Osteoarthritis of the Knee

Okay. The information will be presented in the following categories:

1. Causes -- who gets OA and why

2. Treatments -- therapies that may be helpful

3. Course/prognosis -- what to expect

4. Future directions -- what may lie ahead for the treatment of OA.

Let's start with the causes of OA.

Osteoarthritis is particularly common among older people, but it is not an inevitable part of aging and age does not cause OA. In other words, it is not "normal" for an elderly person to have joint pain. Anyone who has bothersome joint pain, elderly or not, should be thoroughly evaluated by a health care provider. There are many causes of joint pain and many types of arthritis; appropriate treatments vary accordingly. It is never a good idea to assume that joint pain is "just due to aging."

There probably is no single cause of osteoarthritis, and, for most people, no cause can be identified. Factors other than age seem to contribute to osteoarthritis. People who sustain injuries or small repetitive injuries as a consequence of repeated movements on the job or those with sports-related injuries may be at increased risk of developing osteoarthritis; this may occur at any age. There may be a genetic component involved, especially in the development of osteoarthritis in the hands. Obesity seems to be a factor in osteoarthritis of the knees. Other recognized risk factors for osteoarthritis include

• repeated episodes of bleeding into the joint, as may occur in hemophilia or related bleeding disorders

• repeated episodes of gout or pseudogout in which episodes of inflammation follow the deposition of uric acid or calcium crystals into the joint

• avascular necrosis (AVN), a condition in which the blood supply to the bone near the joint is interrupted, leading to bone death and eventually joint damage. The hip is the most commonly affected joint, but the knee can also develop AVN

• chronic inflammation caused by previous rheumatic illness, such as rheumatoid arthritis

• metabolic disorders, such as hemochromatosis, in which a genetic abnormality leads to too much iron in the joints and other parts of the body

• previous joint infection.

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