Summary

This large registry study illustrates that increased lateral posterior tibial slope is associated with higher rates of meniscus injury in acute ACL ruptures.

Abstract

Background

Increased posterior tibial slope has previously been associated with an elevated risk of anterior cruciate ligament (ACL) rupture. Recent studies have suggested there may be a relationship between posterior slope and meniscal tears in ACL ruptures, however, these studies have either included chronic ACL injuries, revision ACL reconstructions or an overall low number of study participants. The goal of this study is to leverage a large ACL registry to assess the impact of posterior tibial slope on meniscal tears in acute ACL ruptures.

Methods

Our institution’s ACL Registry was consulted to identify all patients between the age of 18 and 45 who underwent primary ACL reconstruction between Jan 2019 and July 2022 for acute, noncontact ACL rupture, defined as undergoing surgery within 90 days of injury. Patients with pre-existing meniscal pathology, chronic ACL reconstructions, revisions, multi-ligament knee injuries and nonoperatively managed ACL injuries were excluded. Preoperative MRIs were used to measure lateral and medial posterior tibial slope for all patients. Meniscal pathology seen in-situ during arthroscopy was recorded based on operative reports. Demographics data, including age, sex, and body mass index, were also recorded. Independent cohorts were created for our three main analyses based on the presence or absence of, firstly, any meniscal tear, secondly, any lateral meniscal tear and, thirdly, any medial meniscal tear. Two-tailed student’s t tests were used to compare average medial and lateral posterior tibial slopes between groups. Multiple regression was carried out to determine other risk factors for meniscal injury in this population.

Results

1055 patients ultimately met inclusion criteria. There were 346 (33%) patients with lateral meniscus tears, 245 (23%) patients with medial meniscus tears and 498 (47%) patients with any meniscal tear. The average lateral and medial posterior tibial slopes were 5.5 (-4.2 to 13.4) and 5.7 (0 to 15.7), respectively. Increased lateral tibial slope was associated with a statistically significant increase in rate of any meniscal tear (p<.005) and lateral meniscal tear, specifically (p<.005).

Conclusions

Increased lateral posterior tibial slope is associated with a higher rate of meniscus injury in acute ACL ruptures. This knowledge adds to the growing literature surrounding the impact of posterior tibial slope on ACL and meniscal injuries.