Age-Stratified Comparison of Gait Biomechanics in People with Relapsing–Remitting Multiple Sclerosis and Healthy Individuals: An Exploratory Cross-Sectional Study

Background and Objectives: Gait impairment is a common and disabling manifestation of multiple sclerosis, affecting mobility, independence, and quality of life. However, gait differences between people with multiple sclerosis and healthy individuals have not been well characterized within corresponding age strata. Methods: This exploratory cross-sectional study included 23 participants with relapsing–remitting multiple sclerosis and 50 healthy individuals aged 20–69 years. Participants underwent instrumented gait analysis at self-selected walking speed using a Vicon motion-capture system synchronized with force plates. Spatiotemporal parameters, lower-limb and pelvic kinematics, and ground reaction forces were assessed. Between-group comparisons were performed within predefined age strata (20–39, 40–49, 50–59, and 60–69 years) using one-dimensional Statistical Parametric Mapping and non-parametric analyses. Results: Across age strata, participants with relapsing–remitting multiple sclerosis generally showed slower walking and shorter stride-related measures, together with phase-specific multi-joint kinematic and ground reaction force deviations. Estimated gait-speed and stride-length differences were largest in the youngest stratum, whereas mean stride width was 0.04 m greater in both the youngest and oldest strata; however, confidence intervals were wide, and no between-stratum contrast was tested. Exploratory threshold crossings were not interpreted as evidence that the underlying effects differed among strata. Conclusions: The age-stratified, participant-level analysis identified recurrent differences in forward progression, lower-limb and pelvic kinematics, and loading and propulsion. These findings provide a quantitative description that may support individualized gait assessment and hypothesis generation for adequately powered studies. They do not establish an independent effect of age or an age-by-disease interaction.