Myoelectric Prostheses By Courtney Medeiros BME 281 102611

Myoelectric Prostheses By: Courtney Medeiros BME 281 10/26/11

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 15μV, 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 • Advantages • Greater range of movement • Less bulky compared to a body powered prosthesis • Disadvantages • Expensive! • Not suitable to people involved with heavy work loads • Don’t last that long

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. • 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.