Surgeons test-drive the amputation of the future with a mail-order limb, rerouted nerve, and prosthetic hand that grips like the real thing

By Gideon Gil

WALTHAM, Mass. — The surgeons, peering through loupes with 3x magnification, have dissected away the skin, the layers of fat and fascia, and exposed most of the median nerve, the I-95 of the forearm. Sensory signals travel up this cable from the fingers and, crucially, motor signals flow back down from the brain to move the thumb toward the pinkie, giving us the opposable thumb that makes humans distinct.

Dr. Jason Souza, a plastic surgeon from Walter Reed National Military Medical Center, has reached the hand, resting palm up, where the nerve branches into exit ramps to all the fingers. He masterfully works a pair of scissors, as dexterous as a child cutting construction paper, snipping free the motor branch to the muscles in the fleshy base of the thumb.

“That’s our money right there,” exclaimed plastic surgeon Dr. Matthew Carty of Brigham and Women’s Hospital.

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