As Lehman improved the control of his prosthetic, he noticed his phantom pain started to wane – a finding his doctors plan to explore as a cure for the debilitating syndrome.
"It was unexpected but a happy accident," Lehman said.
But people shouldn't expect miracles right away, cautions Kuiken.
"Patients need to know it takes about six months for the nerves to grow in," he said. "It's OK to wear a regular prosthesis in the meantime, so they're not left frustrated feeling like they're chasing their tail."
Since his surgery in August 2009, Lehman said he'd seen big improvements.
"It's like the difference between driving a 1970s Yugo versus a new Ford Mustang," he said. "Performance-wise, they are in two completely different categories."
"Everything just feels more natural," he added. "Imagine you're playing a crane game and trying to grab a stuffed bear with a claw, then instead imagine just reaching in and grabbing what you want with your arm – it's incredibly different."
Scientists are trying to learn just how much better this new technology really might be. At last week's meeting of the American Association for the Advancement of Sciences, Hargrove and Kuiken reported results of a new study that patients using pattern recognition to control their bionic arms consistently performed better and faster at common tasks -- such as stacking blocks and manipulating clothespins -- than those using conventional controls. The researchers plan to build on this small study with a larger clinical trial.
"That's when it gets really exciting," said Kuiken of the possibility of improving the standard of care for people with prosthetic limbs. "Until it reaches commercial market it's just academic. I'd expect private companies to get this kind of thing on the market within a year."
The cost of surgery and a standard prosthetic run upwards of $150,000 including rehabilitation, according to Dumanian. The bionic arm and pattern recognition technology would increase the cost, Dumanian said, but it might be more cost effective than hand transplantation.
In the meantime, Lehman continues to work with scientists to help them improve the technology for wounded warriors coming home.
"Not everyone is willing to accept going through an additional elective surgery," he said, adding that soldiers should speak to a specialist who can help them understand their options. "It's the next step to getting your arm back."