Isolated Posterior Malleolus Fracture (Paratrooper)

History: Swelling, Twisting Injury (recent on the left, prior from 2018 on right)

Lateral predominant soft tissue swelling, significant and new from prior.  We got some smoke but I'm not seeing the fire yet...

Same. Though those tricky lateral malleolus fractures can be subtle on AP/oblique and then seen through the tib on the lateral. 

¯\_(ツ)_/¯ 

Oh, nice.  We have an accompanying 2 view tib fib.  Even though it's taken the same day, just within minutes of the ankle, it may hold magic. Let's see what's cooking there....

Aha.....Let's zoom in and try a different side by side. 

Well why didn't you say so the first time.  Radiography, you rascal. 

For those with eagle eyes, it was there but oh so faint on the ankle lateral.  It's amazing what just a few mm rotation can do for fracture conspicuity. 

Isolated posterior malleolus fractures area a rare but real thing.  Once known as a "Paratrooper Fracture", they were thought to be secondary to abnormal axial loading, not uncommon in the burgeoning field of jumping out of planes during WW II.  If you see this,  be sure to also do a second and third sweep of the medial and lateral mal to be sure we don't miss a LH/Weber mechanism.

Teaching points:

• Use all the data available to you before putting in your impression.   Chest and shoulder films, ankle and foot films, knee and tib fib films, forearm and wrist films etc, etc; look at both before putting in your 2 cents.  There might be a nickels worth of difference that pays off.
• Use soft tissue findings to remind you to slooowww dooowwwwwnnnnnn......take some extra time to prove yourself right or wrong.

https://radiopaedia.org/cases/paratrooper-fracture?lang=us