- 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:
-
cervical kyphosis
- high incidence of quadriplegia;
- 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;
Disorders of the spine in diastrophic dysplasia.
Bethem D. et al. JBJS. 62-A: 529-536, 1980
The phenotipic variability of diastrophic dysplasia.
Horton W.A. et al.
Journal of Pediatrics. 93: 609-613, 1978
Diastrophic Dwarfism.
Hollister D. W. et al.
Clin. Orthop. 114: 61-69, 1976
Lethal and non-lethal diastrophic dysplasia.
Gustavson K.H. et al.
Clinical Genetics Vol 28, 1985: 321-334.
