Efficacy of an implanted neuroprosthesis for restoring hand grasp in tetraplegia: a multicenter study

OBJECTIVE: To evaluate an implanted neuroprosthesis that allows tetraplegic users to control grasp and release in 1 hand. DESIGN: Multicenter cohort trial with at least 3 years of follow-up. Function for each participant was compared before and after implantation, and with and without the neuroprosthesis activated. SETTING: Tertiary spinal cord injury (SCI) care centers, 8 in the United States, 1 in the United Kingdom, and 1 in Australia. PARTICIPANTS: Fifty-one tetraplegic adults with C5 or C6 SCIs. INTERVENTION: An implanted neuroprosthetic system, in which electric stimulation of the grasping muscles of 1 arm are controlled by using contralateral shoulder movements, and concurrent tendon transfer surgery. Assessed participants' ability to grasp, move, and release standardized objects; degree of assistance required to perform activities of daily living (ADLs), device usage; and user satisfaction. MAIN OUTCOME MEASURES: Pinch force; grasp and release tests; ADL abilities test and ADL assessment test; and user satisfaction survey. RESULTS: Pinch force was significantly greater with the neuroprosthesis in all available 50 participants, and grasp-release abilities were improved in 49. All tested participants (49/49) were more independent in performing ADLs with the neuroprosthesis than they were without it. Home use of the device for regular function and exercise was reported by over 90% of the participants, and satisfaction with the neuroprosthesis was high. CONCLUSIONS: The grasping ability provided by the neuroprosthesis is substantial and lasting. The neuroprosthesis is safe, well accepted by users, and offers improved independence for a population without comparable alternatives.