Meniscal Bone Angle Is a Strong Predictor of Anterior Cruciate Ligament Injury.

Purpose: To evaluate the influence of lateral posterior tibial slope (LPTS) and meniscal bone angle (MBA) on primary anterior cruciate ligament (ACL) tear risk in an adult population through the LPTS-MBA ratio.

Methods: A retrospective case-control study was performed with patients from a tertiary hospital who underwent primary ACL surgery and had preoperative magnetic resonance imaging (MRI). These subjects were matched by age and sex in a 1:1 ratio to patients who had an MRI without ACL tear. LPTS and MBA were measured on MRI scan. Quantitative data are presented in the median ± interquartile range (IQR). Identification of independent risk factors for primary ACL tear was performed using multivariable logistic regression. Receiver operating characteristics curves detected any variable with strong discriminative capacity.

Results: In total, 95 patients with primary ACL tear confirmed on MRI were matched with 95 controls (N = 190). Nearly 80% were male subjects, with a median age of 26 years. In the ACL tear group, the median value of LPTS-MBA ratio was 0.20 (IQR 0.11-0.37) versus 0.12 (IQR 0.08-0.19) in the control group ( = .001). LPTS had a median value of 4.20° in the ACL tear group (IQR 2.05-7.35°) and 2.90° in the control group (IQR, 2.05-5.00°) ( = .026), whereas MBA was 19° (IQR, 16-24°) versus 26° (IQR, 24-30°) ( = .001), respectively. Logistic regression showed that LPTS (odds ratio 1.20, 95% confidence interval 1.03-1.42,  = .021) and MBA (odds ratio 0.78, 95% confidence interval 0.71-0.85,  = .001) were independent predictors. The area under the curve (AUC) of LPTS-MBA ratio was 0.69, greater than that of LPTS alone (AUC = 0.61) but lower than that for MBA (AUC = 0.82).

Conclusions: In this study, a reduced MBA was the strongest predictive variable associated with a primary ACL tear. A threshold of 22.35° of MBA was associated with an increased risk of ACL tear, with a sensitivity of 70% and specificity of 84%. A cut-off of 0.22 of LPTS-MBA was associated with an increased risk of ACL tear, with a sensitivity of 55% and specificity of 87%.

Level Of Evidence: Level III, case-control study.