Regenerative Peripheral Nerve Interface for Control of Lower Limb Prostheses

Individuals with an above-knee lower limb amputation are known to walk more slowly, expend more energy, have a greater risk of falling, and have reduced quality of life compared to individuals without amputation and those with below knee amputation. One of the driving factors behind these deficits is the lack of active function provided by above-knee prostheses with prosthetic knees and ankles. While many prosthetic devices have been developed for functional restoration after major lower extremity amputation, there remains no stable interface to facilitate reliable, long-term volitional control of an advanced robotic limb capable moving multiple joints. Moreover, there is no existing interface that provides useful sensory feedback that in turn enhances the functional capabilities of the prosthesis. To achieve both greater signal specificity and long-term signal stability, we have developed a biologic interface known as the Regenerative Peripheral Nerve Interface (RPNI). An RPNI consists of a peripheral nerve that is implanted into a free muscle graft that would otherwise go unused in the residual limb. As the nerve grows, it reinnervates the free muscle graft which undergoes a predictable sequence of revascularization and regeneration. The main questions it aims to answer are: 1. Can the amplitude, movement specificity and stability of sciatic nerve RPNI electromyography (EMG) signals be detected up to one year post RPNI surgery? 2. Do RPNIs contain information to enable control of a physical motorized prosthetic leg with multiple degrees of freedom? 3. Does stimulation of sciatic nerve RPNIs provides meaningful sensory feedback? Consenting participants with unilateral transfemoral amputation (TFA) will: 1. Undergo RPNI surgery and electrode implantation in the residual limb. 2. Attend regular follow-up visits following surgery to assess the health and signal strength of the RPNIs and their ability to use a prescribed prosthesis between 3- and 12-months followin