During knee examination, forward translation of the tibia when the knee is in about 20 degrees of flexion indicates which test?

• A. Abduction stress test
• B. Anterior drawer sign
• C. Lachman test
• D. McMurray test

Answer: (C)

Evaluating ACL integrity with the knee about 20 degrees of flexion is the Lachman test. In this position, the tibia is pulled forward relative to the femur; if the ACL is torn, that forward translation is increased and the end feel is often soft or absent. This angle minimizes hamstring resistance and isolates the ACL more effectively than the 90-degree anterior drawer test, making Lachman more sensitive, especially in acute injuries. The other tests assess different structures—the abduction (valgus) stress test looks at the medial supporting structures like the MCL, and the McMurray test screens for meniscal tears—so they don’t describe the anterior tibial translation characteristic of an ACL injury observed with Lachman.