Short-term Implanted Electrodes Following Regenerative Peripheral Nerve Surgery for Improving Prosthetic Limb Control Signals

This is a single center, 10 subject early feasibility study in which the primary objective is to ensure the safety of percutaneous intramuscular electrodes implanted in surgically-created RPNI constructs (free muscle grafts attached to the amputated nerves) in subjects with upper limb amputation. The secondary objectives are to assess the efficacy of the electrodes in recording electromyographic signals from the RPNI grafts and in delivering electrical stimulation to the RPNI grafts to evoke sensory percepts.

This study will enroll people who have had upper limb amputations or are planning to have upper limb amputations. Each participant who does not already have RPNI grafts at the time of enrollment will have RPNI grafts implanted on branches or fascicles of nerves of the upper extremity. Several or all RPNI grafts will have a single bipolar electrode implanted in the muscle tissue, with the proximal end tunneled to a percutaneous exit point on the residual limb. Additional electrodes may be placed in innervated muscles in the residual limb, in order to provide a control comparison as well as to provide additional input during prosthesis control experiments. Electrodes will remain implanted for up to 7 years, with a minimum of 2 study visits per month to perform prosthesis control and sensory feedback experiments. Study endpoint will be assessed at a minimum of once per month while electrodes remain implanted. After a maximum of 7 years, electrodes will be explanted and the study ended after a 1 week follow-up.

The results of this study will inform the final design of the electrodes to be implanted long-term in RPNI grafts to provide an increased number of degrees of freedom for prosthetic control and sensory and proprioceptive feedback. This will drastically improve the functionality of the prosthesis, enhance the sense of embodiment of the prosthesis itself, and enable future investigation of a fully-implanted (non-percutaneous) prosthesis control system.

Inclusion criteria

• Participants must be 22 years of age or older.
• Participants must have previously undergone an upper limb amputation proximal to the wrist.
• For participants without existing RPNI grafts (at the time of enrollment), the residual limb must have sufficient soft tissue quality to support performance of the RPNI operative procedure. Participants sustaining severe crushing or avulsion injuries with substantial superficial and deep scarring may not be appropriate candidates for inclusion in the study.
• Participants must be in good health and American Society of Anesthesiologists (ASA) Class I or II (low surgical risk).
• Participants must have reliable transportation.
• Participants must be able to attend at minimum 2 visits per month while electrodes remain implanted.
• Participants must be at least 6 months post-amputation.

Exclusion criteria

• Participants may not be suffering from any severe pain syndrome including complex regional pain syndrome or severe phantom pain. All of these conditions would suggest pathological activity of the nerve and would exclude the participant from participation.
• Participants must not be suffering from any untreated mental health disorders and if they have any DSM-5 diagnoses, they must receive approval to participate from their mental health professional.
• Participants must not have any medical conditions that, in the opinion of the Principal Investigator, would place them at high risk for a surgical procedure including recent myocardial infarction, cerebrovascular accidents, deep venous thrombosis, pulmonary embolus, uncontrolled diabetes, or end stage renal disease.
• Participants must not have used tobacco for at least one month prior to enrollment in the study.
• Participants must agree to not use tobacco for the duration of the study.
• Participants cannot have sustained bilateral upper extremity amputation.
• Participants cannot be pregnant.
• Participants must not have other indwelling electronic implants like pacemakers, implantable cardioverter defibrillators, implantable neurostimulators, body worn insulin pumps, or body worn patient monitoring devices.
• Participants must not have severe peripheral vascular occlusive disease, venous hypertension of the extremity, or severe lymphedema of the extremity.
• Participants must not have an autoimmune condition which is not well controlled by medication.
• Participants will not be considered for enrollment in Primary Upper Limb Amputation with RPNI Grafts and Electrode Implantation if their amputation is a traumatic injury or cancer related