Avascular Necrosis (Osteonecrosis)

Avascular necrosis is a disease that results from the temporary or permanent loss of blood supply to the bone. Without an adequate blood supply, bone tissue starts to die, and as it loses its structural integrity, tiny breaks called microfractures begin to form. These microfractures can cause the collapse of the weight-bearing surface of the bone, causing pain. If the bone affected is near a joint, the joint may also collapse.

Although any bone can be affected, avascular necrosis most often affects the ends of the long bones, such as the upper leg bone at the hip. It may affect one bone, several bones at one time, or different bones at different times.

Avascular necrosis is also called osteonecrosis, aseptic necrosis, or ischemic bone necrosis.

What Causes Avascular Necrosis?

Avascular necrosis can be caused by disease or severe trauma, such as a broken bone or dislocated joint that interrupts blood flow to a section of bone. It can also occur without trauma or disease. Anyone can be affected, but the condition is most common in people between the ages of 30 and 50.

Some of the possible causes include:

  • Musculoskeletal injury
  • Bone surgery
  • Dislocation or fractures around a joint
  • Long-term use of high-dose steroid medications
  • Excessive alcohol use
  • Radiation therapy or chemotherapy
  • Blood disorders, such as sickle cell anemia
  • Autoimmune disease
  • Pancreatitis
  • Clotting disorders
  • High cholesterol
  • Decompression sickness (diver’s disease or “the bends”)
  • HIV or taking HIV drugs

Video Overview: Avascular Necrosis of the Hip