What is the diagnosis?

Lateral Talar Process Fracture (AKA Snowboarder’s Fracture)

Image 2. Annotated image from above with arrow indication location of the finding. 

What is the mechanism of injury?

Typically the result of a high-energy impact, lateral talar process fractures are classically thought to occur during axial load with forced dorsiflexion and inversion.  However, cadaveric studies suggest eversion and external rotation mechanisms may also play an important role [1].

• Pearl: Prior to snowboarding’s rise in popularity, these fractures were rare and usually associated with motor vehicle accidents or falls from height. Studies now suggest lateral talar process fractures account for 15% of snowboarding ankle injuries, and 2.3% to 6.3% of all snowboarding injuries [2,3].

What physical exam findings are expected?

On examination, patients typically present with painful range of motion and localized tenderness, edema and ecchymosis near the tip of the lateral malleolus [3].

•  Pearl: Clinically, up to 40% to 50% of lateral process fractures can be missed due to similar presentation as ankle sprains and indeterminate radiographic features [2,3].

What imaging modalities can be used?

Plain radiographs of the ankle should be obtained including anterior-posterior, lateral and mortise views. CT is considered the gold standard if radiographs are indeterminate and suspicion remains high based on the mechanism of injury and clinical presentation [3,6].  

Image 3. Coronal Bone Window Ankle CT demonstrating displaced lateral talar process fracture. Case Courtesy of Dr. Matt A. Morgan, Radiopaedia.org, rID: 31923

What is the management in the ED?

Initial management consists of immobilization in a posterior ankle splint. Crutches should be provided and non-weight bearing instructions given.

When do you consult Orthopedics?

Orthopedic surgery generally does not need to be consulted from the ED for isolated lateral talar process fractures. However, timely follow-up is important to direct management in order to prevent long-term complications. A clear consensus on optimal management is not defined in the literature and each case should be followed by an orthopedic specialist. Factors influencing treatment decisions include size, location, number and displacement of fracture fragments, as well as the degree of articular involvement and subtalar joint instability [4,5].