We’ve spent a lot of time discussing the many causes of joint pain, especially the many varieties of arthritis, in previous columns. For the most part, it can be said that “arthritis is arthritis, regardless of the cause and this would, in essence, be accurate.
While we all know that arthritis can be caused by factors such as injury, aging, disease and obesity, there is one particular cause of joint degeneration that virtually no one has heard of – Avascular Necrosis, or AVN. I like to call it the “invisible” arthritis, mainly because the pathology that occurs with this condition can often go unnoticed until joint destruction is severe, even end-stage.
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Take the hip and knee for instance. Frequently, at the time of surgical joint replacement, the joint surface of the femoral head, or “ball” of the ball-and-socket joint as well as the femoral condyles or “knuckles” of the thigh bone, will look surprisingly normal in cases of avascular necrosis, unlike the rough uneven surfaces associated with the more common osteoarthritis. This is because the pathology and resultant damage found in AVN lies beneath the actual joint cartilage surfaces in the underlying bone itself.
What is Avascular Necrosis?
First, let’s break the term down to better understand it. The term necrosis literally means “bone death” and avascular means “absence of blood supply.” Thus, an arthritic hip, for example, can be caused by the destruction of the femoral head, or “ball” of the hip, as a result of a loss of blood supply to it.
What joints can be affected?
Since every joint in the body has a blood supply serving it, any joint can be affected. That said, however, a few joints seem to be most commonly affected such as the hip, shoulder and the knee. These are the worst actors because they are the most used, and the majority are weight-bearing in nature.
What causes Avascular Necrosis?
Many things are known to contribute to this condition, such as:
• Chronic excessive alcohol use;
• Systemic steroid use for medical treatment or otherwise such as steroids use in Rheumatoid Arthritis patients or bodybuilding;
• Gout (chronic elevated uric acid levels in the blood);
• Atherosclerosis (“hardening of the arteries”);
• Sickle Cell Disease;
• Traumatic injury such as hip/shoulder dislocation where normal blood supply is traumatized and disrupted. Whereas the “garden variety” arthritis, also known as osteoarthritis, is caused more so by mechanical factors –weight, bone aging etc. – AVN can be condition or disease-related and can arise almost without any warning signals.
Avascular Necrosis is typically diagnosed by several methods, including a good quality orthopedic physical examination and getting a good medical history from the patient. Certain diagnostic studies can be extremely valuable in aiding the diagnosis, such as x-rays, bone scans, CT scans and MRIs.
Symptoms of hip pain are typically the most common. Often there is no history of any trauma, so this is where a good patient medical history and orthopedic examination will go a long way towards diagnosis. A history of long term alcohol use or chronic systemic steroid use can send up red flags as well.
How is AVN treated?
In mild or early forms of AVN, rest, pain relievers can be of significant benefit in allowing the bone to heal.
Treatment options will depend upon the joint(s) affected, the age and the condition of the patient. In younger individuals, treatment of severe AVN can include surgical procedures to stem the destruction of the underlying bone beneath the joint cartilage in order to try and preserve the joint.
One such procedure is called a Core Decompression in which a large hole is literally drilled into the hip to relieve pressure within the bone that can cause “bone edema” or swelling that can “choke” the blood vessels. This procedure is typically performed on the younger patient, in an effort to prolong the health and life span if the hip.
For shoulders and knees, the most common treatment is joint replacement surgery. In smaller joints such as the fingers, fusion of the joint can also be considered as a treatment option.
The key is that when people begin to experience joint pain, especially in the hip, knee or shoulder and they are middle-aged or older-and there has been no history of injury, avascular necrosis should at least be ruled out.
As I said before, AVN creeps up on people and by the time it is visible on x-ray, for example, it may well be too late to save the joint. Those with conditions or disease elements as described earlier can be at particular risk.
It never hurts to be informed and aware. It’s all part of becoming a more informed, educated and thus empowered, patient/consumer.
For more information and support resources regarding avascular necrosis visit www.nonf.org, http://osteonecrosisavnsupport.org or www.arthritis.org.
Chisholm’s expertise in nursing, orthopedics and surgery spans more than 30 years. For more information on orthopedic-related topics, visit www.bone-and-joint-pain.com. Submit questions or comments to Ken at