Scoliosis or Lateral Curvature of the Spine is a deformity where the
spine is deviated in whole or in part to one or the other side of the
median line, which deviation is accompanied by an element of rotation.
Though usually considered as a spinal deformity its =effects= are
obvious outside the spinal area in so much as it will cause deformity
of the pelvis, legs, ribs, sternum, scapulæ, and in severe cases, of
the thoracic and abdominal viscera.
Curvatures of the spine are the result of one of two distinct factors:
first where there is a primary disease of the bone causing more or less
destruction of the bone and spinal articulations, and resulting in
permanent spinal curvature. The most common example of this condition
is seen in the angular curvature of Pott’s disease. =Rickets= is
usually responsible for a general long posterior curvature of the whole
spine, as is osteomalacia with the superimposition of some lateral
deviation. Further, any type of inflammation or trauma is capable
of producing curvatures of various types. Second, where there is no
primary disease of the bone, joints, or ligaments, and where the
curvature is due to external forces acting constantly or at frequently
recurring intervals on the spine.
Scoliosis or lateral curvature belongs to the second class. It is
unfortunately necessary to further subdivide scoliosis into two
classes; one where the curvature is a position permanently maintained
but capable of being reproduced by extreme physiological movement of a
normal spine, and secondly, a position which no normal spine can assume
and which necessarily implies a change in the normal shape of the bones
and intervertebral discs. The first may be described as a functional or
postural lateral curvature, and the second as an organic or structural
lateral curvature. Further, I might say that the first type may
progress until it becomes the organic type.
=Pathology.=—In scoliosis the spine undergoes not only curvature or
lateral deviation but also rotation of the vertebral bodies which you
will note always takes place towards the convexity of the curve.
=Changes in the Individual Vertebræ.=—The bodies may be either
wedge shaped or lozenge shaped. In wedge shaped vertebræ, the bodies
are compressed on the concave side and extended on the convex side,
the intervertebral discs being atrophied on the shortened side. In the
lozenge shaped type, the change in the bodies is most marked at the
junction of the opposite curves, and is thus more commonly observed in
compound curvatures. The pedicles are directed more antero-posteriorly
on the convex side and more transversely on the concave side. The
transverse processes on the convex side are more antero-posterior
than normal, causing the vertical furrow between them and the spine
to be narrower on this side. The spines point towards the concavity
in structural curvatures and toward the convexity in the functional
type. The vertebral foramen is rounded in the convexity and pointed in
the concavity. The edge of the anterior common ligament toward the
convexity is greatly thinned while it has a well marked edge on the
concave border. A fibrous degeneration occurs in the muscles on the
convexity owing to stretching, while atrophy from disuse takes place in
those on the concave side.
=Associated changes in the Viscera.=—The =dorso-lumbar= curvature
decrease in the volume of the lower thorax on the dorso-convex side
tends to cause pleural adhesions with obliteration of the pleural
sac and consequent collapse. Tuberculosis of the =lung= is common in
patients who suffer from scoliosis. The =heart= is often overworked
but the above lessening of the pulmonary area in turn results in
hypertrophy and dilatation of the right ventricle and subsequent
general venous stasis. The =kidney= on the convex side is compressed,
and as a result degenerative changes are prone to occur. The =spleen=
is frequently displaced upward and is liable to pathological changes.
Organs such as the stomach, transverse colon, esophagus and trachea are
frequently displaced owing to the bony deformity and are thereby more
prone to pathological change.
=Etiology.=—The essential factor in the production of scoliosis is
spinal insufficiency, which includes spinal muscles and ligaments as
well as the bones. In many instances, however, the following factors
have an important augmenting or predisposing effect.
=1. Occupational Deformity.=—Primarily under this classification, I
have found faulty positions adopted by school children as being the
most comfortable, to be perhaps most important. Occupations such as
those of nurse-maids, hod carriers, or stone cutters, are apt to induce
scoliosis.
=2. Diseases of the Central Nervous System.=—Unilateral weakness or
paralysis of the muscles of the trunk are common causes of scoliosis.
Anterior poliomyelitis plays a particularly important part as it
may induce deformity by distortion of the lower extremity or by any
inequality in the length of the limbs due to retardation of growth, as
well as inducing general weakness of the muscles of the trunk. Other
nervous disorders that should be considered are spastic paralysis,
locomotor ataxia, syringomyelia and Friedreich’s ataxia.
=3. Incidental Deformity.=—Scoliosis may be caused by direct injury or
by fracture, Pott’s Disease, or organic affections of the spine. Marked
deformity caused by Sciatica or lumbar neuritis, if persistent may
finally induce permanent deformity.
=4. Deformities Due to Diseases of the Chest.=—In =empyema= or
=pleurisy= one side of the chest is retracted and it will be noticed
that the curvature occurs toward the healthy side. Chronic pulmonary
tuberculosis producing fibrosis of the lung gives the same result as
empyema and pleurisy.
=5. Deformity due to obliquity of the pelvis.=—This type may be due to
any inequality of the limbs, such as equinus of the foot. Congenital
dislocation of the hip may play a part while one naturally lays stress
on pelvic and lower lumbar lesions.
=6. Deformity due to Distortion of Other Parts.=—Unequal visions,
unequal hearing, and torticollis by causing malposition are etiological
factors especially in school children. The loss of an arm will tend to
cause an asymmetrical position of the trunk.
=7. Congenital Deformity.=—Congenital scoliosis occurs, but is usually
associated with other congenital deformities of the spine, such as the
reduction or increase of the vertebræ, cervical rib, elevation of the
scapula, etc. The deformity is usually not apparent until later years,
though it may occur at birth.
=8. Spinal Lesions.=—Any osteopathic lesion predisposes to curvature
because it interferes with the nerve supply and tonicity of the spinal
muscles and could readily cause the faulty position.