Peripheral Interfaces in Amputees for Sensorimotor Integration

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Veterans who have lost an upper extremity in service of country have lost both hand function and the sense of touch. Losing these primary sources of physical, manipulative, and emotional connection to the world results in lifelong functional and social deficits. To restore the emotional and functional aspects of the hand to a veteran, we have developed an implanted system of nerve electrodes to restore touch and sense of movement and intramuscular electrodes to provide intuitive, long-term, stable control of prostheses with the look and functions of a human hand. We have successfully deployed these electrode interfaces in four subjects for more than six years without significant adverse events. Several case-series studies in-lab demonstrate multiple important aspects of sensory restoration and prosthesis control. A five-week, in-home case series demonstrated significant advantages to restoring sensation with even a one degree-of-freedom prosthesis. Beyond the traditional prostheses, the new system has been connected to an advanced, human hand-like hand that has sensors at nine locations to be used with the sensory feedback to the user and has individual motion of the index finger, thumb, wrist, and middle through ring finger as a single group. The initial trials implemented wires through the skin as connection to the interfaces, but now we have completed development of a fully-implanted, BluetoothLE™connected system to eliminate these connections. The next step required to move this new technology towards making the treatment available to veterans is a larger, pilot randomized clinical trial (RCT) comparing an advanced prosthesis treatment with implanted nerve and muscles interfaces to traditional, state-of-art, clinically-prescribed prosthesis treatment. The implanted system with sensory feedback and high degree-of-freedom control is expected to improve the subjects’ outcomes over currently-available options. The results of this pilot trial will establish the viability and importance of the advanced prostheses and will support a subsequent pivotal trial. The study has two aims. Aim 1 will determine the functional outcomes, social outcomes, and usage of an advanced prostheses with implanted electrodes compared to the subject’s clinically prescribed, state-of- art prosthesis treatment. Eight subjects will participate in a randomized, 2 x 2 cross-over study comparing the new human hand-like prosthesis with implanted interfaces to the subject’s commercial prosthesis. Our primary hypothesis is that within subject differences of the Othortics and Prosthetics User Survey - Quality of Life (OPUS-QOL) measure will show significant improvement with the advanced prosthesis system. We will collect weekly surveys for psychosocial outcomes and log device usage when subjects are at home. Subjects will come to the lab monthly for functional tests and a larger range of surveys to understand the explore the impact of the prosthesis on the subject’s daily life. Aim 2 will determine if restoration of sensory feedback alone or multiple degrees-of-freedom alone improves functional outcomes, social outcomes, and usage of the prosthesis. Following the Aim 1 cross-over study, subjects will continue in a second 2 x 2 cross-over study comparing sensory feedback with the function of the subject’s commercial prosthesis to no sensory with the fully functional advanced prosthesis. Our primary hypothesis is that within subject differences of the measures will show that both sensory feedback and implanted control significantly improve the OPUS-QOL measure compared to the subject’s clinically prescribed prosthesis treatment, but not as strongly as both together. We will also collect and analyze the same extensive data set as in Aim 1. The proposed research will be the first to deploy a prosthetic treatment with a fully-implanted interface in a long-term, home-use, randomized clinical trial. This is expected to make a significant leap forward toward making advanced sensory-enabled, intuitive, high degree-of-freedom prosthetic systems available to improve quality of life and options for veterans with upper limb loss.