Medial (Tibial) Collateral ligament injuries:
Commonly involves the proximal portion of the ligament near the femoral attachment site.
Grade I sprain: contour irregularity, edema superficial to MCL. Fibers remain intact.
Grade II injury: partial tear: partial discontinuity of the fibers, adjacent areas of abnormal signal. Some fibers remain intact.
Grade III injury: complete disruption: complete discontinuity of MCL fibers, extensive surrounding signal abnormality.