Review Question - QID 217340

This patient has a lateral subtalar joint dislocation. The posterior tibialis tendon is the most common structure preventing successful closed reduction.

Subtalar dislocations are hindfoot dislocations that result from high-energy trauma. The diagnosis is made clinically and confirmed with orthogonal radiographs of the foot. A lateral subtalar dislocation has been associated with fractures of the cuboid, anterior calcaneus, lateral process of talus, and the fibula. Treatment is a trial of closed reduction but may require open reduction given the several anatomic blocks to reduction. Blocks to a successful closed reduction of the lateral subtalar dislocation include medial-sided structures such as the posterior tibialis tendon (most common), flexor hallucis longus, and flexor digitorum longus.

Jungbluth et al. reviewed the functional and subjective results of a cohort of patients with subtalar dislocations. They reported no difference between the results of the medial and lateral subtalar dislocations. They concluded that the intermediate-term results for a subtalar dislocation without an associated osseous injury are good, and the direction of the dislocation does not appear to make a difference with regard to clinical or radiographic outcome.

Veltman et al. reviewed lateral subtalar dislocation. They reported that known complications following these injuries include avascular necrosis of the talus, infection, posttraumatic osteoarthritis requiring arthrodesis and chronic subtalar instability. They noted that negative prognostic factors include lateral and complicated dislocations, total talar extrusions, and associated fractures. They concluded that in cases of uncomplicated lateral subtalar joint dislocation, excellent functional outcomes after closed reduction and immobilization can be expected.

Illustration A shows a posterior tibialis tendon preventing successful reduction of a lateral subtalar joint dislocation. Illustration B is the radiograph of the ankle demonstrating a medial subtalar dislocation.

Incorrect Answers:
Answer 1: The CFL is a laterally based structure and is very unlikely to impede closed reduction of a lateral subtalar joint dislocation
Answers 2,3,5: Extensor digitorum brevis, peroneal tendons, and the talonavicular joint capsule are common blocks to the closed reduction of a MEDIAL subtalar joint dislocation