Joints
are the place where two moving bones come together and are designed
to protect bone ends from wearing away and to absorb shock from
movements like walking or repetitive movements. Cartilage is
the slippery tissue that covers the ends of bones in a joint
and allows bones to glide over one another. The
cartilage is protected by a synovial membrane that produces
synovial fluid.
In
the fluid, is hyaluronan which feels like a gelatinous motor
oil, and provides cushioning and lubrication. In osteoarthritis,
hyaluronan thins and loses its elasticity, causing the surface
layer of cartilage to break down and wear away. In osteoarthritis,
bones rub together causing pain, swelling, and loss of motion
of the joint.
Osteoarthritis
affects more than 20 million people in the United States. Some
younger people get osteoarthritis from a joint injury, but osteoarthritis
most often occurs in older people. In fact, by age 65, more
than half of the population has evidence of osteoarthritis in
at least one joint.
Both
men and women have the disease. Before age 45, more men have
it, while after age 45 osteoarthritis is more common in women.
Osteoarthritis affects each person differently. In some people,
it progresses more quickly; but usually, osteoarthritis comes
on slowly. Osteoarthritis can occur in any joint, but most often
it occurs at the hands, hips, knees, or spine. Early in the
disease, joints may ache after physical work or exercise.
They
may be stiff, swollen, and painful, making it hard to walk,
climb, get in and out of chairs. It is not yet known what causes
arthritis, but there are probably a combination of factors in
the body and in the environment that play a role; diet, weight,
and stresses on the joints from certain jobs.
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Structures
of the Knee:
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Arthritis
treatment usually begins with conservative treatments aspirin
or NSAIDs, steroid injections, physical therapy, and weight
loss. For people with osteoarthritis of the knee who do not
get relief from the above there are two new injectable drugs
that act as hyaluronan replacements.
Hyalgan,
requires a series of five injections given weekly and Synvisc,
requires three injections. Both are injected directly into the
knee joint, with a small syringe. The active ingredient in both
medicines is hyaluronate, a gelatinous material, which is extracted
the rooster combs.
Any
person with an allergy to eggs or chickens should not use this
medicine. These medicines provide cushioning and lubrication
similar to that of the joint fluid in a healthy young knee.
The injected hyaluronan is thought to also stimulate the production
of new synovial fluid rather than to only be a substitute. Researchers
are testing whether hyaluronic acid can actually slow down the
progression of osteoarthritis.
After
the treatments many patients experience pain relief for three
months or longer, with few or no side effects. These new class
of gel injections offer an alternative to people whose stomach
can't handle the more commonly used aspirin and NSAIDs.
Right
now these replacement gels are only for arthritis of the knee,
but may eventually be used for other joints. These gels are
not a cure, but they can reduce the pain of arthritis and are
useful for people who may wish to delay surgery.
No
treatment actually prevents osteoarthritis or reverses or blocks
the disease process once it begins. Present treatments just
relieve the symptoms. The search for drugs that would prevent,
slow down, or reverse joint damage is becoming more important
since the number of older Americans is increasing, so is the
number of people with osteoarthritis.
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