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Arthritis Overview

Arthritis is one of the most common health problems in the United States. An estimated one in six people suffer from arthritis or a related condition.

The following kinds of arthritis are four of the most common types:

Infectious arthritis

This type of arthritis causes pain and swelling in the joints – the places where two or more bones come together. The pain and swelling is referred to as inflammation. The inflammation is caused by a germ, which is usually either a bacterium (back-teer-e-um), a virus, or a fungus. Infectious arthritis normally affects only one joint, but sometimes it affects more. It does not usually last a long time if it is treated early.

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This is the most common type of arthritis, especially among older people. Sometimes it is called degenerative joint disease or osteoarthrosis. Osteoarthritis is a joint disease that mostly affects the cartilage (KAR-til-uj). Cartilage is the slippery tissue that covers the ends of bones in a joint. Healthy cartilage allows bones to glide over one another. It also softens the shock of physical movement. In osteoarthritis, the surface layer of cartilage breaks down and wears away. This allows bones under the cartilage to rub together, causing pain, swelling, and stiffening of the joint. Over time, the joint may lose its normal shape. Also, bone spurs – small growths called osteophytes – may grow on the edges of the joint. Bits of bone or cartilage can break off and float inside the joint space. This causes more pain, catching, and damage.

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Post-traumatic arthritis

This kind of arthritis develops after an injury such as a break or a dislocation, or after some surgeries. Post-traumatic arthritis is a form of osteoarthritis or osteonecrosis.

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Rheumatoid arthritis

This is less common than osteoarthritis and can affect people at any age, but mostly it occurs in people over 40. It is an inflammatory disease that causes pain, swelling, stiffness, and loss of function in the joint. It is caused by a fault in the immune system and can often run in families.

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