Pathology of osteonecrosis of the femoral head. A review of experience at the Hospital for Joint Diseases, New York.

Pathological examination of the resected femoral heads from approximately 2000 total hip replacement operations carried out at the Hospital for Joint Diseases from 1984 to 1989 identified the presence of osteonecrosis in 345 patients (377 femoral heads). In 232 patients the osteonecrosis, referred to as "idiopathic," had occurred in the absence of a subcapital fracture. The present paper describes the pathology of the necrotic lesions in these 232 patients. The use of undecalcified sections and microradiography provides evidence of bone marrow calcification which, at the margin of the lesion, is sufficient to influence the radiographic features of the lesion significantly. Although a subchondral fracture is an almost constant feature of osteonecrosis when it occurs in a femoral head with a normal articular cartilage, no such fracture was found in cases in which osteonecrosis had occurred in an osteoarthritic joint.