Body-powered prosthetic systems

Abstract

Body power refers both to the power source and to the control method for operation of the prosthesis. The prosthetic components are operated through the use of the body's own force and excursion. By harnessing the force and movement of joints more proximal to the amputation, it is possible to operate mechanical terminal devices, wrists, elbows, and humeral rotation devices. Joint movements produce excursion that is captured with the harness straps and transmitted through a cable system to cause movement of the prosthetic components. In this age of computers and miniaturized electronic components, it may be surprising that body power continues to be an effective form of prosthesis control for a select group of users. Several factors contribute to the continued utilization of body-powered control compared to externally powered devices including lower cost, generally more robust design, lower maintenance cost, generally lighter weight, and perhaps most importantly greater proprioceptive feedback through the harness and cable system. However, body-powered systems also have significant disadvantages. Some users may not be able to produce the high forces needed to optimally operate some body-powered systems, or these high forces may cause discomfort or pain during device activation [8]. Also some limb-deficient persons may not be able to produce sufficient excursion to effectively operate the system.