Medial Meniscal Posterior Root Tears Are Associated With Steeper Medial Posterior Tibial Slope and Varus Alignment

Abstract

Purpose

To analyze a series of cases with and without medial meniscal posterior root tears (MMPRTs) to determine whether varus alignment and increased sagittal medial tibial slope (MTS) are risk factors for MMPRTs.

Methods

The study evaluated 2 groups of patients: The tear group included patients with arthroscopically confirmed MMPRTs, and the no-tear group consisted of control patients matched to the tear group who underwent similar imaging but did not have meniscal root tears. Age, sex, side of injury, and body mass index were recorded for all cases. Preoperative joint space height and Kellgren-Lawrence grade were measured on radiographs. Group matching was performed based on demographic factors (age, sex, and body mass index), joint space height, and Kellgren-Lawrence grade. Mechanical axis measurements were determined from full-limb-length radiographs. MTS was analyzed on preoperative magnetic resonance imaging. Two observers performed the measurements on 2 separate occasions, and intraobserver reliability and interobserver reliability were analyzed using the intraclass correlation coefficient (ICC). Multivariate regression analysis was performed to identify potential risk factors associated with MMPRTs.

Results

Of the 142 matched patients included, 76 had root tears (tear group) and 66 did not (no-tear group). Both mechanical axis (183.2° ± 3.2° vs 181.2° ± 2.3°) and MTS (4° ± 1.9° vs 2.4° ± 2.5°) measurements were significantly greater in the tear group (P < .01 for each). However, despite the statistical significance, the small degrees of difference between the groups raises questions about the clinical significance. The intraobserver ICCs were 0.98 and 0.99 for mechanical axis and 0.87 and 0.98 for MTS. The interobserver ICCs showed excellent reliability for mechanical axis (0.95) and good reliability for MTS (0.77). The lower intraobserver and interobserver reliabilities for MTS measurements also suggest a higher likelihood of error. The multivariate logistic regression model indicated that the risk of sustaining an MMPRT increased with varus alignment (odds ratio, 1.268; 95% confidence interval, 1.104-1.478; P = .001) and increased MTS (odds ratio, 1.364; 95% confidence interval, 1.137-1.677; P = .002).

Conclusions

In this study, MMPRTs were associated with varus alignment and steeper MTS. However, the clinical significance of these associations may be limited owing to the small differences between the groups.

Level of Evidence

Level III, retrospective case-control study.