Talus fracture: longitudinal horizontal split
Supination trauma of the ankle. Low energy injury. The patient presented non-weightbearing, with pain and significant soft tissue swelling of the ankle.
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Coronal and sagittal slices (bony windows) of the talus demonstrating a longitudinal fracture of the entire length of the talus in the horizontal plane. Marked comminution medially in region of the talar body and proximal neck immediately below the medial malleolus, likewise significant comminution at the very posterior aspect of the articular dome. Relative sparing of the articular surfaces. Ankle mortise appears congruent. Maked soft tissue swelling of the lateral malleolus consistent with disruption of lateral ligamental structures.
An unusual fracture of the talus, and one not possibly described by any of the typical fracture classification systems - neither the AO classification, nor the Hawkins classification systems adequately describe this pattern of injury.
The typical mechanism of talar injury involves axial load through the tibiotalar joint, resulting in vertical/coronal fractures either through the body (with talar dome involvement) or the talar neck (+- talonavicular joint involvment). One common exception is the so-called "snowboarder's fracture" with isolated fracture of the lateral process of the talus through axial compression of the maximally dorsiflexed foot.
Severity of these typical fracture patterns, and their subsequent classification (and prognosis), is based on comminution, displacement, and dislocation of their components. Description of the longitudinal fracture pattern of the presented case is scarce in the literature, with only one case report from 1968 (Fenoglio V., Minerva Ortop, 1968) describing a comparable fracture (in Italian).
The suspected mechanism of injury in the presented case is a traumatic supination of the foot, with complete disruption of the lateral supporting ligamental structures, and subsequent medial (sub)dislocation of the talus. Impaction of the medial malleolus into the medial aspect of the talar body has functioned as a 'block-splitter' and has driven a fracture in the horizontal plane the complete length of the talus. Comminution to the posterior aspect of the talar dome suggests the foot was in maximal plantar flexion at the time of injury, and that axial compression through the tibiotalar joint has contributed to the forces splitting the talar body.
Due to the lack of articular disruption, and the likely preservation of vascularity given the longitudinal nature of the injury, the fracture in this case was managed non-operatively.