Idiopathic osteonecrosis of the femoral head in the elderly.

Abstract

Idiopathic osteonecrosis of the femoral head (ION) is a disease prevalent in adulthood, and its development in elderly persons is known to show a low incidence. To clarify its characteristics in elderly patients, radiological and histological examinations were performed on 18 patients aged 60 years or older histologically diagnosed as having ION. On roentgenography, three characteristic points were observed, 1) progress of collapse in the femoral head within a short period (12 cases, 66.7%), 2) narrowing in the joint space within a short period (6 cases, 33.3%), and 3) rapid destruction and resorption of the femoral head (4 cases, 22.2%). The lesion expanded to the acetabular region, and a course similar to that of so-called rapidly destructive coxarthrosis (RDC) was developing in 3 cases (16.7%). However, in these 3 cases, changes in the acetabular region were mild, compared with ordinary RDC, and they were considered different from common RDC. These radiological characteristics were found more clearly in women than in men. In the histopathological examination, severe degeneration in the cartilage of the femoral head was found, while wide infiltration of repairing tissue into the necrotic area was seen from the early stage. When necrotic trabecula were collapsed markedly and degraded severely, then destruction and resorption of bone expanded to non-necrotic regions in some cases. Osteogenic sclerotic line (the demarcation line), which has been often seen in ordinary ION, was not developed in most cases. These characteristics were more prominent in women.