Change in Posterior Tibial Slope in Skeletally Immature Patients With Anterior Cruciate Ligament Injury: A Case Series With a Mean 9 Years’ Follow-up

Abstract

Background: Increased lateral posterior tibial slope (LPTS) is associated with increased rates of anterior cruciate ligament (ACL) injury and failure of ACL reconstruction. It is unknown if ACL deficiency influences the developing proximal tibial physis and slope in skeletally immature patients through anterior tibial subluxation and abnormal force transmission. Purpose: To assess the natural history of LPTS in skeletally immature patients with an ACL-injured knee. Study Design: Case series; Level of evidence, 4. Methods: A total of 38 participants from a previous study on nonoperative management of ACL injury in skeletally immature patients were included. During the initial study, bilateral knee magnetic resonance imaging (MRI) was performed within 1 year of enrollment and again at final follow-up. All patients were younger than 13 years at the time of enrollment, and final follow-up occurred a mean 10 years after the injury. MRI scans were retrospectively reviewed by 2 reviewers to determine bilateral LPTS for each patient and each time point. Linear mixed models were used to assess LPTS differences between knees, change over time, and association with operational status. Subgroup analyses were performed for patients who remained nonoperated throughout the study. Results: A total of 22 patients had ACL reconstruction before final follow-up and 16 remained nonoperated. In the entire study population, the mean LPTS was higher in the injured knee than in the contralateral knee at final follow-up by 2.0° ( P < .001; 95% CI, 1.3°–2.6°). The mean LPTS increased significantly in the injured knee by 0.9° ( P = .042; 95% CI, 0.03°–1.7°), while the mean LPTS decreased in the contralateral knee by 0.4° ( P = .363; 95% CI, –0.8° to 0.4°). A significant difference in LPTS was also observed in the nonoperated subgroup. No significant association was observed between LPTS and operational status. Conclusion: Lateral posterior tibial slope increased more in the ACL-injured knee than in the contralateral uninjured knee in a group of skeletally immature patients. Lateral posterior tibial slope at baseline was not associated with the need for surgical reconstruction over the study period.

Graft Signal and Clinical Outcomes of Single-bundle Anterior Cruciate Ligament Reconstruction and Double-bundle ACLR: The Different Effects Related with Posterior Tibial Slope

“…In previous studies, some researchers believed that MTS could affect the prognosis of patients,[36] whereas others believed that LTS could play a greater role. [12,33,37] In this study, MTS and LTS both were risk factors that increased graft SI. Moreover, we believed that it is inappropriate to separate the MTS and LTS as two independent tibial anatomical factors.…”

What’s New in Pediatric Orthopaedics

“…The authors found that the posterior slope increased in the ACL-injured knee more than in the contralateral side over the study period. Twenty-two patients had ACL reconstruction during the study period and 16 did not, and the posterior tibial slope was not predictive of surgical intervention 53 .…”

Editorial Commentary: Increased Tibial Slope Is Associated With Anterior Cruciate Ligament Injury Risk, and Tibial Slope Increases in the Skeletally Immature, Anterior Cruciate Ligament-Deficient Knee: A Chicken or Egg Causality Dilemma?

“…5,6 Recent studies, however, are emphasizing a mutual influence, as tibial slope has been shown to increase over time in the ACLdeficient, skeletally immature knee. 7 It is hypothesized that altered biomechanics with enhanced posterior force transmission in the ACL-deficient knee may influence the developing physis, leading to altered longitudinal growth and increased tibial slope. In addition to tibial slope, the meniscal geometry, including meniscal bone angle and meniscal slope, have been shown to influence the risk of ACL injury.…”