asymptomatic ON lesions particularly in the setting of bilateral disease should be closely observed and surgery reserved for when symptoms arise.