What is osteonecrosis?

Your bones are made up of living cells that need a blood supply to stay healthy. In osteonecrosis, blood flow to part of a bone is reduced. This causes death of bone tissue, and the bone can eventually break down and the joint will collapse.

Osteonecrosis can happen to any bone, but most often it develops in the ends of long bones, such as the:

• Thigh bone.
• Upper arm bone.

Less often, the bones of the elbows, ankles, feet, wrists, and hands are affected.  

When the disease involves part of a bone in a joint, it can lead to the breakdown of the bone and osteoarthritis.

Who gets osteonecrosis?

People of any age can get osteonecrosis, but it is most common in people in their 30s and 40s.

Several factors may increase the chance a person will get osteonecrosis. However, some people who do not have any of these factors may still get the disease. Factors that may increase the chance of getting osteonecrosis include:

• Injury, such as a broken or dislocated bone or a joint injury.
• Medications, such as corticosteroids that are used for long periods at high doses.
• Excessive alcohol and tobacco use.
• Certain medical conditions and treatments, such as chemotherapy.  

What are the types of osteonecrosis?

Health care providers describe two types of osteonecrosis:

• Traumatic, which follows an injury. The most common causes of traumatic osteonecrosis are a bone fracture (break) or dislocation.
• Nontraumatic, when there is no history of injury.