What is the diagnosis?

Medial subtalar dislocation

• Pearl: Subtalar dislocation is 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 [1]. They are classified into medial, lateral, anterior and posterior dislocations based on the displacement of the midfoot [2].

What is the mechanism of injury?

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 [3].  

What physical exam findings are expected?

On examination, subtalar dislocations will present with obvious deformity of the hindfoot and is locked in supination or pronation according to the direction of dislocation [3]. 

Which imaging modalities can be used?

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.

What is the management in the ED?

These patients should undergo closed reduction that often requires procedural sedation [7]. 

• Pearl: Patients should be positioned with their knee flexed to 90 degrees in order to relax the gastrocnemius and soleus muscles. Reduction can then be performed with traction and countertraction, accentuating the deformity and then reversing the mechanism. 

Immobilization can be achieved with placement of a short leg AO splint and made non-weight bearing [5,6].

When do you consult Orthopedics?

Orthopedics should be consulted for open fractures, neurovascular compromise, and irreducible dislocations due to interposed soft-tissue blocking reduction [3,5].