Targeted Muscle Reinnervation

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Targeted Muscle Reinnervation

• Nicholas Mulhern
• 10/9/12
• BME 281

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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

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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

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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
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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

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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
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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

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Post Surgical Rehabilitation
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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

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Proportional Control

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

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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
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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

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Future Innovation
Thumb abduction
Thumb Adduction
Wrist Supination
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Advantages

• Attempt at Advanced motorized neural prosthetic
  control using natural EMG signals
• Doesnt 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

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Sources

• http//en.wikipedia.org/wiki/Targeted_reinnervatio
  n
• http//informahealthcare.com/doi/abs/10.3109/03093
  640409167756
• http//jama.jamanetwork.com/article.aspx?articleid
  183371
• Department of BME URI, BME 468 Slideshow 11