Anterior cruciate ligament is one of the four major knee ligament. It is the central ligament in the middle of the knee. It helps in controlling the rotation of your knees and in anything that involves jumping, twisting, running. It also helps in stabilizing our knees. So when there is a tear in the anterior cruciate ligament, it is known as ACL injury. It is most commonly seen in young athletes and in people who are highly into skiing, tennis, squash, football, and rugby, exercising and high intense physical workouts.