Congenital scoliosis

DEFINITION

· lateral curvature of the spine due to vertebral anomaly that cause an imbalance in longtitudinal growth of the spine

Epidemiology

· more common in girls than boys

· usually thoracic

· associated congenital abnormalities

1. spinal dysraphism (25%)

· eg. diastomatomyelia, tethered cord, fibrous dural bands, intradural lipoma

· clinically associated with hair patches, dimples

2. genitourinary (25%)

· 6% have life-threatening obstructive uropathy

3. cardiac (10%)

· all murmurs should be investigated

4. limbs

· radial club hand

· congenital amputations

· cavovarus foot

AETIOLOGY

· vertebral anomaly due to foetal insult

· at 4th-6th wk of development

CLASSIFICATION

International Spine Society

Failure of formation

· partial

· wedge vertebra (5%)

· complete

· hemivertebra (30%)

Failure of segmentation

· unilateral

· unilateral unsegmented bar (50%)

· bilateral

· block vertebra (5%)

Mixed

· too varied to classify

clinical features

Site of curve

· usually thoracic

· thoracolumbar less common

· lumbar uncommon

Associated features

Upper thoracic

· commonly produce cosmetic deformity

· due to elevation of the shoulder or head tilt

· the higher the apex the more severe the deformity

· patient usually unable to tolerate curve > 30^o

Lower thoracic

· commonly associated with secondary curve

· initially compensatory

· later becomes fixed and deteriorate more rapidly than primary curve

· usually significant rotatory component

Lumbar

· high incidence of pelvic obliquity

radiology

Plain x-ray

· lesion often difficult to interpret

· tomography useful

MRI

· should be performed before operative intervention

· to assess for vertebral anomalies

Natural history

· anomaly present at birth but may not become evident until later life

· diagnosed

· in first few years of life

· age 9-14 yrs

· associated with most rapid growth periods for the spine

· in utero

· from birth to three years

· at puberty

· not all progress

· 25% show no progression and need no treatment

· 50% progress significantly and require treatment

· progression occurs if differential growth

· if more end-plates on one side than other

Prognostic features

Age

· worst with clinical deformity in 1st yr of life

Location

· thoracolumbar curve worst

· upper thoracic curve best

Type

· unilateral segmented bar worst

· because no growth potential on that side while other side grows normally

· even worse if associated contralateral hemivertebra

· intermediate with hemivertebra or wedge vertebra

· because act as enlarging wedge

· often small with limited growth potential (incarcerated)

· worse if two unilateral hemivertebra

· block vertebra best

· bilateral growth impairment

· scoliosis if impairment asymmetrical

treatment

Nonoperative

· observation initially

· continued until skeletal maturity

· unilateral unsegmented bar probably should be operated on at the outset because of poor prognosis

· bracing only useful for compensatory curves

Operative

· for progression

Unilateral unsegmented bar

· principle is to stop growth on other side

· affected segment fused unilaterally on convex (growing) side

· hemi-epiphyseodesis performed anteriorly and posteriorly

· segment effectively converted to block vertebra

· other option is to perform osteotomy

Hemivertebra

· principle is to stop growth on affected side

· segments above and below fused unilaterally on side of hemivertebra

· hemi-epiphyseodesis performed anteriorly and posteriorly

· effectively produce contralateral unsegmented bar above and

· below

· other option is to excise hemivertebra

Growth inhibition

· each vertebra contributes 1cm to height

· potential loss calculated by

· height loss = 1/12 x (12 - age) x levels fused

· substitute 14 for boys

Neuromuscular

definition

· scoliosis associated with neuromuscular disorder

epidemiology

· occurs in 80% of patients

· incidence related to

· ambulation (ability to walk associated with lower incidence)

· age (more severe with earlier onset)

aetiology

· exact biomechanical explanation of origin and progression of curves unclear

· Euler's law states that spinal stability (or freedom from deformity is

· proportional to the condition of the end support of the spine

· inversely proportional to spinal flexibility

· inversely proportional to spinal column length squared

· thought to be associated with loss of

· muscle strength

· voluntary muscle control

· proprioception

CLASSIFICATION

Neuropathic

Upper motor neurone

· cerebral palsy

· spinocerebellar degeneration

· spinal cord tumour

· spinal cord trauma

Lower motor neurone

· poliomyelitis

· spinal muscular atrophy

· spina bifida

Myopathic

· arthrogryposis

· muscular dystrophies

· myotonia dystrophica

Characteristics

Natural history

· develops at a younger age than idiopathic scoliosis

· progression more common and more rapid than idiopathic scoliosis

· progression may occur after skeletal maturity and throughout life

Curve

· long curve

· involves more vertebrae

· C-shaped curve

· less likely to have compensatory curve

Other features

· often associated with

· pelvic obliquity

· bony deformities

· cervical involvement

· hip joint contractures

· hip dislocation (on convex side)

· lower extremity asymmetry

· respiratory problemms common

· decreased pulmonary function

· pneumonia

· atelectasis

· general state of patient usually poorer

· small and undernourished

· pressure areas

· renal impairment

TREATMENT

Aims

· prevent cardiorespiratory embarrassment

· promote mobility and ambulation

· preserve sitting balance

· improve cosmesis

Principles

· brace until age 12

· then perform fusion

· consider earlier with

· loss of control

· large curve

Observation

Indications

· small curves (< 30^o)

· observed for progression before treatment started

· large curves in markedly retarded patients

· with no loss of functional status

· loss of function may be caused by progression of the disease or increased neuromuscular spinal deformity

Orthoses

· best overall initial treatment

· rate of progression slowed

· allows further spinal growth before definitive treatment

Seating

· aims to give progressive trunk and spine control

· able to correct postural curves

· no effect on structural curves

· significantly decreases nursing and handling time

Types

· tumbleform seat

· moulded seat for infants

· 3 sizes

· commercial chairs

· pelvic support, abduction pillow, thoracic support, head support

· less effective for large individuals

· moulded sitting support orthosis (SSO)

· custom fitted support made from patient mould

· provides maximal sitting support with padded supports and belts

Thoracolumbosacral orthoses (TLSO)

· 2 piece custom moulded orthosis

· used to control and correct scoliosis or kyphosis in growing years

· preferable to Milwaukee brace in neuromuscular conditions

· easier to make and wear

· less incidence of pressure sores

· worn at day-time while child is upright

· off at night time

Surgery

Principles

Aim

· to provide solid arthrodesis of balanced spine over level pelvis

Requirements

· long fusion

· upper thoracic to lower lumbar

· solid fusion

· rigid instrumentation and massive bone grafting

Difficulties

· increased bleeding

· osteopenic bone

· fusion to pelvis

· high pseudarthrosis rate

· poor medical state

Considerations

Preoperative

· thorough general medical workup

· cardiac status

· esp. Friedreich's ataxia & Duchenne muscular dystrophy

· pulmonary status

· FVC₁, FEV, ABG's

Ambulation

· trunk movement may be important for ambulation

· fusion may eliminate ability to ambulate

· should test in brace first

· may need to limit extent of surgery

Posterior approach

· indicated for

· moderate curve

· respiratory compromise (Duchenne MD)

Staged anterior and posterior approach

· indicated for

· severe kyphosis

· severe rigid scoliosis (> 45^o)

· posterior fixation compromised (spina bifida)

· young children (to prevent crankshaft phenomenon)

Extent

· usually proximally from T3 or T4

· to prevent later subsequent deformities

· caudally

· to pelvis if >10-15^o of pelvic obliquity

· to L4 or L5 if balanced

Instrumentation

· segmental instrumentation preferable

Bone graft

· massive fusion mass over long segment requires allograft

· fusion rates comparable to autograft

Minimization of blood loss

· problem because

· extensive approach

· small circulating blood volume

· osteopaenic bone that bleeds

· addressed with

· meticulous haemostasis

· hypotensive anesthesia

· haemodilution

· cell saver

Neurological damage

· may consider use of spinal cord monitoring

· probably not justified

· usually wake-up test

· if new neurological deficit, instrumentation removed

Complications

· pulmonary complications

· most common cause of death

· neurologic injury

· esp. if correcting curves greater than 90^o

· SIADH

· careful attention to post-op fluids

· infection

· bacteraemia from remote sites (esp. UTI)

· loss of ability to ambulate

· because trunk flexion/exension lost

SPECIFIC CONDITIONS

Cerebral Palsy

· most common neuromuscular cause of scoliosis in western world

Incidence

· 10% in ambulatory patients

· 70% in total care spastic quadraplegics

Classification

· Lonstein classifies into 4 types of curves

· Group 1 curves (A&B) have level pelvis

· Group 2 curves (C&D) have pelvic obliquity

Treatment

Observation

· curves up to 30^o in the growing child

· curves up to 50^o in skeletally mature

Orthoses

· seating

· most common form of non-operative treatment instituted

· TLSO

· effective in ambulatory patient

· often only postpones arthrodesis until puberty

Surgery

· depends on mental state and functional limitations of the patient

· normal intelligence

· rules as for idiopathic scoliosis

· 40^o-45^o or greater during puberty

· mental retardation

· lean towards conservatism

· unless change in the patients functional status

· fusion to sacrum essential with pelvic obliquity

· Galverston technique

· Luque rods usually used

Spina bifida

Incidence

· >60% of patients with myelomeningocoele develop scoliosis

· the higher the level the more severe

· T12 - 100%

· L1 - 90%

· L2 - 80%

· L3 - 70%

· L4 - 60%

· L5 - 25%

· S1 - 10%

· 40% incidence of spinal dysraphism

· may cause scoliosis progression

· hydrocephalus, syringomyelia, tethered cord, Arnold Chiari

· poor prognostic signs

· early age of onset

· assymetrical motor paralysis

· presence of spasticity

· 10%- 20% have congenital scoliosis

· principles as for congenital curves

Treatment

· curve 20-40^o

· TLSO

· curve > 40^o

· anterior and posterior fusion

· must address UTI

· severe kyphosis

· problems with pressure sores or sitting balance

· kyphectomy indicated

Duchenne's muscular dystrophy

Incidence

· usually lose ability to walk during age 9-12 yrs

· due to progressive weakness

· once wheelchair-bound

· 80% develop severe collapsing scoliosis

· may progress rapidly (2^o-3^o / mth)

· progressive respiratory compromise

· due to respiratory muscle weakness and curve

· with curve > 35^o, vital capacity 40% of predicted

· scoliosis affects ability to sit

· further compromises respiratory problems

· death occurrs in late teens to early twenties

· may be delayed by curve correction

Treatment

Aim

· to prolong ambulation for as long as possible

· to correct curve before severe respiratory compromise

Bracing

· orthotic use little success

· almost all progress

· slows progression (15^o / yr cf 30^o / yr)

· buys false time

Surgery

· indications

· curve greater than 30^o

· FVC <30% predicted

· life expectancy > 2 yrs

· some say for all children as soon as stop walking

· prevents decrease in respiratory function that may preclude opportunity to correct curve

Spinal muscular atrophy

· most patients develop scolioses

· onset by age 7

· usually progressive

· consider surgical treatment when curve reaches 40^o

Friedreich's ataxia

· all have scoliosis

· 50% have hyperkyphosis

· curve patterns resemble idiopathic rather than neuromuscular

· curves appear later

· late teens or early 20's

· consider surgical treatment when curve reaches 40^o

Paraplegia and quadriplegia

· age related with risk of spinal deformity

· 90% if cord injury preadolescent

· due to

· loss of sensory, proprioceptive and motor functions supporting the spinal column

· posttraumatic angular deformities related to crush fractures

Adult scoliosis

Aetiology

Idiopathic

· most common form

· prevalence of 5%

· progresses after skeletal maturity

· usually progresses 1^o per year

· most common with

· thoracic curve > 50^o with significant rotation

· lumbar curve > 30^o esp. if right-sided, or high-riding L5

Degenerative

· arises de novo after skeletal maturity with no specific cause

· most common form in patients > age 50 yrs

· incidence is 30%

· progresses 1^o per yr

· often diagnosed incidentally after x-ray for backache

· may present with features spinal stenosis

· curve usually 15^o to 50^o

· lateral translation common

· often associated with degenerative spondylolisthesis

Clinical

Pain

· major problem

· may be due to

· degenerative facet joints

· spinal fatigue

· spinal stenosis (central or lateral recess)

· disc herniation

· disc degeneration

Cosmesis

· not often major complaint

Treatment

Nonoperative treatment

· usually unsuccessful

Technique

· analgesics and NSAIDs

· exercise programme

· weight loss

· improvement of aerobic capacity, flexibility and strength

· treatment of osteoporosis

· brace

Surgery

Indications

· pain

· progression of deformity

· neurological compromise

· respiratory compromise

Technique

· pain

· staged anterior release and fusion and posterior instrumentation and fusion

· stenosis

· posterior decompression and posterior instrumented fusion

· severe curve

· multilevel osteotomies and rib release

Complications

Persisting pain

· inadequate pain relief in up to 60%

Pulmonary problems

· occurs in 20%

· esp. with anterior procedure

Instrumentation failure

· occurs in 30%

· increased in

· osteopaenia

· fusion to sacrum

Pseudarthrosis

· occurs in 20%

· increased rate in

· osteopaenia

· fusion to sacrum

Degenerative changes

· in remaining mobile segments

· attempted solution is fusion to sacrum

· associated with higher rates of instrumentation failure and pseudarthrosis

· also causes flattening of lumbar lordosis and increased pain

Worsening deformity

· spondylolisthesis or lateral subluxation

· occurs if decompression performed without fusion

Solutions

· segmental instrumentation

· correction of rotational deformity

· limitation of levels fused, esp. lumbar