Talar Fractures

Anatomy

• 70% of the talus is covered with articular cartilage.
• No muscular attachments or insertions.

Blood Supply

• Three main vessels:
  • Posterior Tibial Artery (most important via artery of sinus canal).
  • Anterior Tibial Artery (dorsalis pedis).
  • Peroneal Artery (gives off sinus tarsi branch).
• Anastomotic Sling:
  • Formed beneath the talar neck by sinus canal & sinus tarsi branches.
• Regions supplied:
  • Dorsum: Anterior tibial (dorsalis pedis).
  • Head: Sinus tarsi (peroneal artery).
  • Body: Sinus canal (posterior tibial artery).
• Intraosseous Anastomoses:
  • Medial wall supplied by a branch through the deltoid ligament.

Talar Neck Fractures

• 50% of all talar fractures.
• Mechanism:
  • Axial loading & forced dorsiflexion against the anterior tibia.
  • Neck is narrower with less dense bone, making it prone to fractures.
  • Supination often causes medial malleolar fracture.

Hawkins Classification (Rate of AVN)

1. Type 1:
   • Undisplaced (<2mm).
   • AVN risk: 10-20%.
2. Type 2:
   • Displaced with subtalar subluxation/dislocation.
   • AVN risk: 20-50%.
3. Type 3:
   • Type 2 + Talotibial dislocation.
   • AVN risk: 50-90%.
4. Type 4:
   • Type 3 + Talonavicular dislocation.
   • AVN risk: 100%.

Management

• Type 1: Cast if undisplaced with angulation <5°.
• Types 2-4: ORIF.

Surgical Approaches & Considerations

• Approaches:
  • Combined anteromedial (medial to tibialis anterior) and anterolateral (lateral to EDL).
  • Posterolateral (between TA & FHL) for closed reduction with PA screws.
  • Medial malleolar osteotomy for increased exposure.
• Screw Constructs:
  • Best construct: PA screws.
  • Crossed or AP screws also effective.
  • Sink screw heads to prevent impingement.
• Comminution:
  • Plate medial side if there is medial wall comminution to prevent varus collapse.

Complications

• Varus Malunion.
• Avascular Necrosis (AVN):
  • Hawkins sign: Subchondral osteopenia at 8 weeks (indicates revascularization).
• Post-Traumatic Arthritis.
• Infection: High rate due to compound fractures.
• Salvage Treatment:
  • Arthrodesis for affected joints.
  • Address varus deformity with medial column lengthening or lateral column shortening.

Talar Body Fractures

• Less common than neck fractures.
• High energy injuries, often associated with subtalar dislocation.
• Treatment:
  • Similar to neck fractures.
  • Often intraarticular into the ankle joint.

Talar Process Fractures

• Posterior, anterior, medial, or lateral processes.
• Often mistaken for ankle sprains.
• Non-operative Treatment:
  • Unless fragment is very large and non-comminuted.

Subtalar Dislocation

• Mechanism:
  • High energy injury.
  • Inversion (medial) or eversion (lateral) dislocation.
  • Medial dislocation often associated with medial malleolus fracture.
• Treatment:
  • Open reduction often required due to soft tissue interposition.
  • Medial dislocation: Peronei, EDB, EDC interposition.
  • Lateral dislocation: Tibialis posterior interposition.

Total Talar Dislocation

• Devastating high-energy injury.
• Often open fractures with 100% AVN and arthritis rates.