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Diastrophic Dwarfism

Discussion

  • rare type of skeletal dypslasia characterized by extreme short limb dwarfism, with specific hand, foot, and ear abnormalities;
    • micromelic short-limb dwarfism, cauliflower ears, scoliosis, hitchhiker thumbs, and clubfeet.
    • these individuals have extremely short stature, with a mean adult height of 118 cm;
  • condition was originally referred to as diastrophic dwarfism," which means "crooked or twisted" but was later changed to diastrophic dysplasia in 1977;
  • epiphyseal ossification is delayed, causing flattening & irregularity;
  • may be related to a defect in structure or synthesis of type II collagen in the physis;
  • transmitted as autosomal recessive trait (lesion lies at the distal end of the 5q chromosome);
  • some patients die in infancy but most have a normal life span;
  • intelligence is normal;

Non Orthopaedic Manifestations

  • 59% of affected infants have a cleft palate;
  • peculiar ear deformity, cauliflower ear, occurs later in childhood because of a cartilage abnormality;

Orthopaedic Manifestations

C spine

hands

  • hitchhiker thumb is distinctive feature of dysplasia and is caused by shortening of 1st metacarpal & radial subluxation of 1st MP joint;

spine

  • surgical treatment is required for curves that continue to progress;

hip

  • at hip, dislocation or DJD are common sequelae of coxa vara and incongruity;
  • hip flexion contracture may be seen in most patients;

foot

  • rigid bilateral equinovarus deformities of feet are typical and are extremely resistant to cast treatment;
  • severe, rigid equinovarus deformity usually requires surgery;
  • symphalangism of the proximal interphalangeal joints of the fingers, and an abducted "hitchhiker's"  thumb are also present