# Difference in anterior tibial subluxation measured with the bone axis method predicts high‐grade pivot shift in ACL‐deficient knees: A multicenter cohort study

## TL;DR

This study shows that a specific MRI measurement method can predict severe knee instability in ACL-injured patients, helping guide surgical planning.

## Contribution

The study identifies the bone axis method for measuring anterior tibial subluxation as the best predictor of high-grade pivot shift in ACL-deficient knees.

## Key findings

- D-ATS measured with BAM had the highest ROC-AUC (0.675) for predicting high-grade pivot shift.
- A D-ATS value ≥3.8 mm using BAM was an independent predictor of high-grade pivot shift.
- Female sex, contralateral knee hyperextension, and medial meniscal injury also predicted high-grade pivot shift.

## Abstract

To determine which magnetic resonance imaging (MRI)‐based anterior tibial subluxation (ATS) measurement best reflects rotational instability under anaesthesia in anterior cruciate ligament (ACL)‐injured patients.

This retrospective multicenter cohort study included 291 patients who underwent ACL reconstruction between October 2022 and December 2024. Preoperative MRI measurements of lateral ATS (L‐ATS) and difference between lateral and medial ATS (D‐ATS) were obtained using the plateau method (PM) and the bone axis method (BAM). Rotational instability was assessed under anaesthesia using the pivot shift test and categorized as low‐grade (LG‐PS) or high‐grade (HG‐PS). Receiver operating characteristic (ROC) curve analysis was performed to evaluate the discriminative ability of each measurement. Using the cutoff value derived from the Youden index of the ATS parameter that demonstrated the largest ROC‐AUC, multivariate logistic regression identified independent predictors of HG‐PS.

Compared with the LG‐PS group, D‐ATS measured with PM (p < 0.001) and both L‐ATS and D‐ATS measured with BAM (p = 0.035 and p < 0.001, respectively) were greater in the HG‐PS group. D‐ATS measured with BAM demonstrated the highest ROC‐AUC (0.675) among measurement methods, with a cutoff value of 3.8 mm. In multivariate analysis, D‐ATS measured with BAM ≥ 3.8 mm (odds ratio [OR]: 3.92, p < 0.001), female sex (OR: 1.88, p = 0.025), contralateral knee hyperextension (OR: 3.70, p < 0.001) and medial meniscal injury (OR: 2.27, p = 0.004) were independent predictors of HG‐PS.

Among MRI‐based methods for measuring ATS in ACL‐injured knees, D‐ATS measured with BAM best reflected pivot shift grade under anaesthesia and was an independent predictor of HG‐PS. A D‐ATS measured with BAM value ≥ 3.8 mm may help identify patients at risk of rotational instability and, in combination with other clinical factors, assist preoperative surgical planning.

Level III, cohort study.