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Osteoarthritis of the Knee
Osteoarthritis (OA) of the knee is one of the five leading
causes of disability among elderly men and women. The risk
for disability from osteoarthritis of the knee is as great
as that from cardiovascular disease.
Osteoarthritis of the knee usually occurs in knees that
have experienced trauma, infection, or injury. A smooth,
slippery, fibrous connective tissue, called articular
cartilage, acts as a protective cushion between bones.
Arthritis develops as the cartilage begins to deteriorate or
is lost. As the articular cartilage is lost, the joint space
between the bones narrows. This is an early symptom of
osteoarthritis of the knee and is easily seen on X-rays.
As the disease progresses, the cartilage thins, becoming
grooved and fragmented. The surrounding bones react by
becoming thicker. They start to grow outward and form spurs.
The synovium (a membrane that produces a thick fluid that
helps nourish the cartilage and keep it slippery) becomes
inflamed and thickened. It may produce extra fluid, often
known as "water on the knee," that causes additional
swelling.
Over a period of years, the joint slowly changes. In
severe cases, when the articular cartilage is gone, the
thickened bone ends rub against each other and wear away.
This results in a deformity of the joint. Normal activity
becomes painful and difficult.
Several factors may increase the risk of developing
osteoarthritis of the knee.
- Heredity: There is some evidence
that genetic mutations may make an individual more
likely to develop osteoarthritis of the knee.
- Weight: Weight increases pressure
on joints such as the knee.
- Age: The ability of cartilage to
heal itself decreases as people age.
- Gender: Women who are older than 50
years of age are more likely to develop osteoarthritis
of the knee than men.
- Trauma: Previous injury to the
knee, including sports injuries, can lead to
osteoarthritis of the knee.
- Repetitive stress injuries: These
are usually associated with certain occupations,
particularly those that involve kneeling or squatting,
walking more than two miles a day, or lifting at least
55 pounds regularly. In addition, occupations such as
assembly line worker, computer keyboard operator,
performing artist, shipyard or dock worker, miner, and
carpet or floor layer have shown higher incidence of
osteoarthritis of the knee.
- High impact sports: Elite players
in soccer, long-distance running and tennis have an
increased risk of developing osteoarthritis of the knee.
- Other illnesses: Repeated episodes
of gout or septic arthritis, metabolic disorders and
some congenital conditions can also increase your risk
of developing osteoarthritis of the knee.
- Other risk factors: Other factors
are being investigated, including the impact of vitamins
C and D, poor posture or bone alignment, poor aerobic
fitness, and muscle weakness.
Osteoarthritis of the knee can be diagnosed in two ways:
patient-reported symptoms, such as pain or disability, or
actual physical signs, such as the changes in the joint seen
on X-rays.
In most cases, both pathology and patient-reported
symptoms are present. An evaluation of osteoarthritis of the
knee includes a complete history and physical examination.
The examination should cover:
- The involved limb
- The spine
- The blood and nervous system
- The joints on either side of the knee, particularly
the hip joint, which can also cause knee pain
- Posture
- Gait
Initial treatment is generally directed at pain
management. Osteoarthritis of the knee pain may have
different causes, depending on the individual and the stage
of the disease. Thus, treatment is tailored to the
individual.
A wide range of treatment options is available. You and
your doctor should decide together on the course of
treatment that is right for you.
In general, treatment options fall into five major
groups:
- Health and behavior modifications, such as patient
education, physical therapy, exercise, weight loss, and
bracing
- Drug therapies, including simple pain relievers such
as aspirin or nonsteroidal anti-inflammatory drugs,
COX-2 specific inhibitors, opiates and stronger drugs
for patients who do not respond to other drugs or
treatments, and glucosamine and/or chondroitin sulfate
- Intra-articular treatments, including corticosteroid
injections or injections of hyaluronic acid (viscosupplementation)
- Surgery, including arthroscopy, osteotomy, and
arthroplasty (joint replacement)
- Experimental/alternative treatments such as
acupuncture, magnetic pulse therapy, vitamin regimes and
topical pain relievers
This information is based on the "Improving
Musculoskeletal Care in America" Project of the Council on
Research, Evidence-based Practice Committee, and Department
of Research and Scientific Affairs, American Academy of
Orthopedic Surgeons. The material presented is for
educational purposes only and is not intended to present the
only, or necessarily best, method or procedure for the
medical situations discussed.
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