Introduction
  • A form of short-limbed dwarfism caused by failure of formation of secondary ossification center (epiphysis)
    • associated with progressive deformity
  • Epidemiology
    • more common Finland
    • rare in rest of world
  • Genetics
    • autosomal recessive
    • mutation in DTDST gene (SLC26A2) on chromosome 5 
      • encodes for sulfate transporter protein q q    
      • mutation is present in 1 in 70 Finnish citizens
      • leads to undersulfation of cartilage proteoglycan
Presentation
  • Physical exam and syndrome features
    • short stature ("twisted dwarf")
      • rhizomelic shortening
    • cleft palate (60%)
    • cauliflower ears (80%) 
    • poorly developed UE
    • hitchhikers thumb  q 
    • thoracolumbar scoliosis
    • severe cervical kyphosis 
    • hip and knee contractures
    • genu valgum
    • skewfoot (serpentine or Z foot)
      • tarsometatarsal adductus and valgus hindfoot
    • rigid clubfeet (equinocavovarus) 
Imaging
  • Radiographs
    • recommended views
      • AP and lateral of cervical spine and thoracolumbar spine
      • three joint standing lower extremity films to assess alignment
  • Ultrasound
    • can be used to make diagnosis prenatally
Treatment
  • Nonoperative
    • observation and supportive treatment
      • indications
        • most patients
      • modalities
        • cauliflower ears frequently repsond to early treatment with compressive bandages
        • cervical kyphosis frequently resolves spontaneously
  • Operative
    • occipital-cervical fusion
      • indications
        • atlantoaxial instability with neurologic symptoms
          • risk of quadriplegia is a concern
    • posterior cervical fusion
      • indications
        • cervical kyphosis that does not resolve spontaneously
    • thoracolumbar fusion
      • indications
        • kyphoscoliosis of thoracolumbar spine
        • if progressive may require ASF / PSF
    • soft tissue surgical release
      • indications
        • early foot ankle deformity after initial period of casting
        • severe joint contractures (hip and knee)
    • osteotomies for correction
      • indications
        • progressive valgus deformity of lower extremities (with dislocated patellae)
        • resistant or recurrent clubfeet
        • distal femoral extension osteotomies for fixed knee flexion contractures
        • valgus intertrochanteric osteotomies +/- acetabuloplasty for early hip subluxation
    • total joint arthroplasty
      • indications
        • end stage osteoarthritis of hips