An eight-year-old boy has become the youngest person to receive a double hand transplant.
Zion Harvey, from Philadelphia, had to have both his hands and feet amputated when he was two after fighting a serious infection.
Now doctors have transplanted new forearms and hands onto Zion in a groundbreaking 10-hour operation.
Zion told NBC News he can't wait to pick up his little sister with his new hands. "My favourite thing [will be to] wait for her to run into my hands as I pick her up and spin her around," he said.
Zion's mother, Pattie Ray, said that seeing her son for the first time after the operation was "like having a newborn."
"Like any surgery, it was a risk, and after checking it, it was no more of a risk than a kidney transplant.
"So I felt like I was able to take that risk for him, if he wanted it, but it was ultimately Zion's decision."
Dr L. Scott Levin, who led the 40-strong transplant team involved in the operation, praised Zion's resilience.
"I have met with him and his mother several times and you would think an 8-year-old would be overwhelmed or bewildered, or unclear as to the pathway we were setting for him," Levin explained.
"But when I first met him, I said to him, 'Why do you want hands, Zion?' And he said 'cause I want to swing on the monkey bars. That's a pretty logical answer for an 8-year-old. And a pretty profound statement to me."
Zion, who runs on prosthetics, said that he had secretly wished he might have a pair of hands one day.
"I hoped for somebody to ask me do I want a hand transplant and it came true," he told NBC News.
"I've never seen a tear, never an untoward face, never a complaint," Dr Levin said. "He's always positive. And that, in and of itself, is remarkable."
The donor's hands and forearms were attached by connecting bone, blood vessels, nerves, muscles, tendons and skin.
Dr Levin recalled the moment blood rushed to one of Zion's new hands.
"That hand was now alive," he said. "That became, instantly, part of Zion's circulation, no different than my hand or your hand."
Zion will be able to feel with his new hands in six to nine months.
The surgery may have profound changes on the lives of children who are living without hands, Dr Levin said.