The Lachman test is a clinical test used to diagnose injury of the

anterior cruciate ligament The anterior cruciate ligament (ACL) is one of a pair of cruciate ligaments (the other being the posterior cruciate ligament) in the human knee. The two ligaments are also called "cruciform" ligaments, as they are arranged in a crossed formation ...

(ACL). It is recognized as reliable, sensitive, and usually superior to the anterior

drawer test The drawer test is used in the initial clinical assessment of suspected rupture of the cruciate ligaments in the knee. The patient should be supine with the hips flexed to 45 degrees, the knees flexed to 90 degrees and the feet flat on table. The ...

Description

The knee is flexed at 15 degrees with the patient supine. The examiner should place one hand behind the

tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...

and the other grasping the patient's thigh. It is important that the examiner's thumb be on the

tibial tuberosity The tuberosity of the tibia or tibial tuberosity or tibial tubercle is an elevation on the proximal, anterior aspect of the tibia, just below where the anterior surfaces of the lateral and medial tibial condyles end. Structure The tuberosity o ...

. The tibia is pulled forward to assess the amount of anterior motion of the tibia in comparison to the

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with ...

. An intact ACL should prevent forward translational movement ("firm endpoint") while an ACL-deficient knee will demonstrate increased forward translation without a decisive endpoint - a soft or mushy endpoint indicative of a positive test. More than about 2 mm of anterior translation compared to the uninvolved knee suggests a torn ACL ("soft endpoint"), as does 10 mm of total anterior translation. An instrument called a "KT-1000" can be used to determine the magnitude of movement in millimetres. This test can be done in either an on-field evaluation in acute injury, or in a clinical setting when a patient presents for follow-up with knee pain.

Interpretation

The test may be negative in chronic ruptures as the ACL stump can scar to the PCL.

History and etymology

The test is named after orthopaedic surgeon John Lachman, late Chairman of the Department of Orthopaedic Surgery and Sports Medicine at

Temple University School of Medicine The Lewis Katz School of Medicine at Temple University (LKSOM), located on the Health Science Campus of Temple University in Philadelphia, PA, is one of 7 schools of medicine in Pennsylvania conferring the M.D. (Doctor of Medicine) degree. It also ...

in Philadelphia, Pennsylvania. The original description was submitted by one of his colleagues, JS Torg.

References

{{Orthopedic examination , state=autocollapse Examination of the knee