Which description accurately reflects the Lachman’s test technique and interpretation?

• A. Supine, knee flexed about 20-30 degrees; stabilizes distal femur and translates proximal tibia forward; positive when displacement exceeds 5 mm with a soft end-feel.
• B. Knee is tested with the patient prone and the tibia translated anteriorly; positive when there is a hard end-feel.
• C. The test is performed with the patient seated and the knee hyperextended; positive when varus/valgus laxity is present.
• D. The knee is tested in full extension while applying a posterior force on the tibia; positive when there is no end-feel.

Answer: (A)

Lachman’s test assesses the ACL by looking for abnormal anterior translation of the tibia when the knee is placed in a brief flexion, typically about 20–30 degrees. In this position, you stabilize the distal femur with one hand and gently translate the tibia forward with the other. A positive sign is excess anterior movement of the tibia relative to the femur, often with a soft or absent end-feel, and usually more than normal laxity (commonly around 5 mm or more) compared with the other knee, indicating ACL insufficiency.

The description matches this setup and interpretation exactly: supine position, knee flexed to 20–30 degrees, anterior translation of the tibia with stabilization of the femur, and a soft end-feel with increased laxity signaling a positive test. Other described positions or forces correspond to different tests or ligaments (for example, anterior translation with the knee in full extension or with a hard end-feel, posterior forces testing the PCL, or laxity tests for varus/valgus), which do not reflect the Lachman technique.