Accurate interpretation of the Lachman test

Area of Science:

• Orthopedic Surgery
• Sports Medicine
• Biomechanics

Background:

• The Lachman test is a standard clinical assessment for anterior cruciate ligament (ACL) integrity.
• Accurate interpretation of the Lachman test is vital for diagnosing knee instability.
• Previous studies have not fully elucidated the impact of tibial rotation on Lachman test sensitivity.

Purpose of the Study:

• To investigate the influence of tibial rotation on the accuracy and reliability of the Lachman test.
• To establish optimal patient and examiner positioning for precise Lachman test execution.
• To minimize false positive and false negative results in Lachman testing.

Main Methods:

• Consecutive series of patients presenting with knee complaints.
• Standardized Lachman test protocol with variations in tibial rotation.
• Systematic evaluation of anterior tibial translation under different rotational conditions.
• Comparison of results with injured and contralateral limbs.

Main Results:

• Tibial rotation significantly affects the interpretation of passive anterior tibial translation during the Lachman test.
• Internal tibial rotation decreases the perceived anterior tibial translation, potentially leading to false negatives.
• External tibial rotation, with the examiner on the same side of the bed, optimizes test sensitivity.
• Inconsistent positioning and inadvertent rotation can yield inaccurate diagnostic results.

Conclusions:

• Correct external tibial rotation and examiner positioning are essential for reliable Lachman test interpretation.
• Awareness and control of tibial rotation are critical for maximizing the sensitivity and accuracy of the Lachman test.
• Implementing standardized technique can improve diagnostic precision for knee ligament injuries.