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17
Scoliosis
I. Classification
A. Nonstructural: postural, sciatic, inflammatory, and compensatory
B. Structural (Scoliosis Research Society)
1. Idiopathic (85%)
a. Infantile (3 years)
b. Juvenile (3 to 10 years)
c. Adolescent (10 years through maturity)
2. Neuromuscular
a. Neuropathic: cerebral palsy, syringomyelia, poliomyelitis, spinal
muscular atrophy, Freidrich’s ataxia
b. Myopathic: arthrogryposis, muscular dystrophy, myotonia dystrophica
3. Congenital: diastematomyelia, spina bifida, hemivertebra, wedge verte-
bra, unsegmented bar with contralateral hemivertebra, block vertebra
4. Neurofibromatosis
5. Mesenchymal disorders: Marfan’s, Ehlers-Danlos
6. Rheumatoid disease
7. Trauma (fracture, surgery, radiation)
8. Extraspinal contractures (burns, thoracic surgery)
9. Osteochondral dystrophies
10. Infection
11. Metabolic disorders
12. Related to lumbosacral joint
13. Tumors
Idiopathic Adolescent Scoliosis
I. Etiology
A. Neuromuscular
1. Changes in the muscle fiber types and muscle spindles have been
demonstrated.
178
◆
Chapter 17 Scoliosis 179
2. Increased calmodulin level, which is responsible for regulation of mus-
cle contraction and decreased melatonin levels (calmodulin antago-
nist) have been demonstrated in patients with idiopathic adolescent
scoliosis (IAS).
B. Hormonal
C. Connective tissue
1. Elastic and collagen fibers are the primary elements that support the
spine.
2. Abnormalities in the collagen/proteoglycan in the intervertebral disks
have also been shown.
D. Genetic: 5:1 female preponderance (10-degree curves), familial
(20 times greater in families) with monozygotic twin concordance rate of
73%, genetic (sex-linked trait with incomplete penetrance and variable
expressivity)
E. Melatonin or serotonin abnormalities
II. Anatomic characteristics
A. Lateral curvature or deformity in the coronal plane
B. Decreased thoracic kyphosis or thoracic hypokyphosis (deformity in the
sagittal plane)
1. Earlier accelerated spinal growth as compared with normal individuals
may be related.
C. Vertebral rotation: spinous process rotates toward concavity (deformity in
the axial plane and causes rib hump)
D. Patterns of thoracic scoliosis (King classification is frequently used, but
not every thoracic curve fits into this classification)
1. Double major right thoracic and left lumbar (King I): lumbar curve is
larger than the thoracic curve.
2. Right thoracic and compensatory left lumbar (King II): thoracic curve is
larger than the lumbar curve.
3 Right thoracic (King III): left lumbar curve does not cross the midline.
4. Right thoracolumbar (King IV)
5. Double thoracic (King V)
E. Classification is newer, more extensive and classifies the curves based on
curve type, lumbar modifier, and thoracic sagittal profile (Fig. 17–1).
F. Isolated lumbar or thoracolumbar curves
III. Natural history and prognosis
A. Prevalence: 25/1000 (2.5%) exhibit greater than 10-degree curves and
(0.4%) 4/1000 exhibit greater than 20-degree curves.
B. Factors contributing to curve progression
1. Curve magnitude: the greater the angulation and rotation, the greater
tendency for progression. For example, a 20-degree curve has a 20%
likelihood of progression, and a 40-degree curve has a 60% likelihood
of progression.
2. Age: younger age is a more important prognostic factor than gender or
family history. Ninety percent of spinal growth has occurred at
puberty; however, this age has the highest risk of progression.
180 IV Deformity
3. Risser score of skeletal maturity: score of 1 or less has a higher likeli-
hood of progression
4. Shorter curves progress more
5. Location: the lower the curve is in the spinal column, the greater the
likelihood of progression (thoracic lumbar).
6. Flexibility: stiffer curves in immature individuals and more flexible
curves in mature individual are more likely to progress.
7. Gender: girls are more commonly affected, especially for larger
curves.
8. Positive family history
9. Slender spines
IV. Diagnosis
A. Screening: generally occurs in school children between age 10 and 14
1. Leads to a substantial number of referrals
2. One third of all referrals have scoliosis to some degree.
Figure 17–1 Schematic demonstrating the Lenke classification. From Lenke LG, Betz RR, Harms J,
Bridwell KH, Clements DH, Lowe TG, Blanke K. Adolescent idiopathic scoliosis: a new classification
to determine extent of spinal arthrodesis. J Bone Joint Surg Am 2001; 83-A:1169–1181. Reprinted
with permission.
Chapter 17 Scoliosis 181
B. History: age, gender, onset of menarche, pain, family history
1. Pain occurs in up to 30% of patients with IAS.
2. Peak growth in girls at age 11 to 12 and boys at age 13 to 14
C. Physical examination:
1. Observation:
a. Asymmetry of shoulder level, breasts, waist, or pelvis
b. Protruding scapula or ribs
c. Loss of thoracic lordosis
d. Adams forward bend test
(1) Patient bends at the waist to 90 degrees.
(2) During the process, assess for asymmetry in bending and rota-
tional deformity of thoracic and lumbar curves.
2. Measurements
a. Scoliometer is used to measure rib hump (rotational deformity on
forward bending).
b. Plumb line dropped from C7 indicates coronal balance relative to
gluteal cleft.
c. Leg length discrepancy
3. Neurological examination
a. Deep tendon reflexes
b. Abdominal reflexes
(1) Check for symmetrical umbilical movement upon lateral to me-
dial light stroke on the abdomen.
(2) Asymmetrical movement correlates with neural axis pathology.
D. X-ray examination
1. Cobb angle is used to measure the magnitude of the curve. The upper
and lower end vertebrae of each curve are identified. A line is drawn at
the upper end of the cranial end vertebra along the end plate or by
marking the upper or lower margin of the pedicles. A line is then drawn
at the lower end of the caudal vertebra of the curve, using the end plate
or pedicles. A right angle to this line is then drawn. The angle to be
measured is the angle formed by the two lines at the end vertebrae.
2. Risser sign indicates ossification of the iliac epiphysis, which starts at
the anterior iliac spine and progresses posteriorly. A Risser 5 indicates
the epiphysis has fused with the iliac crest. A Risser 4 indicates com-
pletion of spine growth.
3. Stable vertebra is determined by the center sacral line.
4. Ring apophysis fusion indicates cessation of all vertebral body growth
potential.
5. Bone age is evaluated by X-ray of the left wrist and hand. The X-ray is
compared with standards in the Greulich and Pyle Atlas.
E. Pulmonary function test: greater than 70-degree curves have decreased
vital capacity, particularly with hypokyphosis.
F. Magnetic resonance imaging (MRI) indications
1. Neurological abnormalities
2. Congenital vertebral abnormalities
3. Juvenile and infantile onset
182 IV Deformity
4. Rapid progression
5. Cutaneous manifestations of dysraphism
V. Management
A. Goals of treatment
1. Prevent progression and maintain balance
2. Maintain respiratory function
3. Reduce pain and preserve neurological status
4. Cosmesis
B. Nonoperative treatment
1. Most patients with scoliosis do not have severe enough progression to
require treatment.
2. Observation is indicated for curves 25 degrees in immature patients
and 50 degrees in mature patients.
Figure 17–2 Types of congenital scoliosis. (A) Unilateral unsegmented bar. (B) Block vertebra.
(C) Fully segmented hemivertebra. (D) Semisegmented hemivertebra. (E) Nonsegmented
hemivertebra.
Chapter 17 Scoliosis 183
Figure 17–3 A 17-year-old girl with adolescent idiopathic scoliosis. (A) Anteroposterior radiograph
demonstrating a 49-degree right thoracolumbar curve with maintenance of the overall coronal balance.
(B) Lateral radiograph demonstrates relatively preserved sagittal alignment. (C) Postoperative anteropos-
terior and (D) lateral radiographs with an anteroposterior release and fusion.
184 IV Deformity
a. Obtain X-ray 3 months after the first visit and then every 6 to 9
months for curves 20 degrees and every 4 to 6 months for curves
greater than 20 degrees.
b. A significant change is a progression of 10 degrees in curves 20
degrees and 5 degrees in curves 20 degrees.
3. Exercise: indicated only as an adjunct treatment especially for patients
with obesity, back pain, lumbar hyperlordosis, flexible kyphosis, trunk
and extremity muscle tightness
4. Orthosis: curve 30 to 45 degrees (first visit) and 25 degrees with
documented progression in immature patients (Risser 3 or less)
a. Not for cervicothoracic curves and hypokyphotic thoracic curves
b. The goal is to prevent progression: Eighty-five percent of compliant
patients do stop progression and improve (50% correction), but
most return within 5 degrees of original curve after the brace treat-
ment is ceased.
c. Protocol: the patient must wear the brace 23 hours a day until
2 years after menarche or Risser 4 and wean off in 1 year (part-time
wear is also reported).
d. Orthosis types
(1) Thoracolumbar Sacral orthosis (Boston overlap)
(a) Appropriate up to T8 apex
(b) All curve types
(c) Medium compliance
(2) Bending brace (Charleston)
(a) Thoracolumbar and lumbar curves (25 to 35 degrees)
(b) Best compliance
(3) Cervico Thoracolumbar Sacral orthosis (CTLSo) (Milwaukee)
(a) Thoracic curves with apex above T7
(b) Low compliance
5. Electrical stimulation treatment has been abandoned.
Operative Treatment of Idiopathic Scoliosis (Fig. 17–3)
I. Indications for surgery
A. Progressive curves 40 to 45 degrees in growing children
B. Failure of bracing
C. Progressive curves beyond 50 degrees in adults
II. Goals of surgery
A. Spinal and pelvic balance is more important than curve correction.
B. Prevent respiratory compromise.
C. Prevent back pain.
D. Cosmesis
III. Choice of posterior fusion level
A. Curve patterns (King types)
1. Type I (S-shaped curve, where lumbar curve is larger and less flexible):
fuse both thoracic and lumbar curve, but not below L4.
◆
Chapter 17 Scoliosis 185
2. Type II (S-shaped curve, where thoracic curve is larger and less flexi-
ble): fuse only thoracic curve down to the stable vertebrae.
3. Type III (thoracic curve where lumbar curve does not cross the mid-
line): fuse thoracic curve down to the stable vertebra.
4. Type IV (long thoracic curve where L4 tilts into the curve): fuse the en-
tire curve down to the stable vertebra, L4 or L3.
5. Type V (double thoracic curves): fuse both curves from T1–T2 to the stable
vertebra, particularly if the left shoulder is higher than the right shoulder.
B. Distal extent of fusion
1. Should include Harrington stable zone, which is determined by two
perpendicular lines from the sacral pedicles
2. Should include neutral vertebra, which is the nonrotated vertebrae
3. Generally, the distal vertebra is the stable vertebra, which is deter-
mined by the center sacral line.
4. If possible, avoid fusion beyond the L4 vertebra to preserve distal mo-
tion segments.
5. For type I and IV curves, the fusion may be stopped at one level above
the stable vertebra if bending radiographs reveal the end vertebra be-
comes nonrotated and aligned within the Harrington stable zone.
6. Junctional kyphosis may result if the fusion is stopped at T12 in those
curves with preoperative kyphosis at T12–L1 junction.
7. To prevent postoperative coronal decompensation, particularly in type
II curves, overcorrection of the thoracic curve should be avoided.
8. For type IV, one level above stable vertebra can be fused.
C. Upper level
1. Upper hook should be higher if hypokyphosis is present to correct the
sagittal deformity.
2. Upper thoracic curve should be fused if the curve is structural, T1 is out
of balance, and the left shoulder is high.
IV. Indications for anterior fusion
A. Isolated short and flexible thoracolumbar or lumbar curves without asso-
ciated kyphosis may be treated with anterior fusion with anterior instru-
mentations such as Zielke rod, Texas Scottish Rite Hospital (TSRH) system,
Isola and Moss-Miami. The area of fusion includes only the vertebrae of
the structural curve. In performing anterior fusion of the lumbar spine,
preservation of lordosis is important.
B. A combined anterior and posterior procedure is indicated in the following
thoracic curves.
1. A severe curve 90 degrees that is stiff and unbalanced.
2. Presence of predisposing factors to develop crankshaft phenomenon,
which are Risser 0, Cobb angle 60 degrees, and apical rotation 20
degrees.
3. The procedure of choice is anterior discectomy and fusion with poste-
rior fusion and instrumentation.
V. Instrumentations
A. Harrington rod technique utilizes distraction on the concavity and compres-
sion on the convexity of the curve. Sagittal correction is not well achieved.
186 IV Deformity
B. The Drummond technique is a combination of Harrington and Luque
techniques in which the distraction Harrrington rod is placed in the con-
cavity of curve and the Luque rod is placed on the convexity of the curve,
and both rods are secured segmentally with spinous process wires.
C. Luque rod with segmental sublaminar wires is still effective in paralytic
scoliosis or cases with predominant thoracic lordosis. (Luque-Galveston
technique is used to correct pelvic obliquity.)
D. Multiple hook systems such as Cotrel-Dubousset, TSRH, Isola, Moss-
Miami, etc.
1. More powerful in correcting deformities and have better results in re-
ducing coronal and sagittal plane lmbalance
2. May be used so that either derotation or translation with cantilever
bending forces are applied, followed by segmental fixation with hooks
and/or screws
3. In performing any spinal instrumentation techniques, the goals of sur-
gery must be remembered, which are obtaining solid fusion and bal-
ance.
4. Rigid instrumentations have advantages such as saving distal motion
segments, avoidance of postoperative bracing, and facilitation of post-
operative rehabilitation.
a. Thoracic/lumbar pedicle screws
(1) Provide three-column control
(2) Allow for rotational/deformity control
E. Anterior systems include Zielke, TSRH, Moss-Miami, anterior ISOLA, and
Kaneda rods.
1. Most commonly used for thoracolumbar or lumbar curves
2. Anterior instrumentation may save one to two levels as compared with
using posterior instrumentation systems.
3. Endoscopic anterior instrumentation
a. Reduced morbidity
VI. Surgical technique
A. Intraoperative cell saver system
B. Spinal cord monitoring and wake-up test or motor evoked potentials
C. Fusion technique
1. Subperiosteal dissection out to the tips of transverse processes
2. Decortication, facet cartilage excision
3. Iliac crest autograft or rib graft from thoracoplasty
D. Instrumentation techniques: Most deformity corrections are now per-
formed using the pedicle screw based systems.
VII. Postsurgical care, outcomes, and complications
A. Bracing after surgery is not required.
B. Patient slowly advanced in their activities until full recovery in 6 to
12 months.
C. Depending on instrumentation used, correction percentage varies from
50 to 75%.
D. Fusion below L3 increases the incidence of lower back pain.
Chapter 17 Scoliosis 187
E. Posterior spinal instrumentation has a reoperation rate of 5 to 19%.
F. Other complications
1. Delayed infection
a. Incidence of 1 to 7%
b. Requires hardware removal and antibiotics
2. Late-onset surgical pain
a. Incidence of 5%
b. Requires hardware removal
3. Pseudarthrosis
a. Incidence of 3%
b. Compression instrumentation or bone graft needed for treatment.
VII. Idiopathic infantile scoliosis
A. Usually detected at 2 to 3 months of age
B. Greater incidence in boys than girls
C. More common in England
D. Ninety percent left thoracic
E. Prognosis
1. Sixty to 70% resolve spontaneously.
2. Two types of progressive curves
a. Benign curves are typically characterized by 1 year onset, double
curves, and greater flexibility.
b. Malignant curves are characterized by 1 year onset, thoracic loca-
tion, and rigid curves.
3. Good prognosis if Mehta angle (rib-vertebral angle) is less than 20 de-
grees and the convex rib does not overlap the vertebral body on the pos-
teroanterior radiograph (phase I). In phase II, there is an overlap between
the rib and vertebral body, and the prognosis is worse.
F. Treatment is bracing for curves over 30 degrees. If the curve is progressive,
surgery is recommended. Options include subcutaneous rod or telescoping
rod without fusion or combined anterior and posterior fusion.
VIII. Idiopathic juvenile scoliosis
A. Right thoracic pattern is most common.
B. Variable progression: one third are observed, one third are braced, and
one third require surgery.
C. Brace if greater than 30 degrees.
D. Surgery if progressive curve 45 degrees despite brace treatment, espe-
cially during puberty
IX. Congenital scoliosis (Fig. 17–2)
A. Failure of segmentation or formation or both
B. Associated anomalies: genitourinary
X. Paralytic scoliosis
XI. Neurofibromatosis
XII. Adult scoliosis
A. General considerations