There are over 100 different forms of arthritis, according to the Arthritis Foundation. They vary in symptoms and treatment methods. Although some forms of arthritis are better understood than others, the causes of most are unknown.
Arthritis causes pain and loss of movement.
It can affect joints in any part of the body. Arthritis is usually chronic, meaning it can last for years. The more serious forms generally involve inflammation, with swelling, warmth, redness, and pain. In older people, the three most common types of arthritis are osteoarthritis, rheumatoid arthritis, and gout. It can range from a mild problem with only occasional stiffness and joint pain to a serious condition with much pain and disability.