Feasibility of Sensory Feedback for Lower Limb Amputees

Study Overview
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Brief Summary
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The purpose of this study is to evaluate the effectiveness of providing sensation of the missing limb to individuals with lower limb loss, including above and below knee amputees. The approach involves delivering small electrical currents directly to remaining nerves via implanted stimulating electrodes. These small electrical currents cause the nerves to generate signals that are then transferred to your brain similar to how information about the foot and lower limb used to be transferred to your brain prior to the amputation. Individuals also have the option to have recording electrodes implanted within muscles of the lower limb(s) in an attempt to develop a motor controller that would enable the user to have intuitive control of a robotic prosthetic leg.

Detailed Description
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Electrodes are surgically implanted on one to four nerves of the residual limb. An external wearable device controls the delivery of electrical pulses to the implanted system. The participant will be asked to verbally describe the perceived sensations and highlight their locations on a drawing of a foot presented to them on an electronic screen. An instrumented prosthesis will be developed such that perceived sensations would correspond to prosthesis interactions with the floor. This instrumented prosthesis, also known as a sensory neuroprosthesis, will be worn while the participant is engaging in various functional tasks, such as standing, walking, or climbing stairs, or with visual or mental distractions. Intramuscular recording electrodes can be implanted in the lower limb(s) and/or hip muscles in order to obtain electromyography (EMG) signals. The EMG recordings from the residual muscles will be used to develop an algorithm which can operate an advanced robotic prosthesis in which the movement of the joint(s) could be controlled.

Official Title
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Feasibility of Sensory Feedback for Lower Limb Amputees

Conditions
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Amputation

Intervention / Treatment
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* Device: Stimulating nerve electrodes and intramuscular recording electrodes


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adults age 18 or greater Chronic, medically stable ( > 3 months) unilateral trans-tibial or trans-femoral amputation Potential user of trans-tibial or trans-femoral prostheses for standing or walking Viable target nerves in the lower extremity as determined by standard-of-care clinical tests of nerve conduction, response to stimulation, sensory evoked potentials (SEP) and the like Good skin integrity and personal hygiene Absence of autoimmune deficiencies, seizure disorders or cardiac abnormalities contraindicating stimulation Sufficient social support and personal ability to tolerate study procedures and comply with follow-up schedule Exclusion Criteria: Uncontrolled diabetes with HbA1c greater than or equal to 69 mmol/mol (8.5%). Significant vascular disease Chronic skin ulcerations Significant history of poor wound healing Significant history of uncontrolled infections Active infection Significant pain in the residual or phantom limb Pregnancy Inability to speak English Expectation that MRI will be required at any point for the duration of study or while percutaneous leads are in place Arthritis in the area of implant History of vestibular or movement disorders that would compromise balance or walking Class II or III obesity (Body Mass Index > 35) Poor surgical candidate Uncontrolled depression, psychoses or cognitive impairments

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Device Feasibility
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Stimulating nerve electrodes & intramuscular recording electrodes<br>Fifteen subjects with lower limb amputation will have multi-contact stimulating nerve cuff electrodes implanted around the nerves in their residual limb. These electrodes will be connected to temporary percutaneous leads. During experimental testing, a small amount of electrical current will be delivered to the nerves through multi-contact nerve cuff electrodes. Participants also have the option to have recording electrodes implanted within muscles in their lower limb(s). These muscles are associated with prosthetic movement, and recordings from these muscles will be used to develop a controller for a robotic myoelectric prosthesis. | Device: Stimulating nerve electrodes and intramuscular recording electrodes<br>* See Arm Description<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Stimulation Thresholds | Quantify the minimum stimulation required to evoke electrically induced sensations on the phantom limb. | 9 months post implant | 
| Functional Gait Assessment (FGA) | The Functional Gait Assessment is a 10 task test that measures postural stability. Each task is scored from 0 -3 with 0 indicating severe impairment in the task and 3 indicating normal ambulation. The scores are combined to give a total score. The maximum score is 30. A higher score indicates a better outcome. | 1 year post implant | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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prosthesis user, phantom sensation, sensory feedback, prosthesis, amputee, amputation, limb loss, robotic prosthesis, neuroprosthesis, sensory restoration, robotic, electromyography, EMG, sensation, myoelectric