Step 1: What is osteoarthritis?

Return to Index Step 1: What is Osteoarthritis? Step 2: Symptoms Step 3: Causes Step 4: How Osteoarthritis is Diagnosed Step 5: Overview of Arthritis Treatment Step 6: Heat and Cold Therapy Step 7: Pain Medication Step 8: Other Options Step 9: Unproven Remedies Step 10: Weight Control and Exercise Step 11: Living With Osteoarthritis Key Points MedTest Glossary

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Osteoarthritis develops in a joint when cartilage begins to break down. Cartilage is tough, protective tissue. It cushions the places where bones come together to form a joint. Cartilage can break down for several reasons, including:

"Wear-and-tear" as people grow older
Joint-related injuries
Damage to the joint from infections and diseases

Cartilage normally protects the joint, allowing for smooth movement. Cartilage also absorbs shock when pressure is placed on the joint, like when walking. Arthritis involves the breakdown of cartilage. Without the usual amount of cartilage, the bones of the joint rub together, causing pain, swelling and stiffness.

In most cases, the exact cause cannot be identified. Unfortunately, damaged cartilage cannot heal and become normal again.

Watch an animation about osteoarthritis .

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Osteoarthritis often involves several joints. However, it does not "spread" from joint to joint throughout the body. It typically strikes the:

Weight-bearing joints (knees, hips, back, feet)
Hands
Spine

Toe Spine Knee Hip Hand

The knees, hips, and lower back (spine) are most commonly affected.

Osteoarthritis is a "non-inflammatory" type of arthritis, which means that inflammation is not the key component. It is completely different from the less common rheumatoid arthritis -- in which the body's immune system attacks its own tissues, causing inflammation.

While osteoarthritis sometimes may be painful, it is not always disabling, and unlike rheumatoid arthritis, is unlikely to produce severe deformity of the joints.

Do you know what "osteo" means? Click here.

Review Date: 11/22/2006
Reviewed By: Alan Greene, M.D., F.A.A.P., Stanford University School of Medicine; Chief Medical Officer, A.D.A.M., Inc.

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