Name of test



Pivot shift test

What it tests



ACL function

How to do it



Start with the knee in full extension. Grasp the leg with two hands and tuck the patient’s ankle under your arm. Internally rotate the leg while applying a combination of axial load and valgus stress. Flex the leg while maintaining these forces. In ACL injury, as the knee flexes the tibia shifts from a subluxed to a reduced position on the femur.

Grading of the shift:

Grade 0: no detectable shift

Grad I: tibia moves in a smooth glide during reduction

Grade II: tibia abruptly reduces

Grade III: tibia momentarily locks in a subluxed position before reducing

The normal response



In a normal knee, there will be no "shift". That’s because the ACL is intact, and there is no subluxation of the joint.

What it means if not normal



In an ACL tear, the tibia can sublux anteriorly and rotate on the femur (the anteromedial bundle contributing more to stability in the sagittal plane and the posterolateral bundle contributing more toward rotatory stability).


In position START (full extension), the tibial is subluxed anteriorly on the femur. This is due to gravity and the fact that the pull of the IT band is anterior to the center of rotation of the tibia on the femur and thus acts as a knee extensor, pulling the tibia anterior. As the knee is flexed, the line of pull of the IT band moves posterior to the center of rotation of the tibia on the femur and acts as a knee flexor. As this happens, the IT band pulls the the tibia posterior on the femur into a reduced position. This reduction may occur abruptly, as a "glide" (see grading above)

Comments



The test is easiest to perform when the patient is fully relaxed (or under general anesthesia).

Citations






DeLee, Jesse C., David Drez Jr., and Mark D. Miller, eds. DeLee & Drez’s orthopaedic sports medicine principles and practice. 3rd ed. Vol. 2. Philadelphia: Saunders/Elsevier, 2010.

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