Journal of Rehabilitation Research & Development (JRRD)

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Volume 47 Number 3, 2010
   Pages 201 — 212

Abstract — Feedforward control strategies of subjects with transradial amputation in planar reaching

Anthony J. Metzger, MBE;1-2 Alexander W. Dromerick, MD;3-5 Christopher N. Schabowsky, MS;1-2 Rahsaan J. Holley, MS;4 Brian Monroe, BS;6 Peter S. Lum, PhD1-3*

1Center for Applied Biomechanics and Rehabilitation Research, National Rehabilitation Hospital, Washington, DC; 2Department of Biomedical Engineering, Catholic University of America, Washington, DC; 3Department of Veterans Affairs Medical Center, Washington, DC; 4Neuroscience Research Center, National Rehabilitation Hospital, Washington, DC; 5Departments of Rehabilitation Medicine and Neurology, Georgetown University, Washington, DC; 6District Amputee Care Center, Washington, DC

Abstract — The rate of upper-limb amputations is increasing, and the rejection rate of prosthetic devices remains high. People with upper-limb amputation do not fully incorporate prosthetic devices into their activities of daily living. By understanding the reaching behaviors of prosthesis users, researchers can alter prosthetic devices and develop training protocols to improve the acceptance of prosthetic limbs. By observing the reaching characteristics of the nondisabled arms of people with amputation, we can begin to understand how the brain alters its motor commands after amputation. We asked subjects to perform rapid reaching movements to two targets with and without visual feedback. Subjects performed the tasks with both their prosthetic and nondisabled arms. We calculated endpoint error, trajectory error, and variability and compared them with those of nondisabled control subjects. We found no significant abnormalities in the prosthetic limb. However, we found an abnormal leftward trajectory error (in right arms) in the nondisabled arm of prosthetic users in the vision condition. In the no-vision condition, the nondisabled arm displayed abnormal leftward endpoint errors and abnormally higher endpoint variability. In the vision condition, peak velocity was lower and movement duration was longer in both arms of subjects with amputation. These abnormalities may reflect the cortical reorganization associated with limb loss.

Key words: amputation, feedforward, motor control, prosthesis, reaching, training, trajectory, transradial, upper limb, velocity.

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Last Reviewed or Updated  Monday, May 3, 2010 12:37 PM