Osteonecrosis of the femoral head in SARS patients: seven years later.

This study is aimed to explore the progression of osteonecrosis of the femoral head (OFNH) in severe acute respiratory syndrome patients 7 years after steroid administration and to analyze factors affecting the prognosis. One-hundred and ninety hips in 117 patients with more than 7 years of follow-up were studied. The prevalence of progression to symptoms and collapse was determined. The total dose of steroid, gender, age, stage, lesion location, volume of necrosis, viable lateral column and bone marrow edema were analyzed and correlated with progression. During the 7 years of follow-up, 66 hips progressed to symptoms, 50 hips collapsed and 10 hips showed complete regression. Fifty-seven hips (86.36 %) caused pain and 32 (64.00 %) collapsed within 3 years of steroid administration. The lesion was relatively larger, and there was relatively less viable lateral column in hips that exhibited symptoms or collapsed. Mechanical failure of the necrotic segment of bone principally occurred within 3 years after the administration of steroids. Larger lesions and less viable lateral column were the main risk factors for progression. Small ONFH lesions seldom collapsed.