A Smaller Posterior Tibial Slope May Be Associated with an Increased Risk of Tears in the Anterior Horn of the Lateral Meniscus

Abstract

Background: While lateral meniscus anterior horn (LMAH) tears can increase peak contact pressure in the knee joint, limited research has explored the correlation between LMAH tears and posterior tibial slope (PTS), closely associated with knee joint kinematics. This study aimed to investigate the association between PTS and LMAH tears. It was hypothesized that patients with LMAH tears would exhibit lower PTS values compared to those without such tears. Methods: This study retrospectively included 35 patients with isolated LMAH tears and 83 patients with no pathological findings on magnetic resonance imaging (MRI) between January 2010 and October 2023. PTS was measured using the medial tibial plateau on lateral radiographs, while both the medial and lateral slopes were separately evaluated on MRI. Group comparisons and multi-variable logistic regression were performed, with inverse probability of treatment weighting (IPTW) applied to adjust baseline differences. Receiver operating characteristic (ROC) analysis was conducted to determine a threshold value. Tear types and treatment methods were also analyzed. Results: The mean PTS was significantly smaller in the LMAH tear group (LMAH tear group, 4.70 degrees +/- 2.16 degrees; control group, 6.58 degrees +/- 2.95 degrees, p < 0.001), while MRI-based medial PTS (LMAH tear group, 4.62 degrees +/- 2.43 degrees; control group, 4.81 degrees +/- 2.35 degrees; p = 0.702) and lateral PTS (LMAH tear group, 4.02 degrees +/- 2.24 degrees; control group, 4.78 degrees +/- 2.39 degrees; p = 0.115) showed no significant differences. In multivariable logistic regression, the adjusted odds ratio of PTS in the LMAH tear group was 0.76, indicating that for each 1 degrees decrease in PTS, the odds of an LMAH tear increased approximately 1.32 times (95% CI, 0.62-0.93; p = 0.009). After IPTW matching, mean PTS remained significantly smaller in the LMAH tear group (p = 0.006). The ROC curve analysis identified a PTS cutoff value of 4.49 degrees for distinguishing LMAH tear from controls, and PTS < 4.49 degrees was significantly associated with LMAH tear (odds ratio, 0.25; 95% CI, 0.11-0.60; p = 0.001). Tear types showed no significant differences in PTS, but treatment methods varied significantly, with repair more frequent in simple tears and meniscectomy in degenerative or complex tears. Conclusions: A smaller PTS be associated with an increased risk of LMAH tears.