Faults of the Current Body-Powered Prosthesis

Though very durable and easy to maintain, the body powered prosthetic device is utterly inefficient in the way that its cable system works.  Although the cable system allows for the transfer of tension through the prosthesis and shifts the lever to open the terminal device to allow for grasping of an object, its metal housing as well as the anchor (colored black) in increase friction. This increase in friction is due to the anchors (colored neon-green and black) of the cable. This increase in friction dissipates much of the mechanical energy used by the extension of the arm into heat.  This requires the patient to use 120 Newtons of force and displace the cable 50 millmeters which requires a full extension of the arm to open the hook wide enough to grip an ordinary water bottle.  The biggest fault of the body powered hook is perhaps that the same amount of force required to grip a heavy object is required to grip a simple tooth brush. Used daily, this mechanism becomes very tiresome for the user as the body powered prosthetic requires a great deal of input strength, thus, it becomes a burden to children and the elderly.