Pellegrini-Stieda lesions are ossified post-traumatic lesions at (or near) the medial femoral collateral ligament adjacent to the margin of the medial femoral condyle. One presumed mechanism of injury is a Stieda fracture (avulsion injury of the medial collateral ligament at the medial femoral condyle). Calcification usually begins to form a few weeks after the initial injury. #Pellegrini-stieda #lesion #trauma #knee #xray #stieda #fracture #calcification #radiology