What is Arthritis?

The word "arthritis" is derived from two Greek words: arthron, meaning a joint, and —itis, meaning inflammation. Inflammation typically involves redness, heat, swelling and tenderness. So, technically speaking, arthritis describes a joint that is red, hot, swollen and tender.

Arthritis is a condition in which joints are painful and stiff. If the joints are actually red, hot, swollen, and tender, this condition is often described as inflammatory arthritis.

A related term, used less often by doctors now, is rheumatism. This non-specific term refers to any persistent condition of pain and stiffness related to joints, tendons, ligaments, or bursas (which are small 'cushions' that lie under a tendon to protect it from injury).

Arthritis and rheumatism are common and their frequency increases with age. A Canadian survey in 2000 and 2001 found that less than 5% of those aged 25 to 34 said that a doctor had told them they had arthritis or rheumatism. Among those aged 65 to 74, almost 40% had been given this diagnosis.

Arthritis is not a single disease with a single cause. There are dozens of different types of arthritis, each with its own cause. For instance, bacteria can sometimes cause a severe acute infection called infectious arthritis. Men with hemophilia can have bleeding inside their joints, which over the years can cause a severe arthritis. One particularly severe and sudden type of arthritis, called gout, is caused by crystals of a chemical called uric acid being deposited inside a joint (typically at the base of the big toe).

Rheumatoid arthritis is a specific form of inflammatory arthritis that is caused by your own immune system, which starts (for no known reason) to attack the membrane lining your joints. Because rheumatoid arthritis is caused by your body attacking itself, it is referred to as an autoimmune disease. The most common type of arthritis, osteoarthritis, is caused by wear and tear on the joints. Because of this, some doctors refer to osteoarthritis as degenerative joint disease. Other forms of inflammatory arthritis include ankylosing spondylitis, which affects the spine, and psoriatic arthritis, which tends to develop mainly in people already suffering from a skin condition called psoriasis.