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

ABSTRACf 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 weightbear­ ing surface, and the presence of cystic lesion. Preventive treatment and conservative observation or transtro­ chanteric 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 useful­ ness 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. INTRODUCfION Cases of avascular necrosis of the femoral head (ANFH) are steadily increasing, but their eti­ ology and pathogenesis are still unknown. The determination of what stage and which treatment should be taken for the necrotic area is also controversial because it depends on such a variety of factors including the diverse progress of the necrosis, original disease activity, course of treat­ ment, prognosis, and patient's age and occupation.!) In hope of being able to suggest appropri­ ate treatment for future cases, we observed mainly the transitional radiographic features of the necrotic lesion in the process of its natural course and discussed the choices of treatment method. We also considered the role of steroids in the etiology2,3,4) and the significance of 99mTc bone scintigraphy and magnetic resonance imaging (MRI) for the early diagnosis of femoral head necrosis. 5 ,6)