What is your diagnosis? What else do you need to make a full diagnosis?

Image 1 shows a mid-shaft oblique fibula fracture. Its location should prompt concern for an unstable ankle fracture and clue you in that the oblique/mortise (Image 2) and lateral (Image 3) x-rays will be important for diagnosis. Together, the images show a trimalleolar ankle fracture. 

Images 2 and 3. Oblique (Mortise) and Lateral x-rays. Courtesy of Ortho EM Pearls Image Bank

Image 4. Arrows showing trimalleolar fracture, including Images 1-3. Annotations by author

What classification guideline can help with ankle fractures?

The Weber ankle classification guides treatment of ankle fractures by understanding the stability of a fracture based on its location in the fibula in relation to the tibiofibular syndesmosis, which is at/just proximal to the mortise. Type A is distal at the lateral malleolus, Type B covers the area of the syndesmosis, and Type C is the more proximal fibula (see Image 5).

Image 5. Case courtesy of Dr Matt Skalski, Radiopaedia.org, rID: 35644

• Type A fractures are generally stable and are treated similar to sprains with a walking boot, weightbearing as tolerated, and outpatient sports medicine or orthopedic follow-up.

• Type B may or may not be stable, and a careful examination of the mortise and medial ankle, possibly with stress views, can assist in diagnosis. These should be non-weightbearing until they can be evaluated in clinic. 

• Type C are inherently unstable and should be splinted and set up for surgery, the timing of which will be guided by institutional protocols (inpatient vs urgently outpatient) [1]. Note that not all Type C fractures will have additional pathology on x-ray and can be purely ligamentous apart from the fibula fracture.

What physical exam findings are important in ankle examination?

The Ottawa ankle rules teach the important places to check for fracture - distal 6cm of the posterior lateral and medial malleoli, base of the 5th metatarsal, and navicular [2]. You should also palpate the areas of the commonly sprained ligaments of the lateral ankle (ATFL, CFL, PFL) as well as medial deltoid ligament. For more thorough guidance, click here and here.

• Pearl: A classic missed diagnosis is a Maisonneuve fracture at the proximal fibular head, so don’t forget to palpate there on exam. Check out last week’s article for more.

What additional imaging in the ER can assist diagnosis?

If there is concern for additional fractures or by request of orthopedics for pre-operative planning, non-contrast CT can provide additional information. These only need to be done in consultation with the surgical team and not on a routine basis.

Images 6 and 7. CT scan from original case, Courtesy of Ortho EM Pearls Image Bank

What is your disposition and management? Does orthopedics need to be consulted?

This patient will need operative fixation and should be discussed with orthopedics, though they may be able to follow up urgently outpatient depending on the institution. They should be placed in a stirrup and long posterior slab splint for stability while waiting and remain non-weightbearing. See question 2 for additional guidelines for all ankle fractures.

• Pearl: Displaced fractures can very easily be open fractures, so carefully examine the skin as this would require a more emergent consultation.

Image 8. postoperative x-ray from original case. Courtesy of Ortho EM Pearls Image Bank