A 45-year-old male presents with left foot pain and deformity after he inverted his foot while running on uneven pavement. You obtain foot and ankle x-rays and see the following images (Image 1. AP and lateral views of the left foot. Author’s own images).
Pearl: Subtalar dislocations are a rare injury involving the simultaneous disruption of the talo-calcaneal and talo-navicular joints which is supported by strong ligaments and a tight joint capsule . They are classified into medial, lateral, anterior, and posterior dislocations based on the displacement of the midfoot .
This usually requires a high-energy mechanism like motor vehicle crashes and falls from height. Medial subtalar dislocations are more common and can result from forceful inversion during plantarflexion whereas lateral dislocations occur with eversion .
Plain radiographs of the foot and ankle should be obtained pre- and post-reduction. It is important to obtain a post-reduction CT scan due to the prevalence of occult injuries including fractures of the fifth metatarsal, the talus, malleolus as well as osteochondral fractures [4,5].
Figure 2. Post-reduction CT image that demonstrates a fracture of the anterior process of calcaneus and interval reduction of subtalar dislocation. Author’s own images.
These patients should undergo closed reduction that often requires procedural sedation .
Pearl: Patients should be positioned with their knee flexed to 90 degrees in order to relax the gastrocnemius and soleus muscles. The reduction can then be performed with traction and countertraction, accentuating the deformity and then reversing the mechanism.
Immobilization can be achieved with the placement of a short leg AO splint and made non-weight bearing [5,6].
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