(ii) Scoliosis in children and teenagers · 2015. 8. 21. · Congenital scoliosis A brief history of spinal development The fertilized egg (zygote) divides to produce a ball of cells:

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.

http://dx.doi.org/10.1016/j.mporth.2011.11.001

Figure 1 (a) Painful scoliosis. (b) Bone scan of the same patient showing

intense uptake. The underlying pathology is osteoid osteoma.


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.


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.



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.


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


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



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.


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.


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



Figure 4 Measurement of the RVAD. The rib vertebral angle is the

difference between angle A and B.


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


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.




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


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:



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).


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.


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



Figure 6 (a) and (b) Pre and postoperative PA radiographs of a Lenke 1A-late-onset idiopathic curve.


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


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.



Figure 7 (a) and (b) Pre and postoperative PA radiographs of a Lenke 3CN late-onset idiopathic curve.


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


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




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

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