Hx: Worsening knee pain. H/o trauma 3 weeks ago
Answer: Pelligrini-Stieda Syndrome
Calcification at the femoral insertion of the medial collateral ligament typically seen a few weeks after the original trauma.
There are 2 distinct entities:
Pelligrini-Stieda lesion = the calcification itself. Can be connected or not to the femoral condyle and can be small or very large - typically asymptomatic (more common)
Pelligrini-Stieda Syndrome = when patient is symptomatic at the site of this calcification (presumably due to the inflammatory nature)
Here is the X-ray and CT from 3 weeks ago:
No calcifications at that time. And note the thickened MCL on the CT c/w injury