DIASTROPHIC DYSPLASIA

TIMOTHY P DOMER, D.O., Orthopaedic Resident

WILLIAM MACKENZIE, M.D., Orthopaedic Attending

March 19, 1996

CLINICAL CASE PRESENTATION

ORTHOPAEDIC DEPARTMENT

THE ALFRED I. DUPONT INSTITUTE

WILMINGTON, DELAWARE

CASE HISTORY:

A 9-year-old female was originally evaluated in early infancy for disproportionate short stature. The disproportionate stature was of the short limb type. The head had normal configuration. There was a normal distribution of the hair. The ears were thickened and inflamed. Epicanthic folds were not present. The nose was broad at the root as well as in the mid-bridge. There was clefting of the first part of the palate. The neck had a normal ROM and the nuchal hairline was not low set. There were no heart defects on auscultation. The nails appeared normal. The thumbs bilaterally were in an abducted position. There were bilateral hip and knee flexion contractures. The feet demonstrated a rigid equinus position. She presented at 13-months with an unstable kyphosis of the cervical spine that required posterior spinal fusion from C2 to C7. At 5-years of age she required posterior spinal fusion from T2 to T7 with instrumentation for progressive thoracic scoliosis and bilateral distal tibial osteotomies for equinus contractures of the ankles. At her most recent follow-up at age 9, she presented with increasing hip and knee flexion contractures that altered her gait, the equinus contractures of her ankles had returned and were very rigid. She underwent extension osteotomies of the proximal and distal femurs and supramalleolar osteotomies to correct the equinus position of the ankles.

Diastrophic Dysplasia

DISCUSSION:

• a rare type of skeletal dysplasia characterized by extreme short-limb dwarfism
• typically have severe spinal deformities with characteristic hand, foot, and ear abnormalities
• transmitted as an autosomal recessive trait, so that parents that conceive a child with the disorder will have a 25% chance of having another child with the disorder with each subsequent pregnancy

CLINICAL FEATURES:

• extreme short stature, adult height ranges from 34 to 48 inches
• characteristic facies with narrow root and broad mid-nose, square jaw, prominent area around the mouth, long and full face with broad forehead
• abnormalities of the palate are 50% and include complete, partial or submucous clefts, bifid uvula, or double uvula with a median longitudinal ridge
• initially is swelling of the ears with calcification which later develops into a 'cauliflower' ear deformity in 80% of the cases
• there is rhizomelic shortening of the limbs
• the hallmark hand deformity is the abducted position of the thumb created by the shortened first metacarpal and termed the 'hitchhiker thumb'
• the fingers are short and broad with the presence of symphalangism
• Kyphosis and scoliosis may occur in the spine, with severe cervical kyphosis having the potential to cause neurologic problems
• the feet demonstrate rigid bilateral equinovarus deformities that are extremely resistant to casting
• have normal intelligence

RADIOGRAPHIC FEATURES:

• vertebral bodies show minimal irregularities
• progressive kyphoscoliosis may eventually cause wedging of the vertebral body
• there is an 80% occurrence of scoliosis, kyphosis, or kyphoscoliosis of the thoracic or thoracolumbar spines
• increased lumbar lordosis
• interpedicular distance may narrow at the 4th or 5th lumbar levels
• cervical kyphosis is common, with atlantoaxial instability extremely rare
• the bones are short, broad and with flared metaphyses
• epiphysis is delayed and irregular and become distorted
• epiphyseal- metaphseal regions are expanded
• the bones of the feet and hands are broad
• hip dislocation or osteoarthritis secondary to joint incongruity is common

TREATMENT OPTIONS:

Cervical kyphosis

• no instability in a neurologically normal child-- observation or bracing
• progression of the kyphosis-- bracing ( Milwaukee brace )
• no improvement with bracing or neurologic compromise present
1. without neurologic involvement-- posterior spinal fusion with halo-vest immobilization
2. with neurologic involvement-- anterior decompression and fusion with posterior spinal fusion

Thoracolumbar spinal deformities

• bracing is recommrnended early with Milwaukee bracing, although curve progression is common
• kyphosis greater than 50 degrees may require anterior fusion in conjunction with posterior fusion

Foot deformities

• may have variable hindfoot and forefoot abnormalities
• are usually very rigid and resistant to cast treatment
• plantigrade position of the foot may be obtained by talectomy or supramalleolar osteotomy

Hip deformity

• goal is to obtain functional ROM at the hip and knee, which may require extensive soft tissue releases
• osteotomies to correct severe contractures to improve walking ability
• total hip arthroplasty for severe hip dysplasia

REFERENCES:

1. Herring, J.A. The spinal disorders in diastrophic dwarfism. J Bone Joint Surg, 60-A:177, 1978.
2. Peltonen, J.I., Hoikka, V., Poussa, M., Paavilainen,T., Kaitilia, I. Cementless hip arthroplasty in diastrophic dysplasia. J Arthroplasty, vol. 7 suppl.: 369, 1992.
3. Hollister, D.W., Lachman, R.S. Diastrophic dwarfism. Clin Orthop 114:61, 1976.
4. Scott, C.I. Dysplasias of bone and soft tissue. In the Ciba collection of medical illustrations, vol.8, 1990.
5. Bassett, G.S., Scott, C.I. The osteochonrodysplasias. In Lovell and Winters Pediatric Orthopaedics, 3rd ed., J.B. Lippincott Co., 1990.