More Than 5.5 mm of Internal Rotational Tibial Subluxation Measured on Magnetic Resonance Imaging Predicts High‐Grade Pivot Shift Under Anesthesia in Patients With Primary Anterior Cruciate Ligament Injury

PURPOSE: To identify preoperative predictors for high-grade pivot shift under anesthesia in patients with primary anterior cruciate ligament (ACL) injury, with a particular focus on investigating the association between altered rotational tibiofemoral position measured on magnetic resonance imaging (MRI) and high-grade pivot shift. METHODS: Consecutive patients who underwent primary ACL reconstruction (ACLR) performed by the same senior surgeon between January 2022 and July 2024 were retrospectively reviewed. Patient characteristics, along with MRI measurements of anatomic features and tibiofemoral positions, were compared between the two groups. Multivariable logistic regression analysis was performed to identify predictors of high-grade pivot shift. Receiver operating characteristic (ROC) analyses were conducted to determine the optimal cutoff values for the identified predictors. RESULTS: A total of 52 patients with grade II or III pivot shift under anesthesia were included in this study, along with 156 age- and sex-matched controls exhibiting grade 0 or I pivot shift. ROC analysis indicated that the optimal cutoff value for internal rotational tibial subluxation (IRTS) to predict high-grade pivot shift was 5.5 mm (area under the curve [AUC] = 0.756). The multivariable prediction (AUC = 0.861) identified increased IRTS (odds ratio [OR] = 1.433), longer time from injury to surgery (OR = 1.737), Beighton score ≥ 4 (OR = 2.979), injury to the posterior horn of the lateral meniscus (OR = 3.587), and increased lateral femoral condyle ratio (LFCR; OR = 1.183) as significant predictors of high-grade pivot shift. CONCLUSIONS: Increased IRTS (threshold of 5.5 mm) showed notable diagnostic performance in predicting high-grade pivot shift. Additionally, longer time from injury to surgery, Beighton score ≥ 4, injury to the posterior horn of the lateral meniscus, and increased LFCR were also identified as significant predictors of high-grade pivot shift. LEVEL OF EVIDENCE: Level III, retrospective comparative case series.