Lachman test

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The Lachman test is a quick way doctors check for an ACL injury. It’s reliable and sensitive, and often better than the anterior drawer test. To do it, the knee is bent about 15 degrees while the patient lies on their back. One hand stabilizes behind the tibia and the other grips the thigh, with the thumb on the tibial tuberosity. The tibia is gently pulled forward to see how it moves relative to the femur. If the ACL is intact, the end feel is firm and only a small amount of forward movement occurs. If the ACL is torn, there is more forward translation and a soft or mushy end point. A forward movement of more than about 2 mm compared with the other knee, or a total of about 10 mm, suggests an ACL tear. A KT-1000 device can measure this movement in millimeters. The test can be done in the field after an injury or later in a clinical visit. It may be negative in chronic tears because the ACL stump can scar to the PCL. The test is named after orthopaedic surgeon John Lachman, with the original description by JS Torg.