Ankle Fractures

Basics

Bones: tibia, fibula, talus
Mortise joint: tibial plafond, fibula above (forming medial and lateral malleolus) and talus below
Ligaments: syndesmotic, lateral collateral, and medial collateral (deltoid) ligaments

Two common classification systems help describe most fractures (but do not always predict fracture stability).
- Danis-Weber: based on level of the fibular fracture in relationship to the tibiotalar joint
  - Type A (30%): below ankle joint; usually stable
  - Type B (63%): at the level of the ankle joint; may be stable or unstable
  - Type C (7%): above ankle joint; usually unstable
- Lauge-Hansen (LH): based on foot position and direction of applied force relative to the tibia
  - Supination-adduction (SA)
  - Supination-external rotation (SER): most common (40–75% of fractures)
  - Pronation-abduction (PA)
  - Pronation-external rotation (PER)
Stability-based classification
- Stable
  - Isolated lateral malleolar fractures (Weber A/B) without talar shift and with negative stress test
  - Isolated nondisplaced medial malleolar fractures
- Unstable
  - Bi- or trimalleolar fractures
  - High fibular fractures (Weber C) or lateral malleolar fracture with medial injury and positive stress test
  - Lateral malleolar fracture with talar shift/tilt (bimalleolar equivalent)
  - Displaced medial malleolar fractures
Pilon fracture: tibial plafond fracture due to axial loading (unstable)
Maisonneuve fracture: fracture of proximal 1/3 of fibula associated with ankle fracture or ligament disruption (unstable); high risk of peroneal nerve injury

Pediatric Considerations

Ankle fractures are more common than sprains in children compared to adults because ligaments are stronger than physis.
Talar dome fracture: osteochondral fracture of talar dome; suspect in child with nonhealing ankle “sprain” or recurrent effusions
Tillaux fracture: isolated Salter-Harris III of distal tibia with growth plate involvement
Triplane fracture: Salter-Harris IV with fracture lines oriented in multiple planes: 2-, 3-, and 4-part variants

Ankle fractures are responsible for 9% of all adult and 5% of all pediatric fractures.
Peak incidence: females 45 to 64 years; males 8 to 15 years (average is 46 years)

Incidence
107 to 184 per 100,000 people per year

Most ankle fractures are isolated injuries, but 5% have associated fractures, usually in ipsilateral lower limb.
Ligamentous or cartilage injury (sprains)
Tibiotalar or subtalar dislocation
Other axial loading or shearing injuries (i.e., vertebral compression or pelvic fractures)

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