Diastrophic dysplasia

· syn. diastrophic dwarfism

· extreme proportionate dwarfism

epidemiology

· rare

· autosomal recessive

Pathology

· growth plate abnormality

· proliferative zone - short widely separated columns

· defect of type II collagen

clinical

· extreme short stature

Facies

· characteristic facies

· cleft palate

· cauliflower ear

Limbs

· extremely short limbs

· rhizomelic (proximal > distal)

· flexion contractures of

· elbows

· hips

· knees

Upper limb

· hitch-hiker’s thumb

· adducted hypermobile thumb

· short 1st metacarpal

· symphalangism of PIP jts of fingers

· proximal and middle phalanges fused

Lower limb

· equinovarus feet

· rigid and resistant to treatment

Spine

· thoracic kyphoscoliosis

· cervical kyphosis

radiology

Skull

· superimposed calcified pinnae

Spine

· cervical kyphosis

· may be vertebral wedging

· spina bifida common

· thoracic kyphoscoliosis

· progressive structural curve

· lumbar lordosis

· secondary to flexion contractures

Long bones

· short and broad

· flaring of metaphyses

· flattened and irregular epiphyses

· shortened ulna

· subluxed or dislocated patella

· delayed apperance of capital femoral epiphyses

· central saucer-shaped defect in capital femoral epiphysis

· hip dislocation common

complications and treatment

Neck

· quadriplegia may occur from cervical kyphosis

· if neurological compromise or instability, surgical treatment

· in form of anterior and posterior fusion

Spine

· kyphoscoliosis progresses in adolescence

· treated with early bracing while curve small

· if curve progresses, fusion indicated

Foot

· clubfoot rigid and resistant to cast treatment

· posteromedial release usually required

Hip

· progressive subluxation common

· worsened by hip and knee flexion contractures

· maintain ROM by physiotherapy and soft tissue releases

· consider femoral osteotomy