This disease is caused by reduced blood flow to the bones of the joints. With reduced blood supply the bone dies and the joint breaks down. In the hip, the end of the thigh bone extending from the knee joint to the hip joint is the affected bone.
Osteonecrosis can be very painful. As the hip joint breaks down, it can also lead to arthritis in the joint. In healthy bones, new bone is always replacing the old bone, keeping bones strong. In osteonecrosis, bone breaks down faster than new strong bone can replace it. Without treatment, the disease worsens the bone break down and you may not be able to bend or move the joint well.
The risk for developing osteonecrosis is higher with the use of steroid medications, alcohol use, injury and pressure inside of the bone, as well as radiation therapy, chemotherapy and with kidney and other organ transplants. That means that people with cancer, lupus, HIV, gout, vasculitis, osteoarthritis, osteoporosis may be more likely to develop osteonecrosis.
There are both nonsurgical and surgical treatments, with surgery more often the recommended treatment.