Contributions of Ankle, Knee, Hip, and Trunk Muscle Function to Gait Performance in People With Multiple Sclerosis: A Cross-Sectional Analysis

Background. The relative importance of lower extremity and trunk muscle function to gait in people with multiple sclerosis (MS) is unknown. Objective. This study aimed to investigate the association of lower extremity and trunk muscle function with gait performance in people who have MS and mild-to-moderate disability. Design. This was a cross-sectional, observational study. Methods. Participants were people who had an Expanded Disability Status Scale score of <= 5.5. Eleven lower extremity and trunk muscles were assessed using handheld dynamometry or endurance tests. Gait performance was assessed with the Timed 25-Foot (7.62 m) Walk (T25FW) and 6-Minute Walk Test (6MWT). Regression analysis was used to quantify the association between gait outcomes and muscle variables. Results. Seventy-two participants with MS and a mean Expanded Disability Status Scale score of 3.5 (SD = 1.14) were enrolled. Adjusted for age and sex, the multivariate model including hip abduction, ankle plantar flexion, trunk flexion, and knee flexion explained 57% of the adjusted variance in the T25FW; hip abduction, ankle plantar flexion, and trunk flexion explained 61% of the adjusted variance in the 6MWT. The strongest predictors were ankle plantar flexion endurance for the T25FW and hip abduction strength for the 6MWT: a 1-SD increase in ankle plantar flexion (15.2 heel-raise repetitions) was associated with a 0.33-second reduction in the T25WT (95% CI = -0.71 to -0.14 seconds); a 1-SD increase in normalized hip abduction strength (0.14 kg/body mass index) was associated with a 54.4-m increase in the 6MWT (28.99 to 79.81 m). Limitations. Different measurement scales for independent variables were included because the muscle function assessment used either force or endurance. Conclusions. For the major muscles in the lower extremity and trunk, hip abduction, ankle plantar flexion, trunk flexion, and knee flexion were the strongest predictors of gait performance.