What are the radiographic features of a medial collateral ligament tear on plain film?

Widening of the tibiofemoral joint compartment on the side of the injury
Avulsion fracture at the femoral medial collateral ligament insertion
Pelligrini-Stieda lesion (i.e., ossification at the site where the medial collateral ligament attaches to the femur). This implies an old injury.