Using advanced torque and accelerometer sensors, artificial intelligence
and actuator technology, the second generation of Ossur Americas' motor-powered POWER KNEETM
prosthesis is helping above-knee amputees restore lost muscle function and
enables them to walk naturally without even thinking about their next move.
Ian Fothergill, Ossur's academy manager, says ground contact sensors and
software algorithms control the knee, making it more natural and intuitive than
any prosthesis before it. "The knee takes over the control of the user's
balance when they are on it," he says. "That, of course, requires a different
approach in terms of control."
Fothergill likens the POWER KNEETM to the Segway.
"If you lean forward (on a Segway), it accelerates to speed up, but it
doesn't allow you to fall forward," he says. "(POWER KNEETM) is very intuitive.
It uses the natural system of moving your body first and then your legs
catching up with you."
Fothergill says amputees are constantly on guard, making sure their
prosthetic is positioned correctly and wondering if the knee will buckle under
their weight. With POWER KNEETM the user simply walks and the prosthesis does
the rest. "(Amputees) are always guarding themselves," Fothergill says. "The
POWER KNEETM now takes that thought process completely away from them."
According to Ossur, powered knee motion through actuator technology is
possible simply by lifting the thigh muscle, which generates power according to
the patient's needs. Specific levels of power management are needed depending
on level ground walking, walking up or down stairs, sitting or standing.
Ossur, in partnership with Victhom
Human Bionics, developed the first POWER KNEETM in 2006 for use mainly with
the Dept. of Defense and the Veterans Healthcare Administration.
"The second generation is smaller, sleeker, quieter, lighter and is
expected to become widely used in both unilateral and dual amputees," says Lt.
Col. Dr. Paul F. Pasquina, chief, Integrated Dept. of Orthopedics and
Rehabilitation at Walter Reed Army Medical Center and the National Naval
Army Lt. Col. Greg Gadson is the first in the world to receive the
prosthetic knee, which is expected to be commercially available by 2010,
according to Fothergill. Gadson, who lost both his legs after his truck was hit
by a roadside bomb in Baghdad in 2007, was fit for the prosthesis at Walter Reed
"Ossur is committed to providing these men and women with the most
advanced technology available. Their sacrifice and dedication to their country
has inspired us to work even harder to optimize their mobility," says Jon
Sigurdsson, Ossur's president and CEO. "The result will be that the entire
amputee population will eventually realize a more natural and safe form of