Which statement best describes the Lachman’s test in terms of technique and positive finding?

• A. Supine, knee 20-30 degrees; tibial anterior translation >5 mm with a soft end-feel.
• B. Prone with knee flexion.
• C. Seated with knee extended.
• D. Standing with weight-bearing.

Answer: (A)

The Lachman test checks ACL integrity by assessing anterior tibial translation when the knee is slightly flexed. Position the patient supine and bring the knee to about 20-30 degrees of flexion, a angle that minimizes hamstring guarding and highlights ACL damage. With one hand stabilizing the femur and the other guiding the tibia forward, compare the amount of anterior movement to the opposite knee. A positive sign is excessive forward translation of the tibia, typically accompanied by a soft or absent end-feel, which reflects a compromised ACL. The translation is often cited as greater than about 5 mm compared with the healthy knee.

The described technique is specific to the Lachman maneuver; other positions described would not reproduce the classic Lachman findings and are used for different knee tests.