Targeted Reinnervation In Upper-Limb Prostheses Ryan Dolan, BME 281, Section 02

Problems with Upper-Limb Prosthetics Patients missing an upper-limb struggle everyday to overcome the challenges of completing simple daily tasks Amputees also suffer emotional and social disadvantages, and miss out on many things that non-amputees take for granted. Existing prosthetic options available for upper-limb amputees (mainly shoulder disarticulation amputees) can not provide cutaneous feedback to a prosthetic device to provide sensation to the missing limb Shoulder disarticulation amputees are limited in the choices of prosthetic arms by inadequate control methods

Goals of Targeted Reinnervation Targeted Muscular Reinnervation [TMR] To reroute 4 upper-arm nerves to the pectoral muscles of the chest in order to provide intuitive control of a prosthetic device Targeted Sensory Reinnervation [TSR] Reroute sensory nerves along with the upper arm nerves of [TMR] that provide cutaneous sensory feedback in order to provide sensation to upper-limp amputees using a prosthetic arm capable of interpreting the sensory information and sending the information back to the sensory nerves

Process of Targeted Muscular Reinnervation Phase I: Viability Review Medical records and examinations to determine candidate viability Phase II: Financial and Medical Clearance Insurance approval, then you determine if you go forward based on whether or not you can afford it Takes 2 weeks to 6 months depending on your insurance Phase III: Surgery and Muscle Reinnervation Scheduled 6 weeks after final decision is made Two day hospital stay Wait 5-6 months for nerves to regrow Return for evaluation of nerve growth Phase IV: Device Fitting and training Custom arm built to fit body type/nervous system profile (includes several fittings, physical therapy, and training sessions 2-3 two-week visits spread across a two month period on average

Process of Targeted Muscular Reinnervation Phase I: Viability Review Medical records and examinations to determine candidate viability Phase II: Financial and Medical Clearance Insurance approval, then you determine if you go forward based on whether or not you can afford it Takes 2 weeks to 6 months depending on your insurance Phase III: Surgery and Muscle Reinnervation Scheduled 6 weeks after final decision is made Two day hospital stay Wait 5-6 months for nerves to regrow Return for evaluation of nerve growth Phase IV: Device Fitting and training Custom arm built to fit body type/nervous system profile (includes several fittings, physical therapy, and training sessions 2-3 two-week visits spread across a two month period on average

Qualifications for Procedure The ideal candidate: Will have an (above the elbow) or a (shoulder disarticulation) amputation within the last 5 years (sometimes 10 years can work) At least 14 years old Meet minimum weight requirement Those suffering from nerve degeneration and or nerve damage, or those born without an arm are not ideal candidates for this procedure

How It Works When you lose your arm neural signals still exist, so in theory if you could somehow obtain the signal from the brain and send it to a prosthetic arm you could intuitively control the device Obtaining this neural information directly from the brain is extremely complex and involves 100’s of wires and microscopic electrical devices, as well as an invasive surgery Instead the idea is to reroute the nerves from the brachial plexus (4 total) and implant them into the pectoral muscles of the chest Using surface electrodes you can then obtain the neural command to move the arm and apply pattern recognition techniques before sending the command to the prosthetic Targeted Sensory Reinnervation reroutes sensory nerves as well in order to provide cutaneous sensory feedback in order for the amputee to feel the sensations he/she once felt in their arm Sensors in the hand of the prosthetic send the signal to the rerouted nerves in order to simulate the stimulus the prosthetic is sensing

Jesse Sullivan 54 year-old lineman (touched the wrong wire) Suffered 7200 volt burns Immediate bilateral shoulder disarticulation Study: Box and Block Test w/ Jesse Sullivan (2003) Underwent Targeted Muscle Reinervation He used his original prosthetic for 20 months, and the nerve-transfer prosthetic for about 2 months (same physical arm, different programming) Take a block from one box and place it in the other, over and over. TMR results were significantly higher than the pre-surgery results (by about 72% on average) Opened the door to further Targeted Sensory Reinnervation research

Prosthetic Training In order to fully utilize all of the technologies capabilities a training period is necesarry There is a small micro-controller operating the prosthetic by both receiving and interpreting command signal inputs, and then sending the revised or edited signal to the prosthetic to carry out its intended command Use to take about 4-6 hours to train when tethered to a program on a computer With the microcontroller included in the prosthetic it only takes a few minutes to train depending on how much time you want to spend on ‘perfecting’ the control of the arm

Cost Factors Since Targeted Reinnervation, both muscular and sensory, are tailored specifically for an individuals needs it is almost impossible to estimate the cost of the procedure, hospital stays, physical therapy, and the prosthetic itself. 8 hour surgery Follow-up examinations and therapy Prosthetic Fittings Additional expenses; e.g. travel expenses, training expenses, etc…

Future One of the main issues with Targeted Reinnervation is that there is not enough “real estate” in the pectoral muscles to provide locations where sensors, electrodes, wires, and other miscellaneous electronics can do carry out their intended functions Design very small capsules Insert the capsules in the targeted muscle Much more room for electronics such as motors and electrodes The now ‘cleared up’ real estate of the targeted muscle can house many different sensors (EMG, etc…) that can extract valuable information from the nerve signals

References 1. Video: Todd Kuiken: Prosthetic Arm that Connects with the Human Nervous System. July 2011, Edinburgh, Scotland. 2. Center for Bionic Research: RIC: Multiple Summaries of Research Targeted Muscle Reinnervation: RIC: Phases of Procedure. orthotics/bionic/ orthotics/bionic/ 4. OttoBock: Prosthetic Arm through Targeted Reinnervation. Vienna, Austria Control of a six degree of freedom prosthetic arm after targeted muscle reinnervation surgery: Miller, Lipschutz: 6. Oxford Journals. Robotic touch shifts perception of embodiment to a prosthesis in targeted reinnervation amputees Redirection of cutaneous sensation from the hand to the chest skin of human amputees with targeted reinnervation. Todd A. Kuiken.