summary Down Syndrome is a common congenital disorder caused by the maternal duplication of chromosome 21. Patients present with mental retardation, cardiovascular abnormalities, cervical spine instability, generalized ligamentous laxity, and recurrent joint dislocations. Diagnosis is made with chromosomal testing to assess for trisomy 21. Treatment involves a multidisciplinary approach to improve and maintain function. Surgical spinal instrumentation and fusion are indicated in patients with atlantoaxial instability and occipitocervical with progressive neurological deficits. Epidemiology Incidence most common chromosomal abnormality in the United States 1:700 live births Risk factors advanced maternal age. 1 in 250 if mother > 35 yo, 1 in 5000 if < 30 yo Etiology Genetics maternal duplication of chromosome 21, yielding a trisomy 21 chromosome 21 codes for Type VI Collagen (COL6A1, COL6A2) critical component of skeletal muscle extracellular matrix dysfunction may contribute to generalized joint laxity Associated conditions orthopaedic manifestations generalized ligamentous laxity and hypotonia short stature C1-2 instability Occipitocervical Instability delayed motor milestones (walk at 2-3 years of age) hip subluxation and dislocation patellofemoral instability and dislocation scoliosis & spondylolisthesis pes planus metatarsus primus varus SCFE medical conditions and comorbidities mental retardation cardiac disease (50%) endocrine disorders (hypothyroidism) premature aging duodenal atresia hypothyroidism Alzheimer's disease Presentation Symptoms determining degree of symptoms can be difficult Physical exam HEENT flattened facies upward slanting eyes epicanthal folds upper extremity single palmar crease (simian crease) ligamentous laxity spine scoliosis neuro mental retardation of varying degrees hearing loss Spine Conditions Atlantoaxial Instability epidemiology instability is present in 17.5% presentation may be subtle manifests as a loss or change in gait or bowel/bladder symptoms radiographs may obtain flexion-extension cervical spine radiographs (indications vary, routine screening radiographs likely not needed) flexion-extension films are needed to confirm stability prior to intubation atlantodens interval (ADI) of <5mm is normal In general, 5-10mm of motion can be considered normal in this population treatment nonoperative routine follow up with neurologic evaluation and repeat imaging indications for ADI 5-10, no neurologic findings, and imaging with >14mm space available for the cord. operative C1-2 posterior spinal fusion general indications ADI >5mm and symptomatic/myelopathic or ADI >10mm <14mm space available for the cord complications reported complication rate up to 50% sports participation asymptomatic patients with instability should avoid contact sports, diving, and gymnastic Occipitocervical Instability imaging Powers ratio used to diagnosis occipitocervical instability treatment observation with limitation of contact sports activity indications vast majority of patients posterior occipitocervical fusion indications progressive neurologic deficits and myelopathy Lumbar Spondylolithesis present in 6% of patients with Down's Syndrome Scoliosis treatment bracing for Curves 25-30 degrees spinal Fusion for curves >50 degrees complications complication rate with surgical treatment likely greater than idiopathic scoliosis Knee Conditions Patellofemoral instability radiographs lower extremity to evaluate for genu valgum sunrise or Merchant view to evaluate degree of subluxation or dislocation treatment nonoperative observation only indications in skeletally mature patient with no pain patellar stabilizing brace indicated if symptomatic operative lateral release, medial reefing, semitendiniosus tenodesis, or tibial tubercle osteotomy indications symptomatic patients osteotomy for skeletal mature patients Hip Conditions Hip instability introduction may be subluxation of dislocation caused by ligamentous laxity and muscle hypotonia occurs between 2-10 years of age occurs in 5% of patients treatment nonoperative abduction bracing indications younger child without bony changes or dislocation operative capsulorrhaphy and pelvic and femoral varus osteotomies indications symptomatic older children surgery associated with high complication rate Slipped capital femoral epiphysis introduction evaluate for concomitant hypothyroidism radiographs AP and Frog Pelvis treatment operative pinning of affected and contralateral hip Foot Conditions Pes Planus and Planovalgus introduction seen in 50% of patients treatment orthotics indications if symptomatic surgery correction indications if refractory symptoms Metatarsus primus varus Hallux valgus seen in 25% of patients