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The development of a potential optimized stimulation intensity envelope for drop foot applications
Derek T O'Keeffe1, Alan E Donnelly, Gerard M Lyons
1Biomedical Electronics Laboratory, Department of Electronic and Computer Engineering, University of Limerick, Limerick, Ireland. derek.okeeffe@ul.ie
Summary
A new functional electrical stimulation (FES) intensity profile optimizes drop foot treatment by mimicking natural muscle activity. This approach improves upon traditional methods for better gait restoration in hemiplegic patients.
Area of Science:
- Biomedical Engineering
- Neurorehabilitation
- Biomechanics
Background:
- Hemiplegic drop foot impairs gait due to impaired ankle dorsiflexion.
- Traditional functional electrical stimulation (FES) uses a trapezoidal intensity profile.
- This trapezoidal profile does not align with natural tibialis anterior (TA) muscle activation during gait.
Purpose of the Study:
- To develop an optimized stimulation intensity envelope for hemiplegic drop foot.
- To compare the optimized profile against the traditional trapezoidal approach.
- To improve the naturalness of FES-elicited muscle activation for better gait rehabilitation.
Main Methods:
- Collected experimental FES-elicited tibialis anterior (TA) electromyography (EMG) data during various ankle movements.
- Accounted for TA muscle contraction types (concentric, eccentric, isometric) and ankle rotation speed.
- Developed a normalized EMG versus pulsewidth model based on processed experimental data.
Main Results:
- The traditional trapezoidal stimulation intensity was found unsuitable for reproducing natural EMG profiles.
- The developed model demonstrated the limitations of the trapezoidal approach.
- An optimized stimulation intensity profile was proposed based on experimental data.
Conclusions:
- The proposed optimized stimulation intensity profile is expected to accurately replicate natural TA EMG patterns during gait.
- This optimized profile offers a more effective approach for FES in hemiplegic drop foot rehabilitation.
- Further implementation is needed to validate the clinical efficacy of the optimized profile.