There are many causes of ischemic necrosis of the femoral head, and any damage that affects the blood supply to the hip joint can cause necrosis of the femoral head. Damage to the hip joint itself can affect the blood vessels, a fracture of the femoral neck (the part that connects to the femoral head) can damage the blood vessels, and a dislocation of the hip joint can tear the blood vessels, but it can take several months from the time of injury to ischemic necrosis of the femoral head and up to two years for symptoms to appear. Some drugs can also cause femoral head necrosis, the most common of which are hormonal drugs represented by cortisone. Patients at this time often need to take cortisone daily for a long time because of other diseases such as kidney disease and immune disorders, but for the need to treat the disease, patients often have no other choice. There is no evidence, however, that such short-term use of hormones for the treatment of arthritis or bursitis with one or two occasional joint injections can cause necrosis of the femoral head. There is also a causal relationship between femoral head necrosis and alcoholism. Excessive alcohol consumption can somehow damage blood vessels and lead to femoral head necrosis. Deep sea divers and miners are also at risk of vascular damage due to working under high atmospheric pressure. This pressure causes small air bubbles to form in the blood stream, which can block blood vessels in the hip joint and ultimately affect its blood supply.