Muscle Activity in Upper Extremity Amputees

Abstract

Purpose – Three interdependent studies designed as preliminary investigations of phantom and prosthetic limb control in upper extremity amputees. The purpose was to (1) compare muscle activation patterns of the phantom limb to anatomically expected patterns (2) compare muscle activation patterns of the phantom limb and those used to control a prosthesis (3) compare the use of upper arm muscle activity in phantom limb movements between users of different types of prosthetic devices. These studies aimed to expand the understanding of the role of the peripheral nervous system in movements of phantom and prosthetic limbs. Methods – Fifteen participants with varying levels of upper extremity amputations participated. Kinesiologic EMG (surface/fine wire) was utilized to examine residual limb muscle activation patterns during movements of the phantom and prosthesis. A series of phantom movements based on level of amputation were executed. After completing phantom limb movements participants donned their prosthesis and completed movements of the device. Muscles were considered active when the threshold of activity exceeded two standard deviations above rest trial. Visual analysis of EMG activity and goodness of fit Pearson Chi-Square tests were used to examine frequency occurrences in muscle activation patterns. Results –The majority of muscle activation patterns for the completion of phantom limb movements, regardless of the level of amputation, varied from anatomically expected muscle activation patterns. The majority of participants also used different muscle activation patterns to control similar movements of the phantom limb and prosthetic device. Finally, muscle activation patterns to control the movement of a phantom hand were different based on the type of device participants used, with body-powered prosthetic users activating muscles of the upper arm more frequently than myoelectric prosthetic users. Significance – This dissertation was a preliminary study into novel theories regarding phantom and prosthetic control. Results emphasize a dire need for future research to explore the injury response of the PNS, how this impacts phantom limb experiences, how these changes impact or is impacted by the CNS, and how to utilize the body’s natural response to injury to enhance control and function of prosthetic devices.