What Is Arthritis?

There are over 100 forms of arthritis and other rheumatic diseases. These diseases may cause pain, stiffness, and swelling in joints and other supporting structures of the body such as muscles, tendons, ligaments, and bones. Some forms can also affect other parts of the body, including various internal organs.

Many people use the word "arthritis" to refer to all rheumatic diseases. However, the word literally means joint inflammation; that is, swelling, redness, heat, and pain caused by tissue injury or disease in the joint. The many different kinds of arthritis comprise just a portion of the rheumatic diseases. Some rheumatic diseases are described as connective tissue diseases because they affect the body's connective tissue--the supporting framework of the body and its internal organs. Others are known as autoimmune diseases because they are caused by a problem in which the immune system harms the body's own healthy tissues. Examples of some rheumatic diseases are:

• Osteoarthritis
• Rheumatoid arthritis
• Fibromyalgia
• Systemic lupus erythematosus
• Scleroderma
• Juvenile rheumatoid arthritis
• Ankylosing spondylitis
• Gout

On this site, the term arthritis will be used as a general term to refer to arthritis and other rheumatic diseases.