104 Dance Anatomy and Kinesiology
associated with such dance training has long-term
negative health consequences and whether greater
curvatures automatically return when training stops
will require investigation.
Correction of flat back posture is controversial,
but in some cases may be aided by strengthening
the low back extensors as well as the hip flexors
(iliopsoas). In other cases this posture is more related
to repetitively standing in a passive posture (such as
fatigue posture) in which the pelvis is tucked (poste-
rior pelvic tilt), thereby decreasing the lumbar curve.
In this case, successful correction will require the use
of lumbar supports and a re-education of static and
dynamic alignment focusing on restoring a neutral
pelvis and associated normal lumbar curve.Scoliosis
Scoliosis (G. skoliosis, crookedness) is characterized
by a lateral curvature of the vertebral column in an
approximately frontal plane. When one looks from
behind the vertebral column, the spine ideally runs
approximately straight up and down. It is common to
have a very slight right thoracic curve, which has been
conjectured to be due to the position of the aorta or
handedness (White III and Panjabi, 1978). However,
the presence of an appreciable lateral curve or curves
of the spine as seen in figure 3.23D is termed scolio-
sis. Scoliosis can involve a single lateral curve, termed
a “C” curve, or multiple curves. When two alternating
curves are present the curve is termed an “S” curve as
seen in figure 3.30B. The vertebrae involved with the
lateral curves also frequently rotate, generally with
the spinous processes turning toward the concavity
of the abnormal curvature (figure 3.30D). This gives
rise to the prominent raised portion of the posterior
rib cage (“rib hump”) to one side of the spine, often
evident in dancers with scoliosis, as shown in figure
3.30C. This rotation also appears to have a very nega-
tive impact on spinal mechanics, and current models
of scoliosis suggest that scoliosis be visualized as a
complex three-dimensional deformity with torsion(s)
similar to an elongated helix.
Scoliosis can be divided into two types—nonstruc-
tural scoliosis and structural scoliosis. Nonstructural
scoliosis is reversible and will generally improve when
the underlying condition is treated. Examples of
underlying conditions include leg length difference,
muscle spasms, asymmetrical muscle development,
and handedness patterns. In contrast, structural sco-
liosis is generally considered irreversible and involves
structural changes both within and between the ver-
tebrae. For example, a vertebra may be asymmetrical
as a consequence of having different length pedicles,different orientation of the transverse processes, or a
spinous process that is not centrally located. Surpris-
ingly, about 90% of structural scoliosis occurs with
no known cause (Mercier, 1995); this type of scoliosis
with no known cause is termed idiopathic scoliosis
(G. idios, one’s own + pathos, suffering).
Although the causes of idiopathic scoliosis are
poorly understood, there is strong evidence that
familial factors play a role; the risk of having scoliosis
increases about 10 times if someone in your immedi-
ate family has it. Gender also plays a role in terms
of incidence and severity; females are 8 times more
likely than males to require treatment for scoliosis
(Liederbach, Spivak, and Rose, 1997). Activity also can
influence scoliosis incidence. Although this influence
was originally believed to be linked to muscle imbal-
ances associated with asymmetrical occupations and
sports, the elevated incidence of scoliosis in activities
considered more symmetrical (e.g., swimming and
ballet) suggests this association is more complex than
initially believed (Becker, 1986; Sward, 1992).
While the incidence of scoliosis for the general
U.S. adolescent population has been estimated to be
between 10% and 16% (Akella et al., 1991; Trepman,
Walaszek, and Micheli, 1990), studies of female ballet
dancers have reported incidences of 24% (Warren
et al., 1986), 33% (Hamilton et al., 1997), 40.7%
(Akella et al., 1991), and 65% (Molnar and Esterson,
1997). The higher incidence of scoliosis found in
dancers may relate to a higher familial incidence;
the common recommendation for children with
scoliosis to take ballet; a greater prevalence of a taller,
more ectomorphic body type; a greater prevalence
of increased flexibility or actual hypermobility;
the tendency for prolonged growth spurts due to
delayed maturation; low estrogen levels associated
with delayed maturation and disrupted menstrual
cycles (amenorrhea); and inadequate nutrition
with suboptimal calcium and vitamin D. Further
investigation of causative factors is important so that
prevention can be better addressed. Prevalence of
scoliosis in dance forms other than ballet warrants
further investigation.
Given its high incidence, it is important that danc-
ers and their teachers have a basic understanding of
the detection and treatment of scoliosis. Although it
may be seen at any age, scoliosis is usually detected
clinically between the ages of 10 and 13. Detection
often relates to noticing apparent asymmetries or
results of screening tests such as the forward bend
test (described in Tests and Measurements 3.2) com-
monly used in schools. Early detection is important
because the combination of bracing, therapeutic
exercise, and other therapeutic treatments may be