Augmenting gait in a population exhibiting foot drop with adaptive functional electrical stimulation

Functional electrical stimulation (FES) can be used for improvement of gait in people with foot drop resulting from neurological disease or injury. However, existing FES solutions suffer from significant limitations. First, fixed placement electrode devices are difficult to tune stimulation for improved ankle dorsiflexion while maintaining balanced ankle eversion. Second, standard tilt-sensor-like triggers do not allow for adaptive, configurable stimulation sequencing algorithms. Here, we introduce the first FES system with adaptive current steering for an array of FES electrodes enabling 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. We share results of a pre-test, post-test study on thirty-two participants exhibiting symptoms of foot drop. 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. 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. Gait augmentation using adaptive, current-steering FES improved gait in a population exhibiting symptoms of foot drop. ### Competing Interest Statement J.R., and R.W. are employed by CIONIC Inc. R.G. and B.B. are consultants for CIONIC Inc. D.A. is a former employee of CIONIC Inc. D.W. research is funded in part by CIONIC Inc. ### Clinical Trial NCT05346640 ### Funding Statement This study was funded by CIONIC, Inc. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The present study was carried out according to the Declaration of Helsinki. Participation was voluntary and based on written informed consent from the participant. The study has been approved by the Institutional Review Board at Ethical &; Independent Review Services (E&I 21039-01A) and the Institutional Review Board at Cleveland State University (IRB-FY2021-301). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors.