Avascular necrosis of the femoral head--diagnostic techniques, reliability and relevance.

Diagnosis of avascular necrosis in the early stages (I and II) offers the opportunity to prevent late segmental collapse and secondary degenerative arthritis of the hip through early surgical intervention. Functional bone marrow studies and core biopsy are the simplest and best tests for diagnosing avascular necrosis of the hip. Bone scans are helpful in diagnosis and provide supportive evidence. Routine roentgenography and occasionally tomography are the only tests required for diagnosis in advanced stages of the disease.