Effect of meniscus repair on pivot-shift during anterior cruciate ligament reconstruction: Objective evaluation using triaxial accelerometer

Background: Some types of meniscus tear, especially lateral meniscus tear, have been reported to be associated with rotatory knee laxity. However, precise information regarding the effect of meniscus repair on rotatory laxity is limited. The purpose of this study was to investigate the effects of lateral and medial meniscus repair on rotatory laxity in anterior cruciate ligament (ACL) injured knees. Methods: Forty-one patients who underwent ACL reconstruction were included in the study. The tibial acceleration during the pivot shift test was measured using a triaxial accelerometer preoperatively under anesthesia and intraoperatively before and after medial and lateral meniscus repair and ACL reconstruction during surgery. Effects of meniscus tear and its repair on rotatory laxity were analyzed. Results: Preoperative measurements revealed that patients with lateral meniscus tear showed significantly higher tibial acceleration compared to the patients without meniscus tear (P = 0.006). Intraoperative measurements revealed that medial and lateral meniscus repair significantly reduced tibial acceleration by 1.46 m/s2 (P = 0.002) and 1.91 m/s2 (P < 0.001), respectively. Conclusion: In ACL injured knees, knees with lateral meniscus tear showed greater rotatory laxity compared to the knees without meniscus tear. In addition, lateral meniscus repair, and to a lesser degree medial meniscus repair, reduced rotatory laxity during ACL reconstruction surgery. Therefore, the meniscus should be repaired as much as possible for its role as a secondary stabilizer of rotatory laxity. Besides, the effect of meniscus repair on rotatory laxity should be considered when the indication of anterolateral augmentation is determined.