Progression of avascular necrosis of femoral head and choice of treatment.

Observations of the disease course mainly by X-ray were made in 52 patients (85 joints) with avascular necrosis of the femoral head to determine the prognosis and to decide on treatment. The progression of the necrotic area is related to the activity of the original disease, to the size of the necrotic area in the early stages of the disease, and to whether or not the patient received steroid treatment. On the basis of the size and location of the necrotic area, the disease process is divided into four stages, I to IV. The affected heads are also classified into six types according to their site and extent, the degree of flatness of their weightbearing surface, and the presence of cystic lesion. Preventive treatment and conservative observation or transtrochanteric anterior rotational osteotomy and vascularized pedicle bone graft are applicable to cases in Stages I and II. Total hip joint arthroplasties and salvage procedures are performed in Stages III and IV. The usefulness of 99mTc bone scintigraphy was unexpectedly disappointing for diagnosis of the stages of the disease. However, MRI was sensitive for the diagnosis in the early stages of the disease.