A simple purpose of knee is to bend or straighten so that body can perform many activities like running, walking, kicking, and sitting. We can’t imagine standing up from a chair if our knees couldn't bend. The Medial Collateral Ligament maintains the stability of knee joint and prevents the joint from sliding sideways. It is present on the side of the knee. Functioning of MCL is important for the working of knee. Acute injury and trauma as well as chronic overuse can both cause inflammation and showing the symptoms of pain, swelling, redness and warmth.

The knee is more susceptible to twisting or stretching injuries. If the knee is stressed from a specific direction, then the ligament which holds it in a place can get tear up. Ligament stretching or tears are called sprains. These sprains are categorised as first, second, or third degree which is based upon the damage occured. Grade one sprains stretch the ligament but don't tear the fibres; grade two sprains partially tear the fibres, but the ligament remains intact; and grade three tears completely disrupt the ligament.

Proper footwear minimizes the risk of knee injury. Wearing shoes that are appropriate for the activity can lessen the risk of twisting and other forces that can stress the knee. Strong muscles stabilize joints.