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 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 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
QUESTIONS 1 of 4 1 2 3 4 Previous Next (OBQ12.8) A child with a defect in the DTDST gene would have which of the following classic phenotypes? Review Topic QID: 4368 1 Blue sclera and bowing deformities 7% (300/4156) 2 Mental retardation and cardiac malformations 6% (232/4156) 3 Cauliflower ears and hitchhiker's thumb 63% (2630/4156) 4 Craniosynostosis and complex syndactyly 12% (518/4156) 5 Rhizomelic dwarfism and frontal bossing 9% (392/4156) ML 3 Select Answer to see Preferred Response PREFERRED RESPONSE 3 (OBQ05.29) Figure A is a photograph of a newborn's hand. Genetic testing reveals a mutation in the SLC26A2 gene on Chromosome 5q and both the parents were carriers. What condition does this child have? Review Topic QID: 66 FIGURES: A 1 Achondroplasia 5% (75/1447) 2 Osteogenesis imperfecta 1% (9/1447) 3 Hypochondroplasia 7% (96/1447) 4 Diastrophic dysplasia 83% (1197/1447) 5 Ehlers-danlos syndrome 5% (67/1447) ML 1 Select Answer to see Preferred Response PREFERRED RESPONSE 4 (OBQ09.49) What is the genetic cause of the dwarfism characterized by a hitchhikers thumb, cauliflower swelling of the ears, and severe clubfeet? Review Topic QID: 2862 1 FGFr-2 8% (248/3126) 2 FGFr-3 10% (324/3126) 3 Sulfate transport protein 69% (2156/3126) 4 CBFA-1 8% (245/3126) 5 Gs Alpha Protein 4% (138/3126) ML 2 Select Answer to see Preferred Response PREFERRED RESPONSE 3 (OBQ04.104) A 3-year-old child with short-limbed dwarfism has the clinical features shown in Figures A & B. What is the pathoanatomy of this disease? Review Topic QID: 1209 FIGURES: A B 1 Sulfate transport protein gene mutation affecting cartilage matrix formation 78% (681/874) 2 Mutation in the gene CBFA-1 affecting osteocalcin formation 5% (46/874) 3 Defect in lysosomal-storage 3% (30/874) 4 Defect in lipid-storage 1% (6/874) 5 Mutation in gene FGFR-3 resulting in growth plate growth abnormality 12% (108/874) ML 2 Select Answer to see Preferred Response PREFERRED RESPONSE 1