Indications, technique, and results of shoulder arthroplasty in osteonecrosis.

The most common causes of osteonecrosis of the humeral head are steroid use and trauma. Corticosteroids produce osteonecrosis by alterations in fat metabolism, and trauma, by injury to the anterolateral ascending artery. The need for replacement surgery is influenced by stage and extent of the disease, as well as a history of trauma. Results of replacements are superior in steroid-induced osteonecrosis compared to posttraumatic osteonecrosis.