What is Avascular Necrosis of the Knee?

Avascular necrosis, also sometimes referred to as osteonecrosis, is a condition that occurs when blood flow to the bone is significantly reduced or even stopped. This results in the death of cells that live within the bone tissue and require blood. This rapidly impairs the bone, eventually weakening it to the point of collapse. When this collapse happens, damage is almost always incurred to the rest of the knee joint.


To understand the causes behind avascular necrosis of the knee, it is important to be familiar with the different forms this condition can take.

There are two primary types of avascular necrosis of the knee:

  • Spontaneous Osteonecrosis of the Knee (SPONK): Generally, this is the result of a major accident or unexpected trauma to the knee. While it most often affects a single area of the knee, it causes this area to lose its blood supply and can lead to collapse, sudden pain and limited mobility. This type of avascular necrosis of the knee is often seen in older women who have osteoporosis.
  • Secondary Osteonecrosis of the Knee: While there is no known cause for this particular type of avascular necrosis of the knee, many risk factors that encourage this condition have been identified. These risk factors include alcohol abuse, sickle cell disease, systemic lupus erythematosus (SLE) and Gaucher disease. Multiple areas within the knee, and sometimes even both knees, are affected by this form of avascular necrosis.

Other common causes for avascular necrosis of the knee include:

  • Blood clots
  • Inflammation or damage to the arteries
  • Long-term use of corticosteroids
  • Fracture or dislocation of the femur (thigh bone)
  • Radiation therapy or chemotherapy
  • Pancreatitis
  • Decompression sickness


While in its early stages, this condition may cause mild symptoms or no symptoms at all. However, as avascular necrosis of the knee progresses, so does the pain and discomfort. Once the bone completely collapses, patients will typically experience severe pain.

Other symptoms include:

  • Limited mobility or use of the knee
  • Abnormal shape or contour to the knee
  • Pain that increases at night and/or when bearing weight on the knee

The OrthoCARE Treatment Approach

The goal of any treatment for avascular necrosis of the knee is to restore normal function to the joint, repair damage incurred, halt the progression of further damage and reduce pain. Oftentimes, conservative treatments can be successful in alleviating pain and slowing damage to the joint but most patients that suffer from this condition eventually need surgical intervention.

A combination of non-surgical treatments may be recommended, including:

  • Rest and limited activity
  • Use of crutches, a knee brace or a cast
  • Focused, range-of-motion exercises and physical therapy

If surgery becomes necessary, OrthoCARE Institute features some of the most experienced orthopedic surgeons in North Texas. Depending on the underlying cause of your avascular necrosis, the severity of your symptoms and your health history, your orthopedic physician will recommend the most effective procedure for you. Surgical options include:

  • Partial or total knee replacement
  • Bone graft
  • Core decompression
  • Osteotomy

OrthoCARE Institute, a division of the physician-owned, vertically-integrated Lumin Health system, is North Texas’s premier bone, joint and spinal center. We offer comprehensive and compassionate non-invasive and surgical treatments for a variety of conditions, including avascular necrosis of the knee. Please contact us at 972-255-5588 or by filling out the form on our Contact Us page. We look forward to helping you stay active, pain-free and healthy!

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