ABSTRACT
Avascular necrosis (AVN) of bone occurs in the hip, knee, talus, shoulder and scaphoid. It frequently follows interruption of blood supply by trauma but is also associated with alcoholism, dysbarism (Caisson disease), steroids, radiation therapy, sickle cell disease and Gaucher’s disease. The theories of aetiology include expansion of fat cells in the marrow and repeated intramedullary haemorrhage or thrombosis. Whatever the starting point, the outcome appears to be blockage of the osseous microcirculation. AVN most commonly occurs in the hips in the fifth decade and is bilateral in 50% of cases of idiopathic (Chandler’s) disease but in up to 80% if steroid-induced.
