Down's Syndrome

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

 

Mental retardation / 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