Steeper posterior tibial slope increases the risk of anterior cruciate ligament rupture in a paediatric population.

Abstract

To determine whether posterior tibial slope (PTS) represents an independent risk factor for anterior cruciate ligament (ACL) rupture and to explore its association with concomitant intra-articular injuries within the ACL-injured group in a paediatric population. A retrospective case-control study was conducted, including 190 children (mean age 13.9 ± 1.9 years) with ACL reconstruction and 162 children (mean age 13.6 ± 1.7 years) undergoing medial patellofemoral ligament reconstruction as controls. PTS was measured on standard lateral radiographs and sagittal magnetic resonance imaging (MRI) using the two-circle method. Measurements were performed independently by two blinded raters. Interrater reliability was assessed with the intraclass correlation coefficient (ICC). Univariate and multivariate logistic regression analyses were performed to determine associations between PTS and ACL rupture. On radiographs, ACL-injured patients demonstrated a significantly steeper medial PTS (MPTS) compared with controls (9.9° ± 3.1° vs. 7.8° ± 4.3°, p < 0.001). Similar findings were observed on MRI (8.4° ± 2.8° vs. 5.0° ± 3.5°, p < 0.001). Interrater reliability was excellent for both modalities (ICC > 0.90). Multivariate analysis confirmed PTS as an independent predictor of ACL rupture: each additional 1° increase in MPTS was associated with a 14% higher odds of ACL injury (odds ratio [OR] 1.14, 95% confidence interval [CI]: 1.08-1.21, p < 0.001). Age, sex and body mass index were not significantly associated with ACL rupture. High MPTS is an independent anatomical risk factor for ACL rupture in children. Systematic measurement of PTS on radiographs or MRI should be considered during the evaluation of paediatric ACL injuries. Surgeons should be aware that children with a steep PTS may require more individualized surgical planning and follow-up. Level III.