improvement in their symptoms when they take
vitamin B 6 (pyridoxine) supplements. Certain
YOGA postures that increase FLEXIBILITY and
STRENGTH of the wrists improves symptoms for
some people. Surgery, either open or laparoscopic,
to cut the carpal LIGAMENTis the curative treatment
for most people who have carpal tunnel syn-
drome. Such an OPERATIONopens the carpal tun-
nel, relieving compression against the median
nerve. Full recovery from the open procedure
takes about 12 weeks and from the laparoscopic
procedure about 8 weeks. A rare complication of
carpal tunnel surgery is permanent weakness in
the hand as a consequence of cutting the median
nerve. Other possible complications, also rare,
include excessive bleeding and postoperative
INFECTION.
Risk Factors and Preventive Measures
Doctors believe many people who develop carpal
tunnel syndrome have an inherently narrow
carpal tunnel, making the passage tighter.
Women, who have smaller BONEstructures than
men, are three times more likely to develop carpal
tunnel syndrome. Carpal tunnel syndrome may
also follow injury to the wrist, such as strain or
FRACTURE, or accompany OSTEOARTHRITIS of the
wrist. People who have DIABETES, PERIPHERAL VASCU-
LAR DISEASE(PVD), and other conditions associated
with NEUROPATHY(injury to the nerves) are particu-
larly susceptible to compression syndromes such
as carpal tunnel syndrome.
Work that subjects the wrists to continuous
vibration or repetitive movement also increases the
risk for carpal tunnel syndrome. The highest risk is
among people who do assembly-line work, such as
in manufacturing, professional sewing, meat pack-
ing, and poultry processing. Job tasks in these occu-
pations subject the wrists to repeated flexing under
pressure. Though occupations involving extensive
typing, keyboarding, or data entry were long sus-
pected as prime causes of carpal tunnel syndrome,
recent studies support only a slight increase in risk.
Frequent short breaks to stretch and flex the wrists
during work and wearing supportive wrist braces
can help prevent carpal tunnel syndrome or mini-
mize its symptoms.
See also ENDOSCOPY; OCCUPATIONAL HEALTH AND
SAFETY; REPETITIVE MOTION INJURIES; SPRAINS AND
STRAINS; SURGERY BENEFIT AND RISK ASSESSMENT; TEN-
DON.cartilage Dense connective tissue that provides
the foundation for BONEin the developing fetus
and covers bone ends in the joints in adults. The
fetal SKELETONforms first as a translucent type of
cartilage called hyaline cartilage, with conversion
to bone beginning at about the fourth week of
pregnancy. Calcification continues after birth. In
the adult skeleton, hyaline cartilage forms the
disks between the vertebrae in the back, the rings
that give the TRACHEAstability, and the extensions
that connect the ribs to the sternum. A type of
cartilage that contains fibers of elastin that allow
greater FLEXIBILITY, called elastic cartilage or yellow
cartilage, gives shape to the outer ears (auricles),
auditory canal (EARcanal), and end of the NOSE.
Cartilage consists of a thick, somewhat elastic
base of collagen (an insoluble protein) with small
clusters of cartilage cells (chondrocytes) suspended
within it. Though cartilage does not have its own
BLOODor NERVEsupplies, it continuously renews
itself through a process called remodeling in
which chondrocytes facilitate a slow turnover of
collagen molecules and other substances. This
remodeling provides chondrocytes with the NUTRI-
ENTSthey need to function.
Researchers believe imbalances in the remodel-
ing process, in which the breakdown of collagen
molecules exceeds rebuilding, is the basis for
OSTEOARTHRITIS. Various mechanisms, notably
repeated trauma such as through use of the joints
and activation of CYTOKINESthrough the inflamma-
tory process, contribute to this imbalance. Damage
to cartilage is the foundation of osteoarthritis, HER-
NIATED NUCLEUS PULPOSUS, and most KNEE INJURIES.
For further discussion of cartilage within the
context of musculoskeletal structure and function,
please see the overview section “The Muscu-
loskeletal System.”
See also BURSA; JOINT; LIGAMENT; TENDON.cervical spondylosis Narrowing of the channel
between the vertebrae in the neck through which
the SPINAL CORDpasses. Cervical spondylosis results
from chronic, degenerative OSTEOARTHRITISin which
there is extensive INFLAMMATIONand damage to the
CARTILAGEdisks that separate and cushion the cervi-316 The Musculoskeletal System