The collateral ligaments function as guy ropes at the sides of the knee, protecting the knee against forces which would tend to prise it open sideways.

collateral ligaments

The collateral ligaments on either side of the knee differ in their anatomy. The lateral collateral ligament is a cord-like structure. The medial collateral ligament (MCL) is more of a band, and has both a deep and a superficial component. The MCL is the more commonly injured, although the injuy is more often a sprain than a complete rupture.



rugby injury to knee

Excessive force from one side may stretch and tear the collateral ligament on the other side of the joint, such as might occur in a poor tackle.