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Introduction
  • Epidemiology
    • most common fracture of talus ( 50%)
  • Mechanism
    • a high-energy injury
    • is forced dorsiflexion with axial load
  • Associated conditions
    • ipsilateral lower extremity fractures common
Anatomy
  • Articulation 
    • inferior surface articulates with posterior facet of calcaneus
    • talar head articulates with
      • navicular bone
      • sustenaculum tali
    • lateral process articulates with
      • posterior facet of calcaneus
      • lateral malleolus of fibula
    • posterior process consist of medial and lateral tubercles separated by groove for FHL
  • Blood supply
    • talar neck supplied by three sources 
      • posterior tibial artery
        • via artery of tarsal canal (dominant supply)
          • supplies majority of talar body
        • deltoid branch of posterior tibial artery
          • supplies medial portion of talar body
          • may be only remaining blood supply with a displaced fracture 
      • anterior tibial artery
        • supplies head and neck
      • perforating peroneal artery via artery of tarsal sinus
        • supplies head and neck
Classification

Hawkins Classification
Type Description AVN Images
Hawkins I
Nondisplaced
0-13% AVN
Hawkins II Subtalar dislocation 20-50%
Hawkins III
Subtalar and tibiotalar dislocation
20-100%
Hawkins IV
Subtalar, tibiotalar, and talonavicular dislocation
70-100%
 
Imaging
  • Radiographs
    • recommended views
      • AP and lateral
      • Canale View
        • optimal view of talar neck
        • technique is maximum equinus, 15 degrees pronated, Xray 75 degrees cephalad from horizontal 
  • CT scan 
    • best study to determine degree of displacement, comminution and articular congruity
    • CT scan also will assess for ipsilateral foot injuries (up to 89% incidence) 
Treatment
  • Nonoperative 
    • emergent reduction in ER
      • indications
        • all cases require emergent closed reduction in ER
    • short leg cast for 8-12 weeks (NWB for first 6 weeks)
      • indications
        • nondisplaced fractures (Hawkins I)
      • CT to confirm nondisplaced without articular stepoff
  • Operative
    • open reduction and internal fixation
      • indications
        • all displaced fractures (Hawkins II-IV) 
      • techniques
        • extruded talus should be replaced and treated with ORIF 
      • complications  
        • post-traumatic arthritis
        • mal-union
        • non-union
        • infection
        • wound dehiscence
Techniques
  • ORIF
    • approach
      • two approaches recommended
        • visualize medial and lateral neck to assess reduction
        • typical areas of comminution are dorsal and medial
      • anteromedial
        • between tibialis anterior and posterior tibialis
        • preserve soft tissue attachments, especially deep deltoid ligament (blood supply)
        • medial malleolar osteotomy to preserve deltoid ligament
      •  anterolateral 
        • between tibia and fibula proximally, in line with 4th ray
        • elevate extensor digitorum brevis and remove debris from subtalar joint
    • technique
      • anatomic reduction essential
      • variety of implants used including mini and small fragment screws, cannulated screws and mini fragment plates
      • medial and lateral lag screws may be used in simple fracture patterns 
      • consider mini fragment plates in comminuted fractures to buttress against varus collapse   
    • postoperative
      • non-weight-bearing for 10-12 weeks
Complications
  • Osteonecrosis
    • 31% overall (including all subtypes)
    • radiographs
      • hawkins sign 
        • subchondral lucency best seen on mortise Xray at 6-8 weeks  
        • indicates intact vascularity with resorption of subchondral bone 
      • associated with talar neck comminution and open fractures
  • Posttraumatic arthritis
    • subtalar arthritis (50%) is the most common complication  _
    • tibiotalar arthritis (33%)
  • Varus malunion (25-30%)
    • can be prevented by anatomic reduction
    • treatment includes medial opening wedge osteotomy of talar neck 
    • leads to  
      • decreased subtalar eversion
        • decreased motion with locked midfoot and hindfoot
      • weight bearing on the lateral border of the foot
 

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