What is osteonecrosis (ON)?
Osteonecrosis is a disease that results from a loss of blood supply to the bone. Without adequate blood flow, sections of bone eventually die, weaken and collapse. Because this is most often seen at the ends of bones, your joints may be greatly affected. This is especially true of the hip joint, as osteonecrosis most commonly appears at the end of the femur (the long bone that extends from the knee to the hip joint). Medical experience has shown that wherever osteonecrosis causes bone to degrade in a joint, arthritis develops.
You may hear osteonecrosis referred to as avascular necrosis, asceptic necrosis and ischemic necrosis. The word osteonecrosis literally means “dead bone”.
Who does ON affect?
Each year between 10,000 and 20,000 men and women develop osteonecrosis.3 Although ON can affect anyone at any age, most people who develop ON are between 30 and 50 years old. Orthopaedic surgeons have found that in as many as ten percent of all people requiring hip replacement, osteonecrosis has led to their joint damage.
Even though medical science has learned a lot about osteonecrosis and its potential causes, research into contributing genetic risk factors is ongoing. To date, we know that you may be at an increased risk for developing ON if you’ve dislocated or fractured a hip, suffer with alcoholism, use corticosteroids, or have any number of glandular diseases, including rheumatoid arthritis, Gaucher’s disease, chronic pancreatitis, Crohn’s disease or lupus.
What are the symptoms of ON?
Patients with early stage osteonecrosis may not have any symptoms. Later symptoms include pain, diminished range of motion and the development of osteoarthritis. Osteonecrosis progresses differently in each person affected by it, however the time between feeling the first symptoms of joint pain and losing joint function is usually anywhere from a few months to over a year.
In order to diagnose you properly, your doctor will consider your symptoms and your medical history, examine your joint(s) and order one or more diagnostic tests. Your doctor may order X-rays, a CT scan, bone scan, a biopsy or an MRI to get a clear view of your condition.
How is ON treated?
Your doctor may recommend different treatment options depending on the severity of your ON and its impact on your joint(s) and your body as a whole. Your doctor may be especially interested in the condition of your femur and whether the head of the bone is still intact.