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 login to view 3 more bullets operative login to view 6 more bullets sports participation login to view 1 more bullet Occipitocervical Instability imaging Powers ratio login to view 1 more bullet treatment observation with limitation of contact sports activity login to view 2 more bullets posterior occipitocervical fusion login to view 2 more bullets 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 login to view 5 more bullets operative login to view 4 more bullets Hip Conditions Hip instability introduction hip instability is very common secondary to ligamentous laxity and altered proximal femur/acetabular osteology (i.e. coxa valgum, retroverted acetabulum) may initially present with subluxation or dislocation occurs between 2-10 years of age occurs in 5% of patients treatment nonoperative login to view 3 more bullets operative login to view 4 more bullets Slipped capital femoral epiphysis introduction evaluate for concomitant hypothyroidism radiographs AP and Frog Pelvis treatment operative login to view 1 more bullet Foot Conditions Pes Planus and Planovalgus introduction seen in 50% of patients treatment orthotics login to view 2 more bullets surgery correction login to view 2 more bullets Metatarsus primus varus Hallux valgus seen in 25% of patients