Summary

The pathogenicity of medial meniscus ramp lesions in ACL injuries remains unclear. In this study, the existence of a ramp lesion was associated with a hyperlaxity of the non-injured knee in internal rotation. This hyperlaxity may have increased the risk of appearance of the ramp lesion in non-contact ACL tears.

Abstract

Introduction

Despite a recent growing interest, little information is available on the pathogenicity of ramp lesions of the medial meniscus in anterior cruciate ligament (ACL) injuries. The purpose of the study was to compare anterior and rotational knee laxity of the non-injured knee in ACL-injured patients with a ramp lesion and those without. Our hypothesis was that the presence of a ramp lesion in ACL-injured patients was associated with an increased knee laxity of the non-injured knee.

Material And Methods

Between March 2011 and October 2015, patients undergoing an ACL reconstruction performed by a single surgeon were included if (1) they had a non-contact ACL injury (2) they had no previous ACL injury of the contralateral knee (3) they could be tested for anterior and rotational knee laxity on their non-injured knee before the surgery. The presence or absence of a ramp lesion was determined by a systematic arthroscopic inspection of the posteromedial compartment. Scores based on the laxity of the non-injured knee were calculated as previously published [1] and each patient was classified as being normolax if the obtained score was below 1 or hyperlax for scores equal or superior to 1. Chi-square tests were used to compare the population of ACL-injured patients with and without a ramp lesion regarding their category of laxity in anterior displacement, internal and external rotation of their non-injured knee. Logistic regressions were performed to determine the odds ratio (OR) for significant parameters. Significance was set at p<0.05. All patients signed a written informed consent. The study protocol had previously been approved by the National Ethics Committee for Research.

Results

Eighty-two patients met the inclusion criteria. Eighteen of these patients (22%) had an arthroscopically confirmed medial meniscus ramp lesion. The percentage of patients being hyperlax for anterior displacement or external rotation did not differ between patients with or without a ramp lesion. However, 43% (6 out of 14; average score: 1.4±0.3) of patients being hyperlax in internal rotation had a ramp lesion versus 18% (12 out of 68 average score: -0.3±0.8) of patients being normolax in internal rotation (p=0.04). Patients with hyperlaxity in internal rotation of the non-injured knee had a greater probability of having a ramp lesion (OR: 3.5 [95% CI 1.03-11.96]).

Discussion

We confirmed that the presence of a ramp lesion was significantly associated with patients being hyperlax in internal rotation of their non-injured knee. This hyperlaxity may have increased the risk of having a ramp lesion in ACL-injured patients.

Conclusion

In patients with a non-contact ACL injury, ramp lesions are more likely to occur in those being hyperlax in internal rotation. Their diagnosis is mandatory to improve the understanding of peripheral lesions associated to ACL injuries. So far, it appears unclear if the reported relationship is of causal nature.

[1] Mouton C, Seil R, et al. (2015) Combined anterior and rotational laxity measurements allow characterizing personal knee laxity profiles in healthy individuals. Knee Surg Sports Traumatol Arthrosc 23: 3571-7.