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.
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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 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 and prognosis
type I fractures: short leg cast or boot for 8 to 12 weeks, non-weight bearing for at least 6 weeks
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type II-IV fractures:
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initial management
urgent closed reduction in the emergency department with CT to confirm the position and assist with pre-operative planning 6
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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
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Complications
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hardware complications
loosening
backing out
hardware or peri-hardware fracture
infection
tendon entrapment or injury
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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
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post-traumatic arthritis 6
subtalar (50%)
tibiotalar (33%)
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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.