Abstract

Objective: To investigate the effects of personalized, adaptive, current-steering functional electrical stimulation (FES) of the lower leg to improve gait in people with foot drop.

Design: A one group, pre-test, post-test study.

Setting: Two gait analysis centers.

Participants: Thirty-two participants exhibiting symptoms of foot drop.

Interventions: Adaptive, current-steering FES enables precise control over dorsiflexor and evertor muscles, allowing for personalized treatment to correct key foot drop characteristics including dorsiflexion at heel strike and ankle inversion during swing phase. All participants received adaptive FES of the dorsiflexors and evertors during backto- back walking sets. Participants completed up to three walking sets of unstimulated walking (pre-test) followed by lower-leg stimulated walking (post-test).

Main outcomes measures: The primary outcome measures include ankle dorsiflexion at heel strike and mean ankle inversion during swing phase. Secondary outcome measures include foot angle at heel strike and single-side heel strike to toe strike time (heel-toe time).

Results: The differences in pre-test versus post-test primary and secondary outcome measures were statistically significant (p <0.0125) within our cohort. With adaptive, current-steering FES, ankle dorsiflexion at heel strike increased an average 5.2°, and ankle inversion during swing phase was reduced by an average -3.6°, bringing the ankle to a more neutral position for stabilization.

Conclusion: Gait augmentation using adaptive, current steering FES improved gait in a population exhibiting symptoms of foot drop. By significantly increasing ankle dorsiflexion at heel strike and decreasing ankle inversion during swing phase, adaptive FES enabled a more neutral ankle at heel strike, which is associated with greater ankle stability and decreased fall risk.