The knee is a joint that relies on two sets of ligaments to give it stability. The cruciate and collateral ligaments are strong bands of connective tissue that attach to the femur and the tibia. Healthy sets of ligaments help give the knee and surrounding bones strength and power. The ligaments can get damaged from sports injuries and other traumatic events.
Medial Collateral Ligament
The medial collateral ligament is often torn as a result of sports injuries. Football players who get hit on the outside of the knee can suffer damage to the ligament because the force of the blow can cause a strain a tear. When a running back breaks into the open and gets tackled with a shoulder to the thigh or outside of the knee, it can cause an MCL tear.
Lateral Collateral Ligament
A tear of the lateral collateral ligament also usually results from a sports injury. It is not as frequent as a tear of the MCL. When the LCL is torn, it is usually a result of a blow that strikes the back of the knee. This happens in ice hockey, football and soccer. When the blow on the back of the knee is hard enough, it can strain or tear the ligament on the outside of the knee. In football, a linebacker moving laterally could grab the back leg of the running back or receiver in midstride and when his shoulder pad hits the back part of the knee, that could tear the LCL. A hockey player could lose his balance and make contact with the interior portion of an opponent's or teammate's knee, causing a tear.
Anterior Cruciate Ligament
The anterior cruciate ligament limits rotation and forward movement of the lower leg. When the ACL gets stretched, it is usually called a sprain. When it is torn completely it can be called a rupture. When the tear also rips a piece of the tibia away from the main part of that bone, it is called an avulsion fracture. This injury can happen with a quick change of direction while running or from a poor landing after jumping. It can also result from a direct blow to the back of the knee. This injury is often accompanied by a popping sound as the ligament gets torn. Swelling and pain follow that popping noise. Standing and walking might be difficult or impossible. Surgery is usually indicated for a complete tear.
Posterior Cruciate Ligament
The posterior cruciate ligament limits backward movement of the leg. It is most often injured with a direct blow to the front of the knee. When the PCL is torn, it is often accompanied by a loud, popping sound and swelling. It is likely to be quite painful and it might be impossible to stand or walk after a complete tear. Surgery is often required after this injury.
References
- Orthopaedic Specialties: Ligament Tears
- MayoClinic.com: Posterior Cruciate Ligament
- "Inside the Helmet"; Peter King; 1993
- Joint Healing: Football Injuries
