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

Inclusion Criteria: * Participants must be 22 years of age or older. * Participants must have previously undergone an upper limb amputation proximal to the wrist or are scheduled to undergo 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 6 hours of experiments per month while electrodes remain implanted. * Participants must be at least 6 months post-amputation. * Participants who will receive an amputation at the same time as RPNI grafts and electrodes must be undergoing an elective amputation surgery where loss of useful function of the hand has occurred. They must be at least 6 months post-injury or failed limb salvage to participate. 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