Lachman’s Test

Orthopedic Exam / Special Tests for Physical Therapy: KNEE

The anterior cruciate ligament is one of the four main ligaments of the knee, and the ACL provides 85% of the restraining force to anterior tibial displacement at 30 degrees and 90 degrees of knee flexion. The ACL resists anterior translation and medial rotation of the tibia, in relation to the femur.

The ACL originates from deep within the notch of the distal femur. Its proximal fibers fan out along the medial wall of the lateral femoral condyle. There are two bundles of the ACL—the anteromedial and the posterolateral, named according to where the bundles insert into the tibial plateau. The ACL attaches in front of the intercondyloid eminence of the tibia, being blended with the anterior horn of the medial meniscus.

Special Test: Lachman’s Test:


  • To test for the integrity of the Anterior Cruciate Ligament (ACL).

*** The Lachman’s test is considered to be the most accurate test for ACL integrity.

Video Demo Instructions, Procedure, Positive Test:

Special Test: Lachman’s Test: Video Demo (Procedure below)

 Special Test: Lachman’s Test: PROCEDURE 1:

• Patient is supine.
• Patient’s affected knee is flexed 30°
• Therapist stabilizes distal femur with one hand while grasping patient’s proximal tibia with the other hand
• Therapist applies an anteriorly directed stress the tibia.

Special Test: Lachman’s Test: PROCEDURE 2:

• Patient is seated with their affected leg over the edge of the table
• Therapist sits in front of the patient, supporting the patient’s ankle on therapist’s thigh.
• Therapist places patient’s knee in 30° flexion
• Therapist stabilizes the distal femur with one hand
• Therapist applies anteriorly directed stress on the proximal tibia with the other hand.

Special Test: Lachman’s Test: POSITIVE TEST:

  • Pain or excessive anterior motion of the tibia, and disappearance of the infrapatellar tendon slope.