Describe Fracture of the Neck of the Talus in detail.
Definition & Importance
A fracture of the neck of the talus results from a violent dorsiflexion force (classically the ‘aviator's astragalus’ from the rudder pedal in a crash; now more often an RTA or fall). Like the femoral head and scaphoid, the talus has a tenuous, largely retrograde blood supply and no muscle attachments, so displaced fractures carry a high risk of avascular necrosis of the body.
Clinical Features & Investigations
There is pain, swelling and inability to bear weight, with obvious deformity in displaced fracture-dislocations and, frequently, tented or threatened skin that may progress to necrosis. AP, lateral and Canale-view radiographs demonstrate the neck fracture; the Canale view best profiles the talar neck for reduction. CT defines comminution and any associated body or process fractures and confirms joint congruity.
| Hawkins type | Displacement | AVN risk |
|---|---|---|
| I | Undisplaced neck fracture | Low (~10%) |
| II | Subtalar joint subluxation/dislocation | Moderate (~40%) |
| III | Subtalar + ankle joint dislocation | High (~90%) |
| IV | III + talonavicular dislocation | Very high |
CLINICAL PEARL
The Hawkins sign — a subchondral radiolucent band in the talar dome at 6–8 weeks — indicates preserved vascularity (bone resorption requires blood flow) and is a good prognostic sign; its absence suggests AVN.
Management
Undisplaced (Hawkins I) fractures are treated in a non-weight-bearing cast. Displaced fractures (II–IV) are an emergency requiring urgent reduction (to relieve pressure on skin and vessels) followed by open reduction and internal fixation with screws to restore anatomy and maximise the chance of union and revascularisation. Prolonged non-weight-bearing follows.
DANGER / REMEMBER
A displaced talar neck fracture-dislocation is a surgical emergency — delayed reduction increases skin necrosis and the already high risk of avascular necrosis.
Hawkins sign (subchondral lucency) indicates preserved vascularity.
KEY POINT
Key points TO remember
- Dorsiflexion injury; talus has a tenuous retrograde blood supply → high AVN risk.
- Hawkins I–IV: rising displacement = rising AVN risk (I ~10% to III ~90%).
- Hawkins sign (subchondral lucency at 6–8 wk) indicates preserved vascularity.
- Undisplaced → NWB cast; displaced → emergency reduction + ORIF.
EXAM TIP
Sources: Maheshwari's Essential Orthopaedics; Apley & Solomon's System of Orthopaedics and Trauma; AO Principles of Fracture Management.
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