Peritalar dislocation, also referred to as subtalar dislocation, involves the combined dislocation of the talocalcaneal/subtalar and talonavicular joints without the involvement of the tibiotalar and calcaneonavicular joints. It is generally associated with high-energy trauma and accounts for a small fraction of ankle dislocations (1-2%) 1,2.
Peritalar dislocations can be subdivided in medial, lateral, anterior and posterior, which refer to the position of the calcaneus and distal foot relative to the talus. Medial peritalar dislocation is most frequent (71-80%) 2. Lateral peritalar dislocation is much rarer (17%). Even less frequently occurring are anterior and posterior dislocation 2.
Pertitalar dislocations are strongly associated with high-energy trauma, such as a fall from height or road traffic accidents. However, up to 19% occurs as a sporting injury or sprain 2.
Medial peritalar dislocation results from forced inversion and is also called "basketball foot". Lateral peritalar dislocations result from forced eversion. Anterior and posterior dislocations result from forced hyperextension and hyperflexion, respectively 2.
Plain radiograph and CT
Dislocation of both talonavicular and subtalar joints with preserved tibiotalar and calcaneocuboid joints.
Note the direction of dislocation and look for associated fractures. When fractures are present it may be termed a subtalar fracture-dislocation.
CT is recommended because of a high risk of associated osseous injuries.
Treatment and prognosis
Closed reduction and subsequent immobilisation is the treatment of choice 2. When this fails or remains unstable open reduction is performed. Other indications for open reduction are open dislocation and accompanying fractures that require internal fixation 2.
Medial peritalar dislocations have a good prognosis, while lateral dislocations seem to have a worse prognosis, probably due to a higher risk of associated osseous injury 2.
Associated soft-tissue injuries may cause disruption of the vascular supply to the talus, carrying an increased risk of avascular necrosis, especially when treatment is delayed. Long-term complications include osteoarthritis of the involved joints 3.
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