Causes

Although the exact cause of osteonecrosis is not yet known, one theory is that a stress fracture results in an altered blood supply to the bone. Another theory is that a build-up of fluid within the bone puts pressure on blood vessels and decreases blood circulation.

Women are affected by osteonecrosis at a rate of 3 times more than men are with most being over 60 years of age. Osteonecrosis of the knee is also associated with certain conditions and treatments, such as obesity, sickle cell anemia, lupus, kidney transplants, and steroid therapy. If osteonecrosis is not identified and treated early, it can develop into severe osteoarthritis.