arthrogryposis multiplex congenita

definition

· arthrogryposis = curved joint

· syndrome characterised by nonprogressive congenital rigidity of multiple joints

epidemiology

· 1 in 3000 live births

aetiology and pathogenesis

· fibrosis of periarticular soft tissues during joint development

· leads to development of incomplete fibrous ankylosis

· numerous theories

· CNS abnormalities (anterior horn cell abnormality)

· environmental factors (exposure to toxin)

· oligohydramnios and limitation of foetal movement

pathology

· muscles

· replacement of muscle fibres by fibrous tissue

· spinal cord

· decreased diameter, esp. limb enlargements

· decreased number of anterior horn cells

clinical features

· normal intelligence

· wooden doll facies

· usually involves all 4 limbs

· marked limitation of joint ROM

· only few degrees movement possible

· limbs featureless

· skin tense and glossy

· no skin creases

· scant subcutaneous tissue and muscles

· may be dimpling at joints

· joint contractures with webbing

· typical deformities

· shoulders adducted and internally rotated

· elbows extended

· wrists flexed, pronated and ulnarly deviated

· hips flexed, externally rotated and abducted

· knees flexed

· scoliosis

· most common complications are

· dislocation of hip

· dislocation of patella

· talipes equinovarus

treatment

Goals

· achieve maximum function to permit

· independent mobility or ability to transfer

· self-care wrt. feeding and hygiene

Lower limbs

· plantigrade feet

· extended knees

· reduced hips

Upper limbs

· ability to bring one hand to mouth

· ability to toilet and push off when rising with other hand

Principles

Timing

· correct all lower limb deformities by age 2

· to allow walking

· address upper limb deformities later

· allows bimanual function to be established

· allows functional assessment

Type

· soft tissue procedures in young child

· full-time bracing until age 6

· night splints until skeletal maturity

· bony procedures as approach skeletal maturity

Talipes equinovarus

Infant

· rarely responds to bracing

· requires posteromedial release before walking age

· AFOs required postoperatively until skeletal maturity

· failed correction may be treated with talectomy

Older child

· triple arthrodesis is procedure of choice

Knee flexion contracture

· use nonoperative means to extend knee

· daily passive ROM

· serial casts

· night splints

· surgery for resistant cases

· posterior release (capsule +/- collaterals and cruciates)

· hamstring lengthening

· serial casting

· if fails

· supracondylar osteotomy near skeletal maturity

Hip dislocation

· treated by open reduction +/- femoral shortening and derotation osteotomy

· about age 1

· once knee flexion contracture corrected

· accept situation if reduction not achieved by age 2

· because of increased risk of unilateral failure with pelvic obliquity and scoliosis

Hip contractures

· hip flexion contracture > 30^o leads to

· increased lumbar lordosis

· knee flexion contracture

· treated by

· correction of knee contracture

· maintaining patient prone

· if fails

· subtrochanteric osteotomy near skeletal maturity

Hand

· little to offer for severe deformity

Wrist flexion

· if hand stiff, pronated flexed wrist enables forearm radial borders to appose each other to produce pincer grip

· if hand functional, FFD best treated with

· carpectomy

· wrist fusion

Shoulder internal rotation

· should be addressed before elbow corrected

· external rotation osteotomy in proximal shaft

Elbow extension

· need one elbow bent and one straight

· unilateral posterior capsulotomy and triceps lengthening

Scoliosis

· brace may be successful

· often requires segmental fusion