Natural history of avascular necrosis of the femoral head in systemic lupus erythematosus

Clinical and radiographic studies were performed on 228 hips of 145 patients with avascular necrosis of the femoral head (ANFH). The patients were divided into three groups: group A consisted of 33 patients with systemic lupus erythematosus (SLE) who had been treated with systemic corticosteroids (59 hips); group B consisted of 41 patients with a history of corticosteroid treatment, excluding patients with SLE (69 hips); and group C consisted of 71 patients with no history of corticosteroid use (100 hips). Of the 228 hips, 80 hips at an early stage of the necrosis, but not showing collapse, were selected and classified by the criteria of the Japanese Investigation Committee (JIC) to define the natural history of the disease. In the SLE patients (group A), there was a predisposition to bilateral involvement and multiple sites of bone necrosis. Eighty percent of the femoral heads followed at an early stage had collapsed at the end of the follow-up, the incidence of collapse in group A being higher than that in the other groups. The collapses in group A were predominantly types 1C, 2, and 3B according to the JIC criteria. The incidence of collapse was significantly lower in type 1A and type 3A than in the other types. The classification proposed by the JIC, in terms of types with regard to size and location of the necrotic area on antero-posterior radiographs, was very useful for evaluation of the risk of collapse as well as for selecting appropriate treatment modalities, either conservative or surgical, during the early stages of ANFH.