Osteoarthritis Learning Center

Definition

Osteoarthritis (OA) is the most common joint disorder.

Alternative Names

Hypertrophic osteoarthritis; Osteoarthrosis; Degenerative joint disease; DJD; OA; Arthritis - osteoarthritis

Causes, incidence, and risk factors

In osteoarthritis, the cushioning (cartilage) between the bones wears away in the joints. As osteoarthritis gets worse, the cartilage disappears and bone rubs on bone. Bony spurs or growths usually form around the joint. The ligaments and muscles around the joint loosen and become weaker.

Often, the cause of OA is unknown. It is mainly related to aging, but other factors can also lead to OA.

• Osteoarthritis tends to run in families
• Being overweight increases the risk
• Fractures or other joint injuries can lead to osteoarthritis later in life
• Long-term overuse at work or in sports can lead to osteoarthritis

Medical conditions that can lead to osteoarthritis include:

• Bleeding disorders that cause bleeding in the joint, such as hemophilia
• Disorders that block the blood supply near a joint, such as avascular necrosis
• Other types of arthritis, such as chronic gout, pseudogout, or rheumatoid arthritis

The symptoms of osteoarthritis usually appear in middle age and almost everyone has them by age 70. Before age 55, the condition occurs equally in men and women. After age 55, it is more common in women.

Symptoms

The symptoms of osteoarthritis include:

• Deep aching joint pain that gets worse after exercise or putting weight on it, and is relieved by rest
• Pain that is worse when you start activities after a period of no activity
• Over time, pain is present even when you are at rest
• Grating of the joint with motion
• Increase in pain during humid or moist weather
• Joint swelling
• Limited movement
• Muscle weakness around arthritic joints

Some people might not have symptoms.

Signs and tests

A physical exam can show:

• Joint movement may cause a cracking (grating) sound
• Joint swelling (bones around the joints may feel larger than normal)
• Limited range of motion
• Tenderness when the joint is pressed
• Normal movement is often painful

No blood tests are helpful in diagnosing osteoarthritis.

An x-ray of affected joints will show a loss of the joint space. In advanced cases, there will be a wearing down of the ends of the bone and bone spurs.