Consumer Information Center Osteoarthritis Current Research

The leading role in osteoarthritis research is played by the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), within the National Institutes of Health (NIH). The NIAMS funds many researchers across the United States to study osteoarthritis. It has established a Specialized Center of Research devoted to osteoarthritis. Also, a large number of researchers study arthritis at the NIAMS Multipurpose Arthritis and Musculoskeletal Disease Centers. These centers conduct basic, laboratory, and clinical research aimed at understanding the causes, treatment options, and prevention of arthritis and musculoskeletal diseases. Center researchers also study professional, patient, and public education; epidemiology; and health services.

For years, scientists thought that osteoarthritis was simply a disease of “wear and tear” that occurred in joints as people got older. In the last decade, however, research has shown that there is more to the disorder than aging alone. The production, maintenance, and breakdown of cartilage, as well as bone changes in osteoarthritis, are now seen as a series or “cascade” of events. Many researchers are trying to discover where in that cascade of events things go wrong. By understanding what goes wrong, they hope to find new ways to prevent or treat osteoarthritis. Some key areas of research are described below.

Animal Models: Animals help researchers understand how diseases work and why they occur. In osteoarthritis, animal models help researchers learn many things about osteoarthritis. They help reveal what happens to cartilage, how treatment strategies might work, and what might prevent the disease. Animal models also help scientists study osteoarthritis in very early stages, before it causes joint damage.

Diagnostic Tools: Some scientists want to find ways to detect osteoarthritis at earlier stages so that they can treat it earlier. They seek specific abnormalities in the blood, joint fluid, or urine of people with the disease. Other scientists use new technologies to analyze differences in cartilage from different joints. For example, many people have osteoarthritis in the knees or hips, but few have it in their ankles. Can ankle cartilage be different? Does it age differently? Answering these questions will help us understand the disease better.

Genetic Studies: Researchers suspect that inheritance plays a role in 25 to 30 percent of osteoarthritis cases. Scientists have identified a mutation (a gene defect) affecting collagen, an important part of cartilage in patients with an inherited kind of osteoarthritis that starts at an early age. The mutation weakens collagen protein, which may break or tear more easily under stress. Scientists are looking for other mutations in osteoarthritis. In the future, a test to determine who carries the genetic defect (or defects) could help people reduce their risk for osteoarthritis with lifestyle adjustments.

Comprehensive Treatment Strategies: Effective treatment for osteoarthritis takes more than drugs or surgery. Getting help from a variety of care professionals can often improve patient treatment and self-care. (See Health Professionals Who Treat Osteoarthritis.) Research shows that adding patient education and social support is a low-cost, effective way to decrease pain and reduce the amount of medicine used.

Exercise plays a key part in comprehensive treatment. Researchers are studying exercise in greater detail, finding out just how to use it in treating or preventing osteoarthritis. For example, several scientists have looked at knee osteoarthritis and exercise. They have found that

• The level of muscle strength in the thigh muscle (quadriceps) is very important. Strengthening this muscle can relieve symptoms and prevent more damage.
• Walking can result in better functioning and increased walking distance.
• People with knee osteoarthritis who were active in an exercise program feel less pain. They also function better.

Drugs To Prevent Joint Damage: No treatment actually prevents osteoarthritis or reverses or blocks the disease process once it begins. Present treatments just relieve the symptoms. Researchers are looking for drugs that would prevent, slow down, or reverse joint damage. One experimental antibiotic drug, doxycycline, may stop certain enzymes from damaging cartilage. The drug has responded well in clinical studies, but more studies are needed. Researchers are also studying growth factors or other natural chemical messengers. These potential medicines may be able to stimulate cartilage growth or repair.

Acupuncture: Licensed acupuncture therapists insert very fine needles into the skin at various points on the body. Scientists think that the needles stimulate the release of natural, pain-relieving chemicals produced by the brain or the nervous system. Researchers are looking at acupuncture treatment of patients who have knee osteoarthritis. Early findings suggest that traditional Chinese acupuncture is effective in some patients as an additional therapy for osteoarthritis, reducing pain and improving function.

Nutritional Supplements: Nutritional supplements are often reported as helpful in treating osteoarthritis. Such reports should be viewed with caution, however, since very few studies have carefully evaluated the role of nutritional supplements in osteoarthritis.

• Glucosamine and chondroitin sulfate. Both of these nutrients are found in small quantities in food, and are components of normal cartilage. Scientific studies on these two nutritional supplements have not yet shown that they affect the disease. They may relieve symptoms in some patients, however. The National Center for Complementary and Alternative Medicine at NIH is supporting a clinical trial to test whether either glucosamine or chondroitin sulfate alone, or in combination with each other, reduces pain and improves function. Patients using this therapy should do so only under the supervision of their doctor, as part of an overall treatment program with exercise, relaxation, and pain relief.
• Vitamins D and C. Progression of the disease appears to be less in patients with high levels of vitamin D or C intake. More studies are needed to confirm these reports.

Hyaluronic Acid: Injecting this substance into the knee joint provides long-term pain relief for some people with osteoarthritis. Hyaluronic acid is a natural component of cartilage and joint fluid. It lubricates and absorbs shock in the joint. The Food and Drug Administration (FDA) recently approved this therapy for patients with osteoarthritis of the knee if they do not get relief from exercise, physical therapy, or simple analgesics. Researchers are testing whether hyaluronic acid can slow down the progression of osteoarthritis.

Estrogen: In studies of older women, scientists found a lower risk of osteoarthritis in women who had used oral estrogens for hormone replacement therapy. The researchers suspect that low estrogen levels could increase risk for the disease. Further studies are needed to answer this question.

• Enzyme engineering. Certain body chemicals called enzymes may help cartilage to break down. Scientists are working to genetically engineer cells that would inhibit these enzymes and prevent the damage they cause. Cells are removed from the body, genetically changed, and then injected back into the affected joint. They live in the joint and protect it from damaging enzymes.
• Cartilage cell replacement. Researchers remove cartilage cells from the patient’s own joint, clone or grow new cells using tissue culture and other laboratory techniques, and inject the newly grown cells into the patient’s joint. Patients with cartilage cell replacement have decreased osteoarthritis symptoms. Actual cartilage repair is limited, however.
• Stem cell transplantation. Stem cells are primitive cells that can transform into other kinds of cells, such as muscle or bone cells. They are usually taken from bone marrow. In the future, researchers hope to insert stem cells into cartilage where they will make new cartilage. If successful, this process could be used to repair damaged cartilage and avoid the need for surgical joint replacements with metal or plastics.