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What is the diagnosis?

Posterior-Lateral Left ankle dislocation with associated Weber B Ankle Fracture

• Pearl: A posterior dislocation is the most common type of ankle dislocation [2]. Most ankle dislocations are associated with fracture. Posterior dislocations are associated with rupture of tibiofibular ligaments/lateral malleolus fractures. 

What is the mechanism of injury?

Ankle dislocations are caused by high-energy trauma mechanisms when plantar flexion of the ankle is associated with an inversion/eversion stress upon the foot. It can result in either posterior, anterior, lateral or superior dislocations [4].  In this case, the talus moved in a posterior direction in relation to the distal tibia as the force drove the foot backward [3]. The wider anterior talus wedges back, resulting in forced widening of the joint. This must be accompanied by disruption if the tibiofibular syndesmosis is involved, or fracture if the lateral malleolus is affected, which occurs most commonly when the ankle is plantar flexed. 

What physical exam findings are expected?

Obvious deformity, ankle pain, trauma. Most important emergent steps are to evaluate for neurovascular compromise and indications of an open fracture. Emergent reduction is indicated in setting of vascular compromise or skin tenting. 

Which imaging modalities can be used?

In the ED multiple imaging studies can be utilized. XR in the obvious first step. For operative planning or neurovascular compromise cross sectional imaging may be requested. 

Image 3. Plain radiograph of the reduced and splinted left ankle. Author’s own images.

What is the management in the ED?

In the ED a trauma assessment with primary and secondary survey is necessary. Once deemed stable, the patient will require multimodal pain control for reduction. Reduction is accomplished with assistance as the assistant holds under the knee and distal thigh for counter traction as the reduction is accomplished through holding the dorsum of the mid foot with one hand and the heel with the other. Re-creating the mechanism of injury by pulling longitudinally and anteriorly [1]. Once reduced, the patient will require splinting – posterior as well as stirrups/sugar tong with the foot in 90-degree flexion positioning. 

• Pearl: Hang the patient leg over the edge of the stretcher to allow for adequate room to manipulate the reduction. Flex knee to 90 degrees to relax gastrocnemius and soleus during splinting.

When do you consult Orthopedics?

Orthopedic Surgery should be consulted if pulses are not palpable after reduction. It’s necessary to document a full neurovascular exam before and after attempts at reduction. Once reduced and splinted the patient can be discharged if reduction is successful with a normal neurovascular exam and there are no concerns for compartment syndrome.