Down Syndrome (Trisomy 21)

• Epidemiology: Most common chromosomal disorder.
• Risk Factors: Maternal age, previous Down's child.
• General Manifestations:
  • Endocrine: Hypothyroidism, diabetes.
  • Intellectual disability.
  • Heart disease.
  • Premature aging.
  • Hypotonia.
• Orthopaedic Manifestations:
  • Ligamentous laxity.
  • Atlanto-axial instability:
    • Measure ADI, SAC, Powers ratio.
    • Perform flexion/extension views.
    • Avoid contact sports if present.
    • If symptomatic, severe, or progressive: Fuse up to occiput.
  • Scoliosis (50%).
  • Spondylolisthesis (5%).
  • Hip dislocation.
  • Planovalgus feet.
  • Metatarsus primus varus & hallux valgus.
  • Recurrent patella dislocation.
  • SUFE (screen for hypothyroidism).

Turner's Syndrome (45 XO Females)

• Features: Short stature, hypogonadism, webbed neck, cubitus and genu valgum.
• Orthopaedic Manifestations:
  • Short 4th & 5th metacarpals.
  • Scoliosis.

Noonan's Syndrome

• Features: Similar appearance to Turner's syndrome, but normal sexual organs.
• Orthopaedic Manifestation: Severe scoliosis.

Prader-Willi Syndrome

• Cause: Paternal deletion of chromosome 15.
• Features:
  • Hypotonic infant.
  • Obese adult with insatiable appetite and intellectual impairment.
  • Hypogonadism.
  • Juvenile scoliosis.

Rett Syndrome

• Features:
  • Progressive spasticity and intellectual impairment.
  • Abnormal hand movements.
  • Progresses post-birth, then stabilizes (unlike non-progressive CP).

Beckwith-Wiedemann Syndrome

• Features:
  • Organomegaly, large tongue.
  • Orthopaedic: Severe scoliosis, hemihypertrophy, cerebral palsy.
  • Hemihypertrophy associated with Wilm's tumor.

Nail-Patella Syndrome

• Genetics: Autosomal dominant with variable penetrance.
• Cardinal Features:
  • Dysplastic nails.
  • Hypoplastic/absent patellae.
  • Conical iliac horns.
  • Dysplastic radial heads.
• Complications:
  • Radial head dislocation, elbow arthritis.
  • Knee arthritis and anterior pain.
  • Autoimmune nephropathy (40% - most serious).
• Management:
  • Non-operative in most.
  • Periodic nephropathy screening.
  • Manage arthritis and pain (surgical/non-surgical).

Haematopoietic Disorders

Gaucher’s Disease

• Genetics: AR lysosomal storage disorder (Ashkenazi Jews).
• Cause: Accumulation of cerebroside (glucocerebrosidase deficiency).
• Features:
  • Hepatosplenomegaly.
  • Gaucher crisis: Bone pain.
  • Orthopaedic: Expanded metaphyses (Erlenmeyer flask distal femur), osteopenia, AVN of femoral head.

Leukaemia

• Epidemiology: Most common childhood malignancy (80% ALL).
• Features:
  • 1/3 of children report musculoskeletal pains (leg & back).
  • Bone: Periostitis, lytic areas, demineralization, metaphyseal radiolucent lines ("leukemia lines").

Thalassemia

• Genetics: Autosomal recessive.
• Orthopaedic Manifestations:
  • Bone pain, leg ulcerations.
  • Metaphyseal expansion, osteopenia, premature physeal closure.

Sickle Cell Disease

• Genetics: AR (HbSS gene mutation; 1% full sickle cell, 8% trait).
• Epidemiology: Africans and Sub-Saharan Asians.
• Manifestations:
  • Sickle cell crisis (induced by hypothermia/trauma/stress; mediated by substance P).
  • Bone infarction, extreme pain.
  • Femoral head AVN.
  • Osteomyelitis/septic arthritis: Salmonella typical, but Staph aureus most common.
  • Spine: Biconcave "fish" vertebrae.
• Management of Crises:
  • Adequate oxygenation, supportive analgesia, hydroxyurea.
  • Pre-op: Blood film screening, oxygenation, exchange transfusion.