Diagnosis Early diagnosis requires a high index of suspicion in patients presenting with pain, particularly of the hips, knees, or shoulders. Diagnostic testing depends on the stage of the disease. MRI is the most sensitive and specific technique and should be used for very early diagnosis, when collapse of the femoral head or other bone may be preventable. If duration of disease is not clear, an x-ray or CT scan should be obtained to rule out advanced disease. X-ray findings may not become apparent for months to up to 5 yr after symptom onset.
Characteristics seen on x-ray begin with subtle sclerosis of bone.
Prevention and Treatment Prevention is obviously preferable to treatment. Minimizing corticosteroid doses should also decrease risk. Conservative management often includes analgesics and non-load bearing in lower extremity joints in an attempt to prevent collapse during unassisted healing, although the efficacy of this has been difficult to prove. Disease is generally irreversible by the time it is apparent on x-ray. Cortical bone grafts may provide mechanical support to subchondral bone and articular cartilage to attempt to prevent collapse as the femoral head revascularizes.