| What
is Osteoarthritis?
Osteoarthritis (AH-stee-oh-ar-THREYE-tis)
is the most common type of arthritis, especially among older
people. Sometimes it is called degenerative joint disease
or osteoarthrosis.
Osteoarthritis is a joint disease
that mostly affects the cartilage (KAR-til-uj). Cartilage
is the slippery tissue that covers the ends of bones in a
joint. Healthy cartilage allows bones to glide over one another.
It also absorbs energy from the shock of physical movement.
In osteoarthritis, the surface layer of cartilage breaks down
and wears away. This allows bones under the cartilage to rub
together, causing pain, swelling, and loss of motion of the
joint. Over time, the joint may lose its normal shape. Also,
bone spurs--small growths called osteophytes--may grow on
the edges of the joint. Bits of bone or cartilage can break
off and float inside the joint space. This causes more pain
and damage.
People with osteoarthritis
usually have joint pain and limited movement. Unlike some
other forms of arthritis, osteoarthritis affects only joints
and not internal organs. For example, rheumatoid arthritis--the
second most common form of arthritis--affects other parts
of the body besides the joints. It begins at a younger age
than osteoarthritis, causes swelling and redness in joints,
and may make people feel sick, tired, and (uncommonly) feverish.
Who Has Osteoarthritis?
Osteoarthritis is one of the
most frequent causes of physical disability among adults.
More than 20 million people in the United States have the
disease. By 2030, 20 percent of Americans--about 70 million
people--will have passed their 65th birthday and will be at
risk for osteoarthritis. Some younger people get osteoarthritis
from joint injuries, but osteoarthritis most often occurs
in older people. In fact, more than half of the population
age 65 or older would show x-ray evidence of osteoarthritis
in at least one joint. Both men and women have the disease.
Before age 45, more men than women have osteoarthritis, whereas
after age 45, it is more common in women.
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