Spinal Disorders: Fundamentals of Diagnosis and Treatment Part 66 potx

Figure 7. Technique of posterior scoliosis correction
The technique of posterior scoliosis correction is exemplified using the Universal Spine System. a, b Pedicle screws are
inserted in the target vertebra and a rod is first inserted on the concave side of the curve and connected to the screws,
c, d Insertion of the convex rod and levering it to the lower screws allows the concave apex screw to be narrowed to the
rod achieving a good correction. A posterior fusion is added.
shorter fusion lengths and better vertebral derotation compared to posterior
procedures.
The fusion usually incorporates all segments between upper and lower end
vertebrae [10, 112, 128, 209, 218]. The spine is exposed by a thoracotomy, lumbo-
tomy or a thoraco-lumbotomy depending on the anatomical location of the
curve. The intervertebral discs are completely removed at the levels selected for
fusion. Correction in the coronal, sagittal and axial planes is achieved by proper
placement of the screws into the vertebral bodies and connection to a pre-bent
The rod needs to be
pre-bent, creating a lordosis
single or double rod (Fig. 8, Case Introduction).Thediscspacecanbefilledwith
bone (e.g., resected rib) to enhance interbody fusion. These approaches are obvi-
ously technically more demanding than a posterior approach and are restricted
to the mid thoracic to upper lumbar levels. The morbidity caused by a thoracot-
omy is not negligible but can be kept very low in experienced hands. Recently,
thoracoscopic procedures have been introduced which are even more demand-
ing [134, 152, 177, 178, 181, 206, 232]. Newton et al. [152, 153] reported on compa-
rable results after thoracoscopic correction of thoracic curves compared with
open techniques. Similar findings were reported by Grewal et al. [75] even
though they reported a higher intraoperative blood loss in the thoracoscopic
group. During the first year, the thoracoscopic approach was found to cause
fewer declines in the vital capacity compared to the open anterior approach.
Idiopathic Scoliosis Chapter 23 643
82
Figure 8. Technique of anterior scoliosis correction
The instrumentation is exemplified using the Universal Spine System. Prior to instrumentation the intervertebral discs

are completely excised.
a The insertion of the vertebral screws is anterior to the base of the pedicles. b, c Pedicle screws
are inserted in the vertebral body and a pre-bent rod is connected to the screws in the upper and lower vertebrae.
d A
complex reduction forceps is used to narrow the remaining screws to the rod derotating the spine.
e, f Disc spaces are
compressed on the convex side after filling the disc spaces with bone. Full correction of the deformity is achieved.
Combined Anterior and Posterior Approach
Anterior fusion avoids
the crankshaft phenomenon
in immature patients
Furthergrowthoftheanteriorspinalcolumnafterposteriorfusionbeforethe
pubertal growth spurt may lead to a loss of correction. The so-called crankshaft
phenomenon leads to an increasing angulation and rotation of the spine [55], i.e.,
the spine is crankshafting around the posterior fusion mass. Dubousset, who
first described this phenomenon, concluded that young patients with a high
remaining growth potential should be fused anteriorly and posteriorly to prevent
644 Section Spinal Deformities and Malformations
crankshafting. Shufflebarger et al. [196] and Dohin et al. [51] provided evidence
that this procedure was successful. Open tri-radiate cartilage and surgery before
or during the peak growth velocity are strong positive predictors for the crank-
shaft phenomenon whereas later surgery is a strong negative predictor [190].
Curve rigidity may require
a combined surgery
Another indication for using a combined anterior and posterior approach may
be given by the rigidity of a curve. If the deformity is too rigid to prevent a satis-
factory correction, an anterior release can be done prior to posterior fusion (
Case
Study 1
). By performing a thoracotomy or thoracoscopy, the intervertebral discs

in the apex region are removed. In a second step the correction and fusion of the
spine is done from posteriorly. While a few studies doubt the need for anterior
release even in severe adolescent idiopathic scoliosis [4, 26, 88, 130, 207], Cheung
et al. found it to effectively improve spinal flexibility [33]. Severe deformities of
adult idiopathic scoliosis may also require anterior release and posterior fusion
[1].
Fusion Levels
Pedicle screw fixation allows
forbettercurvecorrection
and shorter fusion
One of the most challenging issues in scoliosis surgery is to define the correct
fusion levels. First, all structural curves must be determined [103, 113]. In a sec-
ond step, the neutral (no rotation) vertebrae at the upper and lower end of the
curve are determined for each curve. Thirdly, the central sacral vertical line is
drawn. The stable lower end vertebra is then defined as the one being closest to
the curve’s lower neutral end-vertebra and most nearly bisected by the central
sacral vertical line. Usually a fusion to the stable end vertebra defined by the cen-
tral sacral vertical line results in a good correction with a balanced spine. How-
ever, the decision whether the fusion may exclude one segment or include one
additional segment is also dependent on the individual curve and the surgeon’s
experience. Bernstein and Hall reported on the selection of fusion levels for ante-
rior fusion of lumbar and thoracolumbar curves [12]. They showed that by
Lumbar levels should
be preserved whenever
possible
including one vertebra above and below the apex vertebra, good results can be
achieved if a slight overcorrection is performed. Only in severe curves (>60°)
and if the apex was an intervertebral disc did they include two vertebrae above
and below. Recently, it has been shown that the posterior segmental instrumenta-
tion with pedicle screws allows for a shorter fusion than with Harrington rods

[114] or hooks alone [101].
Halm et al. [82] showed that anterior instrumentation of lumbar curves allows
one caudad segment to be spared compared to a segmental posterior pedicle
instrumentation. However, Hee et al. [87] found comparable fusion lengths.
Bitan et al. [13] and Min et al. [142] reported shorter fusion lengths by using the
anterior approach compared with a posterior approach.
Spinal Profile and Spinal Balance
A slight hypokyphosis is
common in right thoracic
curves
A thoracic kyphosis of 20°–40° and a lumbar lordosis of 40°–60° can be consid-
ered normal [70, 146, 202]. In AIS a slight thoracic hypokyphosis is common.
However, especially left convex idiopathic curves may be associated with thoracic
hyperkyphosis as well. By using a modern instrumentation system through an
isolated posterior approach, thoracic hypokyphosis can be corrected about 5°–
10° [20]. Even though anterior correction was reported to allow for a better cor-
rection of hypokyphosis [89, 98], severe thoracic hypokyphosis or even thoracic
lordosis may necessitate a combined anterior and posterior approach [18]. In
thoracolumbar and lumbar curves usually a hypolordosis or even a slight kypho-
sis is present in AIS patients. It has been reported that an anterior instrumenta-
tion allows for a good segmental restoration of the lordosis [89, 99]. Despite the
Idiopathic Scoliosis Chapter 23 645
ab c d
ef g
Case Study 1
A 16-year-old patient presented with a severe thoracic idiopathic scoliosis (a). Although a back asymmetry had been
noted for 2 years, the patient did not consult a physician because she was pain free. At the time of presentation, standard
radiographs (
b, c) showed a thoracic curve (T5–T12) of 75 degrees which corrected to 45 degrees on supine bending (d).
Although the anteroposterior radiograph demonstrated Risser Type IV indicating only a minimal remaining growth

potential, surgery was suggested because of the curve magnitude. In a first step, an anterior release was done to allow
for a better curve correction, followed by a posterior instrumentation with pedicle screws and curve correction during
the same intervention. Ten years after the operation, the patient was pain free and working full time as a mechanic (
e).
The follow-up radiographs demonstrate a curve correction to 20 degrees and a balanced spine (
f, g).
646 Section Spinal Deformities and Malformations
kyphogenic character of the anterior instrumentation, a good correction can be
achieved even without structural intervertebral support [127]. Severe hypolor-
dosis or kyphosis in middle-aged adults with degenerative changes often
requires combined anterior and posterior surgery and longer fusion length to
restore sagittal profile and spinal balance [1, 18].
A complication of the early scoliosis correction with Harrington distraction
rods was a proneness to result in a so-called iatrogenic flat back syndrome, i.e.,
a loss of the normal sagittal profile (decreased lumbar lordosis and thoracic
kyphosis). In cases in which the whole lumbosacral spine is flattened, patients
have problems standing upright and need to bend their knees to rebalance the
spine because the trunk is inclined anteriorly. This problem is infrequent today
because the modern instrumentation systems also allow sagittal balance and
profile to be addressed [226].
A special issue of concern after scoliosis surgery is the development of iatro-
genic coronal imbalance. This problem occurs when correcting the major curve
beyond the compensatory potential of the minor curves. The rigidity of the
minor curves has to be taken into account prior to fully correcting the major
curve.
Thoracoplasty
The rib hump in thoracic scoliosis results from vertebral rotation and concomi-
tantdeformationoftheribcage.Therefore,theribhumpcanonlypartiallybe
corrected by vertebral derotation. In cases in which this deformity should be
addressed for cosmetic reasons, a thoracoplasty can be done by a removal of

parts of the most prominent ribs [69, 203]. It is generally accepted that thoraco-
plasty in addition to scoliosis correction should be considered when the rib
hump measures more than 15° [143]. Disadvantages to be considered are a possi-
ble temporary decrease of pulmonary function and the potential risk for compli-
cations such as pneumothorax and intercostal pain [115]. Impaired vascular sup-
ply to the spinal cord by coagulation of the segmental vessels can occur when per-
forming an internal (transthoracic) thoracoplasty [197].
Surgical Decision-Making
A detailed description of treatment guidelines and surgical procedures is far
beyond the scope of this chapter. However, we want to provide here a short over-
view of surgical decision-making (
Table 3).
Infantile and Juvenile Idiopathic Scoliosis
In cases of severe scoliosis in young children, the application of serial orthotic
castsorbracesmaynotbesufficienttostopcurveprogression.Ontheother
hand, fusion in a young child should be avoided to prevent growth arrest or
crankshafting resulting in a short trunk with consecutive disproportionate body
habitus or impaired lung function. Therefore, fusion should be postponed as
long as possible and spinal instrumentation without fusion is performed if con-
Expandable spinal instru-
mentation is indicated
when spinal growth should
be preserved
servative therapy fails to control the curve. The main objective of using expand-
able spinal instrumentation is to stop progression of the curve, maintain spinal
balance and allow spinal growth. Definitive fusion surgery is delayed as long as
possible. In 1984, Moe et al. [145] described a technique using a Harrington dis-
traction rod which was continuously lengthened with growth or, if necessary,
replaced by a longer one. Even though progression may be stopped in most
patients by this procedure, there is the drawback of repeated interventions and

Idiopathic Scoliosis Chapter 23 647
Table 3. Surgical indications and techniques
Age of onset
Infant (0 –2 yrs) Juvenile
(3– 9 yrs)
Adolescent (10– 17 yrs) Adult (>17 yrs)
General
considerations
large age span affords variable
indications
arrest of curve progression, defor-
mity correction and solid spinal
fusion is the main objective
indication guided by
the predominant
symptoms
loss of spinal height, chest wall
growth and lung growth in case of
fusion are a major concern
Age
>6 yrs if possible (maturation of the
lungs) [208]
crankshaft phenomenon must
be avoided
higher risk of surgery
related morbidity
>40 yrs [17, 46, 210]
Cobb angle
progressive curves >45–60° despite
former orthotic treatment [50, 116]

progressive curves > 40° in skele-
tally immature patients
progressive and/or
symptomatic curves
curves >45–50° even in skeletally
mature patients [5, 179, 222]
Techniques
Growing rod young children – –
Anterior and
posterior fusion
older children (8– 10 yrs) at risk of
crankshaft phenomenon [51, 190,
196]
skeletally immature patients at
risk of crankshaft phenomenon
[51, 190, 196]
severe cases with spi-
nal imbalance or flat
back syndrome [1, 46]
Anterior release
and posterior
fusion
––
indicated in patients with severe
rigid deformity [4, 26, 33, 88, 130,
207]
–
Anterior or
posterior fusion
––

depending on the curve type usually only posterior
or combined fusion
complications such as rod fracture or hook displacement [144]. More recent
methods with single or dual growing rod techniques are used [14, 144]. Dual rods
were reported to be stronger than single rods and provide a better correction and
maintenance of correction as well as fewer complications [3, 214]. Despite the
improvements obtained by these newer methods, complications and reintervent-
ions remain unavoidable.
A special instrumentation system, the so-called vertical expandable pros-
thetic titanium rib (VEPTR), allows for an indirect correction of the scoliosis by
lengthening of the deformed thorax on the concave side of the curve [28, 29]. Pre-
liminary data indicate that this technique is particularly effective in the treat-
ment of congenital scoliosis with rib cage deformities [213]. It remains unclear
whether this technique is also effective for juvenile scoliosis.
Adolescent Idiopathic Scoliosis
The main objectives are
arrest of curve progression
and fusion
The main objective of surgical treatment is correction of the deformity and
maintaining the correction by spinal fusion. When surgically addressing AIS,
one would therefore want to improve the coronal deformity (Cobb angle), try to
reduce the most visible deformity, i.e., rib hump, restore a normal sagittal profile
andachieveorpreservesagittalandcoronalspinalbalance.
Thoracic Curves
A single thoracic curve may be treated by anterior or posterior fusion, the latter
being the classic approach. The posterior approach usually includes fusion of the
entire curve. Using pedicle screws instead of hooks offers a better curve correc-
648 Section Spinal Deformities and Malformations
abcd
Figure 9. Anterior thoracic scoliosis correction

a, b Preoperative radiographs showing a decompensated King type III curve (same patient as Fig. 2c). c, d Postoperative
radiographs showing excellent curve correction and restoration of the coronal balance.
Pedicle screws allow for a
better scoliosis correction
tion and enables a slightly shorter fusion length than with the use of hooks [101].
The use of pedicle screws allows for a better rotational and coronal correction
[109]. In the hands of an experienced surgeon, neurological problems were not
found to be higher with the use of pedicle screws [101]. The advantage of an ante-
rior correction is the shorter fusion length and better derotation (
Fig. 9). The
anterior approach has a cosmetic advantage if the operation is performed by
means of a mini-thoracotomy or thoracoscopy leaving only small scars.
Although spontaneous lumbar curve correction occurs after both selective pos-
terior and anterior thoracic fusion, the correction was found to be better in the
In double thoracic curves
attention must be paid to
shoulder balance, curve size
and rigidity
latter approach [111]. When planning surgery for double-thoracic curves,preop-
erative shoulder balance (T1-tilt) and size (Cobb angle) and rigidity of the proxi-
mal thoracic curve must be considered to achieve a good outcome [108]. If the
shoulder is elevated on the convex side of the major thoracic curve (i.e., on the
right side) and the proximal thoracic curve corrects to less than 25° in the side
bending view, spontaneous correction of the proximal thoracic curve with level
shoulders can be expected after isolated selective anterior fusion of the major
curve [108]. If both thoracic curves need fusion, the operation must be done
from posteriorly.
Thoracolumbar and Lumbar Curves
Thoracolumbar curves are
best treated from anteriorly

An isolated fusion of these curve types without addressing the thoracic curve (if
present) is possible if the thoracic curve reduces to less than 25° in the bending
radiograph [142]. These curves benefit most from a short anterior scoliosis cor-
rection (
Case Introduction), preserving more mobile motion segments com-
Idiopathic Scoliosis Chapter 23 649
pared to posterior fusion [60, 142]. If the thoracic curve remains larger than 25°
in the bending radiograph, it should probably be addressed surgically in order to
avoid decompensation of spine and shoulder balance.
Double Major Curves
These curve patterns with a thoracic and a thoracolumbar or lumbar structural
curve are usually operated on from posteriorly indicating that a big part of the
spine has to be fused. Attempts to fuse the lumbar curve anteriorly and only the
thoracic curve posteriorly have recently been suggested. It was reported that an
anterior release with instrumented fusion of the lumbar curve was superior to an
anterior release followed by posterior instrumented fusion [236]. Only prelimi-
nary data is available on the short selective anterior fusion of both the thoracic
Motion segment preser-
vation is an important goal
and the lumbar curve with the potential advantage of preserving motion seg-
ments in double major curves [141].
Adult Idiopathic Scoliosis
The general state of health, age and bone quality play important roles in the sur-
gical decision-making. Morbidity for surgery is lower in younger patients
(<40 years) and the chance of a better outcome will also be higher than in older
Surgical treatment
is strongly influenced
by the pain sources
patients (>40 years) [17, 46, 210]. Surgical decision-making in adult idiopathic
scoliosis strongly depends on the underlying causes of pain, which have to be

explored thoroughly. With predominant irradiating pain or claudication without
relevant back pain, selective spinal decompression may be performed as a stand-
alone procedure [1]. In younger patients a partial correction of the deformity
may already lead to a sufficient decompression without a formal decompression
being performed (
Case Study 2). If additional segmental instability, extensive
degenerative changes and progressive deformity lead to back pain, posterior
and/or anterior fusion and stabilization with/without decompression and cor-
rection may be required [194]. To achieve a ba lanced spine and prevent a postop-
erative collapse of the adjacent segment, the fusion usually has to extend beyond
the major curve. Stopping the fusion of a lumbar curve below the thoracolumbar
junction usually bears a high risk of sagittal decompensation of the spine crani-
ally [83]. It is still controversial whether or not the lumbosacral junction should
be included in the fusion [17, 19, 45, 90]. If unfused, the L5/S1 segment has to take
all the movements and loads of the fused lumbar spine [107, 194]. Furthermore,
a fusion to the sacrum leads to higher stress for the sacroiliac and hip joints.
On the other hand, it is difficult to achieve a solid fusion at this level. Non-
union rates of up to 30% are reported if the fusion is not done circumferentially
[19, 59].
The goal is to achieve
a balanced spine without
pain and normal neurology
It has to be borne in mind that the spine may be in a fragile balance before sur-
gery and that a decompression and/or a partial fusion may lead to a deterioration
of this balance leading to progressive deformity and disability. If spinal balance
is preserved, fusion in situ will often be the method of choice as an adjunct to
decompression [1]. If there is a derangement either in the coronal and/or sagittal
plane (e.g., flat back syndrome), additional correction of the deformity is neces-
sary [1]. An imbalanced spine with secondary degenerative changes requires
extensive release of the posterior structures and in some cases multiple spinal

osteotomies (see Chapter
26 ). Frequently, a combined anterior and posterior
approach may be necessary [46].
650 Section Spinal Deformities and Malformations
ab
cd
ef
Case Study 2
A 25-year-old female with a known but untreated scoliosis
for many years presented because of incapacitating lum-
bar back and leg pain with inability to continue with full
time work. Standard radiographs demonstrated a major
thoracolumbar curve of 56 degrees and a minor thoracic
curve of 42 degrees (
a, b). Both curves corrected to
45 degrees on supine bending. Indication for surgery was
prompted by the painful adult scoliosis (
c, d). A combined
anterior/posterior approach was done during the same
surgery consisting of an anterior release at T11–L3 and
posterior pedicle screw instrumentation at T4–L4 with
scoliosis correction. At 5 years follow-up the patient was very satisfied with the result. The radiographs revealed a bal-
anced spine with excellent curve correction (
e, f).
Complications
The most deleterious complication of scoliosis surgery is a neurological compro-
mise particularly in AIS (
Table 4). Complications of scoliosis surgery are dis-
cussed in more detail in Chapter
39 .

Neurological injury can result from either direct contusion or an ischemic
insult. Generally, resolution of the deficits is more likely to occur after contusion.
In experienced hands,
spinal cord injury is rare
Table 4. Complications in scoliosis surgery
Complication Incidence References
spinal cord injury 0.5– 3% [54, 126]
nerve root injury 0.5% [126]
early wound infection 0.1– 5 % [72, 140, 212, 217]
delayed wound infection 0.6– 1.7% [7, 35, 229]
non-union 0– 2.2% [7, 200, 223]
Idiopathic Scoliosis Chapter 23 651
Ischemia of the spinal cord can result from stretching of the blood vessels feeding
the spinal cord or by prolonged hypotension. Therefore, a reduction of the cor-
rection and restoration of a sufficient perfusion should be achieved if neurologi-
cal injury is noticed intraoperatively. Ligation of anterior segmental arteries has
also been suggested to increase the likelihood of ischemia of the cord [21].
Early wound infections occur within 12 weeks of the initial intervention. Mal-
nourished and immunocompromised patients are at substantially higher risk for
infections [104]. To minimize intraoperative infection, antibiotic prophylaxes are
routinely used. If an early wound infection is diagnosed, wound revision and
antibiotic treatment after isolation of the germ is indicated. The wound is thor-
oughly debrided and loose bone graft is removed. Titanium implants can be left
in place to avoid loss of correction and non-union [212].
Delayed wound infections
are caused by low-virulent
germs
Delayed wound infections occur 20 weeks or longer after the initial interven-
tion. Usually patients become symptomatic only after 2–3 years [35]. If the diag-
nosis is confirmed, surgical intervention is indicated removing all implants. If the

fusion is solid, usually no further measures are necessary besides implant
removal.
Non-union may be associated with hardware loosening, dislodgement or
breakage requiring revision surgery.
Recapitulation
Epidemiology.
Idiopathic scoliosis is the most com-
mon structural spinal deformity in the child and ad-
olescent. The overall prevalence of adolescent idio-
pathic scoliosis is about 2–3% in the adolescent
population. The prevalence decreases to about
0.1–0.3% for curves larger than 30°. Adolescent idi-
opathic scoliosis is the most frequent type (80%).
Only about 1% of idiopathic scoliosis affects chil-
dren younger than 3 years. Considering AIS requir-
ing therapy, girls are three times more often affect-
ed than boys.
Pathogenesis. Thereissomeevidencethatan
asymmetrical vertebral growth of the anterior col-
umn with tethering of the posterior structures
leads to the deformity. Genetic aspects, platelet de-
fects, cell membrane defects, abnormalities of cal-
modulin and melatonin levels have been suspected
to play a role in scoliosis development.
Classification. According to the age of onset,the
disease is divided into infantile (0–3 years), juvenile
(3–10 years), adolescent (10–18 years) and adult
(>18 years) idiopathic scoliosis. King has proposed
a classification of the thoracic curve into five types.
The Lenke classification includes not only thoracic

but also thoracolumbar and lumbar curve types as
well as the sagittal profile. The curve types are help-
ful when selecting fusion levels.
Clinical presentation. Most often scoliosis is discov-
ered accidentally. Pain or functional disability is rare
in adolescent scoliosis. If present, pain should raise
suspicion about a secondary etiology (i.e., non-idio-
pathic), prompting further diagnostic investigations
into the etiology. Family and developmental medi-
cal history must be assessed with emphasis on
growth spurt and menarche. Small asymmetries
such as an S-shaped line of the spinal processes, a
slightly more prominent scapula or asymmetric
lumbar triangles may indicate the presence of scoli-
osis and the location on physical examination. The
most reliable clinical sign for scoliosis is the pres-
ence of a rib hump on the convex side of the curve
best seen in forward bending. Convexity and flexi-
bility of all curves must be assessed.
Diagnostic work-up. Standard radiography of the
entire spine with the patient in standing position is
still the hallmark of the imaging studies. The radio-
logical assessment considers curve size and location,
spinal balance in the coronal and sagittal plane, pel-
vic and shoulder level, as well as the sagittal profile
(i.e., hypo-/hyper-kyphosis/lordosis). Supine bend-
ing radiographs are necessary to determine curve ri-
gidity and are necessary for surgical planning. Atypi-
cal curve pattern (left thoracic curve) and neurologi-
cal deficits such as absent abdominal wall reflexes

may indicate intramedullary pathologies and re-
quire further investigation with MRI.
652 Section Spinal Deformities and Malformations