Myoelectric Prostheses By: Courtney Medeiros BME /26/11

What are Myoelectric Prostheses? Uses electromyography signals/ electric potentials from voluntarily contracted muscles within a person’s 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

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 1920’s: 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 1980’s-Present: Many developments and advancements

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

How it Works

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

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

Advantages & Disadvantages Disadvantages Expensive! Not suitable to people involved with heavy work loads Don’t last that long Advantages Greater range of movement Less bulky compared to a body powered prosthesis

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

Questions?

Sources Meier, R.H. (2004). Functional restoration of adults and children with upper extremity amputation. New York, NY: Demos Medical Publishing Inc. l l /upperlimb/uplimb_imes.html /upperlimb/uplimb_imes.html De Luca, C.J. (1979, June). Physiology and mathematics of myoelectric signals. IEEE Transactions on Biomedical Engineering, 26(6),