Definition

Arthritis means inflammation of a joint. There are more than one hundred different forms of arthritis. They are similar to each other in the symptoms they produce, which includes sore, stiff, inflamed, and painful joints. Beyond these common symptoms, the various forms of arthritis are quite different from each other. Most forms of arthritis can be subdivided into three major categories: rheumatoid (pronounced ROO-muh-toid) arthritis, osteoarthritis (pronounced OSS-tee-o-ar-THRIE-tis), and gout.

Description

A joint is a part of the body where two bones connect with each other. A joint consists of many structures. In the simplest form, there are two bones separated from each other by a slight gap called the joint cavity. The end of each bone is covered with cartilage, a tough, elastic material.

The space between bones is covered with a thin membrane called the synovial (pronounced si-NO-vee-uhl) membrane. The synovial membrane secretes (releases) a...