Longitudinal Performance of a Surgically Implanted Neuroprosthesis for Lower-Extremity Exercise, Standing, and Transfers After Spinal Cord Injury

Abstract

Objective To investigate the longitudinal performance of a surgically implanted neuroprosthesis for lower extremity exercise, standing, and transfers after spinal cord injury. Design Case series. Setting Research or outpatient physical therapy departments of four academic hospitals. Participants 15 subjects with thoracic or low-cervical level spinal cord injuries who had received the 8-channel neuroprosthesis for exercise and standing. Interventions After completing rehabilitation with the device, the subjects were discharged to unrestricted home use of the system. A series of assessments were performed before discharge and at a follow-up appointment approximately one year later. Main Outcome Measure(s) Neuroprosthesis usage, maximum standing time, body weight support, knee strength, knee fatigue index, electrode stability, and component survivability. Results Levels of maximum standing time, body weight support, knee strength, and knee fatigue index were not statistically different from discharge to follow-up (p > 0.05). Additionally, neuroprosthesis usage was consistent with subjects choosing to use the system on approximately half of the days during each monitoring period. Although the number of hours using the neuroprosthesis remained constant, subjects shifted their usage to more functional standing versus more maintenance exercise, suggesting that the subjects incorporated the neuroprosthesis into their lives. Safety and reliability of the system were demonstrated by electrode stability and a high component survivability rate (>90%). Conclusions This group of 15 subjects is the largest cohort of implanted lower extremity neurorprosthetic exercise and standing system users. The safety and efficiency data from this group, and acceptance of the neuroprosthesis as demonstrated by continued usage, indicate that future efforts towards commercialization of a similar device may be warranted.

Posture-dependent control of stimulation in standing neuroprosthesis: Simulation feasibility study

“…Elapsed standing times with conventional FNS systems are also relatively short, typically 10 min, because of the fatigue induced by continuously activating postural muscles [7]. For these reasons, the most effective means for achieving a wide variety of postures and standing maneuvers are best explored in computer simulations that capture as many characteristics of the physical system as possible.…”

Análise Matemática Da Fadiga Muscular Em Indivíduos Saudáveis Durante Contrações Voluntárias

“…A inclinação do encosto foi ajustada para garantir posicionamento de 55° de flexão do quadril e os testes foram realizados com a articulação do joelho a 30° (considerando 0° = extensão total de joelho) [7,8].…”

Feasibility of closed-loop controller for righting seated posture after spinal cord injury

“…In all subjects, the lumbar (L) erector spinae were recruited with bilateral intramuscular stimulating electrodes [31] inserted near the L1-L2 spinal nerves [23,[32][33] for trunk extension, and the gluteus maximus muscles were activated bilaterally with intramuscular electrodes or epimysial electrodes. For additional hip extension, the posterior region of the adductor magnus and the semimembranosus were stimulated bilaterally with intramuscular electrodes in four subjects.…”

“…Participants had an 8-channel implanted receiver-stimulator [21] system for standing transfer [22][23][24] and/or a 16-channel implanted stimulator-telemeter [25] system to study standing balance [26][27][28] or peripheral nerve cuff electrodes [29][30]. Both the 8-and 16-channel stimulators delivered constant current, charge-balanced biphasic stimulus waveforms.…”