maximum functional capacity of the spine. Many
doctors aim for a goal of shaping the fusion so the
spine remains erect, which allows better mobility
than when the spine fuses into a hunched pos-
ture. Ankylosing spondylitis is a lifelong condition.
Risk Factors and Preventive Measures
Ankylosing spondylitis typically begins before age
40 and is more common in men. It is also more
common in people who have INFLAMMATORY BOWEL
DISEASE (IBD) and in people of Native American
heritage. Researchers have identified a GENE, HLA-
B27, associated with ankylosing spondylitis. The
HUMAN LEUKOCYTE ANTIGENS(HLAS) are proteins on
the surfaces of cell membranes that identify the
cells to the IMMUNE SYSTEM. HLA-B27 is one of the
numerous genes that encodes for HLAs.
Researchers believe this variant of the gene pre-
disposes an individual for ankylosing spondylitis
though does not inevitably result in the condition.
Remaining as active as possible helps extend the
spine’s flexibility and range of motion.
See also CERVICAL SPONDYLOSIS; GENETIC PREDISPO-
SITION; REITER’S SYNDROME; ROUTINE MEDICAL EXAMI-
NATION; X-RAY.
arthrogryposis The collective term for a group of
congenital disorders, also called arthrogryposis
multiplex congenita, in which multiple contrac-
tures restrict JOINTfunction throughout the body.
Joints may be partially or completely fused.
Researchers believe about 30 percent of arthrogry-
posis develops when the FETUSis not able to move
freely in the UTERUSbefore birth. The restricted
movement causes muscles and connective tissues
such as tendons and ligaments to grow abnor-
mally around the immobile joints, fixing them in
their positions. Circumstances that may restrict
fetal movement include
- insufficient AMNIOTIC FLUID
- abnormalities of the uterus
- large UTERINE FIBROIDS
- twins or other multiples
- neurologic and other developmental anomalies
in the fetus, such as MUSCULAR DYSTROPHY or
MITOCHONDRIAL DISORDERS, that inhibit normal
movement
Symptoms and Diagnostic Path
The doctor may suspect arthrogryposis when the
pregnant mother reports that the movements of
her unborn baby are infrequent. ULTRASOUNDcan
detect the changes in soft tissue structure and
BONEfusions at the joints before birth; the joint
deformities are obvious at birth. The delivery of an
infant who has arthrogryposis may be challenging
when the affected joints prevent normal passage
through the birth canal. The obstetrician may rec-
ommend CESAREAN SECTION to avoid injury to
infant and mother. Ultrasound after birth may
provide additional information about the extent to
which contractures affect the infant’s joints as well
as help doctors determine whether there are other
anomalies present.Treatment Options and Outlook
Treatment depends on the extent of the contrac-
tures though typically combines surgery to correct
joint deformities and casting with aggressive PHYSI-
CAL THERAPYto restore as much function as possi-
ble. Surgery can relieve the abnormal tension
shortened connective tissue and MUSCLEstructures
place on the joints, and the surgeon often can
reconstruct more functional alignments to
improve movement of the joint. Surgery may also
restructure bone tissue, generally in multiple
operations timed with growth patterns throughout
childhood. Physical therapy helps strengthen the
tissues and extend range of motion.
Although the deformities are permanent, they
are not progressive; thus the condition does not
worsen as the child grows. Aggressive treatment
early in life may allow a relatively normal lifestyle
in late childhood and adulthood when contractures
are mild to moderate. Severe contractures tend to
result in permanent disabilities that require adap-
tive techniques and devices for mobility.Risk Factors and Preventive Measures
Inability of the fetus to move freely in the uterus is
the primary risk factor for arthrogryposis.
Pregnancies in women who have neuromuscular
disorders such as MYASTHENIA GRAVIS, MULTIPLE SCLE-
ROSIS, orMYOTONIAare at higher risk. Extended high
FEVERduring PREGNANCY, such as may occur with
serious INFECTION, may affect the development of
the fetus in ways that impair muscle, connectivearthrogryposis 303