U.S. Army Ranger Bill Dunham, 38, Rogers, Ark., lost his right leg above the knee as a result of participating in the Dec. 20, 1989, invasion of Panama that ousted Manuel Noriega.
"I was on the spearhead of the invasion and we jumped in at about 500 feet," Dunham said. "After about six hours we were in a defensive position, getting ready to move to some buildings. My squad leader saw some troops move from one building to the next and we started to engage them."
During the daybreak engagement at Rio Hato airfield, Dunham said, his squad leader called for helicopter gun support. Had the fight occurred at night, the helicopter team would have noticed the Rangers' reflective clothing, but with the sun rendering the "glint tape" useless, the 'copter opened up mistakenly on Dunham's team.
Friendly fire claimed two men's lives and wounded two others in addition to destroying Dunham's right leg to the point that he agreed, after an eight-day struggle, to an above-knee amputation.
"The doctors worked real hard to try to save it," he said.
Dunham retired as a sergeant and now, with a master's degree in defense and strategic studies, teaches college students about terrorism and security issues. Most recently, he has been speaking about a medical advancement in the area of bionic prostheses to doctors, physical therapists and insurers, including Aug. 23 at Hanger Prosthetics and Orthotics, 6600 College Blvd., Overland Park, and at Hyatt Regency Crown Center, Kansas City, Mo.
Dunham talks to medical professionals about his "smart knee." He explained the idea, saying that several years after learning how to deal with losing his right leg, he heard from prosthetic experts about a hush-hush, intriguing medical innovation.
"It was top secret. Nobody even really knew it was out there," he said. "They came to me and told me about it, and I was fortunate they chose me to be the person to launch this technology for them."
Popular Science referred to the new bionic technology - called Power Knee, created by Ossur of Reykjavik, Iceland - as the first "prosthesis with a brain." Power Knee is a bionic leg that employs artificial intelligence to communicate with an amputee's working leg, and also is the first artificial leg to replace lost muscle activity with internal motors.
Unlike Lee Majors from the 1974 "Six Million Dollar Man" TV series, Dunham discussed bionic technology without the required "suspension of disbelief" that comes with sci-fi. The robotics- and computer-driven device is an everyday part of Dunham's life.
Dunham, the world's first and only person to use the production model, said Power Knee works using a recording device planted in his left shoe. The device captures information about how his left leg works, then sends directions to imitate the behavior to the bionic knee on his right side.
"It takes that information when I take a step and transmits that via Bluetooth (wireless) technology over to the prosthesis. The prosthesis has a computer built in, and gears, and processes the information from the sound side - actually tells the motors what to do based on what happened on the other side," Dunham said. "They communicate back and forth, so the leg actually walks with me as opposed to me kind of dragging the leg behind."
During his first 16 years as an amputee, Dunham said, he could not walk step-over-step upstairs. Instead, he used the step-and-drag walking system that is familiar to anyone who has had an injured leg and has tried to climb stairs on crutches.
"You'd come to a stair, you'd take a step up with your sound side, and then you'd drag the prosthetic device behind you up to the same step," he said.
The bionic knee does not require Dunham to drag his right leg.
"With this device, when I take a step up on the sound side, the prosthesis reads that and then it actually causes the knee to bend," he said. "I place the foot where it needs to go and when I put pressure on it, it knows it's in the right place and it actually powers me up, over the next steps."
Robotic gears give the knee power to lift, Dunham said.
"You can hear the gears working," he said. "Being able to lift somebody who weighs 200 pounds up and over a step, and to mimic the movement on the sound side is very, very advanced. No other prosthetic device has ever been able to do that."
One drawback is that, unlike "the bionic man" with an almost all-bionic body, the real bionic device is based on reality and works only for people missing a single leg.
"If you're missing both legs you can't wear this type of prosthetic device because it takes one sound side to cause the prosthetic side to work," Dunham said.
For those who can use the device, he said, nothing else on the market comes closer to acting like an organic leg.
"It's the most fluid for me. It feels the most natural because it's actually walking with you," Dunham said. "I'll never say it's the same thing, but it's got a very nice gait, the way the leg walks with you. It feels very good. It's some pretty phenomenal technology."
©The Johnson County Sun 2006
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