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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, many researchers study arthritis at NIAMS Multipurpose
Arthritis and Musculoskeletal Diseases Centers and Multidisciplinary
Clinical Research 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 epidemiology, health services,
and professional, patient, and public education. The NIAMS
also supports multidisciplinary clinical research centers
that expand clinical studies for diseases like osteoarthritis.
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. Animal models
help researchers learn many things about osteoarthritis, such
as 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 detectable 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 the differences
between the cartilage from different joints. For example,
many people have osteoarthritis in the knees or hips, but
few have it in the ankles. Can ankle cartilage be different?
Does it age differently? Answering these questions will help
us understand the disease better.
Genetics Studies: Researchers suspect
that inheritance plays a role in 25 to 30 percent of osteoarthritis
cases. Researchers have found that genetics may play a role
in approximately 40 to 65 percent of hand and knee osteoarthritis
cases. They suspect inheritance might play a role in other
types of osteoarthritis, as well. 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 gene mutations in osteoarthritis.
Recently, researchers found that the daughters of women who
have knee osteoarthritis have a significant increase in cartilage
breakdown, thus making them more susceptible to disease. 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.
Tissue Engineering: This technology
involves removing cells from a healthy part of the body and
placing them in an area of diseased or damaged tissue in order
to improve certain body functions. Currently, it is used to
treat small traumatic injuries or defects in cartilage, and,
if successful, could eventually help treat osteoarthritis.
Researchers at the NIAMS are exploring three types of tissue
engineering. The two most common methods being studied today
include cartilage cell replacement and stem cell transplantation.
The third method is gene therapy.
- Cartilage cell replacement: In this procedure,
researchers remove cartilage cells from the patient's own
joint and then clone or grow new cells using tissue culture
and other laboratory techniques. They then inject the newly
grown cells into the patient's joint. Patients with cartilage
cell replacement have fewer symptoms of osteoarthritis.
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 usually are taken from bone
marrow. In the future, researchers hope to insert stem cells
into cartilage, where the cells 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.
- Gene therapy: Scientists are working to genetically
engineer cells that would inhibit the body chemicals, called
enzymes, that may help break down cartilage and cause joint
damage. In gene therapy, 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.
Comprehensive Treatment Strategies:
Effective treatment for osteoarthritis takes more than medicine
or surgery. Getting help from a variety of care professionals
often can 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 and finding
out just how to use it in treating or preventing osteoarthritis.
For example, several scientists have studied knee osteoarthritis
and exercise. Their results included the following:
- Strengthening the thigh muscle (quadriceps) can relieve
symptoms of knee osteoarthritis and prevent more damage.
- Walking can result in better functioning, and the more
you walk, the farther you will be able to walk.
- People with knee osteoarthritis who were active in an
exercise program feel less pain. They also function better.
Research has shown that losing extra weight can
help people who already have osteoarthritis. Moreover, overweight
or obese people who do not have osteoarthritis may reduce
their risk of developing the disease by losing weight.
Using NSAIDs: Many people who have
osteoarthritis have persistent pain despite taking simple
pain relievers such as acetaminophen. Some of these patients
take NSAIDs instead. Health care providers are concerned about
long-term NSAID use because it can lead to an upset stomach,
heartburn, nausea, and more dangerous side effects, such as
ulcers.
Scientists are working to design and test new,
safer NSAIDs. One example currently available is a class of
selective NSAIDs called COX-2 inhibitors. Traditional NSAIDs
prevent inflammation by blocking two related enzymes in the
body called COX-1 and COX-2. The gastrointestinal side effects
associated with traditional NSAIDs seems to be associated
mainly with blocking the COX-1 enzyme, which helps protect
the stomach lining. The new selective COX-2 inhibitors, however,
primarily block the COX-2 enzyme, which helps control inflammation
in the body. As a result, COX-2 inhibitors reduce pain and
inflammation but are less likely than traditional NSAIDs to
cause gastrointestinal ulcers and bleeding. However, research
shows that some COX-2 inhibitors may not protect against heart
disease as well as traditional NSAIDs, so check with your
doctor if you have concerns.
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 shown some promise
in clinical studies, but more studies are needed. Researchers
also are studying growth factors and other natural chemical
messengers. These potential medicines may be able to stimulate
cartilage growth or repair.
Acupuncture: During an acupuncture
treatment, a licensed acupuncture therapist inserts very fine
needles into the skin at various points on the body. Scientists
think the needles stimulate the release of natural, pain-relieving
chemicals produced by the brain or the nervous system. Researchers
are studying acupuncture treatment of patients who have knee
osteoarthritis. Early findings suggest that traditional Chinese
acupuncture is effective for 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 and reduce
joint damage in some patients, however. The National Center
for Complementary and Alternative Medicine at the NIH is
supporting a clinical trial to test whether glucosamine,
chondroitin sulfate, or the two nutrients in combination
reduce pain and improve 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, C, E, and beta carotene: The progression
of osteoarthritis may be slower in people who take higher
levels of vitamin D, C, E, or beta carotene. 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) approved this therapy for patients with osteoarthritis
of the knee who do not get relief from exercise, physical
therapy, or simple analgesics. Researchers are presently studying
the benefits of using hyaluronic acid to treat 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 having low levels of estrogen could increase
the risk of developing osteoarthritis. Additional studies
are needed to answer this question.
Hope
for the Future
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