Clinical analysis of osteonecrosis of the femoral head induced by steroids

Objective: To explore the clinical characteristics of osteonecrosis of the femoral head (ONFH) induced by steroids. Methods: From January 2000 to October 2009, 497 hips in 270 cases of ONFH induced by steroids were studied. A questionnaire was administered when the patients were admitted; the questions concerned the underlying disease, duration of steroid usage, total dosage of steroid, incubation period (time interval between commencement of steroid therapy and onset of pain), severity of pain, location of initial complaint, primary diagnosis, time lag from onset of pain to final diagnosis and physical signs when admitted. The correlations between pain and Association Research Circulation Osseous (ARCO) stage, bone marrow edema (BME) and lesion size were analyzed. Results: The median of time between commencing steroid medication and developing ONFH for the 269 cases was 18 months (range, 2–384 months). 78.82% cases presented with pain within three years of steroid initiation, only 10.41% patients first complained of pain six or more years after commencing steroid therapy. Fifty‐six cases (20.82%) were misdiagnosed, lumbar disorders being the most frequent misdiagnoses. 79.29% of symptomatic hips presented with abnormal physical tests. Of 420 symptomatic hips, 166 hips were type C1, 223 hips type C2; 299 hips had collapsed; and there was BME in 209 hips. Conclusion: Most patients with ONFH induced by steroids complained of pain within 3 years of commencing steroid therapy. Pain was associated with lesion size, collapse and BME. Atypical location of pain, failure to perform a physical examination and MRI findings were the main causes of misdiagnoses.