Upper-extremity (UE) prostheses are increasingly more functional and proportionately more costly, rendering them largely unattainable for impoverished amputees in the United States (US) and abroad. Recognizing the increasing need for appropriate devices, PhysioNetics, LLC is developing a heavy-duty, transradial body-powered (BP) UE prosthesis which can be prescribed with minimal instruction. The design of the key components, the split-hook terminal device [TD] and universal adjustable interface is presented in this paper. The TD is primarily fabricated from plastics to eliminate galvanic corrosion in saltwater environments, weighs 5.4 oz (153 g) and uses inexpensive rubber bands to generate pinch force. Unique gripping contours provide versatile grasp and replicate five (5) prehension patterns while six (6) discrete force settings provide 2 – 17 lbf (8.9 – 76 N) of pinch. Three (3) universal interface sizes (small, medium, and large) accommodate most amputees and comfortably support axial loads up to 40 lbf (178 N). Estimated manufacturing cost for a complete unit is less than US$250. Field testers report lower but comparable comfort to their individually custom-fabricated interfaces, and are highly satisfied with fit and function of the prosthesis overall. Ongoing development includes reduction of manufacturing costs, increasing interface comfort and implementing task-specific variant designs.
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