Aseptic Necrosis
(Avascular Necrosis or Osteonecrosis)

What is aseptic necrosis?

Aseptic necrosis (also referred to as avascular necrosis or osteonecrosis) is a condition that results from poor blood supply to an area of bone causing bone death. This is a serious condition because the dead areas of bone do not function normally, are weakened, and can collapse.

What causes aseptic necrosis?

Aseptic necrosis can be caused by trauma and damage to the blood vessels that supply bone its oxygen. Other causes of poor blood circulation to the bone include a blockage by air or fat (embolism) that obstructs the blood flow through the blood vessels, abnormally thick blood (hypercoagulable state), and inflammation of the blood vessel walls (vasculitis).

What conditions are associated with aseptic necrosis?

Conditions that are associated with aseptic necrosis include alcoholism, cortisone medications, Cushing's syndrome, radiation exposure, sickle cell disease, pancreatitis, Gaucher disease, and systemic lupus erythematosus.

What are symptoms of aseptic necrosis?

Aseptic necrosis begins as a painless bone abnormality. It can remain painless. The involved bone often later develops pain, especially with use. For example, if a hip joint develops avascular necrosis in the ball of the hip joint, pain can be noted especially with weight-bearing. As the ball of the hip joint collapses from the degeneration of the bone from aseptic necrosis, pain in the groin can be felt with hip rotation and pain can sometimes be noted with rest after weight-bearing.

How is aseptic necrosis diagnosed?

The diagnosis of aseptic necrosis can often, but not always, be made with x-rays. By the time changes are apparent by plain film x-ray testing there has been substantial damage to the bone affected. Bone changes visible on plain film x-ray are therefore considered a later-stage finding. Earlier signs of avascular necrosis can be detected with an MRI scan or suggested by a nuclear bone scan.

What is the treatment for aseptic necrosis?

The treatment of aseptic necrosis is critically dependent on the stage of the condition. Early aseptic necrosis (before x-ray changes are evident) can be treated with a surgical operation called a core decompression. This procedure involves removing a core of bone from the involved area and sometimes grafting new bone into the area. This allows new blood supply to form, preserving the bone. Weight bearing or impact of the involved joint is restricted.

Later stages of aseptic necrosis (when x-ray changes have occurred) typically lead to seriously damaged bone and joints, requiring joint replacement surgery. For related information, please read the following articles; Total Hip Replacement and Total Knee Replacement.