POSTERIOR SAG TEST

(GRAVITY DRAWER TEST)

​• Test positioning

The client lies on a table with the involved knee flexed to 90-degrees and the ipsilateral hip placed in 45-degrees of flexion.

​• Action

The therapist observes the position of the tibia relative to the femur in the sagittal plane.

The therapist then instructs the client to actively contract the quadriceps muscle group in an attempt to extend the knee while retaining hip flexion.

The ipsilateral foot should remain fixated to the table during the attempted knee extension.

​• Positive finding

Posterior displacement of the tibia upon the femur, while the client's quadriceps remain silent, indicates a posterior instability.

This may be reflective of injury to any of the following structures: posterior cruciate ligament, arcuate ligament complex, and posterior oblique ligament.

​• Special considerations & comments

lt is imperative for the therapist to identity a neutral tibiofemoral joint position, as this test can be misinterpreted for an anterior instability when one observes an anterior translation of the tibia on the femur.

The Posterior Sag Test is attributed to Dr. William Godfrey for his work on PCL injury diagnosis, with further influence from Dr. James Cyriax’s techniques in assessing knee joint stability and function.