The Food & Drug Administration has approved the sale of a new prosthetic arm, Fox News reported on May 12. The arm is highly computerized and designed respond to the electrical activity in the amputee’s muscles. The development was funded by the Defense Advanced Research Projects Agency (DARPA).
Code named “Luke” after the Star Wars character who lost his arm in combat, the hi tech arm is a product of the DEKA Research & Development Corporation. The robotic arm is intended for use by amputees with limb loss above the mid lower arm. It is not approved for use in elbow or wrist amputations.
The arm was tested by 36 patients in the Veterans Administration health system. Up to 90 percent of users were able to perform tasks such as combing hair or eating, complex tasks that require “multiple, simultaneous movements”. The arm is designed to be the same size and weight as a normal adult arm with the same grip strength.
This is not the only DARPA project exploring bionics as an aid for injured soldiers and civilians.
Targeted muscle re-innervation is being researched at the Rehabilitation Institute of Chicago. This technology wires the patients nerves into the prosthetic just as their nerves connected to the lost limb. When fully developed, it offers the promise of prosthetics that respond to commands from the brain just as well as the missing arm or leg did.
The Alfred E. Mann Foundation has developed a sensor system that reads tiny muscle movements and translates them into commands for a prosthetic hand. Called the implantable myoelectric sensor system, it uses six sensors implanted deep in forearm muscles to control the hand. The system even has two left-over sensors because the hands used with the system have yet allow for more complex movements which those two sensors would control.
Proprioception is the ability that nearly everyone has to be able to move a limb and know that it went where it was supposed to go. It is how you can move your arm with your eyes closed or take a step in the dark. Users of artificial limbs do not have that sensory input and that affects their ability to operate a prosthetic and their confidence while using the device.
DARPA’s new Hand Proprioception and Touch Interfaces (HAPTIX) program is an attempt to remedy that problem for patients who have lost a hand or arm. DARPA describes the progam’s goal as a:
fully-implantable, modular, and reconfigurable neural-interface microsystems that communicate wirelessly with external modules, such as the prosthesis interface link.
The addition of proprioception to a prosthesis may have another benefit, as well. DARPA cites studies that suggest that the phantom pain for a missing limb experienced by many amputees may be reduced or eliminated. They estimate that 80 percent of amputees experience this pain.
Military research intended to improve the lives of wounded warriors is being carried over to the civilian sector. Many patients injured in industrial accidents, car wrecks or other incidents where they lose a hand, arm or leg will benefit from the advances in bionics now being made.