Have you ever found yourself watching a sporting event and seen an athlete lying on the ground with a damaged knee? Maybe you’ve wondered exactly what they mean by ACL, PCL and meniscus? The knee joint is held together by a series of tough ligaments. Ligaments are tissues that attach one bone to another, giving it support and structure across a joint.
The most commonly damaged ligament in any known as the anterior crucial ligament, or ACL. This ligament attaches the femur, which is the bone in your thigh, with the tibia, which is the major bone in your shin. The purpose of this ligament is to prevent the tibia from sliding forward relative to the knee joint. When the ACL is damaged, the knee joint becomes very unstable. This can be quite painful as well. The reason the ACL is the most commonly damaged joint is because it is held taught while the knee is in a slightly flexed position. Having your knee a little bent is the most common position in the leg is in during an athletic event.
Running criss-cross to the ACL is another ligament known as the PCL, or posterior cruciate ligament. The posterior cruciate ligament prevents the tibia from sliding backwards relative to the knee joint. This ligament is less commonly damaged in the ACL because it is loose when the knee joint is in a slightly flexed position. To make the PCL tight and more easily damaged, you would need to stretch your leg into a straight line. This is not commonly done during an athletic event, which is why the PCL is less likely to suffer damage. However, this is still a relative risk, and the PCL can be damaged if you put the wrong kind of stress on the knee.
Running up and down the inner and outer edge of the knee joint are a pair of ligaments known as the collaterals. On the outside edge, from the femur to the tibia is the lateral collateral ligament. On the inner edge of your knee, also from the femur to the tibia, is the medial collateral ligament. These ligaments serve to prevent your lower leg from wiggling side to side. In essence, they keep the knee joint flexing front to back only, which is the way it’s designed. Either of them can be damaged quite easily if the knee joint is pressed sharply in one direction or the other from the side.
The last type of ligaments seen in the knee are known as the meniscal ligaments. The meniscal ligaments are somewhat more difficult to visualize, as they are somewhat internal to the knee joint itself. These ligaments are needed for general stability of the knee joint and are located inside the joint between the collaterals and the ACL/PCL crisscrossing structure which is in the center of the joint.
There is a specific type of injury to the ligaments in the knee which has a oddly sounding yet appropriate name. Known as the “Unhappy Triad”, this injury, not surprisingly, involves damage to three specific ligaments of the knee. When a knee is traumatized by hitting it from the outside towards the midline of your body, the three ligaments that are most frequently damaged include the ACL, the medial collateral ligament, and the medial meniscal ligament. Try to visualize which ligaments would stretch if you were to press the knee from the outside towards the center of your body. The ligaments on the inner edge of your knee, the medial ligaments, would be stretched as in the knee flexes inwards.
Although the structure of the knee may often seem like a miracle of biological engineering, it is actually quite fragile and susceptible to damage. Many athletes have had their careers cut short due to damage to the knee ligaments. However, modern surgeons today are able to repair much damage that in the past would have ended a promising career. Despite this is still a good idea to attempt to maintain your knee in as good a condition as possible.