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What is the diagnosis?

Incomplete oblique fracture through the distal metaphysis of right fibula and incomplete posterior tibial malleolus fracture. 

• Pearl: When evaluating X-rays, always be sure to evaluate the entire image. The posterior tibial malleolus (posterior lip of the tibia) is often overlooked when evaluating ankle fractures and can be seen in up to 44% of all ankle fractures [1].

Image 2. Labeled internal oblique and lateral  X-ray outlining fracture lines. Author’s own images. 

What additional imaging should be obtained?

Once an ankle fracture is identified on X-ray, determining ankle joint stability should be evaluated. There should be a high degree of suspicion for an unstable ankle fracture if any of these are present: >1 malleoli involved, displaced fractures (>2mm), associated ligamentous injuries with laxity on exam [2].

Initial evaluation of stability on radiographs starts with assessing the mortise view for any displacement of the talus (there should be equal distance between the lateral malleolus, distal tibia, and medial malleolus) [2].

Gravity or manual stress mortise radiographs (Image 3) can be helpful in further assessing for instability if there is high suspicion and initial mortise view is inconsistent [2].

• Pearl: If initial X-rays reveal a medial malleolus ankle fracture or widening of the medial ankle joint WITHOUT an associated lateral malleolus fracture, further imaging of the entire fibula should be done to evaluate for a proximal fibula fracture (Maisonneuve Fracture - Image 4). 

Image 3. Stress view of ankle showing medial clear space widening. Author’s own images. 

Image 4. X-ray images of the proximal tib/fib and mortise view of ankle. Case courtesy of Stefan Tigges, radiopaedia.org. From the case rID: 188655

What soft tissue structures are you concerned about?

Displaced malleolar fractures are often accompanied by a ligamentous injury on the opposite side of the ankle, leading to unstable fractures. [2] If an unstable ankle fracture is identified, these structures are often compromised : 

What is the initial management? When to consult orthopedics?

Ensure no vascular/neurologic compromise or open fractures. If either present, emergent ortho consultation is required.

Stable isolated non-displaced lateral malleolar fractures 

• RICE

• splinted at 90 degrees with lower extremity splint (posterior splint or sugar tong splint) for 24-48 hours

Any unstable fracture should be consulted with orthopedics [2]

• Intraarticular fractures

• Bimalleolar/Trimalleolar fractures

• Posterior malleolar fractures with >25% articular involvement or >2mm displacement 

Disposition is typically to home with NWB and a splint in place. Even if surgical fixation is planned, this is typically delayed by several days to allow for swelling to decrease. 

What are complications to watch out for?

• Non-union

• Traumatic arthritis

• Complex regional pain syndrome