Julien Druel, Romir Patel, Christophe Jacquet, Lyes Chaal, Antoine Piercecchi, Matthieu Ollivier
PTS was independently associated with ACL injury and ACL re-rupture, whereas age, sex and BMI had no clinically meaningful independent influence. PTS should be interpreted as one component of a multifactorial anatomical risk profile rather than as a standalone screening test.
PURPOSE: To determine whether posterior tibial slope (PTS), measured on lateral radiographs using the proximal anatomical tibial axis defined by two circles, is independently associated with anterior cruciate ligament (ACL) injury status or influenced by age, sex and body mass index (BMI).
METHODS: A retrospective single-centre cohort study included all 1406 consecutive eligible patients operated between January 2010 and September 2024: 857 ACL-intact controls undergoing medial patellofemoral ligament reconstruction, 498 patients with primary ACL rupture and 51 patients with ACL re-rupture. PTS was measured on standardized lateral radiographs using the proximal anatomical tibial axis defined by two circles. Multivariable linear regression evaluated the independent associations of ACL status, age, sex and BMI with PTS. Receiver operating characteristic (ROC) analyses assessed discrimination of ACL injury.
RESULTS: Mean PTS was 7.3 ± 3.1° in controls, 9.9 ± 3.1° in patients with primary ACL rupture and 10.9 ± 3.5° in patients with ACL re-rupture (p < 0.001). Intraobserver and interobserver reliability were good to excellent (intraclass correlation coefficient [ICC] = 0.88) and moderate to good (ICC = 0.81). Multivariable analysis demonstrated that ACL injury status was the dominant independent determinant of PTS. Compared with controls, primary ACL rupture and ACL re-rupture were associated with 2.52° and 3.63° greater PTS, respectively (both p < 0.001). Age showed a minimal inverse association (-0.019° per year; 95% confidence interval [CI], -0.036° to -0.003°; p = 0.024), whereas sex and BMI were not independently associated with PTS. ROC analysis identified a Youden-derived value of 10°, with an area under the curve of 0.731 (95% CI, 0.705-0.758) for primary ACL rupture and 0.791 (95% CI, 0.741-0.841) for ACL re-rupture.
CONCLUSION: PTS was independently associated with ACL injury and ACL re-rupture, whereas age, sex and BMI had no clinically meaningful independent influence. PTS should be interpreted as one component of a multifactorial anatomical risk profile rather than as a standalone screening test.
LEVEL OF EVIDENCE: Level III, retrospective comparative cohort study.