Measurement of the tibial anterior-posterior translation for Lachman test in the awake state and under anesthesia using electromagnetic measurement system.

Introduction: Anterior cruciate ligament (ACL) deficiency causes an increase in anterior tibial translation. To assess the amount of the anterior-posterior tibial translation, KT-arthorometer has been widely used. However it has been suggested by some reports that the practical reliability of the KT-1000 arthrometer measurement is doubted due to the interand intra-examiner errors. The Lachman test has been recognized as one of the most reliable clinical test in diagnosis for the anterior cruiciate ligament deficiency. Previously, we have developed an electromagnetic measurement system (EMS) to assess anterior knee laxity during Lachman test and reported that EMS provided more accurate measurement for determining the bony movement and had better correlation to the fluoroscopic measurement than KT-1000 arthrometer. However the study was conducted under anesthesia and it still remains to be tested whether the anterior knee laxity during the Lachman test can be measured accurately when the subjects were awake for daily practice. In this study, we assessed the anterior knee laxity using the EMS measurement system and compared the difference between under awake and anesthesia conditions.