Causes / typical injury mechanism: Posterior cruciate ligament (PCL) injuries typically occur as a result of high-energy trauma, primarily associated with either motor vehicle incidents (dashboard injury) or sports-related injuries. Injury most often occurs as a result of shearing forces created by posterior translocation of the tibia relative to the femur with the knee in a flexed position. Hyperextension, hyperflexion, and valgus / varus forces may also cause PCL injury, although these movements typically result in damage to multiple structures of the knee. Sports most commonly implicated include soccer, football, rugby, and skiing.

Classic history and presentation: All patients presenting with knee pain after high-energy trauma should be evaluated for PCL injury. One of the most classic presentations is the dashboard injury, in which contact with a vehicle dashboard during a high-speed collision puts posterior force on the tibia with the knee in a flexed position. In the context of athletics, patients usually report a fall onto a flexed knee with a dorsiflexed foot or direct contact to the anterior tibia. Major symptomatic complaints include knee instability, decreased range of motion (ROM), and inability to bear weight. In the case of an isolated, mild PCL injury, patients may report posterior knee pain, swelling, and stiffness.

Prevalence: PCL injuries are quite rare in the general population, estimated to affect 2 out of 100 000 people. Even within the context of athletics, PCL injury is uncommon, accounting for less than 1% of all sports-related knee injuries. Most trauma-related PCL injuries occur in combination with other structural injuries of the knee, whereas athletic injuries are more likely to be isolated.

• Age – The largest portion of PCL injuries occur in patients between the ages of 20 and 29 years, and approximately 80% occur in patients between the ages of 10 and 39 years.
• Sex / gender – PCL injuries occur predominantly in men.

Risk factors: Motor vehicle accidents and high-energy athletic incidents.

Pathophysiology: The PCL is the largest ligament of the knee and is composed of 2 components: the anterolateral bundle (ALB) and the posteromedial bundle (PMB). Together, they serve to limit posterior translation and rotation of the tibia relative to the femur.

Grade / classification system: PCL injury grading is based on the amount of posterior displacement of the tibia during physical examination –

• Grade 1: 0-5 mm
• Grade 2: 6-10 mm
• Grade 3: > 10 mm