TARGETED MUSCLE REINNERVATION Nicholas Mulhern 10/9/12 BME 281

What is TMR Surgical Method for patients with upper extremity amputations Reassigns nerves that once controlled the hand and arm Enables patients the ability to control motorized prosthetics and regain sensory feedback

Historical Background First proposed in 1980 by Dr. Hoffer and Dr. Leob – Nerve-Muscle Grafting Developed in 1995 by Dr. Todd Kuiken and DR. Gregory Dumanian NWU – Hyper-reinnevation on animals TMR for artificial limb control – First Human work 2002 – Bilateral shoulder disarticulation amputee

Nerves Use the Brachial Plexus Nerve bundle Allow EMG Signals to be generated naturally by transferred residual nerves Allows for sensory feedback to the brain (natural connection) Brachial Plexus nerves drive all joint degrees of freedom

Surgical Procedure Pectoral Muscles chosen for innervation Close to Shoulder Biologically unused due to amputation First Muscles are denervation Ligated Proximal end to prevent reinnervation

Musculocutaneous nerve  Clavicular head of the Pectoralis major Radial Nerve  Lower sternal end of the Pectoralis Major Median Nerve  Upper Sternal of the Pectoralis Major

Surgical Procedure The pectoralis minor is translocated From under the major to the chest wall Connect the Ulnar nerve Removal of subcutaneous fat From over pectoral muscles to allow electrodes to be close to the muscles

Post Surgical Rehabilitation

Post Surgery 3 months  First muscle Twitches Bending Phantom Elbow 5 Months  Could contract all 4 pectoralis positions separately Placed in training for all 27 motions Use 128 monopolar electrodes to detect signal impulse

Proportional Control Proportional EMG Control 4 EMG signal controls for 4 motions Elbow (Flexion/extension) Hand(open/ close) Allows 2 degrees of freedom

EMG recording and Proccesing Prosthetic control based on EMG from TMR muscles EMG: Electromyography Purple: Direct control site Green: Electrode Placement Most electrodes placed over muscles reinnervated by the median and radial nerves

Future Innovation Enhance the Signals recorded Eliminate Crosstalk from other muscles Create a more distinct signal during multiple contractions Incorporate a 6 motor prosthesis TouchEMAS shoulder a humeral rotator Hand (Flex/ Exten) Improve TMR based NMI Using more neural information TMR uses nerves capable of controlling many muscles

Future Innovation Thumb abductionThumb Adduction Wrist Supination

Advantages Attempt at Advanced motorized neural prosthetic control using natural EMG signals Doesn’t require any implants, Biocompatible Targeted muscle acts as a natural amplifier Multiple EMG signals produced allowing separate functions controlled all at once Intuitive to patients, based on nerves used

Sources Department of BME URI, BME 468 Slideshow 11