Relative changes in ankle and hip control during bilateral joint movements in persons with multiple sclerosis

•Impairments in coordination of the hips and ankles in people with MS were documented by negative work during imposed bilateral leg movements.•Measurements of negative work at the hip, but not the ankle, were correlated to clinical measures of balance and gait speed in people with MS.•These results suggest that people with MS rely more strongly on hip control than ankle control for functional balance and walking.

ObjectiveThe purpose of this study was to quantify hip and ankle impairments contributing to movement dysfunction in multiple sclerosis (MS).MethodsVolitional phasing of bilateral hip and ankle torques was assessed using a load-cell-instrumented servomotor drive system in ten participants with MS and 10 age-matched healthy participants. The hips and ankles were separately bilaterally oscillated 180° out of phase (40° range of motion) at a frequency of 0.75 Hz while the other joints were held stationary. Participants were instructed to assist in the same direction as the robot-imposed movement. The hip and ankle torques were measured and work was calculated for each movement.ResultsTotal negative work at the ankle was significantly different between groups (p = 0.040). The participants with MS produced larger negative work during hip flexion (p = 0.042) and ankle flexion (p = 0.037). Negative work at the hip was significantly correlated with the Berg Balance Scores and Timed 25 Feet Walk Test, and trends demonstrated increasing negative work with increasing clinical impairment in MS.ConclusionsThese results suggest an increased importance of the hip in functional balance and gait in MS.SignificanceRehabilitation strategies targeting ankle recovery or compensation using the hip might improve movement function in MS.