A patient sustains an isolated talar neck fracture with subtalar dislocation (Hawkins type II). The most feared late complication and its radiographic predictor (the Hawkins sign) are:
- A Avascular necrosis (AVN) of the talar body — Hawkins sign (subchondral osteopenia of the talar dome at 6–8 weeks post-injury on anteroposterior ankle radiograph) indicates vascularity is PRESERVED ✓
- B Post-traumatic subtalar arthritis — predicted by persistent step-off on CT
- C Non-union of the talar neck — Hawkins sign predicts non-union
- D Tibiotalar arthritis — Hawkins sign indicates impending ankle arthritis
Explanation
Avascular necrosis of the talar body is the most feared complication of talar neck fractures because the talus is 60% cartilage with a retrograde, tenuous blood supply via the artery of the tarsal canal (from posterior tibial artery) and the dorsalis pedis — both of which are disrupted in displaced fractures. The Hawkins sign is a subchondral lucency (osteopenia) appearing on AP ankle radiograph at 6–8 weeks after fracture reduction: it represents hyperaemic bone resorption from active revascularisation, confirming that blood supply is INTACT. Absence of the Hawkins sign is the ominous finding indicating probable AVN. Hawkins sign is therefore a favourable prognostic indicator, not a marker of AVN.
Reference: Maheshwari Essential Orthopaedics, 6th ed.
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Written and medically reviewed by the StethoPrep medical team.