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A Novel Method to Enhance Sensory Feedback and Improve Function of Myoelectric Prostheses after Upper Limb Amputation
Michael Morhart; Jaret Olson; Ming Chan; Jacqueline Hebert
University of Alberta, Edmonton, AB, Canada
Purpose: To investigate the feasibility of a new surgical procedure for transhumeral amputees that would allow regenerating sensory nerve fibers from the median and ulnar nerves to reach the target receptors in specific areas of reinnervated skin for digital sensory feedback during functional prosthetic tasks.
Methods: Cadaveric dissections were performed to examine the feasibility of isolating the cutaneous nerves in the upper arm close to the entry points of the cutaneous nerves to specific areas in the skin. This information was then used in the pre-surgical planning for a targeted motor and sensory reinnervation procedure in a transhumeral amputee. Somatosensory evoked potentials were recorded intra-operatively to determine the appropriate donor sensory nerves. Physiological measures and functional outcomes were obtained post-operatively to determine whether this novel procedure could be successful in providing meaningful sensory feedback to the subject while performing a functional task.
Results: Cadaveric dissection provided potential sensory nerves with their associated skin territories. The size of the denervated cutaneous territories were mapped 6 weeks following surgery in our transhumeral patient and baseline results on pressure sensibility, 2 point discrimination, hot, cold and pain thresholds were recorded. The patient started experiencing hand sensations at 2 months following surgery, then at 4 months we performed detailed sensory mapping including pressure sensation, hot, cold and pain thresholds of the hand and digits.
Conclusions: We show that targeted sensory reinnervation is possible and that this procedure will greatly improve the ability of amputees to use the myoelectric prostheses naturally without direct visual input or aid.
Learning Objectives: To understand the novel approach of using both targeted muscle and sensory innervation in amputees using myoelectric prosthetics and the dramatic implications in their functional daily use.
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