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Chapter 27 Idiopathic Scoliosis 453
noted.31 Curve rotation is assessed by performing an Adams
forward-bend test and is quantied with a scoliometer. is is
of critical importance when considering a selective thoracic
fusion. is assessment is modied in infants by laying the
patient on the examiner’s knee, which also helps in assessing
the rigidity of the curve, an important factor in terms of
prognostication. Alternatively, a sitting forward-bend test can
be performed. e latter maneuver can also help assess for
plagiocephaly and developmental hip dysplasia, especially in
infants. Leg-length discrepancy and pelvic obliquity are also
evaluated.32 When leg-length discrepancy is the likely cause of
the deformity, a shoe li is used to reevaluate the patient to
determine if the curve corrects. A thorough neurologic examination includes all cranial nerves, motor strength, reexes
(including abdominal reexes, oen associated with Chiari
malformations), sensory modalities, and gait.33 Finally, other
possible causes of scoliosis—such as congenital, syndromic,
and neuromuscular types, as well as infection, neoplasms, and
spondylolisthesis—must also be ruled out.
Radiographic Evaluation
Initial posteroanterior and lateral 36- × 14-inch standing long
cassette views are obtained. Coronal and sagittal Cobb angles
are measured.2 Curves greater than 20 degrees in infants and
children; any neurologic symptoms present in patients with
idiopathic scoliosis; and le-sided, sharp angular, or irregular
curve patterns require further investigation, including screening with total spine magnetic resonance imaging.
34,35
When
anomalies of the nervous system are present on magnetic resonance imaging, a pediatric neurosurgical consultation is
indicated.
36,37
In advanced curves when surgery is planned,
supine, side-bending, and push-prone lms are obtained for
curve classication and to assess curve exibility.
Classication Systems
Currently, there are no accepted formal curve classication
systems for infantile or juvenile scoliosis. However, utilizing
formal consensus-building methods, surgeons experienced in
treating early-onset scoliosis (EOS) have developed a novel
classication system for EOS, with all core components demonstrating substantial to excellent interobserver reliability.
is classication system will likely serve as a foundation to
guide ongoing research eorts and standardize communica-
tion in the clinical setting.38 Similarly, in their eort to develop
a classication system for juvenile scoliosis, Lenke et al. have
modied the initial Lenke classication for AIS. is basically
follows all the tenets of the AIS classication, but uses the C7
plumb line and the central sacral vertical line (CSVL) to
decide on whether the minor thoracic or thoracolumbar
curves are structural or not, respectively. e proximal thoracic curve’s structural character is assessed by the relationship
of the rst rib to the main thoracic curve. Although such
classication has not gained wide use, it attests to the authors’
desire to continue to contribute to the treatment of deformity
patients.
39
e rst treatment-based AIS classication was developed
in 1983 by King and colleagues.40 Based on a series of 405
patients with AIS, their uniplanar system analyzed thoracic
curves only in the coronal plane. is system allowed for
surgical planning and helped in assessing whether or not a
King II curve could be selectively fused.41 Interobserver and
intraobserver reliability of this traditional thoracic classica-
tion system has proven to be fair at best.
42,43
Additionally,
coronal decompensation has been reported aer King II
selective fusions, leading Lenke et al. to develop stricter criteria for selective thoracic fusions.
Lenke and colleagues44 developed a comprehensive, practi-
cal classication system in 2001 that analyzes the coronal and
sagittal planes (Fig. 27.1). It includes not only thoracic curves,
but also TL/L curve patterns. Its interobserver and intraobserver reliability has been demonstrated.
42,43
Its denition of
the structural characteristics of the proximal thoracic curve
has been deemed reliable, leading to shorter proximal fusions
when that curve is nonstructural.45 It also allows a stricter
evaluation of a curve’s structural nature, permitting a more
objective analysis of when a given curve can tolerate a selective
fusion leading to a balanced outcome.
46,47
e latter is clini-
cally signicant, as one of the most important principles in
preventing postoperative decompensation is proper identication of curve patterns, including which curves can tolerate a
selective fusion.
41,48
is three-tiered classication combines a
curve type (1 through 6) with coronal lumbar (A, B, or C) and
sagittal thoracic (−, N, or +) modiers to produce a triad
comprehensive curve classication (e.g., 1A−).
Recent advances based on the Lenke classication system
have led to the tentative inclusion of a third modier: the last
touched vertebra (TV). e TV is the most cephalad TL/L
vertebra, T12–L5, of the lowest structural curve that is touched
by the CSVL. In curve types 3 to 6, the TV is the most cephalad
vertebra (T12–L5) touched by the CSVL below the apex of the
structural TL/L curve, whether that curve is included in the
fusion or not. Such a modier aids in a more thorough evalu-
ation of the Lenke curve classication (e.g., 5CN–L3, where
L3 is the TV of the lowest structural curve), and serves as a
landmark for the objective selection of the lowest instrumented
vertebra (LIV) in Lenke 1A curves as well as selective thoracic
fusions. Identication of the TV and comparison with the
selected LIV also helps in postoperative curve analysis, assessment of distal fusion length, and overall evaluation of the
surgical treatment of AIS.
49,50
If the LIV is the preoperative TV,
then the TV to LIV relationship is (0); if the LIV is one level
cephalad to the TV, then it is (−1); and (+1) when the LIV is
one level caudal to the preoperative TV.
Three-Dimensional Classication
Scoliosis is a known three-dimensional deformity, and
although the Lenke classication system takes into account
the coronal and sagittal planes, it does not account for the axial
or transverse planes of the deformity. A task force of the
Scoliosis Research Society continues to work on developing a
clinically useful three-dimensional analysis to aid in further
dening the classication of scoliosis. e key factor in a
SECTION
IV
454 PEDIATRICS
THE LENKE CLASSIFICATION SYSTEM FOR AIS
Curve type Proximal thoracic Main thoracic Thoracolumbar/lumbar Descripition
1
2 Structural* Nonstructural Double thoracic (DT)
3
4 Structural
5 Nonstructural Nonstructural Structural* Thoracolumbar/lumbar (TL/L)
6 Nonstructural Structural
*Major curve: largest Cobb measurment, always structural; †Minor curve: remaining structural curves; §Type 4 - MT or TL/L can be the major curve
Lumbar coronal
modifier
Nonstructural Structural* Nonstructural Main thoracic (MT)
Structural
Nonstructural Structural* Structural
Proximal thoracic
Thoracolumbar/lumbar
A
B Touches apical body(ies)
C Completely medial
†
†
STRUCTURAL CRITERIA
(Minor curves)
– Side bending Cobb ≥25°
– T2–T5 Kyphosis ≥+20°
Main thoracic
Center sacral vertical line to
– Side bending Cobb ≥25°
– T10–L2 Kyphosis ≥
– Side bending Cobb ≥25°
– T10–L2 Kyphosis ≥
lumbar apex
Between pedicles
Structural
§
†
+
20°
+
20°
AB C
†
Structural
Structural* Thoracolumbar/lumbar-main thoracic (TL/L-MT)
MODIFIERS
§
LOCATION OF APEX
CURVE APEX
Thoracic
Thoracolumbar
Lumbar
Double major (DM)
Triple major (TM)
(SRS definition)
T2 to T11/12 disc
T12/L1
L1/2 disc to L4
Thoracic sagittal profile T5-T12
Modifier Cobb angle
– (Hypo) <10°
N (Normal) 10°–40°
+ (Hyper) >40°
Curve type (1–6) + Lumbar coronal modifier (A. B, C) + Thoracic sagittal modifier (–, N, +) =
FIG. 27.1 Lenke adolescent idiopathic scoliosis (AIS) classication system schematic.
Curve classification (e.g. 1B+): ______
three-dimensional assessment is the plane of maximum curvature, which is the three-dimensional deformity that occurs
as the spine translates and rotates out of the normal sagittal
prole in scoliotic deformities. is work is expected to
provide further understanding so that three-dimensional
analysis and classication will become a standard for all scoliosis surgeons.
1,51
Treatment Options
ree fundamental treatment options exist for idiopathic
scoliosis: observation, casting/bracing, and surgery. ese
treatment modalities are based on the natural history of
idiopathic scoliosis or the potential or probability of curve
progression.
to slow or halt curve progression, such as electrical stimulation and physical therapy. Yet, none of these modalities has
been scientically proven to be a viable alternative in the
treatment of scoliosis.53 Romano et al. noted that there is a lack
of high-quality evidence to recommend the use of scoliosisspecic exercises for AIS, although a very low-quality study
1,52
However, other modalities have been proposed
suggested that these exercises may be more eective than
electrostimulation, traction, and postural training to avoid
scoliosis progression.54 Better-quality research needs to be
conducted before the use of scoliosis-specic exercises can be
recommended in clinical practice. Similarly, Mordecai et al.
concluded from their extensive literature search that there is
poor-quality evidence supporting the use of exercise therapy
in the treatment of AIS.
55
Observation
Up to 90% of infantile curves have been known to resolve
spontaneously, but they can progress.56 Deciphering which
infantile curves will progress can be guided by the RVAD and
the relationship of the apical rib head to the vertebral body, as
previously noted.27 Infants with curves less than 30 degrees
and RVAD less than 20 degrees and juveniles with curves less
than 20 degrees should be followed clinically and radiographically every 3 to 6 months. Adolescent idiopathic patients with
curves less than 25 degrees are also followed clinically and
radiographically every 3 to 6 months. Brace treatment is
started for curve progression.
Chapter 27 Idiopathic Scoliosis 455
Bracing and Casting
Bracing57 is the nonoperative treatment of choice in small but
progressive scoliosis in growing children and adolescents. In
about 75% of cases, bracing can control the curve and avoid
progression, rendering the curve small enough so that the risk
of progression aer growth is unlikely.53 In a younger child
whose growth potential remains a signicant issue, bracing
allows curve control and continued growth until the patient
requires eventual operative treatment should curve progression ensue.
With infantile cases, serial Mehta casting (derotational
type) or a thoracolumbar orthosis are appropriate treatments
in exible curves, Cobb angles greater than 30 degrees, RVAD
greater than 20 degrees, and curves with a phase II vertebralrib relationship. Bracing alone can be employed where there
is incomplete correction with Mehta casting. Bracing and
casting of these patients comes with potential consequences,
however, that include pulmonary restriction, which can have
future ramications.
serial casting to be benecial in the treatment of infantile
scoliosis. ey reported that curves less than 60 degrees oen
fully corrected in infants if casting was started before age 20
months.
Juveniles with curves 20 to 50 degrees are candidates for
bracing. Here, the intent is to prevent curve progression and not
so much attain correction. ese patients are essentially braced
16 to 23 hours a day until the completion of skeletal growth
or until they become surgical candidates. Patients with thoracic hypokyphosis should not be braced.
In adolescents with curves between 20 and 30 degrees,
bracing is started if a curve progresses greater than or equal
to 5 degrees or more in two consecutive visits or greater than
or equal to 10 degrees in one visit. Bracing is usually started
aer the rst oce visit if the patient is skeletally immature
(Risser ≤2) and presents with a 25- to 40-degree curve. is
treatment modality is eective only for exible curves and, as
with the juvenile type, the goal is to stop progression versus
curve correction. Male, obese, and noncompliant patients, as
well as those with poor in-brace correction and hypokyphotic
curves, are less likely to benet from bracing. Patients must
wear their brace 16 to 23 hours a day until the completion of
skeletal growth or until they become surgical candidates.
Bracing is deemed successful if there is less than 5 degrees
progression at brace discontinuation (skeletal maturity).
Conversely, if the curve progresses to greater than 60 degrees
aer brace discontinuation and/or if there is absolute progression to greater than 45 degrees at or prior to discontinuation,
the patient is considered to have failed bracing treatment.
Several brace options exist. Deciding which brace to use
depends on the apex of the curve and physician preference.
Curves with an apex above T6 would likely require the use of
a Milwaukee (cervicothoracolumbosacral orthosis).61 Conversely, curves with apices at T7 or below and above L2 do well
in a Boston underarm thoracolumbosacral orthosis. ese
braces are more socially acceptable due to lack of a cervical
extension. e Charleston bending brace is an option if the
child is noncompliant to wearing the brace during the day.
58,59
Yet, Sanders and colleagues60 found
Although the ecacy of a brace seems to depend on the length
of time the brace is worn,62 this brace is typically worn at night,
and some studies have shown its ecacy.
63,64
Modications to
the standard thoracolumbosacral orthosis include variations
of the Chêneau brace (Jacques Chêneau) and the SpineCor
dynamic brace (SpineCorporation). e Chêneau 2000 ortho-
sis allows for a greater amount of initial correction by using a
hypercorrected mold and pads, which provide derotational
forces.65 is brace is the rst that uses the theory of expansion
to allow for active correction by respiratory movements.66 e
SpineCor67 and TrIAC (Boston Brace International) are nonrigid braces. ey work by using straps, which correspond to
a specic correcting movement depending on the curve
pattern, producing a progressive positional change, dynamic
curve correction, and appropriate muscle balance. When
bracing is initiated and pad placement is deemed appropriate,
patient follow-up occurs every 4 to 6 months, with in-brace
radiographic evaluation and appropriate tting adjustments
made when necessary.
Operative Intervention
Operative intervention is usually recommended for patients
whose curves progress despite nonoperative management.67 In
infants, operative intervention is controversial. It is occasionally performed in infants with thoracic curves greater than 45
degrees, TL/L curves greater than 40 degrees, or those who
fail Mehta casting or bracing. Juveniles are typically more
prone to curve progression and are more likely to require
operative intervention, particularly with curves greater than
50 degrees. Other patients who are likely to benet from
operative intervention are skeletally immature patients with
AIS with a greater than 40- to 45-degree curve and mature
patients with curves greater than 50 degrees.
Surgical Techniques
Anterior-only, posterior-only, and circumferential procedures
remain the mainstay of surgical treatment options.68 However,
the prevalence of anterior-only and circumferential procedures
has declined with a concomitant development of surgical
technologies permitting successful posterior-only procedures.
Surgeons are now aware that early intervention with a denitive anteroposterior fusion for progressive infantile and juvenile curves leads to loss of trunk height development, which
can lead to chest wall and lung underdevelopment.
problem has promoted innovative techniques to try to control
progressive curves surgically without denitive fusion, includ-
ing epiphysiodesis,
27.2),73 intervertebral stapling (Fig. 27.3),
(Fig. 27.4),
76,77
rib (VEPTR),78 with the last used more in progressive EOS, in
which rib and chest wall deformities can be quite severe. In
those cases, Cobb angles greater than 45 degrees and failed
Mehta casting or bracing are operative indications, with fusion
as close to skeletal maturity as possible. Among juveniles,
fusionless techniques are also indicated in small children with
71,72
dual growing rod placement (Fig.
and the vertical expandable prosthetic titanium
27
69,70
74,75
spinal tethering
is
SECTION
IV
456 PEDIATRICS
GH
2+9
122°
AB
5.5yrs po
6
5.5yrs po
2+9 18# Tx 18# Tx
5
54°
3
C D
30°
2
EF
FIG. 27.2 (A–B) Radiographs of a girl, age 2 years + 9 months, who presented with severe infantile-onset
idiopathic scoliosis. Her left thoracic curve measured 122 degrees. (C–D) She was placed in halo-gravity traction
and underwent a short apical anterior release and fusion, and was prepared for a growing rod construct. (E–F)
She had a dual-rod, pedicle screw growing rod construct placed. At 5 years + 6 months after initiation of
growing rod treatment, she continues to be lengthened with overall good coronal and sagittal balance and
acceptable lung elds. (G–H) Preoperative and latest postoperative clinical images show maintenance of trunk
alignment and growth.
curves greater than 40 to 50 degrees with signicant growth
potential, allowing continued spinal growth over unfused
segments, until a denitive fusion can be performed close to
or at skeletal maturity. Anteroposterior fusions are reserved
for younger patients with curves greater than 50 degrees with
a potential to cranksha or for very severe curves. Anterior-
only instrumentation and fusions are indicated for TL/L
curves greater than 40 to 50 degrees with a normal sagittal
prole. Posterior-only fusions are performed for curves greater
than 50 degrees as well as double major curves, when the child
has grown closer to skeletal maturity, or even in those who are
skeletally immature with the use of segmental pedicle screws
and adequate fusion levels that will prevent the adding on
phenomenon.
Many surgeons today still prefer to perform an anterior
approach in younger patients when there is risk of cranksha
development and especially for thoracolumbar and lumbar
major curves. However, with the introduction of pedicle
screws, a posterior approach has shown numerous benets
over an anterior procedure, such as better maintenance of the
obtained correction, more powerful corrective forces, threecolumn control, and oen obviating the need for anterior
releases and thoracoplasties.
79–85
In addition, a posterior
approach avoids the negative consequences of chest cage
disruption and pulmonary compromise that can result from
an open anterior approach
86,87
(Fig. 27.5). Yet, according to
a 2010 study by Tis and colleagues,88 with the advances in
anterior instrumentation, surgeons theoretically should see
Chapter 27 Idiopathic Scoliosis 457
7+9 7+9 8+4 8+4 5yrs po
62°
1
42°
5
6
+34°
12
34°
5
–59°
12
SAC
38°
6
60°
12
27°
5
AB
5yrs po
5
5
+18°
12
–50°
SAC
CDE
18°
1
25°
6
SECTION
IV
12
2°
5
12
SAC
FG HI
FIG. 27.3 (A–B) Radiographs of a boy, age 7 years + 9 months, who presented with progressive juvenile-onset
right thoracic idiopathic scoliosis. His main thoracic curve measured 60 degrees and was progressive despite
bracing. (C–D) He had anterior thoracic stapling performed but had slow progression of his deformity with
growth. (E–F) A posterior dual screw-rod growing construct was placed. Five years after insertion, his deformity
correction has been maintained to 18 degrees in the main thoracic curve with a good sagittal prole. (G–I)
Clinical images before surgery, status post-stapling, and 5 years status post–growing rod construct show
improvement of truncal deformation.
a reduction in the rate of rod breakage, pseudarthrosis, and
sagittal decompensation, and obtain improved correction
rates. ese authors concluded that open anterior spinal
fusion surgery is a safe method for the treatment of thoracic
AIS. At 5-year follow-up, they reported good coronal and
sagittal correction of the main thoracic and compensatory
TL/L curves, but they also reported that pulmonary function was mildly decreased as with any procedure in which a
thoracotomy is performed. Tis and colleagues also concluded
that in skeletally immature patients, an open anterior spinal
fusion can increase kyphosis; however, newer techniques used
in their series seemed to limit progressive kyphosis, which has
been noted in previously published reports.
89
Adolescent curves can typically be surgically treated via an
anterior or posterior approach (or both) with instrumentation
and fusion.88 oracoscopic procedures have shown advantages over open anterior thoracotomy procedures. Kishan and
colleagues90 showed that anterior thoracoscopy had fewer
adverse eects on pulmonary function. Sucato and colleagues91
found that adding a thoracoscopic release performed in the
prone position to a posterior instrumentation and fusion
oered the advantages of minimally invasive surgery and did
not require repositioning to perform the posterior procedure.
In addition, when double-lung ventilation is used, acute pulmonary complications are signicantly reduced. A signicant
learning curve is required, however, and these techniques have
diminished in popularity owing to the proliferation of pedicle
screw constructs.
During surgical planning, determination of proximal and
distal fusion levels is paramount because choosing incorrect
458 PEDIATRICS
CD
8+8 8+8 4yrs po 4yrs po
4
4
5
25°
1
1
–65°
SAC
+21°
12
AB
FIG. 27.4 (A–B) Radiographs of a girl age 8 years + 8 months who presented with progressive left thoracic
scoliosis. She had a positive family history of scoliosis, with her mother requiring scoliosis fusion as a child. Her
left thoracic curve progressed to 25 degrees with a normal sagittal prole. (C–D) She was treated with a single
left thoracic mobile tether, with slow progressive correction of her deformity to 6 degrees with a normal
sagittal prole 4 years after treatment. She had only one surgery and did not wear a brace postoperatively.
levels is the main reason for postoperative decompensation.
31,92
Adding on is another phenomenon that can result if a fusion
is stopped “short.” Suk and colleagues93 reported 5-year results
of 203 patients in which they found that adding on occurred
in 17 patients who were fused, on average, two levels short of
the neutral vertebra.
of main thoracic curve correction planned (dynamic criteria).
In general, when the le shoulder is elevated, the PT curve is
structural and/or kyphotic (T2–T5 >20 degrees) and marked
correction is planned (apical translation), T2 is a wise choice
for the upper instrumented vertebra in this scenario. When the
shoulders are level and the PT curve is close to being structural
and/or mildly kyphotic (T2–T5 >10 degrees and <20 degrees),
with marked correction planned, T3 is an appropriate choice.
Upper and Lower Instrumented Vertebra Selection
With anterior-only approaches, fusion levels typically extend
from end-to-end vertebrae, as measured with the Cobb technique. Short fusions above and below the apex, depending on
whether the apex is a disc or a vertebra, have been advocated
for exible thoracolumbar curves.9 In this technique, if the
apex is a vertebral body, the discs above and below the apex
are included in the fusion. If the apex is a disc, the two discs
above and below the apex are included in the fusion. Brodner
et al.94 predicted fusion levels based on the supine-pull
(“stretch”) lms, ensuring that a thorough release is performed
to obtain a bone-on-bone fusion. Anterior structural gras
have been used to counter the kyphogenesis associated with
anterior instrumentation.
With posterior approaches, the selection of the upper
instrumented vertebra is based on clinical and radiographic
shoulder height, size, and stiness of the proximal thoracic (PT)
curve, hyperkyphosis of the upper thoracic region and amount
88
Finally, T4 or T5 is a wise choice when the right shoulder is
elevated and the PT curve is nonstructural and not kyphotic.
identication of the end, neutral, and stable vertebra (SV) of
the distal structural curve to be included in the fusion.95 A safe
place to end the fusion is the SV; however, the Lenke classication and current correction techniques employing pedicle
xation and derotation maneuvers allow for shorter distal
fusion levels (Fig. 27.6). As noted earlier, in addition to all
Lenke 1A curves, in selective thoracic fusions of Lenke 1C and
2C curves, the TV can be the LIV if it is proximal to the stable
vertebra. With possible selective thoracic fusion of Lenke 3C
and 4C curves, the TV is still going to be below the apex of
the structural TL/L curve even when that curve is not included
in the fusion. Similarly, with nonselective thoracic fusions, as
well as Lenke 5C and 6C curves, the LIV can be cephalad to
the SV provided that the intended LIV touches the CSVL, does
not have signicant rotation (Nash-Moe grade ≤1.5), and the
disc below is parallel or closed on the convexity and the apex
of the TL/L curve is L1 or the L1–L2 disc, not L2.
6°
Selection of the lower instrumented vertebra (LIV) requires
AB
CD
GH
Chapter 27 Idiopathic Scoliosis 459
SECTION
IV
EF
FIG. 27.5 (A–D) Radiographs of a female, age 14 years + 9 months, with a Lenke 5CN curve. She was treated
with a posterior-only approach. (E–H) Note postoperative balanced spine and excellent clinical results.
In placing thoracic screws, it is essential to follow sequential
steps at every screw placement.
79,80
With small pedicles, time
should be taken to expand the pedicle to accommodate a
screw.96 Alternatively, parapedicular screw placement is a safe
possibility.97 Although we advocate the use of pedicle screws
whenever possible, when employing hook-and-rod segmental
instrumentation, it is imperative to reverse hook orientation
where the discs are reversed in orientation to maintain coronal
and sagittal balance.98 We also advocate selective thoracic
fusions whenever feasible.
situations arise when one considers fusing nonstructural,
secondary curves for the sake of cosmesis, spinal balance,
or both.
e Lenke classication system provides an objective way
to decide when to perform selective fusions in patients with
AIS, especially with type C curve patterns, including Lenke
1 and 2C, and possibly Lenke 3C and 4C types.
tive fusions of the latter types are achieved by having stricter
criteria that dene the structural characteristics of individual
curves, leading to an objective analysis that helps in choosing
which curves can be selectively fused without ensuing clini-
Selective Fusions
e term selective fusion refers to minor structural thoracic
or lumbar curves that cross the midline, but are not included
in the fusion. at is, they are le untreated. Similarly, rare
cal imbalance.
cannot be overemphasized because it plays as important a
role as the radiographic assessment when deciding whether
to perform a selective fusion. Hence, the analysis of whether
or not to proceed with a selective thoracic fusion (STF) begins
43,44,99,100
Clinical assessment of the deformity
47,92
Selec-
460 PEDIATRICS
GH
A BC D
EF
FIG. 27.6 (A–D) Radiographs of a female, age 14 years + 7 months, with a Lenke 1BN/L1 curve. She was
treated by posterior-only approach, T3–L1 (0). (E–H) Note postoperative balanced spine with spontaneous
lumbar correction from B to A modier and excellent clinical results.
with the clinical assessment of the patient’s deformity as well
as skeletal maturity.
41,43,92
e magnitude of the thoracic and
lumbar prominences are evaluated in order to decide if the
patient is willing to accept a moderate lumbar hump when
contemplating an STF. Next, the radiographic analysis entails
comparing the relative Cobb angle measurements and apical
vertebral rotation and translation ratios of the thoracic and
TL/L curves.
48,49
Also, one cannot overlook the thoracolumbar
sagittal prole because this can lead to curve misclassication
and incorrect operative management; that is, proceeding with
an STF in a curve pattern when selective fusion might not
be recommended. In terms of operative management, attention must be paid to the degree of tilt le on the LIV when
carrying out an STF; this is guided by the lumbar modier
to allow for harmonious balance of the unfused structural
lumbar curve.
A rough estimate of the degree of tilt to be le on the
LIV is equal to the remaining tilt on a preoperative supine
lm. is tilt is further assessed with intraoperative full-spine
radiographs.99 Again, this is imperative in allowing for accommodation of the structural component of the lumbar curve,
especially with selective fusions.47 e lower endplate of the
Chapter 27 Idiopathic Scoliosis 461
HJ
AB CDE
SECTION
IV
FG I
FIG. 27.7 (A–D) Radiographs of a girl, age 11 years + 9 months, with progressive right thoracic compensatory
left lumbar scoliosis. Her main thoracic curve progressed to 70 degrees, and her compensatory 46-degree curve
decreased on side bending to 16—a 1CN/T12 classication. (F–G) She underwent a selective thoracic fusion,
T3–T12 (0) with a pedicle screw construct, with nicely matched 14-degree thoracic and 13-degree lumbar
scoliotic curves 1 year postoperatively with spontaneous lumbar correction from modier C to B and adequate
sagittal balance. Preoperative and postoperative clinical images show improved truncal correction on upright
(E, J) and forward bend (H, I) views.
LIV should be horizontal for type A lumbar modier curves,
a mild tilt should be le on type B curves, and an appropriate
degree of tilt should be le on the LIV for type C curves
(Fig. 27.7).
Selective anterior fusions of major TL/L curves associated
with minor and partially structural thoracic curves in Lenke
5C and 6C curves can also be considered.92 e analysis here
parallels that of a thoracic STF. Additionally, the thoracic
curve should be less than 50 degrees, bend out to 20 degrees
or less, the TL/L-to-thoracic Cobb ratio should be 1.25
or greater, and the triradiate cartilages should be closed.46
However, such selective fusions should not be undertaken
when shoulder depression ipsilateral to the TL/L curve exists,
the patient is highly skeletally immature, or a clinically unacceptable thoracic hump is present. To prevent decompensation, if the lumbar curve bends out more than the thoracic
curve does, the lumbar curve should not be overcorrected
because the thoracic curve likely would not compensate to
achieve postoperative balance.91 One study showed an average
spontaneous correction of 14 degrees or 36% improvement
of the thoracic curve when a selective TL/L fusion was
performed.
47
Adjuncts to Correction
Direct Vertebral Rotation
In the past, curves greater than 75 degrees, curves that do not
correct below 50 degrees, and curves needing a thoracoplasty
have required anterior releases. With the use of modern
techniques of multisegmental pedicle screw xation and the
addition of direct vertebral rotation (DVR) techniques, safe
and eective procedures demonstrating greater coronal and
sagittal realignment along with acceptable cosmesis without
the need for an anterior procedure have been reported.
Additionally, in the thoracic region, DVR helps derotate the
spine and signicantly decreases the rib prominence. Care
must be taken to use stier rods, prebent in the sagittal prole,
to prevent inducing hypokyphosis in the thoracic spine. DVR
also helps to obtain better three-dimensional correction in the
101-103
462 PEDIATRICS
TL/L component of Lenke double major curves and to minimize the LIV tilt angle.
101
A DVR is performed only if screw placement is adequate,
if the thoracic spine is not overly lordotic or kyphotic, and
when there is a clinically signicant thoracic or lumbar prominence. e DVR technique necessitates accurate placement
of pedicle screws at the apex of the deformity and the three
levels at the proximal and distal ends of the fusion. When
the thoracic spine has a (+) sagittal modier, per the Lenke
classication, a DVR maneuver is not performed because
increased kyphosis places considerable strain on the proximal screws unless appropriate releases via posterior column
osteotomies are performed. Otherwise, the coronal and sagittal deformities are addressed simultaneously by convex rod
instrumentation rst.
Osteotomies
Several osteotomy choices are available to correct sagittal,
coronal, and multiplanar deformities associated with previously fused or more severe idiopathic scoliosis curves, including posterior column osteotomies (Ponté, Smith-Petersen),
pedicle subtraction osteotomy, and vertebral column resection
(VCR). A Smith-Petersen osteotomy classically refers to an
osteotomy performed through a previous lumbar fusion
mass, whereas a Ponté osteotomy refers to a posteriorly based
thoracic osteotomy through a previously unfused spine. We
prefer the term posterior column osteotomy, as it avoids this
prevalent confusion. Like sagittal imbalance, coronal imbalance can be classied as type A or B. In type A, the shoulders
and pelvis are tilted in the opposite direction, whereas in type
B, they tilt in the same direction.
type A deformities can be addressed with one pedicle subtraction osteotomy (PSO); multiple or asymmetrical pedicle
subtraction osteotomies can be used when dealing with sti
or kyphoscoliotic cases. Simple trigonometric calculations
at the vertebral body where the osteotomy is going to be
performed permit precise determination of the angle of bony
resection required for global balance.
likely require a VCR.
VCRs can be performed via a combined anterior and posterior approach (i.e., circumferentially) or from a posterior-only
approach (Fig. 27.8).
107
Compromised pulmonary function
lends consideration, however, to performing a posterior-only
approach. e surgeon must balance the potential pulmonary compromise of the patient with the understanding that
the extracavitary approach (i.e., posterior only) requires
a higher level of surgical expertise and is technically more
demanding.
108,109
As with all surgical procedures, adherence
to safety is the most important principle, and if the surgeon
is uncomfortable with a particular approach or technique,
a referral should be made.
modality is appropriate in the setting of congenital cases,
multiplanar or sti kyphoscoliotic curves, curves previously
fused circumferentially, and cases of global imbalance.
In the last-mentioned situation, attention must be paid to
the direction of the shoulder and pelvic tilt imbalance (see
Fig. 27.8).
104,105
Typically, single-plane
106
Type B deformities
110
Nevertheless, this correction
Minimally Invasive Techniques
Minimally invasive spine surgery is a popular concept that
uses imaging, retraction, and implant technologies to help
surgeons locate the exact area on which they are to operate.
is type of procedure is done through incisions less than 1
inch long, minimizing damage to surrounding muscles and
other tissues, which rapidly increases the healing and reduces
recovery time. It also uses technology to perform the surgery
more eciently. One example is a video-assisted thoracoscopic
procedure. According to Newton and colleagues,
111
this procedure can be used for an anterior thoracic release or to
achieve deformity correction via rod-screw constructs. Given
the small incisions and the muscle-splitting technique used, a
reduction in chest wall disruption and subsequent lung volume
decrease, as is the case with an open thoracotomy approach,
was noted. is procedure oers comparable curve correction
and a faster return to presurgical function.
90,91
However, with
advances in instrumentation as mentioned previously and the
enhanced ability to perform a direct vertebral derotation with
posterior pedicle screw constructs, the use of video-assisted
thoracoscopic instrumentation procedures has declined substantially. e decision between an anterior and a posterior
approach is based purely on surgeon preference at this point.
Postoperative Care
Patients are usually observed in the intensive care unit overnight. Sitting and standing with assistance is permitted, and
physical therapy is usually started on the rst postoperative
day. When stable, patients are transferred to the regular oor.
As bowel function returns and patients are able to tolerate
clear uids, routine intravenous narcotics are replaced with
oral narcotics as needed. Typically, no postoperative bracing
is used. When patients are ambulatory, the urinary catheter is
removed. On postoperative day 3, the drains are discontinued
along with prophylactic antibiotics. Aer discharge, usually on
postoperative day 4 or 5, patients may start to slowly resume
activities.
Complications
Complications can occur during any of the treatment stages—
preoperative, intraoperative, or postoperative.
preoperative stage, inappropriate curve classication and
inadequate surgical planning can lead to inappropriate surgical decisions. us, it is essential to ensure that when performing a selective fusion, the clinical exam is considered and
appropriate structural curve criteria are met.92 Choosing
of preoperative complications.
114
Intraoperative complications most commonly result from
technical errors, including instrumentation misplacement.
Hooks that do not hug the lamina or misplaced pedicle screws
can lead to devastating complications, including spinal cord
insults. Overcorrection of curves and, conversely, inadequate
112,113
At the