The MCL is one of two collateral ligaments in the knee. It connects the femur (thigh bone) to the lower tibia (shinbone) and provides stability to the inner side of the knee. Together the MCL and lateral Collateral Ligament (LCL) provide stability for side-to- side movement, as well as normal walking. The MCL is the most frequently injured ligament of the two – usually sustaining damage when there is a hard impact to the outside of the knee while the foot is planted firmly on the ground, or an unexpected stumble that results in a severe twist. A sharp pain is usually felt on the inside of the knee. And injury can range from a minor ligament sprain to a partial or complete tear. The MCL responds well to conservative treatment and is almost never treated surgically unless associated with an ACL or meniscus tear, and then surgical attention is only directed to the associated lesions.