Posterior Drawer Test

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A posterior drawer test is a specific maneuver used to test the stability of a joint.  Most commonly used to test the stability of the knee joint, the posterior drawer test specifically tests the function of the posterior cruciate ligament (the PCL).  The posterior drawer test is considered positive when there is an injury to the PCL, such as a PCL tear.

The posterior drawer test is part of a normal examination of the knee joint.

  When your doctor examines the knee joint, he or she will inspect the joint, feel for abnormalities, test the ligaments and mobility, determine if there is swelling, and perform specific maneuvers to detect abnormalities.

How a Posterior Drawer Test Is Performed

With the patient lying flat and relaxed, the examiner bends the knee to a right angle (90 degrees). The examiner then places his fingers on the knee joint, and attempts to shift the tibia backwards.  As the examiner is placing pressure on the top of the shin bone, he or she can feel the resistance that comes from the PCL.  In patients with an injured PCL, the examiner may note excessive translation (movement) of the tibia backwards, and may not feel the normal resistance of the ligament.

The test places stress on the PCL. Both the amount of movement (shifting) of the shin bone, as well as the feel of the endpoint of movement (how solid the ligament feels), offer information about the PCL.

Knees with a damaged PCL may demonstrate more movement and a less firm endpoint during a posterior drawer test.

PCL Tears

A PCL tear is an uncommon injury, that typically occurs as a result of a fall directly on a flexed knee.  This injury can also occur when a front seat passenger of a motor vehicle is involved in a collision.

  In this case, the shin is forcefully pushed backwards by contact with the dashboard.

People who sustain a PCL tear may have sensations of knee instability.  Often a PCL tear occurs in conjunction with other ligament injuries of the knee.  Treatment of isolated PCL injuries is most often done with nonsurgical treatment, although in some high demand athletes, surgery may be necessary.  Where the PCL tear is associated with other ligament injuries, surgery is more commonly performed to restore stability to the knee joint.

If a PCL tear is suspected, typically an MRI is performed to determine if the injury is present.  However, the severity of the injury is best determined by the examiner detecting how unstable the joint is as a result of the injury.  PCL tears are graded 1 to 3, with grade 1 injuries having a very good prognosis with often minimal symptoms, and grade 3 injuries causing more problems, and possibly requiring more invasive treatment.

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