The way the MCL is torn because it’s on the inside of the knee. The knee acts like a hinge joint. It goes straight, up and down. If the knee is pushed on the outside, it collapses in, then the MCL is under high forces and if it gets very high, it serves the tear. And it comes in three grades of tear; a partial tear, a grade one, a grade two is almost a complete tear and a grade three is a complete tear.