Abstract:Objective To analyze the influencing factors of old anterior cruciate ligament (ACL) injury with medial meniscus tear.Methods The clinical data of 200 patients with old ACL injury in Changde First Hospital of Traditional Chinese Medicine from September 2018 to October 2021 were analyzed retrospectively.The patients were divided into study group (with medial meniscus tear) and control group (with normal medial meniscus),with 100 cases in each group.All patients were scanned by magnetic resonance imaging to measure the anatomical parameters of the knee joint(knee varus angle,ACL tibial stop width,medial tibial plateau retroversion angle,tibial coronal inclination angle,medial tibial plateau depth).The anatomical parameters of knee joint were compared between the two groups,and the influencing factors of medial meniscus tear were analyzed by logistic regression model.Results The knee varus angle,medial tibial plateau retroversion angle and tibial coronal inclination angle of the study group were greater than those of the control group,and the ACL tibial insertion width and medial tibial plateau depth were less than those of the control group,the differences were statistically significant (P<0.05).Multivariate logistic analysis showed that the decrease of medial tibial plateau depth (OR=1.152),the increase of tibial coronal inclination angle (OR=1.279),the decrease of ACL tibial stop width (OR=1.346),the increase of knee varus angle (OR=1.769) and the increase of medial tibial plateau caster angle (OR=1.957) were the risk factors of medial meniscus tear in patients with old ACL injury (P<0.05).Conclusion There is an influence mechanism between medial meniscus tear and tibial plateau caster.The increase of medial tibial caster is a risk factor for medial meniscus tear in patients with old ACL injury.