From the Guidelines
The Lachman maneuver is a test used to assess anterior cruciate ligament (ACL) tears or instability in the knee, as evidenced by a positive Lachman test indicating ACL damage 1. The test is performed with the patient lying supine and the knee flexed at approximately 20-30 degrees, allowing the examiner to assess the anterior translation of the tibia relative to the femur.
- Key aspects of the test include:
- The examiner stabilizing the distal femur with one hand
- The other hand grasping the proximal tibia and pulling it forward
- A positive test occurring when there is excessive anterior translation of the tibia relative to the femur, often accompanied by a soft or absent endpoint
- The test being considered more sensitive and reliable than other ACL tests like the anterior drawer test, especially in acute injuries when pain and muscle guarding may limit other examinations 1. The Lachman test works by directly assessing the primary function of the ACL, which is to prevent anterior displacement of the tibia relative to the femur.
- If a positive Lachman test is found, further imaging such as MRI is typically recommended to confirm the diagnosis and assess for associated injuries before determining appropriate treatment, as seen in cases where the presence of minor osteoarthritic changes does not influence the treatment decision-making 1.
From the Research
Lachman Maneuver Test
The Lachman maneuver test is used to assess the integrity of the anterior cruciate ligament (ACL) in the knee. The test is performed by flexing the knee to about 20-30 degrees and then applying an anterior force to the tibia while stabilizing the femur. The test is considered positive if there is excessive anterior translation of the tibia relative to the femur, indicating a potential ACL injury.
Diagnostic Accuracy
Studies have shown that the Lachman test is a reliable and accurate method for diagnosing ACL tears. According to 2, the Lachman test is the most accurate test for detecting an ACL tear. Another study 3 found that the Lachman test had a sensitivity of 90%, specificity of 87.5%, and diagnostic accuracy of 89.53% compared to arthroscopy.
Comparison with Other Tests
The Lachman test has been compared to other diagnostic tests, including the anterior drawer test and magnetic resonance imaging (MRI). A study 3 found that MRI had a higher sensitivity and specificity than the Lachman test, but the Lachman test was still a useful diagnostic tool. Another study 4 found that the Lachman test was reliable and accurate when used in conjunction with a digital hand-held arthrometer.
Key Findings
- The Lachman test is a reliable and accurate method for diagnosing ACL tears 2, 3
- The test has a high sensitivity and specificity compared to arthroscopy 3
- The Lachman test can be used in conjunction with other diagnostic tests, such as MRI and the anterior drawer test 3, 4
- The test is reliable and accurate when performed in a prone position 5
Test Performance
The performance of the Lachman test can be affected by various factors, including the experience of the examiner and the position of the patient. A study 5 found that the prone Lachman test had a sensitivity of 70% and a specificity of 97%, resulting in a positive likelihood ratio of 20.17 and a negative likelihood ratio of 0.32. Another study 4 found that the Lachman test had excellent intrarater reliability and predictive validity when used in conjunction with a digital hand-held arthrometer.
Some key statistics about the Lachman test include: