The ABCs of Your Knee’s Crucial Ligaments

To understand the importance of the ligaments in your knees, you must first understand what a healthy ligament does for you and how it performs. The human knee is made of three bones – the tibia, femur, and patella (shin, thigh, and kneecap). At the most basic explanation, a ligament is a thick, fibrous band that encompasses the bones to hold them together and provide stability to them during movement. There are four types of ligament in the knee, with each providing a unique function.

The Collateral Ligaments

Two of the knee’s ligaments – the lateral collateral and medial collateral ligament- work in unison holding the bones together to provide sideways stability to the knee. These are located on either side of the joint.

Medial Collateral Ligament (MCL)

Your MCL is located on the inner portion of the joint, resisting the outside leg force during periods of movement. The MCL is one of more commonly injured ligaments, which can occur if too much force is applied to it during movement. When damaged, the MCL can provide severe pain inside the knee and reduce the over-all stability and function of the joint.

Lateral Collateral Ligament (LCL)

The LCL is a smaller ligament than the MCL, and is found on the outer portion of the joint, where it attaches the fibula and femur to one another. The LCL serves to resist interior forces to the knee to maintain stability during movement. While the LCL is not injured as frequently as the MCL, it is still a possibility. Pain and a feeling of lost stability during movement may be indicative of a torn LCL.

The Cruciate Ligaments

The remaining two ligaments – the anterior and posterior cruciate ligaments (ACL and PCL) – are the most important ones in providing function and stability to the joint. Located inside the joint, the cruciate ligaments are extremely strong bands that hold the femur and tibia together. Together these ligaments function to provide movement to the knee, allowing for both forward and reverse movements. They also serve a secondary purpose of providing the body a feeling of balance.

Anterior Cruciate Ligament (ACL)

The most commonly injured ligament, it prevents the tibia from sliding beyond the femur during movement. If your knee becomes bent backwards suddenly, or is twisted with enough force, your ACL may tear resulting in your knee giving way. This is one of the more common injuries during physical activity, especially when contact with other individuals is involved such as with sports.

Posterior Cruciate Ligament (PCL)

Shorter than the ACL, the PCL prevents the tibia from sliding too far behind the femur during movement. Although smaller, the PCL is twice as strong as the ACL, making it much more difficult to injure.

How do These Ligaments Provide Support?

Unlike other joints, which are commonly a safe and secure ball inside a socket (such as the shoulder or hip), the knee does not have a solid structural housing. Instead, the ligaments provide structural support by binding the bones of the joint together to both contain the joint where the bones of the legs meet, and to keep the joint stable during flexion and extension of the joint. By restricting the amount the joint can be extended (performed by the ACL and PCL), the joint can be kept in a safe range of motion to maintain balance during movement.

Why do the Ligaments Provide Support?

If the ligaments were not present, the knee joint would have a very negligible amount of support, as the joint consists of a juncture where three bones are meeting. There is no structure to the joint without the ligaments, which function to hold the bones together and keep them stable during movement. Without ligaments, the knee would not function as a load-bearing joint and we would simply not be able to use our knees.

Is Your Knee Giving You Pain?

If you are experiencing pain in your knee, or feel as if it is not as stable as normal during movement, you may have injured one or more ligaments. Ligament injuries are very important to take notice of, as while they may start off as minor injuries they can quickly become severe and debilitating if left untreated. Since knee injuries tend to not heal on their own, the quicker you have your knee examined for potential ligaments injuries the quicker you may be to obtaining relief.