What is avascular necrosis?

Avascular necrosis (AVN) is a condition that occurs when bone tissue dies because of too little blood supply. With avascular necrosis, the bone eventually collapses after tiny breaks (or microfractures) occur. Commonly, the condition affects the thigh bone (femur) in the hip area, but it can affect other bones in the body, including the jaw, hand/wrist, elbow, shoulder, knee, and foot locations. Avascular necrosis typically will progress with time, but may remain with only minimal symptoms for quite some time. The condition is also called osteonecrosis, aseptic necrosis, or ischemic bone necrosis.

What causes avascular necrosis?

There are various reasons for lack of blood supply to the bone. The most common reasons include:

  • Previous injuries to the bone where the blood supply to the bone is disrupted. This may occur following a broken bone or a dislocated joint.
  • Excessive alcohol intake.
  • Long-term use of oral steroids.
  • Use of certain medication families, such as bisphosphonates (though very rare).
  • Congenital (childhood) conditions (ie, Legg-Calve Perthes Disease).

Other less common causes of avascular necrosis include:

  • Cancer treatments like radiation and chemotherapy.
  • Lupus.
  • Sickle cell anemia.
  • Decompression disease (the “bends” – commonly related to scuba diving).

What are the symptoms of avascular necrosis?

The condition may cause no symptoms; however, some people have pain or a loss of motion in the affected joint. If avascular necrosis affects the hip, there may be groin pain that spreads down the thigh to the knee. In the wrist, the condition may cause wrist pain and weakness in the fingers. In the shoulder, avascular necrosis can result in pain and stiffness in the upper arm. In the knee, the condition can cause pain in the lower end of the thighbone. In some cases, the pain may come on suddenly and be severe, but may “burn out” with time.