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.

Mechanism

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. They are 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° internal rotation, with 15° tube angle from vertical (similar tube angle to an AP foot) better demonstrates the fracture 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 but congruent tibiotalar joint

• type III: displaced fracture with subtalar and tibiotalar joint dislocations

• type IV: displaced fracture with subtalar, tibiotalar, and talonavicular joint dislocations

  • rare pattern not in the original Hawkins classification but added by Canale and Kelly ²

Treatment and prognosis

• 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 osteonecrosis 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