Pelligrini-Stieda Lesion:
A Pelligrini-Stieda lesion is shown in the radiograph below. This lesion was originally described in 1905, and is associated with a tear of the Medial Collateral Ligament. Heterotrophic calcification forms causing chronic pain, which typically needs to be surgically excised.
So for the students out there, it is possible to diagnosis an MCL tear on plain radiographs. Just not very often.
