Multiple: Osteoarthritis

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Multiple: Osteoarthritis

Causes and Symptoms
The Future
For more information


Osteoarthritis, or OA, is a disease of the joints in which the cartilage that cushions the bones in the joints starts to break down and wear away. As the cartilage disappears, the bones begin to rub against each other, causing pain, stiffness, loss of flexibility and mobility in the affected joints, and the formation of bony spurs around the joints.

OA can be classified as either primary or secondary. Primary osteoarthritis occurs without an injury to the joint or other obvious cause. Secondary OA develops as a result of another disease or injury to the joint.


Osteoarthritis is a disorder of the joints in which the gradual wearing away of the cartilage within joints leads to pain, stiffness, and loss of the ability to move the joint freely. OA can affect almost any joint in the body, although it is most commonly found in the large weight-bearing joints—the hips, knees, spine, and feet—and in the hands and fingers. Although osteoarthritis is not caused by the aging process itself, it is largely a disease of older adults. In most cases the disorder comes on slowly and gradually over a period of years rather than appearing suddenly.

Osteoarthritis differs from rheumatoid arthritis (RA) in that it does not affect organs or body systems other than the joints. Although OA may be painful, it does not affect the blood vessels, digestive system, lungs, or other internal organs. Fever or redness in the joints is more likely to indicate RA than osteoarthritis.

It is possible for people to have osteoarthritis without noticeable pain or swelling. For example, some doctors estimate that 80 percent of adults

over sixty-five have evidence of OA when they are x-rayed, but only 60 percent of this group have joint pain and other troublesome symptoms of the disease.

The severity of osteoarthritis varies from patient to patient. Some people are only mildly affected and can manage their symptoms with over-the-counter pain relievers when needed. Others, however, find their lives disrupted by the disease. They may have to change occupations, become completely unable to work, or lose their ability to carry out ordinary daily activities. Elderly adults with severe OA may no longer be able to live independently.


Osteoarthritis is the most common joint disease among older adults in the United States. It affects nearly 21 million people in the United States and accounts for 25 percent of visits to primary care physicians. Half of all prescriptions for nonsteroidal anti-inflammatory drugs (NSAIDs) are written for patients with OA.

The rate of OA in the population increases with age; it affects about 30 percent of people over forty-five but almost 80 percent of people over eighty. Osteoarthritis is equally common in men and women between the ages of forty-five and fifty-five. However, more women than men are affected in the over-fifty-five age group. Younger adults, however, can

develop OA as a result of repeated injuries to their joints, abnormally shaped joints, or genetic disorders that affect the joints.

Some people are at increased risk of osteoarthritis:

  • People who are severely overweight. Obesity increases the strain on such weight-bearing joints as the knees, lower spine, and hips.
  • People from families with a history of OA. Some researchers think that genetic factors are involved in as many as 60 percent of OA cases, although no specific genes have been linked with OA currently. Women are more likely than men to be affected by a family history of osteoarthritis in the hands and fingers.
  • People with misshapen joints or defective cartilage. Structural abnormalities in a person's joints increase the risk of OA.
  • Race and ethnicity. African American women are at increased risk of developing osteoarthritis of the knee, although the reasons for this difference are not completely understood.
  • Pregnant women.
  • People who have injured a joint in an accident or participation in sports that puts pressure on the joints (running, martial arts, contact sports, tennis, baseball, etc.)
  • People who have been diagnosed with other diseases that affect the joints, such as gout, Lyme disease, rheumatoid arthritis, or Paget disease.

Coping with Osteoarthritis

One of the most effective forms of self-care in coping with OA is keeping a positive attitude. In addition to watching their weight and getting a good night's sleep, people with OA can help themselves by:

  • Focusing on what they can do rather than what they cannot.
  • Breaking down daily chores and activities into smaller tasks.
  • Looking at ways to minimize emotional stress as well as stress on their joints.
  • Balancing rest with activity; keeping up moderate levels of exercise without overdoing.
  • Practicing meditation, relaxation techniques, or guided imagery to manage pain.
  • Putting together a support community of friends, family members, and health care professionals.
  • Learning to listen to their body's signals and recognize their limits.

Causes and Symptoms

Primary osteoarthritis is caused by a gradual loss of water from the cartilage in the joints. Healthy cartilage contains between 65 and 80 percent water, which allows it to protect the bones against the effects of gravity

on the body and to keep the joints moving smoothly. The bones in the joints and the cartilage that surrounds them are encased in a structure called a joint capsule. The joint capsule in turn is lined with a membrane that secretes a fluid that lubricates the joints. As people age and their cartilage shrinks from loss of water, the ends of the bones begin to produce outgrowths known as osteophytes or spurs. As the cartilage wears away, it releases breakdown products into the fluid produced within the joint capsule, resulting in a mild inflammation and swelling of the joint. The swelling in turn stretches the joint capsule, leading to the pain and stiffness associated with OA.

In secondary OA, the gradual loss of cartilage is triggered by a traumatic injury or infectious disease. The disease progresses in the same way as in primary osteoarthritis.

The symptoms of OA typically include:

  • Pain in the joint during use, especially when used after a period of inactivity
  • Soreness in the joint when light pressure is applied
  • Stiffness in the joint, usually worse in the morning
  • Cracking, popping, or grating sensation or sound when the joint is moved or used
  • Swelling of the tissues around the joint
  • Hard bumps or lumps around the joint caused by bone spurs
  • Discomfort in the joint that gets worse during rainy or humid weather


Pain is the symptom of OA that is most likely to bring patients to their doctor. The doctor will begin by taking a history of the symptoms, including a family history of osteoarthritis. The doctor may ask whether the symptoms are affected by the type of activity, level of activity, or weather conditions.

The next step in diagnosing osteoarthritis is a physical examination of the affected joints. The doctor may press on the joints, feel the area around the joints for bony lumps, or try to move the joints to see whether their range of motion is limited.

Laboratory tests and imaging studies may include a blood test to rule out rheumatoid arthritis; an x-ray of the affected joint; withdrawal of a

small amount of fluid from the affected joint to rule out gout or an infection; or the insertion of a miniature camera to look inside the joint. This type of examination is called arthroscopy.


There is no cure for OA. Therapy is aimed at relieving pain and swelling, and keeping the joint functional. Treatment of osteoarthritis begins with a combination of lifestyle modifications, mild pain relievers, and exercises or physical therapy. Overweight patients are encouraged to lose weight to reduce stress on the weight-bearing joints of the body. In some cases, the patient may be advised to correct poor posture, which can also place stress on the joints. Muscle-strengthening exercises can help to keep the joints flexible. Physical therapy may include exercising in a pool, low-impact stretching exercises, or other exercises tailored to the individual by a licensed physical therapist.

Applying heat or cold to the affected joints is helpful for many patients. Using hot packs for twenty minutes several times a day, sitting in a warm (not hot) bath, or using a heating pad relieves stiffness, while applying ice packs relieves muscle spasms. Some people are also helped by therapeutic massage, provided that the therapist understands the symptoms of osteoarthritis and does not put too much pressure on the affected joints.

There are several types of medications that can be used to relieve the pain of OA:

  • Tylenol. Tylenol (acetaminophen) is a pain reliever that has few side effects and works well for patients with only mild symptoms of OA.
  • NSAIDs. These medications reduce inflammation as well as relieve discomfort. Many are available over the counter, including Motrin, Advil, and Aleve. NSAIDs may, however, upset the stomach or cause stomach ulcers and kidney problems when used in high doses over a long period of time. Patients should check with their doctor about long-term use of NSAIDs.
  • Cortisone injections. These are given for relief of severe joint pain. They should not be used more than four times a year, however, as they can cause long-term damage to the joints.
  • Tramadol. Tramadol is a stronger pain reliever than NSAIDs but carries the risk of addiction. It requires a doctor's prescription.
  • Viscosupplements. These are drugs resembling a compound that is normally found in joint fluid. They can be used only for osteoarthritis of the knee. The doctor injects the supplement into the knee joint over a period of three to five weeks. Viscosupplements are effective for about six months.
  • Glucosamine and chondroitin sulfate. These are dietary supplements that some doctors recommend for joint pain. There is some evidence that these supplements can help control the pain of OA, although they do not seem to grow new cartilage.

Severe osteoarthritis may require surgical treatment. Procedures that have been done to treat OA include:

  • Joint replacement. This type of surgery is usually done for hip and knee joints. The damaged joint is removed and replaced with an artificial joint made of plastic, metal, or ceramic parts.
  • Arthroscopy. Surgeons can use an arthroscope to remove torn and damaged cartilage or wash out a joint as well as look inside the joint.
  • Realignment of a damaged or misshapen bone to relieve stress on an arthritic joint.
  • Bone fusion. Surgeons can fuse bones together in a damaged joint to relieve the pain of arthritis. This procedure reduces the joint's flexibility, however.


The prognosis of osteoarthritis varies. It depends on the patient's age, weight, general health, and the specific joints that are affected.


Keeping one's weight within recommended limits for one's age, gender, and height is a good preventive measure, as is keeping physically fit.

The Future

Osteoarthritis has been regarded for decades as a disorder produced by simple wear and tear on the body's joints. More recent research indicates, however, that arthritic joints produce abnormal chemicals that lead to the breakdown of cartilage. Geneticists are now looking for specific genes that may be involved in the production of these chemicals. If such genes

are identified, scientists may be able to find ways to block their production of cartilage-destroying substances. Another area of research involves the study of doxycycline, an antibiotic used to treat sinus infections and acne, which may also be effective in slowing the destruction of cartilage in arthritic joints.

SEE ALSO Lyme disease; Obesity; Rheumatoid arthritis


Arthroscopy : The use of a small device called an arthroscope to look inside and diagnose or treat an arthritic joint.

Cartilage : A type of dense connective tissue that serves to cushion bones within joints.

Gout : A disorder of the large toe or other joints caused by deposits of uric acid crystals in the affected joint.

Osteophyte : A bony outgrowth or spur that develops in a joint affected by osteoarthritis. Osteophytes usually cause pain and limit the motion of the joint.

Paget disease : A chronic disorder caused by a slow virus infection that results in deformed or enlarged bones.

For more information


Clough, John D. Arthritis: A Cleveland Clinic Guide. Cleveland, OH: Cleveland Clinic Press, 2006.

Dickson, John, and Gillian Hosie. Osteoarthritis: Your Questions Answered. New York: Churchill Livingstone, 2003.

Lane, Nancy E., and Daniel J. Wallace. All about Osteoarthritis: The Definitive Resource for Arthritis Patients and Their Families. New York: Oxford University Press, 2002.


Baruchin, Aliyah. “Cautious Optimism for Sufferers of Joint Pain.” New York Times, January 15, 2008. Available online at (accessed July 5, 2008).


Arthritis Foundation. Osteoarthritis. Available online at (accessed July 5, 2008).

Mayo Clinic. Osteoarthritis. Available online at (updated October 11, 2007; accessed July 6, 2008).

National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). Handout on Health: Osteoarthritis. Available online in PDF format at (updated May 2006; accessed July 5, 2008).

National Institute on Aging (NIA). Age Page: Arthritis Advice. Available online at (updated December 29, 2005; accessed July 5, 2008).

National Library of Medicine (NLM). Osteoarthritis. Available online at (accessed July 6, 2008). This is an online tutorial with voiceover. Viewers have the option of a self-playing version, a text version, or an interactive version with questions.