New Prosthesis Could Help Keep Troops in the Fight
Microprocessor Controls Knee
By Fred W. Baker III
American Forces Press Service
7/18/2007 - WASHINGTON (AFPN) -- A new prosthesis under development will give servicemember
amputees more flexibility and help them better perform their military jobs if they choose to stay
on active duty.
A preview of the new technology July 17 at Walter Reed Army Medical Center here drew key
staff and several servicemember amputees. The open forum allowed users to see improvements in
prototype form and ask developers questions or offer suggestions.
In 2006, Otto Bock HealthCare, a global provider of prosthetic components that started out
providing devices for German World War I veterans in 1919, began developing a prosthetic knee
system that is an upgrade to its already popular C-Leg. It was awarded a three-year $1 million
contract to develop a leg that will allow more servicemembers to stay on active duty if they choose
to.
The prosthesis is for above-the-knee amputees and uses a microprocessor to control the knee's
hydraulic functions and anticipate the wearer's actions and make changes in real time.
This will give servicemembers greater flexibility to change speeds or directions without
sacrificing stability.
The project began in 2006 and developers are through the prototype development. Barring any
technical problems, the new prosthesis should be available to servicemembers in 2009.
Mobility will be improved, allowing more movement without the user having to concentrate on
the knee, said Hans-Willem van Vliet, the program manager.
The new system will have more sensors, a faster hard drive, more memory and will provide
smooth transitions between movements such as level-ground walking, climbing stairs and running.
It also will allow servicemembers the ability to turn around while walking and walk backward
in one fluid movement, something that is not possible with the current C-Leg. It will adapt
automatically between walking speeds and gaits, Mr. Vliet said.
He emphasized that engineers have not simply improved the C-Leg, but have completely rebuilt
the technology on the inside.
Engineers also are working to stretch battery life to 50 hours on one charge. This will give
servicemembers on long road marches the duration they need to reach a power supply for recharging.
Requirements also call for making the system salt-water resistant, a difficulty with the
onboard computer systems. They also are planning a remote control, about the size of a car-lock
remote, that will allow the user to switch among as many as 10 modes with the click of a button.
The current C-Leg allows servicemembers two operating modes: one for walking and one for
bicycling or other activity. To switch between modes, the wearer has to swing the leg forward in a
jerky fashion. In some instances the user may not be able to switch modes because of limited
movement. Reprogramming a mode requires a visit to a technician.
Air Force Lt. Col. Andrew Lourake, a pilot at Andrews Air Force Base, Md., is the first
above-the-knee amputee to return to active duty as a pilot. He was fitted with a C-Leg five years
ago.
Colonel Lourake said he could not do his job without the C-Leg because it allows him to
switch between walking and flying modes. Still, he said, he is impressed with the new design and
plans to be one of the first to own one, even if he has to pay for it out of his own pocket. The
current C-Leg costs about $30,000. The new system is expected to cost about the same.
"I'm excited," Colonel Lourake said. "It has a lot of the stuff that I asked for a couple of
years ago. It's huge in functionality and active living."
Right now, he has to reprogram his second mode from flying mode to bicycling or running. With
the new leg, he won't have to make as many visits to his prosthetic technician.
"I'll have everything right in the leg, and I'll never have to touch the computer again," he
said.
Original article reprinted with permission of the Air Force and available at:
http://www.af.mil/news/story.asp?id=123061130
