The Spine 151Facet Syndrome
While complaints of low back pain with hyperex-
tension (such as the arabesque position) are often
associated with spondylolisthesis in the younger
dancer, in the older dancer these complaints may
be associated with the facet syndrome (Drezner and
Herring, 2001). The same mechanism of forceful or
repetitive hyperextension and rotation places stresses
on the facet joint as well as the pars interarticularis.
In response, the facet joints and associated structures
can become inflamed and undergo degenerative
changes (Trepman, Walaszek, and Micheli, 1990).
Pain may be localized to the involved side of the low
back or may radiate down the lower extremity.
Disc Herniation
The intervertebral disc tends to degenerate with
aging and exhibits decreased water content, height,
ability to absorb shock, ability to return to normal
shape after being deformed, and thickness of the
annulus fibrosus (Deckey and Weidenbaum, 1997;
Panjabi, Tech, and White III, 1980). These factors
all make the annulus fibrosus more vulnerable to
damage that can allow the nucleus pulposus to actually
extrude out through the annulus fibrosus and into the
neural canal, termed disc herniation, as seen in figure
3.49. Such disc herniation occurs most frequently in
the third or fourth decade of life, when the disc is
undergoing the structural changes associated with this
marked dehydration (approximately 35% reduction
in water content), and the resilient disc under age
30 and the dry, scarred disc over age 50 may be less
likely to fragment and displace (Hall, 1999; White III
and Panjabi, 1978). Disc herniation most commonly
occurs in the posterolateral region of the disc, where
the annulus fibrosus is thinner and the posterior
longitudinal ligament is weak. Spinal nerves traverse
the posterolateral part of the disc, and so herniation
in this region can readily compress the spinal nerve.
Compression of the spinal nerve can lead to pain,
numbness, and weakness in areas related to those
served by the nerve that is being compressed.
Disc herniation occurs most frequently in the
lower lumbar region; 95% of lumbar lesions occur
in the discs located between L4 and L5 or L5 and S1
(Mercier, 1995). The mechanism of injury is contro-
versial, but it often involves flexion or hyperextension
combined with rotation. As with spondylolysis, sports
associated with these mechanisms appear to have a
higher incidence of disc degeneration; 75% of retired
world-class gymnasts showed signs of disc degenera-
tion (Sward et al., 1991). The intensity of training at
a young age may also be a factor, and in gymnasts the
incidence of degenerative disc disease rose from 9%
to 43% to 63% in pre-elite, elite, and Olympic-level
female gymnasts (Gerbino and Micheli, 1995). Early
rigorous training, the common use of hyperextension,
partnering, and the repetitive use of flexion combined
with rotation in modern dance could all potentially
increase risk for disc injury in dancers.
The onset of symptoms can be sudden or more
vague. One of the primary classic complaints of
lumbar disc injury is pain radiating from the back or
buttock down the posterior or posterolateral aspect
of the thigh, termed sciatica, which may be accompa-
nied by weakness or numbness in select areas of the
lower extremity (depending on the nerves involved).
This pain tends to be exacerbated by coughing,
sneezing, the Valsalva maneuver, or prolonged sit-
ting; all of which increase the pressure within the
disc. Sitting reduces the lordosis in the lumbar spine,
which creates a relative forward shift of the center of
gravity (increased moment arm), thus increasing the
pressure in the intervertebral discs (figure 3.36 on
p. 115). The dancer may lean toward or away from the
affected side, a tactic that can increase the space in
the appropriate intervertebral foramen and reduce
pressure on the compressed nerve root. Tenderness
is generally present in the midline of the low back,
and spinal muscle spasm is often evident. However,
adolescents with disc herniations may sometimes
present with back pain and hamstring tightness, but
with little of the classic radiating pain or neurologic
signs (Deckey and Weidenbaum, 1997).
As with spondylolysis, disc injury does not neces-
sarily mean long-term pain and the inability to dance.
First, approximately 25% of healthy adults with no
low back pain have evidence of disc herniation (Cail-
let, 1996); the site of the herniation in relation to
the size of the spinal canal and effect on stability of
the motion segment may be critical in determining if
there is associated pain (Levangie and Norkin, 2001).FIGURE 3.49 Herniated intervertebral disc: L4 disc
herniation compressing L5 nerve (posterior view with
vertebral arch removed).