Posterior Cruciate Ligament (PCL) Tears: Overview

Posterior Cruciate Ligament (PCL) Tears: Overview

Joints are stabilized by ligaments that connect and hold bones together. In addition to having ligaments on the outside of the joint, the knee is one of the few joints that also has ligaments on the inside of the joint that provide stability. The cruciate ligaments, named for their crossed shape, form an X within the knee joint from front to back and back to front.

The posterior cruciate ligament, or PCL, is the counterpart to the more familiar anterior cruciate ligament, or ACL. Together, these ligaments prevent excessive forward and backward movement and twisting movement while still allowing the knee to bend and straighten. The PCL connects the thighbone, or femur, to the shinbone, or tibia, and maintains the most tension when the knee is bent. This helps prevent the shinbone from shifting too far backward.

PCL tears are not that common on their own, making up only an estimated 3% of all knee injuries. If there is a traumatic injury that causes injury to multiple structures within the knee, it is estimated that 40% of those knee injuries will involve a PCL tear. PCL tears most often occur with a direct blow to the front of the shin. This can occur with being kicked in the shin, tackled from a low position, or falls directly landing on the knee. Motor vehicle accidents involving the shin hitting the front of the dashboard is another common cause of PCL tears. Hyperextension injuries where the knee is forcefully straightened can also cause the PCL to tear.

With a PCL tear, there will likely not be the characteristic pop or feeling of instability that occurs with an ACL tear. Most of the time, symptoms of a PCL tear include mild to moderate pain, swelling, and stiffness. Instability is typically experienced when there is also injury to another part of the knee. To diagnose a PCL tear, a health care provider will ask a patient about their symptoms and examine the knee. Specifically, they will look to see if the shin slides or sags back when the knee is bent.

Imaging methods may also be used. Generally, x-rays cannot be used to diagnose a PCL tear but may be performed to make sure that no bones are broken. An MRI is typically the best option to examine the PCL to see if it is torn. PCL tears are graded based on their severity. Grade 1 tears are mild, microscopic tears, grade 2 tears are moderate, partial tears, and grade 3 tears are severe, complete tears. A health care provider will consider a patient's symptoms, age, activity level, and the grade of the PCL tear, as well as if any other structures of the knee are injured, to determine the best course of treatment.