Myoelectric Prostheses

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Myoelectric Prostheses

• By Courtney Medeiros
• BME 281
• 10/26/11

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What are Myoelectric Prostheses?

• Uses electromyography signals/ electric
  potentials from voluntarily contracted muscles
  within a persons residual limb to control
  movements of the prosthesis.
• Electromyography (EMG) process of detecting
  electric potentials and translating them into
  motions.
• Movements include
• Elbow flexion/extension
• Wrist supination/pronation
• Opening/closing of fingers

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History of Myoelectric Prostheses

• The typical alternative to myoelectric prostheses
  are hook prostheses (which began in the middle
  ages with pirates), body-powered prostheses, and
  cosmetic prostheses
• 1920s Ferdinand Sauerburch Aurel Stodola in
  Zürich, Switzerland created a hand prosthesis
  controlled and powered by muscles of residual
  limb
• WWII (1945) America the rest of the world
  started mobilizing for research and development

• 1949 Alderson external power source to develop
  first electrically powered arm
• 1958 Russians first myoelectric arm
• 1980s-Present Many developments and advancements

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Who is Eligible?

• Used for congenital limb deficiencies and
  amputations from cancer, trauma, or surgery.
• Must have EMG voltage of at least 15µV, the scar
  must be able to hold the weight of the arm, and
  must pass motor/control test

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How it Works
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More Device Information

• Weight
• Can weigh as little as ¼ the weight of an average
  human arm
• For children it can be made to weigh as little as
  a ½ pound
• Has a rechargeable battery
• Proprioceptive feedback

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Maintenance

• Can get first myoelectric prosthesis between 16
  to 24 months of age
• When used on a child, the sockets need to be
  replaced every year due to growth
• Typically come with one-year warranty
• Motor and drive last about two to three years
• With heavy use, the entire prosthesis may need to
  be replaced after only five years

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Advantages Disadvantages

• Advantages
• Greater range of movement
• Less bulky compared to a body powered prosthesis

• Disadvantages
• Expensive!
• Not suitable to people involved with heavy work
  loads
• Dont last that long

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Future

• Smoother motions
• Cheaper
• Eventually make lower limb myoelectric protheses
• Make them more durable to last longer and make
  them available to people who have heavy work loads

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Questions?
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Sources

• Meier, R.H. (2004). Functional restoration of
  adults and children with upper extremity
  amputation. New York, NY Demos Medical
  Publishing Inc.
• http//www.aetna.com/cpb/medical/data/300_399/0399
  .html
• http//www.ballert-op.com/myoelectric_control.asp
• http//www.ncbi.nlm.nih.gov/pubmed/10989484
• http//medtraining.northwestern.edu/repoc/research
  /projects/upperlimb/uplimb_imes.html
• http//www.scribd.com/doc/18651364/Myoelectric-Arm
  
• De Luca, C.J. (1979, June). Physiology and
  mathematics of myoelectric signals. IEEE
  Transactions on Biomedical Engineering, 26(6),
  313-325.