Review Question - QID 602

The radiograph shows a lateral subtalar dislocation with an associated talonavicular dislocation as well. Dislocations of the talonavicular are often seen with subtalar dislocations and one needs a high index of suspicion in order not to miss this associated injury.

Subtalar dislocations are associated with high energy, open(25%), and irreducible (33%) fractures. Lateral subtalar dislocations are thought to result from forceful eversion of a plantar-flexed foot, with the anterior process of the calcaneus acting as a fulcrum around which the anterolateral corner of the talus pivots. The reduction maneuver involves initial traction and foot hyperpronation, followed by supination for lateral dislocations.

Saltzman and Marsh present a review article about acute hindfoot dislocations and discuss their management and long term follow up. Lateral dislocations that are irreducible are blocked most commonly by the posterior tibialis tendon. The tendons of the FHL and FDL less commonly block reduction. These dislocations often require emergent open reductions, tendon relocation, and stabilization. Medial dislocations account for 65%, and reduction is often blocked by the extensor digitorum brevis. They are thought to be more common due to the strong buttress of the lateral malleolus.