(Arthritis & Rheumatism) -- Osteoarthritis (OA) is the world's most common form of joint disease, primarily affecting the elderly. According to experts, up to 50 percent of America's baby boomers - men and women over age 50 - may be affected. A degenerative illness, OA is characterized by cartilage damage, pain, stiffness, and sometimes disability. Unlike rheumatoid arthritis, a joint disease that affects young adults, it is not generally thought that inflammation causes OA.

Researchers from the United Kingdom, however, have found strong evidence linking severe synovitis, or inflammation of the tissue lining the joints, with osteoarthritis of the knees and hips. Published in the August 2003 issue of Arthritis & Rheumatism, their study indicates that inflammation may, in fact, be a common early sign of OA and a significant factor in its progression.

The study focused on 104 patients - 51 women and 53 men, between the ages of 62 and 75 - with OA of the knee or hip, confirmed by radiographs. Samples of synovial tissue were taken from the participants. From this representative group of OA patients, 31 percent showed evidence of severe inflammation. These same patients also showed signs of angiogenesis, or new blood vessel formation - a condition routinely associated with inflammatory joint disease.

"Synovial inflammation was not confined to patients with extensive radiographic joint damage or end-stage disease," notes research team leader, Dr. D. Walsh. "Further studies are required to determine the importance of angiogenesis and inflammation in early OA and their possible contribution to progressive joint damage."