Interactive Microprocessor Foot Adjusts to User Specifications

LAS VEGAS — At the Hanger Education Fair and National Meeting here,
David Boone, CP, MPH, PhD, Orthocare Innovations, described how the
company’s Magellan microprocessor foot, currently in beta trials,
automatically adjusts to the user’s needs.

“What we care about is how a patient feels and interacts with their
world through their prosthesis,” he told an audience here. As
prosthetists, “we force users into adapting to the limitations we’re
giving them,” he said. “We want to make the prosthesis adapt to the

The Magellan combines smart pyramid thinking with smart adaptation
through a 38° range of dorsiflexion and plantarflexion based on the
Magellan foot learning the patient’s unique gait dynamics. It features
auto stance balancing, with a compliant joint and a dynamic elastic response.
The foot eliminates 5 foot-pounds of extra torque off the foot, and provides a
42% reduction in the amount of stress on the user’s limb.

“It measures forces going through the limb and controls the ankle
based on that,” Boone said. “It maintains smooth gait, efficient
gait, and improves gait symmetry. It learns the patient’s own gait and
adjusts and optimizes movement. The foot provides automatic stance balancing
within a couple of degrees of neutral, he said.

“It’s a very robust system. Any time Magellan decides it
can’t make decision, it doesn’t know exactly how to adjust, then the
user just has a very good carbon fiber foot under them.”

Boone pointed out the ease and speed with which a Magellan wearer can
stand and walk from a sitting position. The foot responds immediately, with no
hesitation, and no user adjustment required. “We’ve made the system
extremely fast and smooth,” Boone said.

The foot uses proprietary mesofludic control technology, which uses very
small hydraulics and actuators in a pressurized fluid system. The system
provides high force density and low friction with lower energy expenditure.
There are no drive motors.

“It works in stance phase primarily. In stance phase, the pressures
generated in the mesofludics from the act of standing affect balance and
control,” he said.

Low friction advanced technology bushings won’t wear out, Boone
said. “They’re designed to be used in dirty, filthy, environments,
and they help keep Magellan low maintenance.”

Boone said the self-contained Magellan is designed for use in a broad
range of patients. “There are no wires at all, no external batteries, no
external chargers. The charging circuit is built into the ankle.”

The guided set up is easy for the user and the prosthetist, allowing
them to turn features on and off. “The set up can literally be done in 60
seconds,” Boone said. The prosthetist connects to it and records no load,
standing and walking specifications.

At 1.9 lbs, the Magellan requires minimal maintenance. Its neutral
position is 3/8” with a 3” maximum heel height. A small lithium
battery requires just a mini USB port, requires 2 to 3 hours for recharge, and
lasts 2 days on one charge.

“There is low demand on the user. We want the amputee to have the
benefit of feeling better without having to tell the prosthesis to make him
feel better. We want the amputee to limit what they have to deal with, with the
prosthesis,” Boone said. “We made the charging easy with a mini USB
port. You can charge it in the car, or on your laptop, if you wanted to wait
that long. The patient shouldn’t try to accommodate; let Magellan adapt to
the patient.”

The foot is interactive. Programming specifications can be accessed with
an app on a user’s smart phone, laptop or tablet, allowing the. user to
check battery life and change functions online.

Orthocare expects to release the the Magellan foot by spring or early
summer this year.

Also in the session, Kevin Carroll, MS, CP, FAAOP, vice president
of prosthetics, Hanger Prosthetics & Orthotics, spoke about the general
resistance to fitting microprocessor feet.

“The most neglected area in prosthetics is the foot and
ankle,” he said. The lack of success of other clinicians affects efforts
of others to try, he said. Prosthetic feet have reliability issues, and
patients report a fear of failure and lack of confidence in their feet.
Microprocessor feet, in particular, cannot get wet.

“Perhaps we are not doing a good job of educating,” Carroll
told the audience. He lauded the increasing investment in technology and
acknowledged the role of competition in moving the field forward.

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