Long-Term Performance and User Satisfaction With Implanted Neuroprostheses for Upright Mobility After Paraplegia: 2-to 14-Year Follow-Up

Objective: To quantify the long-term (>2y) effects of lower extremity (LE) neuroprostheses (NPs) for standing, transfers, stepping, and seated stability after spinal cord injury. Design: Single-subject design case series with participants acting as their own concurrent controls, including retrospective data review. Setting: Hospital-based clinical biomechanics laboratory with experienced (>20y in the field) research biomedical engineers, a physical therapist, and medical monitoring review. Participants: Long-term (6.2 +/- 2.7y) at-home users (N=22; 19 men, 3 women) of implanted NPs for trunk and LE function with chronic (14.4 +/- 7.1y) spinal cord injury resulting in full or partial paralysis. Interventions: Technical and clinical performance measurements, along with user satisfaction surveys. Main Outcome Measures: Knee extension moment, maximum standing time, body weight supported by lower extremities, 3 functional standing tasks, 2 satisfaction surveys, NP usage, and stability of implanted components. Results: Stimulated knee extension strength and functional capabilities were maintained, with 94% of implant recipients reporting being very or moderately satisfied with their system. More than half (60%) of the participants were still using their implanted NPs for exercise and function for >10min/d on nearly half or more of the days monitored; however, maximum standing times and percentage body weight through LEs decreased slightly over the follow-up interval. Stimulus thresholds were uniformly stable. Six-year survival rates for the first-generation implanted pulse generator (IPG) and epimysial electrodes were close to 90%, whereas those for the second-generation IPG along with the intramuscular and nerve cuff electrodes were >98%. Conclusions: Objective and subjective measures of the technical and clinical performances of implanted LE NPs generally remained consistent for 22 participants after an average of 6 years of unsupervised use at home. These findings suggest that implanted LE NPs can provide lasting benefits that recipients value. Published by Elsevier Inc. on behalf of the American Congress of Rehabilitation Medicine