Magnetic Resonance Imaging-Derived Anterior Tibial Translation After Anterior Cruciate Ligament Reconstruction and Its Association With Postoperative Adverse Events: A Retrospective Cohort Study.

Abstract

Anterior tibial translation (ATT) measured on magnetic resonance imaging (MRI) is a reproducible marker of anterior cruciate ligament (ACL) deficiency. However, its longitudinal evolution after ACL reconstruction (ACLR) and its potential prognostic value for postoperative events remain uncertain. The purpose of this study was to quantify changes in lateral compartment ATT between preoperative and 9-month postoperative MRI after primary ACLR and to evaluate whether persistent abnormal ATT is associated with postoperative adverse events. This retrospective cohort study included 137 patients who underwent primary ACLR between 2018 and 2023 and had both preoperative and postoperative MRI at approximately 9 months. ATT was measured in the lateral compartment in knee extension using the method described by Tanaka et al. Change in ATT was defined as postoperative minus preoperative values. Abnormal ATT was defined as >6 mm, and resolution was defined as improvement from >6 mm preoperatively to ≤6 mm postoperatively. Pre- to postoperative changes were analyzed using paired t-tests for continuous variables and McNemar tests for categorical variables. Logistic regression models adjusted for age, sex, and body mass index evaluated associations between ATT measures and postoperative events (graft re-rupture, contralateral ACL tear, and new postoperative meniscal injury) during clinical follow-up. Mean ATT decreased from 9.1 ± 2.8 mm preoperatively to 7.3 ± 2.3 mm postoperatively (mean change -1.8 ± 2.2 mm; p < 0.001). The proportion of patients with abnormal ATT (>6 mm) decreased from 91.2% preoperatively to 65.7% postoperatively (p < 0.001), with 25.5% of patients meeting criteria for ATT resolution. During follow-up, postoperative events included graft re-rupture, contralateral ACL tear, and new meniscal injury. In adjusted analyses, no statistically significant association was observed between change in ATT or ATT resolution and postoperative events. Anterior tibial translation measured on MRI showed a statistically significant improvement after primary ACLR, although complete normalization was observed in only a minority of patients. Within the statistical power of this cohort, no statistically significant association was observed between MRI-derived ATT measured at 9 months and graft re-rupture, contralateral ACL injury, or postoperative meniscal injury. III.