Osteoarthritis Learning Center

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What Is Osteoarthritis

Osteoarthritis (OA) is the most common type of arthritis. It is also known as:

  • degenerative joint disease
  • degenerative arthritis
  • wear-and-tear arthritis

OA is a disease of aging. According to the Centers for Disease Control and Prevention (CDC),, OA affects more than 25 million men and women over the age of 25 in the United States. That is almost 14 percent of all adults. It is even more common in the elderly. More than one-third of adults over the age of 65 suffer from OA.

OA is a leading cause of disability in adult Americans.

Men and women of any age can develop OA. However, the demographics of OA change with age. According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases, before the age of 45, OA is more common in men. After 45, it is more common in women.

Other risk factors for OA include:

  • obesity
  • a job that puts stress on the joints
  • joint injury
  • joint malformation

Causes and Symptoms of Osteoarthritis

OA is caused by a breakdown in the cartilage that covers the joints. The protective tissue is damaged by age and repeated motion. This increases the friction as the bones of the joint rub against each other. It can also cause damage to the bone.

The most common symptoms of OA are pain and stiffness. OA can occur in any joint. However, the most commonly affected joints are in the:

  • hands
  • knees
  • hips
  • spine

OA is different than rheumatoid arthritis (RA). RA is an autoimmune disorder. The body’s immune system attacks joint tissue. This leads to swelling and pain.


Cartilage is a tough but rubbery substance covering the end of bones. It protects joints and allows bones to move easily against each other. OA occurs when your cartilage begins to degrade. The degeneration exposes the bones of the joint. Bone-on-bone contact can cause extreme pain. The loss of cartilage may also affect the shape of the joint. This may keep it from functioning smoothly.

Severity of Osteoarthritis

OA varies in severity. Some people may have evidence of OA during testing without any symptoms. Other people may develop severe pain and stiffness.

According to the CDC, up to 80 percent of people with OA have some change in their mobility. One-quarter cannot perform some activities related to daily life. These include problems:

  • getting in and out of chairs
  • bathing
  • dressing
  • putting on shoes

In rare cases, damage from spinal OA can affect the function of your bowels and bladder. Spinal OA can also cause tingling or weakness in the arms and legs.

Long-Term Outlook for Osteoarthritis

OA is a slow-developing disease. It is a silent disorder that can be difficult to diagnose until it begins to cause painful or debilitating symptoms. Early OA is usually only diagnosed after an accident or other incident that results in a fracture requiring an X-ray.

Over time, OA can cause:

  • pain
  • swelling
  • stiffness
  • limited range of motion

Treatment varies from individual to individual. Many people can get symptom relief with options such as:

  • exercise
  • weight loss
  • physical therapy
  • medication

Other people may require surgical treatment. Surgery may involve anything from cleaning up damaged joint tissue to joint replacement.

Content licensed from:

Written by: David Heitz and Valencia Higuera
Published on Mar 13, 2014
Medically reviewed on Feb 10, 2017 by William Morrison, MD

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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