Getting a Good Grip; New advances in prosthetics enable amputee soldiers to use brain signals to move their artificial limbs.

Byline: Ginanne Brownell (With Abby Dalton in Washington)

Sgt. Juan Arredondo's life forever changed on Feb. 28, 2005, when, on a routine patrol between Ramadi and Fallujah, an IED exploded through the door of his vehicle. Arredondo's left arm was severed below the elbow, his hand still clinging to the wheel. Arredondo stuffed it in his pocket. Surgeons at the field hospital tried for five hours to reattach the limb. "I asked the surgeon if I could keep my hand," Arredondo says. " 'No, son,' he told me." Instead, Arredondo got a hook.

Doctors can perform near miracles in reattaching severed limbs, but when these attempts fail, the options have been slim indeed, particularly for patients who lose a hand. Prosthetics researchers have tended to focus on the leg, because legs account for a vast majority of amputations, and because the leg's relatively few muscles and bones and simple network of nerves make it an easier limb to mimic. For decades, hand and arm amputees got either a cosmetic arm with no functional use, a hook or pinchers, which can grab things but has limited flexibility. In recent years, however, a research boom inspired in large part by the wars in Iraq and Afghanistan has begun to offer not only prosthetic legs with active joints but also artificial arms and hands that more accurately mimic the complex movements of the real limb. And now scientists have found ways to connect prosthetic limbs to the patient's nervous system--with an ultimate aim of allowing patients to send signals directly from the brain to the artificial hand or leg.

A few months ago, Arredondo was one of the first patients to receive an experimental bionic hand that allows for more control than anything currently on the market. The $17,000 hand, called the i-LIMB, offers five individually powered articulating fingers and allows for thumb rotation. Doctors attach electrodes on the surface of the skin that pick up signals from nerves. A computer chip in the hand reads the sensors and drives a tiny motor in each finger. It not only looks like a real hand, but it also allows for users to do things like tie their shoelaces, play golf and even fold laundry. Arredondo says it's like something out of "The Terminator." "It really is amazing to see how far technology has come," says Arredondo, 27, who's now ...