An Investigation of the Effect of Modifying Stimulation Profile Shape on the Loading Response Phase of Gait, during...

Drop foot stimulators today operate open loop with a trapezoidal stimulation profile. The traditionally applied profile originated as much from technological constraints as suitability for the physical pathology. It was proposed that by increasing the stimulation intensity during the loading response phase of gait, the ankle angle trajectory would become closer to that of normal gait and a more efficient heel rocker would be introduced. One patient, who used an implanted stimulator, was tested. Various profiles, which provided increased stimulation during loading response, were tried and joint angle trajectories, electromyograms, and footswitches were recorded. Statistical analysis was performed using a one way anova and posthoc Tukey tests. The experiment showed that increasing stimulation intensity during loading response increased the duration of the heel rocker. Statistical analysis revealed that this was significant at p = 0.05 level. Increasing stimulation intensity during loading response prolongs the heel rocker. This is an essential mechanism for advancement over the stance limb and providing shock absorption during weight acceptance, thus, we conclude that this improves the gait pattern of the drop foot sufferer.