Impact of an implanted neuroprosthesis on community ambulation in incomplete SCI

Objective: Test the effect of a multi-joint control with implanted electrical stimulation on walking after spinal cord injury (SCI). Design: Single subject research design with repeated measures. Setting: Hospital-based biomechanics laboratory and user assessment of community use. Participants: Female with C6 AIS C SCI 30 years post injury. Interventions: Lower extremity muscle activation with an implanted pulse generator and gait training. Outcome Measures: Walking speed, maximum distance, oxygen consumption, upper extremity (UE) forces, kinematics and self-assessment of technology. Results: Short distance walking speed at one-year follow up with or without stimulation was not significantly different from baseline. However, average walking speed was significantly faster (0.22 m/s) with stimulation over longer distances than volitional walking (0.12 m/s). In addition, there was a 413% increase in walking distance from 95 m volitionally to 488 m with stimulation while oxygen consumption and maximum upper extremity forces decreased by 22 and 16%, respectively. Stimulation also produced significant (P 0.001) improvements in peak hip and knee flexion, ankle angle at foot off and at mid-swing. Conclusion: An implanted neuroprosthesis enabled a subject with incomplete SCI to walk longer distances with improved hip and knee flexion and ankle dorsiflexion resulting in decreased oxygen consumption and UE support. Further research is required to determine the robustness, generalizability and functional implications of implanted neuroprostheses for community ambulation after incomplete SCI.