Paediatric Orthopaedics Presentation2nd July 2014

IntroductionMotor neuron disorders are neurologic disorders

that selectively affect motor neuronsGenerally progressive causing increasing disabilityOf orthopaedic interest due to contractures,

subluxations and spine deformities that may occur as a consequence

Can be:AcquiredHereditaryUpper motorLower motor

Lower motor neuronThis originates from

the brainstem cranial nerve nuclei or

Anterior horn cells of the spinal cord

They directly innervate skeletal muscles

Clinical presentationMuscle paresis/paralysis

Hypotonia/atonia

Fibrillation/Fasciculation

Hyporeflexia/areflexia

Muscle atrophy

ClassificationAcquired:

PoliomyelitisTraumaIatrogenic

Hereditary:Spinal Muscular AtrophyHMSNs

Poliomyelitis Acute infectious disease caused by a neurotrophic

virus; type I,II and II poliovirus

Spread via faecal – oral route

Virus causes necrosis of anterior horn cells

Results in loss of innervation of motor units

Virtually eradicated by extensive vaccination campaigns

PathologyMost commonly affect lumbar and cervical

enlargement

Involvement from minimal injury with recovery to complete irreversible injury

Percentage of damaged motor units varies corresponding with resulting muscle weakness

Clinical course

Acute: 5 – 10 days. Pre paralytic and paralytic phases. Complete when fever absent for 48 hrs. Asymmetric paralysis

Convalescent: 16 – 18 months. Varying degree of recovery. Sensitive and insensitive phase

Chronic: after recovery of muscle power has occurred

Prognosis

Recovery most marked in the first 3 – 6 months, potential for recovery upto 18 months

Total paralysis beyond 2 months, chance of recovery poor

Muscle spasm, antagonist muscle contracture, deformity and inadequate care influence recovery

Treatment: acute phaseSupportive by paediatric team

Patient positioning in correct anatomic alignment

Frequent turning

Passive range of motion exercises

Moist heat application for muscle pain

Convalescent phaseAttainment of maximal recovery in individual

muscles

Restoration and maintenance of normal joint ROM

Prevention and correction of deformities

Serial muscle testing: monthly 1st four months, bimonthly next 8 months then quarterly upto 2 years

Attaining maximal recovery

Replacement of action of weaker muscle by stronger synergistic muscles avoided by physical therapy centred on strengthening this muscle

Avoiding fatigue of weak muscle which may retard it’s recovery

Restoration of normal joint ROM

Vigorous passive stretching exercises

Night splints to keep joint in anatomical position

Prevention and correction of deformitiesActive exercises preventing fatigue to

address muscle imbalance

Passive stretch and nigh splints to prevent contractures

Pain relief to reduce muscle pain and sensitivity

Readjustment to cater for growth

Chronic phase: physical therapy

Active hypertrophy exercises. To increase strength of synergistic muscles to obtain function

Passive stretch exercises: to prevent deformity. Augmented by night splints to maintain joint in anatomical position

Functional training: teaching to use all available muscles to perform tasks

Chronic phase: orthosesSupport:

Enable walking and functional capabilitiesPrevent deformity and malpositionProtect weak muscle form overstretching

Substitution:Augment weak muscleReplace paralysed muscles

Correction:Stretch muscle that have contracted

Lower limb orthosisPlantar flexion assist

- dosriflexion stop ankle orthosis– weak/paralysed plantar flexors and vice versa

Surgical management

Performed for correction of paralytic deformities

Examples: Tendon transfersFasciotomyCapsulotomyOsteotomyArthrodesis

Tendon transfer

Moving insertion of muscle to new site with aim of replacing paralysed muscle or to restore dynamic muscle balance

Principles (Green – 1957)Muscle to be transferred must have adequate

motor strength to carry out new function

Range of motion of muscle transferred must equal that of muscle being replaced

Gain from transferred muscle > loss from donor site

Joints on which transferred muscle is to act must have functional ROM

Smooth gliding channel must be created – use native tendon sheath, sub muscular, wide opening in septa

Preserve neurovascular supply of muscle

Ensure straight line of contraction without angles or pulleys

Reattachment with sufficient tension to allow maximal range of contraction

Post operative rehabilitationSupport joint in overcorrected position until

full function achieved

Preoperative training to localise contraction of muscle to be transferred

Training of patient to use previously localised muscle to perform new movement

Incorporation of transfer into new functional pattern

ExamplesIlipsoas or external oblique transfer to GT in hip

abductor paralysis

Erector spinae or iliotibial band transfer to GT for G max paralysis

Anterior transfer of peroneus longus in dorsiflexor paralysis

Semitendinosus and biceps femoris transfer to patella in quadriceps paralysis

FasciotomyIliotibial band

contracture contributes to multiple lower limb deformities

Flexion, abduction, external rotation contracture of the hip

Flexion and valgus deformity of the knee joint with external torsion of tibia upto posterolateral subluxation

Pelvic obliquity

Lumbar scoliosis

Subluxation of contralateral hip

Exaggerated lumbar lordosis – bilateral flexion contractures

FasciotomyInitial conservative management

Ober’s fasciotomy – proximal lateral incision with release of fascia over the sartorius, rectus femoris, tensor fasciae lata, and gluteus medius and minimusSection of lateral intermuscular septum and iliotibial

band upto greater trochanter

Yount procedure – excision of segment of iliotibial band and lateral intermuscular septum in distal thigh

May be combined with fractional hamstring lengthening to correct the tibial version

Post operative care

Bilateral long leg cast

Suspension traction

Passive extension, adduction and internal rotation exercises

For 3 weeks

Paralytic hip dislocationMuscle imbalance – weak abductors, normal

flexors and adductorsProgressive coxa valgus deformity upto neck

shaft angle of 180 degreesExcessive anteversionCapsular laxitySubluxation then dislocationAcetabular dysplasia late

Surgical managementTendon transfers to address muscle imbalance

Indicated at 4 – 5 years of age with coxa valga < 150o

Coxa valga > 1500, then a varization osteotomy performed with tendon transfer later

Varization osteotomy – intertrochanteric oblique osteotomy to correct coxa valga and excessive anteversion

Osteotomy and arthrodesisSupracondylar osteotomy for fixed flexion

deformity of knee

Dome osteotomies of proximal tibia for genu recarvatum

Knee arthrodesis for flail knee

Hip athrodesis

ShoulderDeltoid paralysis managed with transfer of

trapezius to proximal humerus

Supraspinatus – levator scapulae transfer

Infraspinatus – latissmus dorsi

Subscapularis – upper 2 digitations of serratus anterior

Trapezius transfer for deltoid paralysis

Serratus anterior transfer for subscapularis paralysis

Levator scapulae transfer for supraspinatus paralysis

Shoulder arthrodesis

Indicated in paralytic subluxation/dislocation and extensive paralysis of the scapulohumeral muscles

Optimum position – 50o abduction, 20o flexion, 25o internal rotation

Scapulo-thoracic motion compensates to position hand in space for function

Elbow flexor paralysis

Morbidity high due to inability to lift hand to face, trunk

Steindler flexorplasty

Pectoralis major transfer

Anterior transfer of triceps brachii

Steindler’s flexorplasty

Brooks and Seddon

Clark

Anterior transfer of triceps brachii

Supination contracture of forearmParalysed forearm flexors with normal biceps

Progressive supination contracture due to interosseous membrane contraction and radial bowing

Radial corrective osteotomy performed to correct

Transfer of insertion of biceps to radial aspect of radius (pronator)

Spinal muscular atrophyHereditary disease characterised by

degeneration of anterior horn cells of the spinal cord

Progressive hypotonia

Lower limb > upper limbs

Proximal > distal muscles

1:15,000 – 20,000 live births

PathogenesisAutosomal recessive in chromosome 5q

Neuronal Apoptosis Inhibitory protein (NAIP) abnormal in 67% of patients

Survival Motor Neuron (SMA) abnormal in 98% of patients

Leads to unregulated apoptosis of α motor neurons

1st trimester molecular genetic technology diagnosis possible

*Type I – acute infantile/Werdnig-Hoffmann SMAOnset between 0 – 6 months

Floppy and inactive, frog leg posture, unable to lift head, fingers and toes active

Tongue fasciculation characteristic

Progressive course, usually death by 2 years due to respiratory failure

*Byers and Banker classification

Type II – chronic infantileOnset 6 – 12 months

Achieve head control, 75% sitting. Wheelchair ambulators

Tongue fasciculation and upper limb tremors

Patella areflexia, biceps and triceps reflex may be present

Survival upto 5th decade

Type II - Kugelberg-WelanderOnset 2 – 15 years

Proximal muscle weakness – difficulty climbing stairs, trendelenburg gait, lumbar hyperlordosis

Ambulant upto adolescence, wheelchair bound as adults

Normal lifespan

Orthopaedic complications

Contractures

Hip subluxation/dislocation

Scoliosis

ContracturesHip and knee flexion contractures in non

ambulant patients

Gentle passive stretch exercises to prevent and treat

Surgical releases of dubious value in non ambulant child and frequently recur

Orthoses to prevent equinus and cavovarus foot deformities

Hip subluxation/dislocationProximal muscle weakness – coxa valga –

subluxation – dislocation

Bilateral dislocation – lumbar hyperlordosis

Unilateral dislocation – pelvic obliquity – pressure sores – aggravate scoliosis

Passive stretch exercises to prevent, derotation osteotomies to reduce the hip

Poor results of surgical procedures reported

ScoliosisUniversal in non ambulatory patients, prevalent in

type III

Predominance of thoracolumbar curves

Typically more flexible but progress rapidly

Orthoses assist sitting posture but do not retard progression

Surgical management – posterior fusion and segmental instrumentation

Herditary Motor and Sensory NeuropathiesGroup of hereditary neuropathies

Characteristics:Predominant motor involvementAutosomal dominantSlowly progressiveSymmetric

Charcot –Marie – Tooth (CMT) disease most common

Has six other types

CMTMost common heritable neuropathy. 1:2500 – 5000

Multiple subtypes

Defects in genes that regulate myelin sheath formation

Lead to demyelination and axonal degeneration

Onset variable but most common in 2nd decade

Clinical featuresSymmetric distal muscle atrophy

Areflexia proceeding proximally

Palpable enlargement of peripheral nerves

More involvement of peroneal muscles as opposed to tibial muscles

Leads to toe, midfoot and ankle deformities

Sensory loss variable

Orthopaedic manifestationsPes cavovarus:Increased

longitudinal arch due to intrinsic muscle atrophy and fibrosis

Imbalance between tibialis posterior and anterior puts hind foot in varus

Meary’s angle between longitudinal axis of talus and 1st metatarsal

On standing lateral radiograph

Normal 0 – 5o

Average 18o in CMT

ManagementSoft tissue releases – capsulotomies and

plantar fascia release

Muscle transfers – posterior tibial to dorsum

Proximal metatarsal osteotomies to correct forefoot plantar flexion

Triple arthrodesis when deformity fixed

Orthopaedic manifestations

Hip subluxation/dislocation

Scoliosis

Managed as for the previous muscle paralysis