What is Osteo Arthritis?
Osteoarthritis (OA), also known as degenerative joint disease, is a form of arthritis (inflammation of a joint) caused by degeneration of cartilage. Cartilage serves an important role in joint function. Its gel-like nature provides protection to the ends of bones by acting as a shock absorber. Without the cartilage in the joint, bone literally rubs against bone, leading to pain, deformity, inflammation, and limitation of motion in the joint.
There are good reasons to believe that neither aging nor the normal use of joints causes osteoarthritis. But exactly what the cause of osteoarthritis is remains unknown. In one study, no obvious cause could be found in more than 90 percent of people with osteoarthritis.
There are hints that active disease processes are involved that upset the normal breakdown and remodeling of cartilage. Some researchers suggest that inappropriate loads placed on the bones may change the way their metabolism works. This can happen when the bones are used too much or not enough, when injuries occur that upset normal joint function, or when unusual stress is placed on the joint (by, say, operating a jackhammer).
Recent evidence suggests, too, that certain enzymes (metalloproteinases) are involved in the destruction of cartilage and bone in osteoarthritis. The loss of glycosaminoglycans (large molecules that help trap water) by cartilage during the disease process also may play a role.