Posterior Drawer Test of the Knee is used to evaluate the integrity of the posterior cruciate ligament (PCL) of the knee.
It’s a test for PCL injury.
How do you test for PCL injury?
The patient is supine and the knee is flexed to approximately 90 degrees (Same position for anterior drawer test).
The examiner Sits on the foot of the patient with both the thumbs over the anterior joint line and fingers over the back of the upper tibia, feel for relaxed hamstrings.
Then he gives a posterior force on upper tibia to assess abnormal backward movement.
The test is done in neutral position of the foot, in internal rotation and external rotation position of the foot.
What does a positive Posterior Drawer Test of the Knee mean?
The Posterior Drawer Test is considered positive if a posterior displacement of the tibia more than 5 mm, or a “soft” end point, indicates posterior cruciate ligament insufficiency.
Sensitivity & Specificity
In a blinded, randomized, and controlled study1 involving 39 patients to assess the clinical examination skills of orthopaedic surgeons with fellowship training in sports medicine, Rubinstein et al. reported that the accuracy for detecting a PCL tear was 96%, with a 90% sensitivity and a 99% specificity.
Sensitivity: 90 %
Specificity: 99 %
The examination accuracy was higher for grades II and III posterior laxity than for grade I laxity. Eighty-one percent of the time, the examiners agreed on the grade of the PCL tear for any given patient.
In a patient with a torn posterior cruciate ligament, a dropback phenomenon (or the posterior sag sign) usually occurs in this position: gravity causes the tibia to sublux posteriorly with respect to the femur, resulting in an abnormal appearance that is best appreciated when both knees are viewed in profile. When such a dropback phenomenon occurs, the tibial tubercle appears less prominent than usual, and the patella appears more prominent than usual. Subtle changes may often be detected by comparing the injured with the normal knee. In the acute injury situation, the dropback is less likely to occur or may be masked by acute swelling.
If considerable dropback has already occurred, the application of a posterior force may not sublux the tibia much further.
Unlike the anterior drawer test, a fairly firm endpoint is usually felt once the abnormal posterior laxity has been taken up, even in the case of complete PCL rupture.
The patient lies in the prone position with the foot in neutral rotation and the knee flexed to 80–90 degrees.
The patient is asked to isometrically contract the hamstrings while the clinician stabilizes the foot. A positive Posterior Drawer Test of the Knee is a posterior subluxation of the lateral tibial plateau indicating a posterior cruciate ligament tear.
Posterior Cruciate Ligament Injury
This most commonly results from a direct bow to the upper tibia in a flexed knee-dashboard injury or hyperflexion without a blow or in frank dislocation.
Loss of confidence in the knee and giving way feeling may be present.
Positive posterior sagging, posterior drawer test, external rotation recurvatum test and posterolateral instability tests may be present.
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.
Shino K, Horibe S, Ono K. The voluntarily evoked posterolateral drawer sign in the knee with posterolateral instability. Clin Orthop Relat Res. 1987 Feb;(215):179-86. PMID: 3802636.
Clinical Tests for the Musculoskeletal System 3rd Edition.
Dutton’s Orthopaedic Examination, Evaluation, And Intervention 3rd Edition.
Sarvdeep S. Dhatt, Sharad Prabhakar – Handbook of Clinical Examination in Orthopedics.