Heard about ACL. What about PCL?

Have you ever hit your knee against the dashboard of your car coming to an emergency stop? Or fallen onto the ground on the front of your knees resulting in your knees fully bent backwards? Chances are you might end up with a tear in a major ligament in your knee without you knowing, the posterior cruciate ligament (PCL).

The posterior cruciate ligament or PCL , is a lesser known cousin of the anterior cruciate ligament (ACL) but of no less importance. It is one of the 4 key ligaments that stabilize your knee. Its primary functions are to prevent your tibia (shin bone) from sliding too far backwards and providing rotational stability to your knee.

How is PCL injured?

These are some common ways the PCL may be injured:

• Commonly known as the “dashboard injury”, it happens in car collisions where the shin hits the dashboard hard. The shin is forcefully pushed backwards when the knee is already in a bent position
• Falling onto the front of the knee where the tibial tuberosity (top part of the shin bone which protrudes out) hits the ground first, causing the shin bone to move backwards forcefully.
• Forceful pressure on the front of the shin while the knee is hyperextended (during a soccer game, a player’s knee is extended out during the end of a kick and received a hard tackle from the front of the shin)

How to know if you have injured your PCL?

If your knee is injured in the above few ways, there is a high chance you might have torn your PCL. The signs and symptoms for a PCL injury is similar to an ACL injury, i.e. swelling, pain, decreased mobility of the knee. However, the sensation of instability of the knee is not as common and pronounced as an ACL injury. If you do have sensation of instability, such as the knee giving way while turning or pivoting on it, surgical intervention might be necessary.

How is PCL injury diagnosed?

A major part of the diagnosis stems from you remembering as closely as possible how your injury occurred. A reliable test that your doctor or physiotherapist usually does is the posterior drawer test to test the integrity and laxity of the PCL. Further investigations such as X-Ray and MRI can help to confirm and assess the damage of the injury and reveal any other bony, ligament or cartilage injury.