Knee Posterior Drawer Test: How to Perform It, What a Positive Result Means, and How Accurate It Is
What Is the Knee Posterior Drawer Test?
The knee posterior drawer test is a physical examination maneuver used to assess the integrity of the posterior cruciate ligament (PCL). The PCL is one of the main stabilizing ligaments of the knee, and it helps prevent the shinbone (tibia) from sliding backward relative to the thigh bone (femur). When the ligament is torn or stretched, the tibia can shift backward more than it should, and this test is designed to detect that abnormal motion.
Clinicians, physical therapists, and sports medicine professionals commonly include this test in a knee physical exam when a PCL injury is suspected. It is simple, needs no equipment, and can be done in a few seconds at the bedside, in the clinic, or on the sports field.
What Is the Knee Posterior Drawer Test Used For?
The test is used to evaluate PCL integrity. If a patient has knee pain, swelling, or instability after trauma, the posterior drawer test helps the examiner decide whether the PCL may be involved. It is usually combined with other findings from the history and physical exam, and with imaging when needed, to build a complete picture of the injury.
How to Perform the Knee Posterior Drawer Test
Follow these steps to perform the test correctly:
- Position the patient. The patient lies supine (on their back) with the knee to be tested flexed to approximately 90 degrees.
- Stabilize the leg. The examiner sits gently on the toes of the tested extremity to hold the foot in place.
- Place your hands. Grasp the proximal lower leg, at about the level of the tibial plateau or joint line. Place your thumbs on the tibial tuberosity.
- Apply the force. Attempt to translate the lower leg posteriorly (backward) and observe how far the tibia moves and how the movement stops.
Comparing the injured knee with the uninjured knee gives the examiner a useful reference for what is normal for that patient.
What Is a Positive Result?
The test is considered positive if there is either of the following:
- Lack of a firm end feel. Normally, the ligament stops the backward movement of the tibia with a firm endpoint. A soft or absent endpoint suggests the ligament is not doing its job.
- Excessive posterior translation. The tibia slides backward further than expected, especially when compared with the opposite knee.
A positive result suggests a PCL injury, but the clinician interprets it together with the rest of the exam and any imaging.
How Accurate Is the Posterior Drawer Test?
The accuracy figures reported for this test are:
- Sensitivity: 90%
- Specificity: 99%
These values come from a clinical study of the accuracy of physical examination in PCL injuries by Rubinstein and colleagues, published in the American Journal of Sports Medicine (PMID: 7943523, indexed on PubMed). A sensitivity of 90% means the test correctly identifies most people who have a PCL injury. A specificity of 99% means a positive result is very unlikely to occur in people without one. This is why the posterior drawer test is considered one of the more reliable clinical tests for the PCL.
Key Takeaways
- The posterior drawer test evaluates the posterior cruciate ligament.
- The knee is flexed to about 90 degrees, and the tibia is pushed backward.
- A positive test shows excessive posterior translation or no firm end feel.
- Reported sensitivity is 90% and specificity is 99%.
- Results should always be interpreted by a qualified healthcare professional.
Frequently Asked Questions (FAQ)
What does the posterior drawer test check?
It checks the integrity of the posterior cruciate ligament (PCL) in the knee.
At what angle is the knee tested?
The knee is flexed to approximately 90 degrees with the patient lying on their back.
What does a positive posterior drawer test mean?
A positive test means there is excessive backward movement of the tibia or a lack of a firm end feel, which suggests a possible PCL injury.
How accurate is the posterior drawer test?
Published data report a sensitivity of 90% and a specificity of 99% for PCL injuries.
Where should the examiner place their hands?
The hands grasp the proximal lower leg near the tibial plateau or joint line, with the thumbs on the tibial tuberosity.
Why does the examiner sit on the patient’s foot?
Sitting on the toes of the tested leg helps stabilize the foot while the tibia is pushed backward.
Can I diagnose a PCL injury myself using this test?
No. The test should be performed and interpreted by a trained healthcare professional, who may also order imaging to confirm the diagnosis.
Is the test painful?
Mild discomfort can occur, especially after a recent injury, so the examiner applies the force gently and stops if the patient has significant pain.
References
- Knee Posterior Drawer Test, Orthofixar
- Knee Physical Exam, Adult, Orthobullets
- Rubinstein RA Jr, Shelbourne KD, McCarroll JR, VanMeter CD, Rettig AC. The accuracy of the clinical examination in the setting of posterior cruciate ligament injuries. Am J Sports Med. 1994 Jul-Aug;22(4):550-7. doi: 10.1177/036354659402200419. PMID: 7943523