Which exam finding is most directly used to assess anterior tibial translation in ACL injury?

Which exam finding is most directly used to assess anterior tibial translation in ACL injury?

• A. Decreased ROM
• B. Swelling
• C. Positive Pivot Shift test
• D. Positive Lachman's test with soft end feel or increased tibial translation

Answer: (D)

An ACL tear directly allows the tibia to move forward relative to the femur, so the test that most directly measures this forward (anterior) movement is the Lachman test. By placing the knee in about 20–30 degrees of flexion, the Lachman isolates the ACL and assesses how far the tibia shifts forward compared with the other knee. A positive sign is increased anterior translation, often with a soft or absent end-feel, which reflects ACL insufficiency. This is more direct for anterior laxity than the other maneuvers. The pivot-shift test mainly evaluates rotational instability and dynamic subluxation, not pure anterior translation. The anterior drawer test also assesses forward movement but is typically less sensitive in acute injuries due to hamstring guarding and joint management. Decreased range of motion or swelling do not quantify anterior tibial translation.

An ACL tear directly allows the tibia to move forward relative to the femur, so the test that most directly measures this forward (anterior) movement is the Lachman test. By placing the knee in about 20–30 degrees of flexion, the Lachman isolates the ACL and assesses how far the tibia shifts forward compared with the other knee. A positive sign is increased anterior translation, often with a soft or absent end-feel, which reflects ACL insufficiency.

This is more direct for anterior laxity than the other maneuvers. The pivot-shift test mainly evaluates rotational instability and dynamic subluxation, not pure anterior translation. The anterior drawer test also assesses forward movement but is typically less sensitive in acute injuries due to hamstring guarding and joint management. Decreased range of motion or swelling do not quantify anterior tibial translation.