Shoulder Osteonecrosis: Pathogenesis, Causes, Clinical Evaluation, Imaging, and Classification.

The humeral head is the second most common site for nontraumatic osteonecrosis after the femoral head, yet it has attracted relatively little attention. Osteonecrosis is associated with many conditions, such as traumatism, corticosteroid use, sickle cell disease, alcoholism, dysbarism (or caisson disease), and Gaucher's disease. The diagnosis is clinical and radiographic with MRI, with radiographs being the basis for staging. Many theories have been proposed to decipher the mechanism behind the development of osteonecrosis, but none have been proven. Because osteonecrosis may affect patients with a variety of risk factors, it is important that caregivers have a heightened index of suspicion. Early detection may affect prognosis because prognosis is dependent on the stage and location of the disease. In particular, the disease should be suspected in patients with a history of fractures, steroid usage, or sickle cell disease, and in divers. This report reviews osteonecrosis of the humeral head, with an emphasis on causes, clinical evaluation, imaging, and classification.