- Diseases, Disorders & Conditions
Osteo-What? Osteonecrosis or avascular necrosis?
At first it was a dull ache; gradually the pain In your knee became quite severe. "Aha!" said your doctor after reading an x-ray that didn't show any fracture or dislocation. Thinking that you had sprained your knee and that it would heal on it's own, she prescribed
non- steroidal anti-inflammatory medications (ibuprofen, for example), Ice and rest. When this was not effective in treating your pain, she wrote an order for physical therapy because surely this was tendonitis. Unfortunately, after 6 weeks you still had pain in your knee.
The next test in her bag of tricks was an MRI and it showed something quite different: osteonecrosis (avascular necrosis). What was the name again? What is osteonecrosis?
Definition and Causes
Osteonecrosis is a condition that results when blood flow to bones is cut off. Blood flow to bones? Yes, bones are just as alive as any other structure in the body; this blood carries necessary oxygen and nutrients. If the blood doesn't get to the bones, they die.
So, there you have it: osteo= bone and necrosis = death. So, osteonecrosis means dead bone. How do you got osteonecrosis? Germs on the doorknob? Is it a virus like the common cold?
No. Some people just develop osteonecrosis because they might have a condition that predisposes them. For example, there might be a fracture of the long bones in your leg (your thigh or calf bone). If these bones fracture, tiny little bone chips may form blood clots in arteries and veins resulting inA decreased blood supply yet again.
Divers who surface too rapidly and develop “the bends” often form nitrogen bloodclots which obstruct blood vessels and have the same result. Individuals with sickle cell anemia can develop osteonecrosis due to the shape of their red blood cells. The shape may block the blood vessel, again depriving bone of blood.
People with autoimmune diseases develop osteonecrosis for several reasons. Autoimmune diseases are frequently treated with corticosteroids, such as prednisone. 35% of
medication-induced osteonecrosis is caused by corticosteroids. Scientists aren't really sure how prednisone might cause osteonecrosis; but, one theory is that corticosteroids cause the formation of fatty blood clots.
Also, several autoimmune diseases cause blood clots, in the absence of corticosteroids. the autoimmune disease lupus provides one example of this in antiphospholipid syndrome (the subject of another hub).
What causes osteonecrosis?
So, now that you know you have osteonecrosis, how is it treated? Doctors first prescribe rest, acetaminophen, ice or non steroidal medications. By rest, they just don't mean for you to minimize usage of the joint; ofttimes they mean not putting weight on it at all for a few months.
Sometimes osteonecrosis needs to be treated surgically. Often, the first surgery offered might be one called a core decompression. in this surgery, minute-sized holes (cores) are drilled into the bones, releasing gases and other necrotic debris: thereby decreasing the pain.
Several other surgical treatments are available including complete or partial joint replacement. Research shows promise in treating osteonecrosis with stem cells, coral matrix and bone grafts and human growth hormone.