The Lachman Test

     The Lachman test is an orthopedic test used for examining the anterior cruciate ligament.

    - the knee is flexed at 30 degrees

    - examiner pulls on the tibia to assess the amount of anterior motion of the tibia in comparison to the femur

    - an ACL-deficient knee will demonstrate increased forward translation of the tibia at the conclusion of the movement.

     To do this, lay the patient supine on an examination table. Put the patient's knee in about 20-30 degrees flexion,the examiner should place one hand behind the tibia and the other on the patient's thigh. It is important that the examiner's thumb be on the tibial tuberosity. On pulling anteriorly on the tibia, an intact ACL should prevent forward translational movement of the tibia on the femur. 

     This test can be done in an on-the-field evaluation in an acute injury setting, or in a clinical setting when a patient presents with knee pain. In either situation, ruling out fracture is important in the evaluation process. Also when evaluating the integrity of the ACL, it is important to test the integrity of the MCL, because this is a common ligament torn in an ACL injury as well.