(ii) Scoliosis in children and teenagers · 2015. 8. 21. · Congenital scoliosis A brief history...
Transcript of (ii) Scoliosis in children and teenagers · 2015. 8. 21. · Congenital scoliosis A brief history...
MINI-SYMPOSIUM: SPINAL DEFORMITY
(ii) Scoliosis in children andteenagersNigel W Gummerson
Peter A Millner
AbstractScoliosis is a three-dimensional deformity of the spine whose cardinal
feature is a curve in the coronal plane with a Cobb angle that exceeds
10�. In the growing spine and the degenerative spine scoliosis will evolve
over time; the fourth dimension. This article discusses the possible
causes of scoliosis in the paediatric population. The aim is to provide
the reader with a basic understanding of spinal growth, the natural
history of scoliotic spinal deformity and outline the options for treatment.
Keywords congenital abnormalities; scoliosis; spine
Introduction
Scoliosis is a common and relatively slowly evolving condition.
With the exception of some neuromuscular conditions, young
patients with scoliosis are usually active and mobile. Scoliosis in
children tends to present as a cosmetic problem, whereas scoli-
osis in adults more often presents with pain and neurological
symptoms.
Deformity of the axial skeleton may have a bearing on other
musculoskeletal problems in the upper or lower limb and
vice versa. Patients with spinal deformity will often present to
non-spinal orthopaedic surgeons with other joint problems
(particularly shoulder and hip problems). These observations
mandate that all orthopaedic surgeons should have a basic
understanding of scoliotic spinal deformity. Surgical trainees
should also be aware that paediatric patients and their parents
are usually very happy to appear at higher surgical examinations!
The normal spinal profile
The spine is a three-dimensional structure and spinal deformities
can only be fully described in these three dimensions. Scoliosis is
defined as a deformity primarily in the coronal or frontal plane
(a Cobb angle of >10� seen on an AP or PA erect spine radio-
graph). The plain radiograph is a repeatable investigation and
much of what is known regarding the natural history of scoliosis
comes from serial measurement of the Cobb angle. This is merely
a two-dimensional assessment of the deformity, but it still has its
uses. However, in order to fully understand the spinal deformity,
one must consider the axial (transverse) plane and the sagittal
Nigel W Gummerson MA FRCS(Tr&Orth) Consultant Orthopaedic Spinal
Surgeon, Leeds General Infirmary, Great George Street, Leeds, UK.
Peter A Millner BSc FRCSOrth Consultant Orthopaedic Spinal Surgeon,
Leeds General Infirmary, Great George Street, Leeds, UK.
ORTHOPAEDICS AND TRAUMA 25:6 403
(lateral) plane. Consideration of time, the fourth dimension,
requires the surgeon to judge the possible therapeutic effect or
potential damaging effects of growth on the spinal deformity.
At birth, the spine has a gentle C-shaped curve throughout its
length in the sagittal plane and is straight in the coronal plane.
The normal cervical lordosis develops as the child gains head
control and begins crawling; the lumbar lordosis begins to
appear at the time of walking. There are subtle changes in the
sagittal profile throughout growth until the normal adult pattern
is achieved. The sagittal profile is never fixed, and will continue
to change as the spine ages, becoming more kyphotic with
advancing years.
The net effect of the normal spinal sagittal profile is to posi-
tion the head and thoracic cage over the centre of the pelvis. It is
the relative positioning of head, shoulders, thorax and pelvis that
gives the normal body surface contour. Normal shape is much
harder to define than a simple Cobb angle. It is accepted that
symmetry is important, but beyond that questions of ‘normal’ or
‘attractive’ become very subjective.
Clinical assessment of scoliosis
The clinical assessment of patients presenting with scoliosis and
the subsequent radiological investigation is described in another
article in this mini-symposium.
Causes of scoliosis
Scoliosis may be structural or non-structural. A non-structural
curve will usually have no rotational element, being a pure
coronal plane deformity. A non-structural scoliosis may be due
to:
� Pelvic tilt secondary to leg length inequality
� Pain or irritation
� Hysterical scoliosis.
The key feature of non-structural scoliosis is that the curve
will spontaneously straighten when the underlying cause is
corrected or removed. In the case of pelvic tilt scoliosis, the curve
will disappear when the pelvis is leveled and this can be achieved
by sitting the patient or by equalizing any leg-length-discrepancy
with blocks. This may be done prior to radiographic examina-
tion. Pain-induced or irritant scoliosis is seen with disc prolapse
and other painful conditions, such as osteoid osteoma, typically
triggering muscle spasm (Figure 1). The scoliosis will resolve
when the underlying pathology is treated. Hysterical scoliosis is
very, very rare and should only be diagnosed once all other
possible diagnoses have been eliminated.
Structural scoliosis may be classified according to the under-
lying aetiology. The aetiology may be reasonably obvious, as it is
in congenital (15%) or neuromuscular (10%) cases. Trauma,
tumour and infection are also possible causes, but are not
frequently encountered. In most cases there is no detectable
underlying cause (idiopathic). This is the most common
aetiology, with 70% of all cases of paediatric scoliosis being of
the idiopathic type. A long list of rare conditions, including
hereditary and mesenchymal abnormalities such as neurofibro-
matosis, Marfan’s syndrome, EhlerseDanlos syndrome etc. make
up the remainder; a detailed discussion of these rare conditions is
outside the scope of this article.
� 2011 Elsevier Ltd. All rights reserved.
Figure 1 (a) Painful scoliosis. (b) Bone scan of the same patient showing
intense uptake. The underlying pathology is osteoid osteoma.
MINI-SYMPOSIUM: SPINAL DEFORMITY
Congenital scoliosis
A brief history of spinal development
The fertilized egg (zygote) divides to produce a ball of cells: the
morula. A cavity forms within this ball, now called the blastocyst
(the cavity is the blastocoele). A group of cells at one side of the
blastocoele forms the inner cell mass. The inner cell mass
(embryoblast) will go on to form the bilaminar embryo by week
two of gestation. The amniotic cavity forms dorsal to this bila-
minar disc and the yolk sac forms ventrally. By week three, the
primitive knot (also known as Hensen’s node in bird embryo-
genesis) and the primitive streak form. Gastrulation occurs, with
an ingress of cells (derived from primitive ectoderm) through the
primitive streak, to form a three-layer embryo with ectoderm,
mesoderm and endoderm. Bone Morphogenic Proteins and
Fibroblast-derived Growth Factors are important signalling
molecules during this process.
Ectoderm will go on to form the nervous system and
epidermis. The endoderm will form the epithelium of GI tract and
associated organs, the respiratory system and the urinary
bladder. The mesoderm (middle layer) goes on to form bones,
muscles, dermis, haemopoietic tissue, spleen, the renal system,
the reproductive system and much of the circulatory system.
During gastrulation the notochord forms from mesoderm.
The notochord induces changes in the overlying cells of the
ectoderm, causing them to form the neural plate, which then
develop into the neural tube.
The mesodermal cells cluster into lateral mesoderm, interme-
diate mesoderm and paraxial mesoderm. The lateral mesoderm
forms the limbs and the intermediate mesoderm differentiates into
the kidneys.
ORTHOPAEDICS AND TRAUMA 25:6 404
The paraxial mesoderm is a condensation around the neural
tube and notochord. This paraxial mesoderm segments to form
paired somites (42e44 in humans, up to 500 in some snakes).
This occurs in a time-dependent manner from cranial to caudal
and is under the control of the hairy gene. The expression of
hairy is seen to cycle over a 90-min period in the chick embryo,
acting like a molecular clock. Other fantastically named genes,
such as notch and lunatic fringe are also involved!
Under the influence of signalling molecules from either the
notochord or the neural tube, the somite will differentiate into
sclerotome and dermomyotome. The dermomyotome goes on to
form the dermis of the back and the muscles of the back and
limbs. The cells of the sclerotome migrate ventrally and dorsally
around the notochord and neural tube and give rise to the
vertebrae and ribs.
The somites will then go through a process of re-segmentation
(week 5e6). Each somite forms the inferior half and posterior
elements of the superior vertebra, the intervertebral disc and the
superior half of the vertebral body below. A fissure arises in each
somite (vonEbner’s fissure),whichwill form the intervertebral disc.
Notochord remnants within the discs become the nucleus
pulposus. Notochord within the vertebral body degenerates.
Chondrofication (appearance of three paired centres of chon-
drofication) begins at week 6. Ossification centres appear at week
8, beginning at the thoracolumbar junction and progressing
rostrally and caudally.
It is the process of somite formation and re-segmentation that
may be disrupted, leading to congenital vertebral anomalies.
Bilateral failures of formation or segmentation may have no
structural consequences. A shift of ventral fusion between the
two sides (hemimetameric shift) may lead to balanced hemi-
vertebrae, separated by a normal level, again with little structural
consequence. It is the asymmetric anomalies that will affect
spinal growth leading to progressive spinal deformity (Figure 2).
The commonest congenital deformity is congenital scoliosis.
Congenital kyphosis or lordosis may also occur dependent on the
3D configuration of the anomaly.
It is common for other developmental anomalies to cluster
with congenital spinal anomalies. Neural axis anomalies such as
Chiari malformation, diastematomyelia, syringomyelia and
tethered cord occur in around 40% of patients with congenital
scoliosis. Renal anomalies are seen in 30% of patients and
cardiac anomalies in 20%. These associated anomalies reflect the
timing of the development of these organ systems, their common
embryonic origin and the underlying genetic and intercellular
signalling pathways, which control their development.
In general, congenital scoliosis is not a hereditary problem.
The majority of patients do not have affected relatives. There are
a few families with multiple affected members. In these cases the
parents are more likely to be closely related.
Spinal growth in congenital scoliosis
Neonates are approximately 50 cm long at birth. In the first year,
the length increases by 25 cm and then by 12.5 cm in the second
year. A 2-year-old child is therefore approximately 87.5 cm tall.
Children then grow at around 6 cm per year until the pubertal
growth spurt, which peaks at approximately10 cm per year at the
age of 11e12 years for girls and approximately11 cm per year at
the age of 13e15 years for boys.
� 2011 Elsevier Ltd. All rights reserved.
a
d
c
f
b
e
Figure 2 Defects of formation and segmentation in congenital scoliosis.
(a) Semisegmented hemivertebra. (b) Unsegmented hemivertebra.
(c) Hemimetameric shift, with balanced hemivertebrae. (d) Fullysegmented hemivertebra. (e) Multiple hemivertebrae. (f ) Unilateral bar.
MINI-SYMPOSIUM: SPINAL DEFORMITY
If a deformity progresses with growth, then the most signifi-
cant period of progression will be during the first 2 years of life,
with a second at-risk period during the pubertal growth spurt.
Classification
The classification of congenital scoliosis is largely descriptive
(Table 1). Congenital anomalies are divided in to defects of
segmentation, defects of formation, mixed defects and a small
Descriptive classification of congenital scoliosis
Defects of segmentation Bilateral
Unilateral
Defects of formation Partial unilateral
Complete unilateral
Mixed anomalies
Unclassifiable anomalies
Table 1
ORTHOPAEDICS AND TRAUMA 25:6 405
group of complex anomalies that defy description. This classifi-
cation comes from the work of Winter, Moe & Eilers1 and
McMaster & Ohtsuka,2 which was based largely on plain radio-
graphs. Kawakami et al. have suggested an update to this system,
analyzing the 3D CT appearances of the deformity.3 CT will
reveal additional abnormalities in 50% of patients, over and
above those seen on the plain films.
A 3D CT analysis allows for a better understanding of the
relative (3D) position of the abnormalities, as well as providing
more information regarding fusions between levels and the
anatomy of the posterior elements around the abnormality.
Consideration of any associated rib anomalies is an important
aspect of congenital scoliosis. Multiple rib fusions may be seen in
JarchoeLevin syndrome (spondylothoracic dysostosis). This
condition causes marked a reduction in thoracic growth and
results in early death from thoracic insufficiency syndrome.
A lesser form, spondylocostal dysostosis, causes less severe rib
problems and has no appreciable effect on life expectancy.
Isolated rib abnormalities may be seen in cases that do not have
these syndromes, reflecting the common embryonic origin of the
rib and vertebral body from the sclerotome of the somite. Non-
syndromic rib anomalies are most commonly seen with unseg-
mented bars.
Specific examples of congenital vertebral anomalies are
considered below as we discuss what is known regarding the
natural history (Figure 3).
Natural history
Our knowledge of the natural history comes from the work of
Winter et al.1 and McMaster et al.2 Around 50% of all cases of
congenital scoliosis will progress by a significant degree, 25% do
not progress and the remainder progress only slightly or not at all.
The most benign form of congenital spinal anomaly is a block
vertebra. This is the result of bilateral failure of segmentation.
Block vertebrae do not cause progressive curves, but may cause
shortening of the trunk when multiple block vertebrae are
present.
An incarcerated or non-segmented hemivertebra has very
little potential for progression. A wedged vertebra will cause only
1e2� progression per year. A single semisegmented or fully
segmented vertebra will progress at 1e3.5� per year, worse at the
thoracolumbar junction. Multiple hemivertebrae will progress
more rapidly.
Block vertebra
Unsegmented bar
Wedge vertebra
Hemivertebra Incarcerated
Unsegmented
Semisegmented
Fully segmented
Unsegmented bar with
contralateral hemivertebra
� 2011 Elsevier Ltd. All rights reserved.
Figure 3 (a) Complex congenital scoliosis. Demonstrates:
� segmented hemivertebra at L3
� bony diastematomelia at L1
� multiple semisegmented hemivertebrae on the right side in the thoracic spine
� abnormalities right 3rd and 4th ribs. (b) MRI scan showing split cord and bony diastematomelia. (c) CT scan showing diastematomelia at L1.
MINI-SYMPOSIUM: SPINAL DEFORMITY
An unsegmented bar will cause progression of between 2 and
9� per year. Again this is worse at the thoracolumbar junction.
The most troublesome combination is the mixed defect of
unsegmented bar with a contralateral, fully segmented hemi-
vertebra.The thoracolumbar junction is the problematic location for
this abnormality, where it may progress at more than 10� per year,necessitating early (prophylactic) surgical treatmentwhendetected.
ORTHOPAEDICS AND TRAUMA 25:6 406
Treatment
There is a choice between continued observation and surgery in
congenital scoliosis. Neither bracing nor physiotherapy can alter
the natural history of these curves. Surgery is indicated for
progressive curves. The potential for progression can be deter-
mined by a thorough work up with CT and MRI. Associated
conditions should be actively sought and the possibility of an
� 2011 Elsevier Ltd. All rights reserved.
Figure 4 Measurement of the RVAD. The rib vertebral angle is the
difference between angle A and B.
MINI-SYMPOSIUM: SPINAL DEFORMITY
underlying syndrome considered prior to surgery. A formal
assessment of pulmonary function before intervention, as
a baseline, will guide treatment and prognosis.
The surgical options range from hemiepiphysiodoesis (short
segment anterior growth arrest over the convexity of the curve)
to more complex osteotomies such as resection of a hemivertebra
or vertebral column resection.
The choice of treatment will depend on the nature of the
abnormality and the age at presentation. Techniques such as
hemiepiphysiodoesis rely on significant growth potential in the
concavity and are of little use in the older patient.
There is little to be gained by waiting ‘to preserve growth’
with a progressive deformity. Combined anterior and posterior
fusion is often indicated in these cases. ‘Normal’ levels should be
preserved where possible, but the whole curve may need to be
instrumented to restore normal spinal balance.
Each congenital curve pattern must be assessed on its own
merits but, as a general rule, early surgical treatment should be
considered for curves with more than one hemivertebra,
a unilateral bar or a mixed defect, as these are the curves which
tend to progress.
Neuromuscular scoliosis
The clinical presentation and treatment of patients with neuro-
muscular scoliosis is described in another article in this mini-
symposium.
Idiopathic scoliosis
Idiopathic scoliosis is a structural curve in the absence of any
other underlying problem (such as a congenital anomaly,
neuromuscular disorder, connective tissue disease etc.). By
definition, the deformity is self-generating and the underlying
cause is yet to be established, although there are many theories
with regard to aetiology and some of these will be explored later
in this article. It is possible that ‘idiopathic scoliosis’ describes a
heterogeneous group of patients who have curves with a variety
of underlying causes. As yet, we do not have evidence to support
this theory.
Idiopathic scoliosis has been subdivided by a number of
authors. James described three groups: infantile, juvenile and
adolescent. Dickson proposed a strong case for division into two
groups: early and late onset, with the cut-off being the age of 5
years. The logic behind this comes from an analysis of thoracic
and lung development and the consequence of spinal deformity
on this development. It is well recognized that the patients
who present with progressive infantile curves will develop
life-shortening respiratory complications, whilst adolescent
scoliosis has little effect on physical well-being or life expectancy.
The difference between the two groups relates to the timing of
respiratory development. Alveolar numbers and thoracic volume
increase most rapidly during the first 5e8 years of life (full alve-
olar number by age 8, 30% of adult thoracic volume by age 5).
Curves that appear early will have the most deleterious effect on
both lung volume and alveolar numbers; curves appearing after
the age of 5 will have less of an effect.
It is argued that the juvenile group represents a mixture of late
presenting infantile cases and early presenting adolescent type
cases. Therefore, the description of a juvenile group is in fact
ORTHOPAEDICS AND TRAUMA 25:6 407
a description of a small and heterogeneous group. This term is of
little value for the purposes of treatment, prognosis or research.
Early onset idiopathic scoliosis (EOIS)
Classification and natural history
EOIS is rare (1% in the USA, w5% in Europe). It is typically
a left-sided curve, which develops after birth, but is not present
at birth. It is more common in boys (M:F ¼ 3:2). EOIS is
strongly associated with other conditions such as talipes
equinovarus, developmental dysplasia of the hips, torticollis
and inguinal herniae. The classification of EOIS is descriptive,
with useful discriminating features being the curve size, the rib-
vertebral-angle difference (RVAD) and the appearance of the rib
heads.
In true EOIS, 90% of cases will resolve spontaneously. Inter-
estingly and inexplicably, girls with a right sided-curve have
a much poorer prognosis than those with left-sided curves.
Progressive EOIS is associated with increased mortality and
a consequent reduction in life expectancy.
It is likely that the historical descriptions of this group of
patients included many who had an underlying cause for their
scoliosis. 22% of patients with presumed EOIS with curves less
than 20� have an underlying neural axis anomaly (i.e. they were
not truly idiopathic). In one series, eight out of 10 patients with
a neural axis anomaly required neurosurgical intervention.
For prognostic purposes it is useful to differentiate curves
according to the RVAD (rib-vertebral-angle difference). This
measurement was defined by Mehta4 and is the difference
between the right and left sides in the magnitude of the angle
measured from the long axis of the rib and a line drawn
perpendicular to end plate of the vertebra at the apex of the curve
(Figure 4). Mehta showed that if this difference in the angles was
less than 20�, then there was an 85e90% chance that the curve
would resolve spontaneously. She went on to describe a second
feature: the phase of the rib head on the convex side at the apex.
A ‘phase 1’ rib head does not overlap the vertebral body and is
associated with resolution in 84e98% of cases. A ‘phase 2’ rib
head does overlap the vertebral body and is associated with
progression in 84e97% of cases. Double curves are more likely
to progress than single curves.
� 2011 Elsevier Ltd. All rights reserved.
MINI-SYMPOSIUM: SPINAL DEFORMITY
Aetiology
It has been suggested that EOIS is the result of intrauterine
moulding; the counter to this suggestion is the fact that EOIS is
rarely seen at birth. Others argue that it is the result of ‘body
moulding’ from the positioning of the child. If the infant lies in
the lateral decubitus position a curve will develop; this is
supported by the observation of plagiocephaly in this group.
Treatment
Most spinal surgeons agree that serial casting is a reasonable
non-operative treatment option for progressive EOIS. Rigid
braces are of little use, due to the rapid growth rate of the child,
but serial plaster casts such as those popularized by Cotrel and
used to good effect by Mehta (elongation de-rotation flexion, or
EDF casts) can be moulded to control a small, progressive curve.
Large curves (greater than approximately 50� Cobb angle) are
best treated surgically. The dilemma is that early spinal fusion
will prevent thoracic growth and this in turn will lead to thoracic
insufficiency syndrome, respiratory failure and reduced life
expectancy. Therefore the goal of surgical treatment is to control
the curve, whilst maintaining growth. Many techniques have
been tried. Our favoured technique is a dual rod growing system.
Here, the curve is instrumented proximally and distally (usually
two levels at each end), but the centre of the curve is left
undisturbed. Rods are used on each side to connect the proximal
and distal instrumentation. The rods have to be lengthened every
four to 6 months to allow growth and clearly this necessitates
repeated surgical procedures. Complications such as wound
infection or rod breakage will be encountered in all of these cases
eventually, due to repeated extension of instrumentation through
the same scar. A rod with an intrinsic magnetic motor that allows
telescoping has recently entered clinical use and offers the
possibility of repeated lengthening using an external magnet in
the outpatient clinic, obviating the need for repeated surgery.
Another possible solution is to selectively inhibit growth on
the curve convexity. This technique is still somewhat experi-
mental and not widely adopted although it has been used in both
EOIS and late-onset idiopathic scoliosis (LOIS). Memory metal
(Nitinol) staples are used on the convexity of the spine to arrest
or slow growth in much the same way as staples across the
physis are used to correct deformity around the knee. Memory
metal staples undergo a change in shape at a sharply defined
temperature, being inserted ‘open’ and closing when they reach
body temperature. The problems with this technique relate to the
staples themselves and the application of the staples. Nitinol is
difficult to make and work with and contains nickel, which is
a potential carcinogen. It is difficult to be sure of the optimum
position for a staple around the physis (which is a circular
structure); misplaced staples will induce sagittal plane deformity.
Late-onset idiopathic scoliosis (LOIS)
Late-onset idiopathic scoliosis is a relatively common condition.
Small curves are more common than large curves. The preva-
lence of curves greater than 10� is 2%; for curves greater than
30�, the prevalence is 0.2e0.3%. Overall, only 6 in 10 000
children will require treatment for LOIS.
The gender ratio approaches 1:1 for curves of 10� although for
curves greater than 20�, the male/female ratio is 1:5. Small
ORTHOPAEDICS AND TRAUMA 25:6 408
curves do not present clinically. The data on small curves
originates from school screening programs.5 School screening
programs have largely been abandoned, as there is no reliable
treatment that we can offer to children with small curves that
would alter the natural history of the curve.
The development of a late onset curve is an insidious process.
It is unsurprising that small curves go unnoticed by parents, who
rarely see their teenage children undressed.
Classification
We have yet to find the ideal classification6,7 system for LOIS.
Currently, the most widely used classification is that of Lenke
et al., published in 2001. Lenke and the Harms Study Group have
provided us with a useful tool, which allows reproducible
description of LOIS curves, can guide treatment and facilitates
research. The Lenke classification is based on static erect and
supine bending radiographs. There are three component; curve
pattern, lumbar modifier and sagittal thoracic modifier
(Figure 5).
Three structural curves are identified. Thoracic curves have
an apex at T2 to the T11/12 disk, thoracolumbar curves have an
apex at T12 to L1 and lumbar curves have their apex at L1-L2
disk to L4. A curve which bends down to less than 25� does not
meet the structural criteria in this classification unless it is the
main curve or has more than 20� of local kyphosis. Identifying
the structural curves gives six groups (see figure). The next step
is to examine the position of the lumbar pedicles relative to the
central sacral vertical line (CSVL) to give the lumbar modifier. If
the pedicles of the most displaced lumbar vertebra fall either side
of the CSVL the modifier is A. If both pedicles lie to one side of
the CSVL the modifier is C. If a pedicle falls on the line or there is
uncertainty, the modifier is B. The lumbar modifier gives
a measure lumbar coronal plane deformity. The final measure is
the degree of kyphosis from T5-T12, normal (in this classifica-
tion) is 10e40�.This classification is two-dimensional and addresses both the
sagittal and the coronal plane. Work continues to find a truly 3D
classification. These classification systems do not address the
problems of which the patients complain e their cosmesis.
Aetiology
Idiopathic e arising spontaneously or from an obscure or
unknown cause.
There are many theories regarding the aetiology of LOIS, but
much remains unknown. Endocrine, neurological, muscular and
skeletal causes have all been postulated. It is more common in
tall and slim (exomorphic) females. The deformity is lordosis
with scoliosis, or lordo-scoliosis. The rotation of the curve as the
spine deforms may give the appearance of kyphosis on the
standard lateral radiograph, but a derotated view will give a more
accurate assessment. It is thought that excess anterior spinal
growth relative to posterior growth reduces the stability of the
thoracic kyphosis, which then buckles to produce a scoliosis.8
Natural history
The main driver of progression in late onset curves is remaining
growth. Indicators of remaining growth correlate with curve
progression:
� 2011 Elsevier Ltd. All rights reserved.
Risk of progression (>5�)
C Age <10 88%
C Age >15 29%
C Pre-menarche 53%
C Post-menarche 11%
C Risser grade 0 68%
C Risser grade 3e4 18%
Figure 5 The Lenke classification of late-onset idiopathic scoliosis.
(Illustration Copyright by AOSpine International, Switzerland).
MINI-SYMPOSIUM: SPINAL DEFORMITY
The Risser grade is the degree of fusion of the iliac apophysis as
seen on an AP radiograph. At grade 0 the apophysis has yet to
appear. At grade 5 it is fully fused. Grades 1e4 represent
progressive fusion of the apophysis to the iliac blade from lateral
to medial.
Menarche is a useful indicator of growth. Girls grow rapidly for
18 months before and 18 months after menarche. Formal
assessment of bone age using a radiograph including the left hand
and wrist is also useful. Even with significant remaining growth,
small curves are unlikely to progress. Data for curves of 5e19�
shows that 22% progress if the child is Risser grade 0e1, and only
1.6% progress if the child is Risser grade 2e4. Note that a curve of
5� is below the current accepted threshold for a diagnosis of
scoliosis.
ORTHOPAEDICS AND TRAUMA 25:6 409
In the long term, LOIS patients have a normal life expec-
tancy.9,10 The incidence of back pain is no higher than the
general population, but when painful episodes do occur they may
be a little more severe and last a little longer than the average.
Unexplained back pain in this group should prompt a search for
other possible causes, especially pathologies that cause painful
scoliosis, such as osteoid osteoma or spondylolysis.
There is an increased awareness of body image in this group,
and there is certainly a psychological effect of the deformity. Girls
with LOIS have a higher incidence of eating disorders and a lower
BMI (body mass-index).
LOIS does not cause significant cardiopulmonary compromise
unless the curve is very large. A curve size of 80e90� is oftenquotedas a threshold for such compromise, although in truth some degree
ofmeasurable pulmonary dysfunctionmay be seen across all curve
sizes. In contrast, severe pulmonary dysfunction is much more
common in EOIS. The important distinction is where pulmonary
dysfunction becomes clinically significant. Patients with a curve of
more than 50� may have symptoms of exertional dyspnoea.
There is little evidence that LOIS causes any significant
problems in pregnancy of childbirth. There may be difficulties in
siting an epidural in women who have had previous long
posterior fusions.
There is long term data to suggest that all curves progress
a little, even after skeletal maturity. This progression is approx-
imately 0.5� per year on average. Progression is more rapid in
� 2011 Elsevier Ltd. All rights reserved.
Figure 6 (a) and (b) Pre and postoperative PA radiographs of a Lenke 1A-late-onset idiopathic curve.
MINI-SYMPOSIUM: SPINAL DEFORMITY
larger curves (>50�). This data comes from a study where the
patients were Risser grade 4e5 at entry and one could argue that
they were not truly skeletally mature; it should be noted that the
spine continues to grow for a couple of years after growth of the
long bones has ceased.
A number of LOIS patients will represent to spinal surgeons as
adults with progression and degeneration in the curve, with
symptoms of pain and possibly nerve root compression.
Natural history e genetic studies
There is a genetic component to LOIS. Patients with LOIS will
have a first degree relative with the condition in 8e20% of cases.
The search for the genes responsible continues. It is likely that
scoliosis is the result a complex interaction between multiple
genes. A couple of candidate genes have been identified.
A genetic test (ScoliScore�) is currently being marketed. This
aims to stratify the risk of progression for patients with small
curves. If a patient is stratified to a low risk group, monitoring of
the curve may be less frequent. If a patient is in a high-risk group,
then the decision to treat the curve surgically may be made
earlier, when the curve is smaller and surgery is technically
easier. The test is only suitable for Caucasian patients aged 9e13
ORTHOPAEDICS AND TRAUMA 25:6 410
years with curves less than 25�. The test costs US$3000 and the
full scientific methodology behind the test has yet to be fully
disclosed.
Treatment
Many areas of possible treatment in LOIS remain controversial
and are still hotly debated at scientific meetings.
Physiotherapy can be helpful for those children who develop
back pain and in those who have significant coronal imbalance.
There is no good evidence that physiotherapy can alter the
underlying curve.
Spinal bracing is still a common treatment in the USA.
A spinal brace has to be worn for the majority of the time for
there to be any measurable effect. There is evidence that the
brace changes the spinal shape while the brace is worn, but no
good evidence that the brace alters the long-term natural history
of the curve being treated. There is a strong argument, which
suggests that the brace may improve the coronal plane deformity
at the expense of the sagittal plane.11 However, bracing comes
with other problems, particularly with compliance; the braces are
rigid and restricting and can be unsightly. Dynamic (elasticated)
braces have been developed, and are still being evaluated.
� 2011 Elsevier Ltd. All rights reserved.
Figure 7 (a) and (b) Pre and postoperative PA radiographs of a Lenke 3CN late-onset idiopathic curve.
MINI-SYMPOSIUM: SPINAL DEFORMITY
Surgery can change the underlying spinal shape and the
cosmetic appearance (Figures 6 and 7).12e15 A curve of less than
40� is unlikely to require surgical treatment on the grounds of
dyscosmesis. The aims of scoliosis surgery are to prevent
progression and leave a stable and well-balanced spine with the
maximum safe cosmetic correction, preserving as many motion
segments as possible. Cosmetic correction equates to level
shoulders, centralization of the trunk with balanced waist crea-
ses and correction of spinal axial rotation to reduce the rib or loin
prominence.
There is a decision to be made regarding the approach taken
and which levels to fuse.16 The majority of scoliosis surgery is
done via a posterior approach. Anterior surgery may be indicated
for larger, stiffer curves and is usually combined with posterior
fixation. Thoracotomy in scoliosis results in a statistically
significant decrease in lung function (10%).17 The clinical
significance of this is unclear.
To identify fusion levels, the simple rule followed in the
majority of cases is to identify the end vertebrae i.e. the vertebrae
with endplates that are most tilted from the horizontal plane and
fuse all structural curves from upper end-vertebra to lower end
ORTHOPAEDICS AND TRAUMA 25:6 411
vertebra. The highest level should be chosen to ensure that the
shoulders become or remain level and there should be a normal
sagittal profile at the junction from fused to unfused. The lowest
level should be selected based on the neutral and stable vertebra
on the standing film, as well as examining the correction
achieved across the disc spaces on the bending films. Choices
regarding the precise levels of fusion will be determined by the
choice of approach and the philosophy of correction.
Scoliosis surgery is a major undertaking and carries signifi-
cant risks. Spinal cord function is monitored during the proce-
dure, most commonly using somatosensory evoked potentials
(SSEPs) using posterior tibial nerve stimulation at the ankle and
detection of evoked potentials by scalp electrodes or an epidural
electrode placed in the upper thoracic or lower cervical level. In
recent years the monitoring standard has developed to include
motor evoked potentials (MEPs) in conjunction with SSEPs.
As the motor and sensory pathways travel in different spinal
tracts, multimodal monitoring gives much more information
regarding spinal cord function and is believed to increase the
safety profile for scoliosis surgery. EMG monitoring is more
frequently being used in conjunction with SSEPs (the motor and
� 2011 Elsevier Ltd. All rights reserved.
MINI-SYMPOSIUM: SPINAL DEFORMITY
sensory pathways travel in different spinal tracts and monitoring
both gives more information regarding cord function). Neural
complications occur in 1:150 cases (e.g. dural tear and nerve root
injury). Spinal cord injury occurs in approximately 1:325 cases.
In the two recent large reported series of complications, all cord
injuries recovered.
Patients should be counselled pre-operatively regarding the
degree of correction that surgery can deliver. It is unlikely that
that the correction will normalize all measurable parameters. In
some cases it is better to leave small balanced curves, than
attempt 100% correction. The important factor is overall cosm-
esis and this is the hardest outcome to measure!
Conclusion
Late-onset idiopathic scoliosis is the most commonly seen
scoliotic deformity in the paediatric population. The clinician
should keep an open mind to alternative diagnoses, even in the
‘typical’ late-onset idiopathic scoliosis patient. A
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Acknowledgement
The authors would like to thank Dr James Rankine, who provided
a number of radiographic images for use in this article.
� 2011 Elsevier Ltd. All rights reserved.