Your 14 year old male patient fails the Ottawa Knee or Pittburgh Knee clinical decision tool after gettting whacked in the knee with some object of some kind or another.
He’s tender near the tibial tuberosity and he refuses to extend his leg.
You can’t tell whether this is pain limited or whether something else is going on.
Your AP knee xray shows this. The radiologist is busy interpreting a lot of CT heads that you ordered earlier. Now you must read your own film because ortho might need to be consulted. So…you do a “wet read.”
You have no clue how to read this so you check out this link on How to Read a Knee Xray (peds specific) so that you have a framework for your wet read.
Hmmm. Looks like no fractures, good femur-tibial alignment, and no significant effusions. Not too helpful so far. What about the lateral view?
Is the lateral view useful at all? Yes! One use: patellar tendon rupture.
A patellar tendon rupture should be considered likely when the distance between the inferior aspect of the patella is GREATER than than the length of the patella itself +20%
Extra credit: what is this?
This is not a fracture but a normal variant called the “fabella.”
Resources:
http://www.wikiradiography.net/page/Knee
http://www.foamcast.org (episode 22)
Tintinalli’s Emergency Medicine Manual, 7e > Chapter 179. Hip and Knee Pain
