Factors affecting the quantitative value of the pivot shift test using a navigation system in anterior cruciate ligament-injured knees.

This study aimed to identify factors associated with greater quantitative pivot shift in anterior cruciate ligament (ACL)-injured knees by quantitatively assessing the pivot shift under anaesthesia using a navigation system prior to ACL reconstruction. A total of 114 patients (66 males and 48 females) who underwent ACL reconstruction were included. Prior to reconstruction, the pivot shift test was performed under anaesthesia and measured using a navigation system. The maximum difference in the anterior-posterior position of the tibia during knee flexion-extension without stress and during the pivot shift test-termed peak coupled anterior tibial translation (peak c-ATT)-was recorded as the quantitative value. Multiple regression analysis was used to determine factors associated with the quantitative pivot shift value, with nine independent variables: sex, age, preoperative side-to-side difference in anterior knee laxity, time from injury to surgery, presence of medial and lateral meniscus injuries, knee extension angle, femorotibial angle, and pre-injury Tegner activity score. Among the 114 participants, 80 (70.2%) had normal lateral menisci and 34 (29.8%) had damaged lateral menisci. Multiple linear regression identified three variables significantly associated with greater quantitative pivot shift: time from injury to surgery (standardized partial regression coefficient (β) = 0.38, p = 0.000), knee extension angle (β = 0.29, p = 0.001), and presence of lateral meniscus injury (β = 0.29, p = 0.001). Other variables-including age, sex, anterior laxity, medial meniscus injury, femorotibial angle, and Tegner score-did not reach statistical significance. Three factors- prolonged time from injury to surgery, knee hyperextension, and lateral meniscus injury-were significantly associated with greater quantitative pivot shift in ACL-injured knees. The strongest predictor was the time elapsed between injury and surgery.