Review Question - QID 215732

This patient has a lateral process fracture of the talus. Subtalar arthritis is found in 45% of patients with lateral process fractures, treated either non-operatively or operatively.

Lateral process fractures account for 10.4% of talus fractures. These injuries are common in snowboarders and are the result from forced dorsiflexion, axial loading, and inversion with external rotation. The lateral process articulates with posterior facet of calcaneus. These injuries are often misdiagnosed as ankle sprains. With respect to diagnosis, the lateral process fractures may be viewed on AP radiographs, however, plain radiographs may be falsely negative. Therefore, advanced imaging, such as CT scan, should be considered to aid in the diagnosis.

Vlahovich et al. review occult lateral talus process fractures in snowboarders. They report that CT imaging is a very useful tool for the assessment of these injuries. They concluded that these injuries should be suspected in snowboarders' "ankle injuries."

Young et al. review talar fracture involving the lateral or posterior process. They reported that the mechanisms of injury are typically the result of low energy trauma. They conclude that a talar body fracture and a talar neck fracture should be considered in the differential diagnosis of patients with acute and chronic ankle pain after a minor ankle injury.

Figure A is the radiograph of the ankle that demonstrates a lateral process of the talus fracture. Figure B is the corresponding CT image that more clearly depicts a lateral process fracture

Incorrect Answer:
Answer 1: The lateral process articulates with the lateral facet of calcaneus
Answer 2: Incompetence of the lateral talocalcaneal ligament is expected with excision of a 1 cm fragment
Answer 3: The posterior process consist of medial and lateral tubercle separated by a groove for FHL
Answer 5: Short leg cast immobilization is recommended for non-displaced (<2 mm) lateral process fractures, ORIF is indicated with >2 mm of displacement