Epidemiology
Trisomy 21
1 in 800
Aetiology
Advanced maternal age
- 1/ 50 mothers > 45
- however mothers < 30 still most common
Genetics
- 95% non disjunction during meiosis
- 4% are result of translocation (Chr 21 joins to Chr 14)
- 1% are mosaics
General Features
Developmental delay
Short stature
Hypotonic
Simian crease (palmar)
Clinodactyly
- coronal deformity fifth ray
- can see at US screening
Ligament Laxity
- patellar subluxation
- planovalgus feet
Characteristic Facies
Foreshortened head
Eyes slant upwards
Prominent epicanthic folds
Ears low-set
Nose flattened
Lips parted
Macroglossia
Medical Complications
Cardiac defects (ASD VSD)
- 50%
Endocrine disorders
- hypothyroidism 15%
- DM 1%
Duodenal atresia 10%
Alzheimers 70%
Orthopaedic Issues
2 main orthopaedic problems
- atlanto-axial instability
- hip instability
Also
- scoliosis
- spondylolithesis
- SUFE
- patella dislocation
Atlantoaxial Instability
Clinically
- present in 20%
- diagnosed with dynamic views
- usually causes no problems
- occasionally have neurological defects from dislocation
Asymptomatic
Children shouldn't
- play contact sports
- dive
- perform gymnastics
Symptomatic
Children should undergo C1/2 fusion
Hip Instability
Epidemiology
- 3% incidence dislocating hip
- doesn't present at birth
- presents later in life
- can be highly unstable
Aetiology
- ligamentous laxity
- capsule thin and deficient
- increased femoral anteversion
- acetabulum shallow and anteverted / deficient posteriorly
Examination
- walk ER to maintain location
- can dislocate hip spontaneously
Investigation
- MUA arthrogram demonstrates subluxation
Treatment
- FDRO + capsular plication
- spica 6/52, abduction brace 6/12 at night
Results
- 1/4 poor results, continued instability
- difficult problem to treat