MEDICAL DEVICE INNOVATION - Medical Device Daily

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Bionic Proprio foot fitted on
first U.S. amputee patients
By LYNN YOFFEE
Medical Device Daily Staff Writer
A bionic foot that replicates a natural human walking
gait has, to date, been used primarily for members of the
military. Further refined and now available to the general
public, the Proprio Foot is likely to change the prosthetic
landscape.
“It’s the technology of the future,” said prosthetist Joe
Reda, CPO, who is among the first technicians in the U.S. to
be certified in the fitting of this device. “One of my first
patients, a motorcycle rider, wore it on his bike to Sturgis
Motorcycle Rally this week.”
Reda is an assistant director at Kessler Institute for
Rehabilitation (West Orange, New Jersey), one of the first
rehabilitation centers in the country to offer the Proprio
Foot developed by Ossur (Reykjavik, Iceland).
“It’s the only computerized foot on the market,” Reda
told Medical Device Daily. “The biggest limiting factor is the
cost right now and reimbursement.”
With a price tag of $34,000, it’s a bigger commitment
than other foot prosthetics, which range in price from
$5,000 to $18,000.
The artificially intelligent prosthesis for transtibial
amputees operates like natural, anatomical functioning.
Developed by Ossur’s R&D department, the foot’s motion
analysis capabilities are facilitated by real-time sensor
technology from Dynastream Innovations (Cochrane,
Alberta).
The foot’s name is derived from its ability to detect
where the foot is in space, known as proprioception.
“It’s got tilt sensors,” Reda said. “It analyzes what the
patient is doing and picks the toe up to allow the foot to
clear the ground easier. Going up an incline, an amputee
would generally walk on his toes and then down an incline
on the heels because a regular prosthetic foot doesn’t have
the flexibility. With the Proprio, after the second step it flexes
the foot going up, so the patient does a natural heel-totoe
gait. On the decline it does the same thing. When
amputees go from sitting to standing, they usually use
their good leg only, but with this foot, it flexes more so they
can use both feet.”
The Proprio includes sensor technology that mimics
the body’s own neural receptors that are sensitive to
mechanical change, providing artificial proprioception –
the sense of where the limb is in space, according to Ossur.
The artificial intelligence (AI) processes information from
those sensors and activates the most appropriate response
for the next step. The AI transmits an ongoing stream of
signals that instruct precise actuator technology to act and
deliver optimal function.
It works unlike any other prosthetic limb Reda has ever
MEDICAL DEVICE INNOVATION 2010
used. But it lacks any cosmetic attributes.
“It’s not a cosmetic leg by any stretch of the imagination.
It’s fairly bulky,” said Reda, who is not affiliated with
Ossur. “The ankle weighs 2 to 2.5 pounds with a large battery
pack located on back of the socket. You can’t cover it.
But the function of the foot outweighs the cosmetic aspect.”
Designed for below-the-knee amputees, Proprio
requires some basic programming when fitted with a
patient that takes about 45 minutes. The battery stays
charged for 36 hours before recharging is required.
“The technology is there,” Reda said. “I’d like to see a
smaller battery and unit.”
He added that while the foot is not intended for athletic
use such as running, it is designed for active people.
Until now, the Department of Defense and the U.S.
Department of Veterans Administration have actively used
the foot to benefit service men and women returning from
the Iraq and Afghanistan conflicts, as well as veterans of
past wars, according to Ossur.
The company is currently working to obtain Medicare
reimbursement coding.
(This story originally appeared in the Aug. 6, 2009, edition
of Medical Device Daily)
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