What is Osteoarthritis?
Osteoarthritis is a condition that affects your joints. The surfaces within your joints become damaged so the joint doesn’t move as smoothly as it should (see Figures 1 and 2). The condition is sometimes called arthrosis or osteoarthrosis. Older terms are degenerative joint disease or wear and tear.
When a joint develops osteoarthritis, some of the cartilage covering the ends of the bones gradually roughens and becomes thin, and the bone underneath thickens. All the tissues within the joint become more active than normal – as if your body is trying to repair the damage:
- The bone at the edge of your joint grows outwards, forming bony spurs called osteophytes.
- The synovium (the inner layer of the joint capsule which produces synovial fluid) may thicken and make extra fluid. This causes your joint to swell.
- The capsule and ligaments (tough bands that hold the joint together) slowly thicken and contract as if they were trying to make your joint more stable.