POSTERIOR LACHMAN'S TEST

TEST POSITIONING

The client lies supine with the test knee flexed to 20 to 30-degrees.

The therapist stands with the proximal hand on the client's distal thigh (laterally) immediately proximal to the patella and the distal hand on the client's proximal tibia (medially) immediately distal to the tibial tubercle.

ACTION

From a "neutral" (anterior-posterior) position, apply a posterior force to the tibia with the distal hand while the femur is stabilized with the proximal hand.

POSITIVE FINDING

Excessive posterior translation of the tibia (as compared to the uninvolved knee) from the neutral position with a diminished or absent end-point is indicative of a partial or complete tear of the posterior cruciate ligament.

CONSIDERATIONS & COMMENTS

If the posterior Lachman's test is not performed from a neutral position, the involved knee may actually present with decreased posterior tibial translation as compared to the uninvolved knee.

This decrease is most likely due to PCL pathology that allows the proximal tibia to translate posteriorly, thus producing decreased posterior translation and subsequent false-negative findings.

Therefore, the presence and quality of the endpoint must be determined before PCL integrity may be accurately assessed.