Presentation
Motor vehicle accident.
Patient Data
Comminuted fracture of the talar neck and sustentaculum tali.
Two cannulated, headless, fully threaded, variably pitched, tapered compression screws transfix the talar neck.
Hawkins sign (subchondral lucency at the talar dome) reflects disuse osteopenia and is an expected finding that should be sought.
In this case, there is a partial Hawkin sign at the talar dome superolaterally. There appears to be subchondral sclerosis superomedially (absence of Hawkins sign) suspicious of devascularisation.
Subchondral sclerosis at the superomedial talar dome is now more obvious due to progressive demineralization around the region of devascularisation.
In addition, there is now subtle collapse of the articular surface on the lateral projection, indicating avascular necrosis.
Geographic subchondral signal abnormality at the talar dome is consistent with avascular necrosis.
Case Discussion
The dominant blood supply of the talus is via the artery of the tarsal canal (branch of the posterior tibial artery), which supplies most of the talar body. The deltoid branch of the PTA supplies part of the medial talar body.
The talar head and neck are supplied by the anterior tibial artery, as well as the artery of the tarsal sinus (branch of a perforating peroneal artery).
Fractures through the tarsal neck may disrupt these vessels, particularly if displaced. Absence of Hawkins sign raises the suspicion of devascularisation and subsequent development of avascular necrosis.
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