Knee

Posterior cruciate ligament injury

Mechanism

A blow to the front of the lower leg with the knee flexed: the dashboard injury in a collision, or a fall onto the flexed knee with the foot plantarflexed.

Recognition

First look at the neutral position from the side: with a posterior sag the tibia visibly drops back. The posterior drawer test confirms it and is the most reliable of the knee ligament tests.

Course

Missed more often than an ACL injury, because the complaints are milder and the knee does not give way acutely. An isolated rupture is usually managed conservatively, emphasising quadriceps strength.

Structures

• Posterior cruciate ligament (PCL)

Joints involved

• Knee joint

Clinical tests

• Posterior drawer test
• Posterior sag sign

Sources

• Magee DJ, Manske RC. Orthopedic Physical Assessment, 7e editie. Elsevier. 2021