Covering, Support, and Movement of the Body
Current theory holds that normal joint use prompts the re-
lease of (metalloproteinase) enzymes that break down articular
cartilage, especially its collagen ﬁbrils. In healthy individuals,
this damaged cartilage is eventually replaced, but in people with
OA, more cartilage is destroyed than replaced. Although its spe-
ciﬁc cause is unknown, OA may reﬂect the cumulative eﬀects of
years of compression and abrasion acting at joint surfaces, caus-
ing excessive amounts of the cartilage-destroying enzymes to be
released. Te result is soFened, roughened, pitted, and eroded
articular cartilages. Because this process occurs most where
an uneven orientation of forces cause extensive microdamage,
badly aligned or overworked joints are likely to develop OA.
As the disease progresses, the exposed bone tissue thickens
and forms bony spurs (osteophytes) that enlarge the bone ends
and may restrict joint movement. Patients complain of stiﬀ-
ness on arising that lessens somewhat with activity. Te aﬀected
joints may make a crunching noise, called
as they move and the roughened articular surfaces rub together.
Te joints most oFen aﬀected are those of the cervical and lum-
bar spine and the ﬁngers, knuckles, knees, and hips.
Te course of osteoarthritis is usually slow and irreversible.
In many cases, its symptoms are controllable with a mild pain
reliever like aspirin or acetaminophen, along with moderate ac-
tivity to keep the joints mobile. Rubbing a hot-pepper substance
called capsaicin on the skin over the painful joints helps lessen
the pain of OA. Glucosamine and chondroitin sulfate, nutritional
supplements consisting of macromolecules normally present in
cartilage, have been widely used by arthritis suﬀerers. However,
several recent studies suggest that these supplements are no more
eﬀective than placebos. Osteoarthritis is rarely crippling, but it
can be, particularly when the hip or knee joints are involved.
Rheumatoid arthritis (RA)
toid) is a chronic inﬂammatory disorder with an insidious on-
set. Tough it usually arises between the ages of 30 and 50, it
may occur at any age. It aﬀects three times as many women as
men. While not as common as osteoarthritis, rheumatoid ar-
thritis aﬀects millions, about 1% of all people.
In the early stages of RA, joint tenderness and stiﬀness are com-
mon. Many joints, particularly the small joints of the ﬁngers, wrists,
ankles, and feet, are aﬄicted at the same time and bilaterally. ±or
example, if the right elbow is aﬀected, most likely the leF elbow is
also aﬀected. Te course of RA is variable and marked by ﬂare-ups
(exacerbations) and remissions (
susceptible to change).
Along with pain and swelling, its manifestations may include ane-
mia, osteoporosis, muscle weakness, and cardiovascular problems.
RA is an
—a disorder in which the
body’s immune system attacks its own tissues. Te initial trigger
for this reaction is unknown, but various bacteria and viruses
have been suspect. Perhaps these microorganisms bear mol-
ecules similar to some naturally present in the joints (possibly
glycosaminoglycans, which are complex carbohydrates found
in cartilage, joint ﬂuid, and other connective tissues), and the
immune system, once activated, attempts to destroy both.
RA begins with inﬂammation of the synovial membrane
) of the aﬀected joints. Inﬂammatory cells (lym-
phocytes, macrophages, and others) migrate into the joint cavity
from the blood and unleash a deluge of inﬂammatory chemicals
Certain ligaments, like the anterior cruciate ligament, are
best repaired by replacing them with graFs. ±or example, a
piece of tendon from a muscle can be attached to the articu-
±or many ligaments, such as the knee’s medial collateral liga-
ment, we’ve come to realize that time and immobilization are
just as eﬀective as any surgical option.
occurs when bones are forced out of
alignment. It is usually accompanied by sprains, inﬂammation,
and diﬃculty in moving the joint. Dislocations may result from
serious falls and are common contact sports injuries. Joints of
the jaw, shoulders, ﬁngers, and thumbs are most commonly dis-
located. Like fractures, dislocations must be
; that is, the
bone ends must be returned to their proper positions by a phy-
is a partial dislocation of a joint.
Repeat dislocations of the same joint are common because the
initial dislocation stretches the joint capsule and ligaments. Te
resulting loose capsule provides poor reinforcement for the joint.
Inﬂammatory and Degenerative Conditions
Inﬂammatory conditions that aﬀect joints include bursitis and
tendonitis, various forms of arthritis, and Lyme disease.
Bursitis and Tendonitis
is inﬂammation of a bursa and is usually caused by a blow
or friction. ±alling on one’s knee may result in a painful bursitis of
the prepatellar bursa, known as
water on the
. Prolonged leaning on one’s elbows may damage the bursa
close to the olecranon, producing
. Severe cases are treated by injecting anti-inﬂammatory
drugs into the bursa. If excessive ﬂuid accumulates, removing
some ﬂuid by needle aspiration may relieve the pressure.
is inﬂammation of tendon sheaths, typically caused
by overuse. Its symptoms (pain and swelling) and treatment (rest,
ice, and anti-inﬂammatory drugs) mirror those of bursitis.
describes over 100 diﬀerent types of inﬂam-
matory or degenerative diseases that damage the joints. In all
its forms, arthritis is the most widespread crippling disease in
North America. One in ﬁve of us suﬀers its ravages. ²o a greater
or lesser degree, all forms of arthritis have the same initial symp-
toms: pain, stiﬀness, and swelling of the joint.
Acute forms of arthritis usually result from bacterial inva-
sion and are treated with antibiotics. Chronic forms of arthritis
include osteoarthritis, rheumatoid arthritis, and gouty arthritis.
is the most common chronic
arthritis. A chronic (long-term) degenerative condition, OA is of-
ten called “wear-and-tear arthritis.” OA is most prevalent in the
aged and is probably related to the normal aging process (although
it is seen occasionally in younger people and some forms have a
genetic basis). More women than men are aﬀected, but nearly half
of us will develop this condition by the age of 85.