Ankle Fracture/dislocation



Common mechanisms and injury patterns of the ankle:
  • Mechanism of injury:
    • Inversion injury: Lateral ankle distraction and medial ankle compression
      • Avulsion fracture of the lateral malleolus
      • Oblique fracture of the medial malleolus
    • Eversion injury: Medial ankle distraction and lateral ankle compression
      • Avulsion fracture of medial malleolus
      • Oblique fracture of the fibula
    • External rotation injury:
      • Disruption of the tibiofibular syndesmosis, or a fibular fracture above the plafond
      • Anterior or posterior tibial fracture with separation of the distal tibia and fibula (unstable fracture)
    • Inversion and external rotation (Maisonneuve fracture):
      • Medial malleolus avulsion fracture or deltoid ligament tear
      • Disruption of the tibiofibular syndesmosis
      • Oblique fracture of the proximal fibula
    • Inversion and dorsiflexion (snowboarders’ fracture):
      • Fracture of the lateral process of the talus
    • Posterior dislocation is most common. Results from backward force on plantar flexed foot. Often with rupture of tibiofibular ligaments or lateral malleolus fracture
  • Epidemiology:
    • Most ankle fractures are malleolar
    • Common in young male and 50–70 yr old female
    • Associated with cigarette use and high BMI

Pediatric Considerations
  • Ankle fractures in children often involve the physis (growth plate):
    • May result in angular deformity from growth plate injury
    • Associated with sports requiring sudden changes in direction and obese children
    • In children <10 yr old, growth plate is weaker than epiphysis
  • Tillaux fracture: Salter–Harris type III injury of the anterolateral tibial epiphysis external rotation of the foot
  • Triplane fracture: Uncommon fracture of distal tibia with fracture lines in 3 distinct planes (coronal, transverse, sagittal)

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