Hidden Ankle Fractures
By MSK Teaching Cases
Last updated on: January 15, 2024
History: Left ankle pain and swelling
Impressive soft tissue swelling along the lateral ankle. Lateral malleolus looks intact, but we better take a 2nd look on oblique just to be sure. Could still just be an ankle sprain...
Dang. Lateral malleolus cortex looks pretty good (ain't ever that easy). Great opportunity to look at the normal ankle mortise too. Surely, there is something abnormal...
See it??
CLLLLAASSIIIICCC.
We will discuss the more common malleoli fractures in another article, but here we will discuss 2 more common “hidden” fractures of the ankle, both best seen on the lateral radiograph.
Always, always, always look at the base of the 5th metatarsal on the lateral but especially so when you have lateral ankle swelling w/o a lateral mal fx.
The other point of interest is the anterior process of the calcaneus....
Even when they are obvious, anterior process fractures are subtle to the eye because they often melt into the adjacent joint lines or bony superimposition. Unfortunately, they often also have a minimum amount of tissue edema. Do your best to trace your eye along that nub of bone and make sure it is intact (blue line).
Another example:
Subtle, which explains why it's one of the most missed fractures on radiograph (check out the Radiopaedia link). But you'll have a better chance of finding it if you actively look to rule it out.
Summary: After the malleoli have been cleared, be sure to trace the base of the 5th metatarsal base and the anterior process of the calcaneus. You'll find stuff there and be the hero from time to time.
