JUVENILE ARTHRITIS
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The skeletal system of the body is made
up of different types of the strong, fibrous tissue known as
connective tissue. Bone, cartilage, ligaments, and tendons are all
forms of connective tissue which have different compositions, and
thus different characteristics.
The joints are structures which hold two or more bones together.
Some joints (synovial joints) allow for movement between the bones
being joined (called articulating bones). The simplest model of a
synovial joint involves two bones, separated by a slight gap called
the joint cavity. The ends of each articular bone are covered by a
layer of cartilage. Both articular bones and the joint cavity are
surrounded by a tough tissue called the articular capsule. The
articular capsule has two components: the fibrous membrane on the
outside, and the synovial membrane (or synovium) on the inside. The
fibrous membrane may include tough bands of fibrous tissue called
ligaments, which are responsible for providing support to the
joints. The synovial membrane has special cells and many capillaries
(tiny blood vessels). This membrane produces a supply of synovial
fluid which fills the joint cavity, lubricates it, and helps the
articular bones move smoothly about the joint.
In Juvenile Arthritis, the synovial membrane becomes intensely inflamed. Usually
thin and delicate, the synovium becomes thick and stiff, with
numerous infoldings on its surface. The membrane becomes invaded by
white blood cells, which produce a variety of destructive chemicals.
The cartilage along the articular surfaces of the bones may be
attacked and destroyed, and the bone, articular capsule, and
ligaments may begin to be worn away (eroded). These processes
severely interfere with movement in the joint.
Juvenile Arthritis specifically refers to chronic arthritic conditions which affect
a child under the age of 16 years, and which last for a minimum of
three to six months. Juvenile Arthritis is often characterized by a waxing and
waning course, with flares separated by periods of time during which
no symptoms are noted (remission). Some literature refers to Juvenile Arthritis as
juvenile rheumatoid arthritis, although most types of Juvenile Arthritis differ
significantly from the adult disease called rheumatoid arthritis, in
terms of symptoms, progression, and prognosis. |
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