Influences of variation in force application on tibial displacement and strain in the anterior cruciate ligament during the Lachman test

OBJECTIVE: The purpose of this study was to examine the influence of Lachman test performance technique on tibial displacement and strain in the anterior cruciate ligament. DESIGN: Model simulation of experimental Lachman test performance by trained clinicians. BACKGROUND: Differences in clinician hand placement during Lachman test performance have been observed. METHODS: A two-dimensional computer sagittal plane model of the knee was designed to simulate experimentally observed Lachman test performance, and determine anterior cruciate ligament strain and tibial translation that occurred during variation in clinician hand placement and force magnitude. RESULTS: Anterior cruciate ligament strain and tibial translation were greater under conditions mimicking clinician hand placement utilizing a more proximal force application on the tibia. CONCLUSIONS: Tibial translation and strain behavior of the anterior cruciate ligament during the Lachman test appear to be influenced by clinician hand position used in the application of force to the tibia.