Most attention in the literature has been devoted to fractures of the neck of the talus, whereas fractures involving processes of the talus have been relatively neglected. Consequently, questions persist regarding these fractures and misdiagnosis is common.

A woman in her 50s slipped off decking and landed with her foot in hyper planter flexion sustaining a fracture of the posterior process of the talus (fig 1). This was treated conservatively.

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Figure 1 X ray and CT scan showing fracture of the posterior process of the talus.

Fracture of the posterior process of the talus is rare and is often misdiagnosed as ankle sprain. In one case series, 17 of 20 patients with fractures were misdiagnosed with ankle sprains.1 It is most likely caused by forceful plantar flexion of the ankle producing a nutcracker-like compression of the posterior process between the posterior malleolus and the calcaneus.

An understanding of the complex anatomy of the hind foot is required. The clinician must be knowledgeable in the interpretation of plain radiographs and in the use of additional studies, such as CT scans. Failure to diagnose and initiate proper immobilisation frequently results in painful non-union and disability.