Summary

Knee rotation predicts ALL injury and pivot-shift grading

Abstract

Introduction

While MRI and clinical examination reliably diagnose anterior cruciate ligament (ACL) injuries, accurately assessing concomitant injuries, such as anterolateral ligament (ALL) tears, remains difficult. The pivot-shift test is effective for evaluating anterolateral rotatory laxity, but its assessment can be hindered by patient discomfort, particularly during the early stages. This study aims to evaluate the association between tibiofemoral rotation, concurrent ALL injury, and pivot-shift grading in patients with ACL tears.

Methods

This multicenter cross-sectional study, serving as a secondary analysis of previous research, involved reviewing medical records and MRI scans of patients with unilateral primary ACL injuries. Data on demographics and pivot-shift grading were collected. The anterolateral ligament was identified and classified as either intact or injured based on coronal MRI images. Tibiofemoral rotation angle (TFA) was measured from axial MRI scans. The optimal TFA cutoff for predicting ALL injury was determined using a receiver operating characteristic (ROC) curve.

Results

The study included 206 patients with a mean age of 28.3 ± 11.3 years. Of these, 152 patients (73.8%) showed evidence of ALL injury. Most pivot-shift tests were graded as 2 (71.4%), and all grade 3 pivot-shift assessments were associated with ALL injury. The average TFA was 4.5 ± 3.8 degrees, significantly higher in patients with ALL injury (5.2 ± 3.6 degrees) compared to those with an intact ALL (2.7 ± 3.5 degrees; p < 0.001). A positive correlation was found between pivot-shift grading and TFA (r = 0.204, p = 0.003). The optimal TFA cutoff for predicting ALL injury was 2.5 degrees, with a sensitivity of 0.77 and a specificity of 0.55. Patients with a TFA = 2.5 degrees had a significantly increased risk of ALL injury (OR 3.34, 95% CI: 1.74 to 6.42, p < 0.001). When a TFA of 2.5 degrees or greater was combined with a pivot-shift grade of 2 or 3, the risk of ALL injury rose substantially to 13.68 (95% CI: 6.29 to 29.84, p < 0.001)

Conclusion

In ACL-deficient patients, an increased TFA was linked to a greater prevalence of ALL injuries and more severe pivot-shift grades. Patients with a TFA = 2.5 degrees were three times more likely to have ALL injuries at the time of ACL injury, with this risk increasing further with higher-grade pivot-shifts. Therefore, evaluating TFA in patients undergoing ACL reconstruction can help determine the need for concomitant anterolateral reconstruction, especially when a high-grade pivot-shift is present.