Chromosomal & Teratologic Disorders

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.
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