The Science of PCL Injuries

Posterior cruciate ligament (PCL) injuries involve damage to the ligament that prevents excessive backward movement of your tibia relative to your femur. The PCL is the strongest ligament in your knee and has a better blood supply than the ACL, giving it superior healing potential when injured. PCL injuries are graded from I to III based on severity: Grade I involves stretching with microscopic tears, Grade II involves partial tearing with some functional loss, and Grade III represents complete rupture. Unlike ACL injuries, isolated PCL tears have an excellent capacity for healing due to their rich vascular supply. The mechanism of injury typically involves a posteriorly directed force on the proximal tibia, such as falling onto a bent knee or dashboard injuries in motor vehicle accidents. Sports injuries often occur during hyperflexion or hyperextension movements, particularly in contact sports. The PCL works in conjunction with other knee structures to provide stability. When injured, the quadriceps muscle becomes crucial as it can partially compensate for PCL function by preventing excessive posterior tibial translation during functional activities.