Arthritis refers to inflammation of a joint. The inflammation can affect any of the important structures inside a joint, including the joint lining (synovium), bones, cartilage, or supporting tissues.
The condition may affect one, a few, or many joints throughout the body.
There are many possible causes of arthritis, although some are much more common than others. Some types of arthritis respond well to treatment and resolve without any lingering effects, whereas other types of arthritis are more difficult to control and can be disabling.
Joint symptoms — The most common symptoms of arthritis include joint pain and stiffness. There may also be joint tenderness, swelling, and limited movement of one or more joints. The skin over the joint is sometimes red and warm.
There are two main types of arthritis: inflammatory and noninflammatory. Examples of inflammatory arthritis include infectious arthritis, rheumatoid arthritis, and gout. An example of noninflammatory arthritis is osteoarthritis, the most common type of arthritis. The location and pattern of joint pain, the presence or absence of joint swelling, the rapidity of its onset, as well as the presence of signs and symptoms outside the joint (such as rash), can help to distinguish between inflammatory and noninflammatory arthritis.
Inflammatory arthritis — Inflammatory arthritis usually causes joint stiffness with rest, especially morning stiffness. Certain types of inflammatory arthritis, such as rheumatoid arthritis and the arthritis of systemic lupus erythematosus (SLE), affect joints symmetrically (ie, affect the same joints on both sides of the body).
Noninflammatory arthritis — Noninflammatory arthritis usually causes pain that is aggravated by movement and weightbearing and is relieved by rest. Joints on one or both sides of the body may be affected.