Acute septic arthritis in chronic osteonecrosis of the hip.

Osteonecrosis is not well documented as a predisposing factor of septic arthritis despite such a relationship having obvious clinical significance. We report 4 patients with involvement of 5 hips with septic arthritis in established osteonecrotic joints. The etiologies of the osteonecrosis in our study included corticosteroid therapy, sickle cell disease and one case of idiopathic osteonecrosis. Osteonecrosis appears to render the hip more susceptible to hematogenously derived bacterial infection. In some cases, removal of the necrotic tissue may be necessary to cure the infection.