What Is Arthritis?

Arthritis and other rheumatic diseases are characterized by pain, swelling, and limited movement in joints and connective tissues in the body. According to the Centers for Disease Control and Prevention, nearly 66 million people in the U.S. have some form of arthritis or chronic joint symptoms.

Arthritis, which literally means inflammation of a joint (where two or more bones meet), actually refers to more than 100 different diseases. Rheumatic diseases include any diseases that cause pain, stiffness, and swelling in joints or other supportive body structures, such as muscles, tendons, ligaments, and bones.

Arthritis and other rheumatic diseases are often mistakenly associated with old age, because osteoarthritis (the most common form of arthritis) occurs more often among elderly persons. However, arthritis and other rheumatic diseases affect people of all ages.

Arthritis is usually chronic, which means that it rarely changes, or it progresses slowly. Specific causes for most forms of arthritis are not yet known.