What Is the Posterior Drawer Test for a PCL Injury?

What to expect when undergoing this test

Man holding injured knee, cropped

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Doctors often perform a posterior drawer test to assess the function of the posterior cruciate ligament (PCL)—one of the four ligaments of the knee. If your doctor suspects a PCL tear, the posterior drawer test is the best test to diagnose it. The test simply involves your practitioner inspecting and manipulating your knee to assess its movement and level of resistance.

Doctors can also perform different versions of this test on joints like those of the shoulders and ankles.

Purpose of the Test

The posterior drawer test is part of a normal knee exam. When your doctor examines the knee, they inspect the joint, test ligaments and mobility, determine if there is swelling, and perform specific manipulations to detect abnormalities.

A PCL tear typically occurs as a result of a fall directly on a flexed knee. This injury can also occur from a hard impact on the knee or tibia (such as a front seat passenger's shin hitting the dashboard in a car collision), from bending the knee backward, or a knee dislocation.

This injury rarely happens in isolation, with nearly eight out of 10 PCL tears occurring with other ligament damage. Severe injuries could also include cartilage damage, nerve injuries, or knee fractures.

The posterior drawer test only diagnoses PCL injuries, however. If your doctor suspects further knee damage, other tests will follow.

How It's Done

While you lay flat and relaxed, the examiner bends your knee to a right angle (90 degrees). They then place their fingers on the knee joint and attempt to press the tibia (the front lower leg bone) backward. 

While applying this pressure, your doctor will look for two things:

  • Backward movement of the tibia
  • How firm the endpoint of that movement feels

Results and Next Steps

A healthy PCL will resist this pressure and keep the tibia stable.

An injured PCL, in contrast, offers less resistance and allows too much backward movement of the tibia (doctors call this movement "translation"), and the endpoint of that movement will be much less firm than it's supposed to be.

A "positive" result in this case likely indicates a PCL tear.

Additional Testing

If your doctor suspects a PCL tear or related knee injuries, they typically order an MRI to confirm the damage. However, the severity of the injury can usually be gauged by the examiner testing joint stability via the PCL test itself.

Once diagnosed, your doctor will grade the injury:

  • Grade 1 and 2 ligament injuries (partial tears) don't require surgery to repair and are usually treated with some combination of rest, elevation, pain management, and physical therapy.
  • Grade 3 injuries indicate a complete ligament tear. Repairing the ligament requires surgery, but doctors don't always recommend it. For example, older patients who are less active may be able to recover and live normally without surgery. Younger, more active patients—competitive athletes, in particular—will need the surgery to restore normal knee function.

In cases where the PCL tear is associated with other ligament injuries, surgery may be more commonly performed because of the complex nature and damage needed to be repaired.

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