Summary

Although proximal tibial articular surface tilt has been associated with ACL injury, this study found that tilt of the more posterior portion of the lateral tibial articular surface was associated with ACL injury.

Abstract

Introduction

Large posterior tibial slope (PTS) has been reported to be a risk factor for Noncontact ACL injury, but many of these reports are plain x-ray assessments that do not allow individual assessment of the medial and lateral sides of the PTS. In a report in which PTS was evaluated separately on the medial and lateral sides using MRI, it was reported that the Meniscus slope (MS) was large in the ACL-injured knee. We hypothesized that the cartilage tilt of the tibial articular surface is associated with ACL injury.

Methods

Patients:
we reviewed an institutional database of consecutive patients (age 10-39 years) who sustained noncontact ACL tears and ultimately underwent ACL reconstruction. Patients were excluded if they sustained a multi-ligament knee injury. MRIs for all ACL-injured subjects were obtained between 2002 and 2020 and included 50 patients. Age- and sex-matched controls who had knee MRIs for knee pain between 2015 and 2020 were selected for comparison..
Measured Data:
The previously used methods (Hashemi et al.) were performed to measure medial (lateral) posterior tibial slope (mPTS, lPTS) and medial (lateral) meniscus slope (mMS, lMS). In addition to these parameters, two newly devised parameters were measured. The line connecting the lowest point and the rearmost point of the anterior portion of the meniscus was defined as alCS, and the line connecting the foremost point and lowest points of the posterior portion of the meniscus was defined as plCS.
Statistical Analysis:
We used t-tests to compare the averages of continuous variables between the groups. Multivariable logistic regression analysis was used to identify potential risk factors. All statistical analyses were conducted using SPSS version 23 statistical software package (IBM-SPSS, Inc., Chicago, IL). The threshold for significance was P<0.05.

Results

In the ACL group, lPTS (8.3° vs 6.5°), lMS (4.1° vs 1.7°), and plCS (22.0° vs 16.6°) were significantly larger than those in the control group. A subgroup analysis by gender showed that there was no difference between the ACL group and the Control group in any of the parameters in females, but lPTS, lMS and plCS were significantly larger in the ACL group in males. The multivariable logistic regression analysis reveals that ACL injury was significantly associated with plCS (OR 1.112; 95% CI 1.043–1.185).

Discussion

The most important finding of this study was that the ACL group had larger lPTS, lMS and plCS than the Control group, and plCS was an independent risk factor for ACL rupture.
Previous reports have reported that greater PTS or MS is a risk for ACL injury, but in this study, plCS was a risk factor for ACL injury. Greater tilt of the more posterior portion of the lateral tibial articular surface may be more likely to be subjected to rotational forces.

Conclusion

The morphology of the lateral tibial articular surface was associated with ACL injury. In particular, a large posterior cartilage inclination was a risk factor.