Gait Kinetics in Medial Meniscus Posterior Root Tears: Investigating Protective Strategies and the Effects of Root Repair

Abstract

Objectives To investigate changes in external moments in medial meniscus posterior root tear (MMPRT) patients, and the effect of medial meniscus posterior root repair (MMPRR) in restoring normal kinetics. Methods We present preliminary findings from six subjects with MMPRT, four with MMPRR, and three healthy age-matched control participants (CON). Participants walked on level ground at a self-selected gait speed. Data were collected using high-speed cameras and ground-embedded force plates. Peak knee moments for flexion-extension (KFM and KEM), abduction-adduction (KAbM, KAdM), and internal-external rotation (KERM, KIRM) were calculated using inverse dynamics during the stance phase of gait, and normalized to body mass and height. Group comparisons were conducted using the Kruskal-Wallis and Dunn test with Bonferroni correction. Results were considered statistically significant if p-values were less than 0.05. Results Both MMPRT and MMPRR groups exhibited significantly lower KFM relative to the CON group, suggesting a strategy to reduce quadriceps activation in both patient groups, which may persist after surgery. MMPRT patients showed significantly diminished KEM relative to both MMR and CON groups, indicating a strategy to reduce external knee forces following injury. MMPRR patients presented KEM that resembled the healthy control group, showing that repair surgery could potentially restore this gait variable. KAbM was statistically higher in the MMPRR and CON groups relative to MMPRT patients, which presented lower KAM than the other groups, suggesting a protective strategy to offload the medial compartment. KERM were significantly higher in the CON group compared to the MMT group, suggesting a protective strategy to avoid excessive external rotation by the MMT group. No significant differences were observed in KIRM across the three groups. Conclusion MMPRT leads to alterations in gait kinetics, compatible with a protective strategy to unload the knee and compensate for increased medial compartment contact pressures, which are partially restored following root repair.