Poster 48. Gait Biomechanics in Medial Meniscus Posterior Root Tears and Repairs: Assessing Established Risk Factors for Knee Osteoarthritis

Objective: A large proportion of individuals affected by medial meniscus posterior root (MMPR) tear progress to knee OA even after surgical repair. Gait analysis could assist in the identification of modifiable biomechanical (kinetic and kinematic) risk factors to optimize knee joint loading through gait modification interventions. The objective of this study was to define gait kinematics and kinetics in patients with MMPR tear and repair, compared to healthy, age-matched controls. We hypothesized that MMPR tear and repair patients would present altered gait characteristics associated with joint degeneration. Methods: In this cross-sectional study, a total of 58 knees were analyzed: MMPR tear (n=20), MMPR repair (n=21), and healthy controls (n=17) (Table 1). All individuals in the repair group had previously undergone transtibial pullout repair performed by a single fellowship-trained surgeon. Gait analysis was performed using a marker-based 3D motion capture system and force plates. Primary outcomes included knee joint kinematics and kinetics. Statistical comparisons were conducted using discrete analysis and Statistical Parametric Mapping to evaluate intergroup differences across the gait cycle. Patient-reported outcomes were also assessed using IKDC, KOOS Jr., VR-12, and VAS pain scores. Group comparisons were performed using the Kruskal-Wallis test. The significance level was set at 5%. Results: Both MMPR tear and repair groups exhibited increased varus thrust range of motion (Tear: 5.0° ± 2.1; Repair: 5.2° ± 2.0; Control: 3.3° ± 0.9), increased tibial internal rotation at loading response (Tear: -6.2° ± 5.3; Repair: -2.1° ± 3.6; Control: 2.2° ± 5.8), and greater knee adduction angle (varus) at midstance (Tear: 0.1° ± 3.9; Repair: -0.1° ± 5.0; Control: -5.9° ± 4.1) (Figure 1 and Table 2). The MMPR repair group exhibited higher functional scores (IKDC: 75.3 ± 19.9 vs. 43.6 ± 14.2; KOOS Jr.: 84.7 ± 15.4 vs. 59.7 ± 8.9), lower pain levels (VAS: 1.5 ± 2.1 vs. 3.8 ± 2.4) (Table 3), and higher tibial internal rotation compared to the tear group (p<0.05). Conclusions: The repair group demonstrated more favorable clinical and biomechanical characteristics than the tear group, however, both displayed established biomechanical risk factors for knee OA progression, such as varus thrust. Motion analysis can be used to detect early biomechanical dysfunction and may help identify MMPR tear and repair candidates for timely gait-modification interventions to optimize long-term joint health.