n. death of bony tissue, usually adjacent to a joint surface where it is enclosed by avascular cartilage. It is usually caused by loss of blood supply (avascular necrosis) due to trauma and is a definitive feature in a variety of conditions, including Legg-Calvé-Perthes disease, sickle-cell disease, Gaucher’s disease, epiphyseal infection and fractures, alcohol abuse, and high-dosage corticosteroids. Sites that are particularly susceptible include the head of the femur, the scaphoid and lunate bones of the wrist, the capitulum of the humerus, and the talus and navicular bones of the ankle. In its earliest stages there is localized pain without any changes visible on X-ray examination; a bone scan or MRI will assist with diagnosis.
Subjects: Medicine and Health.