Osteoarthritis (OA) | Arthritis | CDC

What is osteoarthritis (OA)?

Osteoarthritis (OA) is the most common form of arthritis. Some people call it degenerative joint disease or “wear and tear” arthritis. It occurs most frequently in the hands, hips, and knees.

With OA, the cartilage within a joint begins to break down and the underlying bone begins to change. These changes usually develop slowly and get worse over time. OA can cause pain, stiffness, and swelling. In some cases it also causes reduced function and disability; some people are no longer able to do daily tasks or work.

What are the signs and symptoms of OA?

• Pain or aching
• Stiffness
• Decreased range of motion (or flexibility)
• Swelling

How many people have OA?

OA affects over 32.5 million US adults.

What causes OA?

OA is caused by damage or breakdown of joint cartilage between bones.

What are the risk factors for OA?

• Joint injury or overuse—Injury or overuse, such as knee bending and repetitive stress on a joint, can damage a joint and increase the risk of OA in that joint.
• Age—The risk of developing OA increases with age.
• Gender—Women are more likely to develop OA than men, especially after age 50.
• Obesity—Extra weight puts more stress on joints, particularly weight-bearing joints like the hips and knees. This stress increases the risk of OA in that joint. Obesity may also have metabolic effects that increase the risk of OA.
• Genetics—People who have family members with OA are more likely to develop OA. People who have hand OA are more likely to develop knee OA.
• Race— Some Asian populations have lower risk for OA.

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How is OA diagnosed?

A doctor diagnoses OA through a review of symptoms, physical examination, X-rays, and lab tests.
A rheumatologist, a doctor who specializes in arthritis and other related conditions, can help if there are any questions about the diagnosis.