Talar neck fracture

Talar neck fractures extend through the thinnest cross-sectional portion of the talus, just proximal to the talar head. They represent one of the most common types of talus fracture (~30-50%), along with chip and avulsion fractures of the talus (~40-49%). These fractures are commonly associated with subtalar dislocation and/or posterior body fractures ⁴.

Pathology

Mechanism of injury

These fractures usually result from forced hyperdorsiflexion of the ankle with associated axial loading. There may be a rotational component with hindfoot supination and impact on the medial malleolus ⁶. Usually a result of high energy mechanisms. There is a 20-38% incidence of open injuries and 50% incidence of other associated injuries ⁶.

Radiographic features

Plain radiograph

• Canale view (15 degree internal rotation with 15 degree, tube angle (similar tube angle to an AP foot)) demonstrates the fracture well ⁵

CT

• useful adjunct to plain radiograph to identify subtle incongruities and assist with pre-operative planning
• undisplaced type I fractures may potentially be misclassified and the majority of talar neck fractures are not able to be classified according to the Hawkins classification ⁶
• the majority of apparent isolated talar neck fractures are actually talar body fractures with extension into the neck ⁶

Classification

Hawkins classification ¹:

• type I: undisplaced fracture
• type II: displaced fracture with subluxation or dislocation of the subtalar joint and a normal ankle joint
• type III: displaced fracture with the body of talus dislocated from both subtalar and ankle joint

Canale and Kelly ² described a rare type IV category which in addition to features described for type III there is dislocation or subluxation of the head of the talus at the talonavicular joint.

Treatment

• type I fractures: short leg cast or boot for 8 to 12 weeks, non-weight bearing for at least 6 weeks
• type II-IV fractures:
  • initial management
    • urgent closed reduction in the emergency department with CT to confirm the position and assist with pre-operative planning ⁶
  • definitive management
    • may require initial percutaneous pinning prior to definitive open reduction - internal fixation (ORIF) to allow adequate time for soft tissues to settle ⁶

Complications

• hardware complications
  • loosening
  • backing out
  • hardware or peri-hardware fracture
  • infection
• tendon entrapment or injury
• risk of avascular necrosis (AVN) increases with increasing classification type
  • type I fractures have a 0%–15% risk
  • type II fractures have a 20%–50% risk
  • type III fractures approach a 100% risk
  • type IV fractures have a 100% risk
• post-traumatic arthritis ⁶
  • subtalar (50%)
  • tibiotalar (33%)
• mal-union ⁶
  • varus mal-union (25-30%)

History and etymology

The classification of talar neck fractures was described by Dr Leland G Hawkins in 1970 ¹.

See also

• Hawkins sign