What is arthritis?

Arthritis is a joint disorder featuring inflammation. A joint is an area of the body where two different bones meet. A joint functions to move the body parts connected by its bones. Arthritis literally means inflammation of one or more joints.

Arthritis is frequently accompanied by joint pain. Joint pain is referred to as arthralgia.

There are many forms of arthritis (over 100 and growing). The forms range from those related to wear and tear of cartilage (such as osteoarthritis) to those associated with inflammation resulting from an overactive immune system (such as rheumatoid arthritis). Together, the many forms of arthritis make up the most common chronic illness in the United States.

The causes of arthritis depend on the form of arthritis. Causes include injury (leading to osteoarthritis), abnormal metabolism (such as gout and pseudogout), inheritance, infections, and unclear reasons (such as rheumatoid arthritis and systemic lupus erythematosus).

Arthritis is classified as one of the rheumatic diseases. These are conditions that are different individual illnesses, with differing features, treatments, complications, and prognosis. They are similar in that they have a tendency to affect the joints, muscles, ligaments, cartilage, tendons, and many have the potential to affect internal body areas.