bone, joint, and muscle disorders
Osteonecrosis
Introduction
Osteonecrosis is the death of a segment of bone caused by an impaired blood supply. Osteonecrosis is most commonly caused by an injury but can also occur without an injury. Typical symptoms include pain, limited range of motion of the affected joint, and, when the leg is affected, a limp. The diagnosis is based on symptoms, the person's risk of osteonecrosis, and the results of x-rays and magnetic resonance imaging. Various surgical procedures can be done if nonsurgical measures (such as rest, physical therapy, and pain relievers) do not relieve symptoms. Stopping smoking, stopping excessive alcohol use, and minimizing the use of or lowering the dose of corticosteroids reduce the risk of developing osteonecrosis. Each year in the United States, approximately 20,000 people develop osteonecrosis. The hip is most commonly affected, followed by the knee and shoulder. The wrist and ankle are affected less often. Osteonecrosis does not usually affect the shoulder or other less commonly affected sites unless the hip is also affected. However, Medication-Related Osteonecrosis of the Jaw (MRONJ) is a disorder involving only the jaw bone. 