Case 24 Answer: Good job to everyone that answered. I expected some “radial head fractures” but you ll were on the ball. The...

Case 24 Answer:

Good job to everyone that answered. I expected some “radial head fractures” but you ll were on the ball. 

The two keys to this are the posterior fat pad (ie joint effusion) and the “teenager”.  So you see the effusion and you have to decide is it traumatic or nontraumatic (more common than not, the former - plus it’s a young patient). So assuming it’s a traumatic joint effusion, there is a fracture somewhere. But as we said, it’s a teenager, so you need to be looking for a supracondylar fracture rather than a radial head fracture that you would see in adults.  

Now, you can use your lines, specifically the anterior humeral line. A line drawn down the anterior humeral cortex should pass through the middle 1/3 of the capitellum. Supracondylar fractures tend to create a vertex anterior angle here so your line with “move” anteriorly to pass through the anterior 1/3 or completely anterior to the capitellum.

http://www.radiologyassistant.nl/en/p4214416a75d87