Arthritis ('arth' meaning joint, 'itis' meaning inflammation)
isn't a one-note story or even a few variations on a single
theme; it actually consists of more than 100 different
These can be anything from relatively mild forms
of tendinitis (as in 'tennis elbow') and bursitis to crippling
systemic forms, such as rheumatoid arthritis. There are pain
syndromes like fibromyalgia and arthritis-related disorders,
such as systemic lupus erythematosus, that involve every part
of the body. There are forms of the disease, such as gout that
almost nobody connects with arthritis and there are other
conditions - like osteoarthritis, the misnamed 'wear and tear'
arthritis - that a good many people think is the only form of
True, many older people do have arthritis, but it's not just a
disease of the old. Some forms of arthritis affect children
still in diapers, while thousands of people are stricken in
the prime of their lives. The common denominator for all these
conditions is joint and musculoskeletal pain, which is why
they are grouped together as 'arthritis.' Often that pain is a
result of inflammation of the joint lining.
Inflammation is involved in many forms of arthritis. It is the
body's natural response to injury. The warning signs that
inflammation presents are redness, swelling, heat and pain.
These are the same kinds of reaction the body has to a sliver
in the hand, for example. When a joint becomes inflamed, it
may get any or all of these symptoms. This can prevent the
normal use of the joint and therefore it can cause the loss of
function of that joint.
Anatomy of a Joint
There are more than 100 joints connecting the body's 206
bones. Most of the major bone connections in the body are
joints designed to allow a broad range of motion. There are
different kinds for different functions: ball-and-socket (hips
and shoulders), saddle joints (which connect thumb to hand),
hinge joints (fingers and knees) or pivot joints (wrists).
Tied together by ligaments, the bones of joints are capped
with a smooth substance called cartilage. This tough elastic
material acts as a shock absorber and allows the bone ends to
glide smoothly across each other. If the cartilage is
destroyed (as in osteoarthritis), the bones of a joint can
grind against each other causing pain, loss of mobility,
deformity and dysfunction.
Between the bones is a joint cavity, which gives the bones
room to move. The joint space between two bones is enclosed by
a capsule that's flexible, yet strong enough to protect the
joint against dislocation. The inner lining of this capsule,
the synovium, produces a thick fluid that lubricates and
nourishes the joint. In many forms of arthritis, the synovium
becomes inflamed and thickened, producing extra fluid which
contains inflammatory cells. The inflamed synovium and fluid
can damage the cartilage and underlying bone.
No one knows what causes arthritis, though scientists have
uncovered a host of clues. Something can be done to manage
most forms of arthritis, but it's very important that a
correct diagnosis is established early. Most therapies work
best when started early in the disease process. You can read
more specific information under Types of Arthritis.