Northern Lights: Bright Ideas in Canadian Research
By Judith Otto  Dr. Stephen Naumann, director of the
Rehabilitation Engineering Department at Bloorview MacMillan
Children's Centre, Toronto, Ontario, discussed some current
projects.
Electrical Elbow
Dr. Naumann's department is currently developing an electrical
elbow for teens or petite women, designed to swing freely in full
extension with no rotation.
In pursuit of a market debut early next year, Naumann is meeting
regularly with clinical colleagues and engineers. He reported that
the research itself is completed, but the mold-making process will
likely require another six months of work. Consumer feedback will
continue to be solicited during this period as well.
Variety Ability Systems, Inc. (VASI), Toronto, which
manufactures and markets prosthetic and orthotic devices for
children, was established in the early ‘70s to fill a need
for production and consumer feedback. Although the market for these
items was minimal and production on such a small scale was neither
cost-effective nor profitable, VASI nonetheless began production,
relying largely on donor funding for the benefit of children whose
lives would be enriched by the possession of such a device. Today,
VASI continues to serve as a manufacturing and marketing partner,
supporting the research efforts of the Children's Centre and making
their O&P advances more readily available to the public.
Soft UE Socket
Also in development is a soft silicone upper limb socket. Such
sockets are already used for certain sports prostheses. They allow
the socket to be simply peeled on and off the stump.
"We can't afford the hazard of exposed or broken wires," Naumann
said. "In order to remotely detect what the muscle is doing, we
place microphones at the distal end of the stump. Even at that
distance, a tiny $10 microphone picks up the noise of the muscle
contracting." The problems they have encountered have been created
by the microphone's ability to hear too well and pick up too much
interference-potentially allowing an inappropriate noise-like an
unexpected jar or bump-to trigger it. Their solution is to
electronically filter out this noise.
"We're about a year to a year and a half away from introducing
this to the public," Naumann said. "We're trying to come up with a
kit that prosthetists can easily incorporate."
Pediatric Knee Joint
There's also a knee joint for young children, in advanced
development stages, which will possibly be available through VASI
within the year. "Some such knees are already available," said
Naumann, "but ours will be simple, more robust, and still retain
the same features. It will be smaller and weigh less, so it can be
fitted to smaller children."
 Improved Standers
Naumann's group is active with research on the orthotic side, as
well.
"Parapodiums or standers for children with spina bifida have
been around since the ‘70s," he pointed out. "We're trying to
get more weight-bearing-this not only helps to strengthen bone and
potentially prevent osteoporosis, but it also prevents bladder
problems and allows children to stretch and reach things
better."
Current models allow a swing walk, but orthotists have concerns
regarding the prohibitive expense of such standers, which lack
adjustability to accommodate the child's growth. Most insurance
plans will not cover the cost of replacement standers as the child
outgrows them.
Naumann's three sizes of standers allow multiple modifications.
"Just by loosening and tightening a few bolts you can make
adjustments," he said. "Even if the child's knees are not at the
same level, or if contractures prevent a child from straightening
up, you can adjust for these conditions."
The new standers should be available from VASI in about six
months.
New Materials for AFOs
New materials are also being developed for AFOs, Naumann said.
Currently the fitting process for polypropylene AFOs is very
labor-intensive, involving casting, molding, vacuum-forming, and
custom heat-adjustments.
Naumann's researchers worked with Dr. Paul Santerre in the
dentistry department at the University of Toronto and Dr. Shiping
Zhu at McMaster University, Hamilton, Ontario, to develop a
composite that can be cured by light rather than heat. This project
has been underway for a number of years, but with a resin now
available that "works very well," Naumann expects to complete the
project within the next two years. "The materials we first used
were toxic," he said. "What we have derived now is even safer than
the materials dentists put in your mouth."
Myoelectric Controls Research
Cennet Iley, age 9, enjoys activities in her stander. Photo by
Fraser Shein, PhD, PEng, Bloorview MacMillan
Bernie Hudgins, PhD, PEng, Director of the Institute of
Biomedical Engineering at the University of New Brunswick, cites
the Institute's venerable history of research concerning
myoelectric control systems for powered upper-extremity
prostheses-award-winning studies which have led to the Institute's
current work from a new 14,000 sq ft on-campus facility, R.N. Scott
Hall, just christened in ceremonies on May 24.
Although they were first designed before World War II, powered
upper-extremity prostheses weren't introduced for popular use until
around 1965, Hudgins said. At that time, the Institute was involved
in the first all-Canadian fitting of myoelectric prostheses. The
Institute also was first to develop the three-state system that
allowed people with only one muscle control site to use varying
amplitudes to control their prosthetic arm.
Today, the Institute has diversified its areas of investigation
into telehealth, biological signal acquisition, and motion
analysis, according to Greg Bush, BA, CP (c), research prosthetist
at the Institute. Bush has also chronicled the Institute's current
research activities in a story for Alignment, the Canadian
Association of Prosthetists and Orthotists (CAPO) 2002
Yearbook.
Research prosthetist Greg Bush, BA, CP(c) demonstrates a new
control system to client Daryl Arsenault.
According to Bush, the Institute's new facility is equipped with
a VICON motional analysis system that allows closer examination of
"various aspects of human motion, particularly upper limb
function...the new six-camera system will allow 3-D tracking of
these complex functions (and) ...permit comprehensive analysis of
function and posture when using an upper extremity prosthesis."
An Institute research team has been working for eight years to
perfect an "intelligent" control system for upper-limb prostheses
which has three degrees of freedom, with elbow, hand, and wrist all
operated myoelectrically. "Since 1997," Bush said, efforts "have
focused on making the control more fluid and the control interface
between the prosthesis and limb more natural. This will provide a
dynamic cosmetic appearance to the prosthesis, so that it looks
natural in function with the actions being less robotic."
Hudgins agreed, noting that the project's goal is to make the
selection of prosthetic function more instinctive for the subject.
The new controller uses a specialized computer embedded in the
prosthesis which "learns" the characteristics of the myoelectric
signals of an individual much as the brain recognizes familiar
patterns. Recent advances in microprocessor technology have
expedited their progress by delivering high performance while
requiring minimal power.
"Our control systems have now progressed beyond the capabilities
of the components currently available," he pointed out.
Hudgins observed that there are a limited number of above-elbow
amputees available to test their sophisticated new control system.
Cost has been another cause of delay; locating sources of funding
has been a major stumbling block. For an above-elbow amputee, a
typical cost of fitting a myoelectric prosthesis is in the $27,000
(Canadian) range. Additionally, "We can't fit the limb with an
experimental control system until the patient has a duplicate
backup system," said Hudgins-which further escalates the costs. And
unfortunately, he pointed out, it is difficult to do a cost-benefit
analysis without testing the system on a patient who can
demonstrate those benefits.
"Funding is the only thing stopping us at this point. We're
ready to fit the system on patients and pursue clinical trials;
we've already tried an in-house fitting. But it still looks like a
long way to our final destination. The control system is ready to
go; it can now switch smoothly between sequential movements.
Simultaneous movement-such as bending the elbow while rotating the
wrist-is on the horizon, but won't be a reality for another five
years."
The fact that not every upper-extremity amputee is a candidate
for trial is another complication, Hudgins pointed out. "Depending
on their injury, some amputees may have very little muscle
remaining. And while some people are capable of making optimum use
of even a small amount of muscle, some are unable to generate the
differing signals necessary to utilize the controller."
Other factors may also disqualify a candidate: farmers and
fishermen, for example, function in a myoelectrically unfriendly
environment. Other Institute projects include innovative approaches
to socket fitting, new comfort-conscious ideas regarding suspension
systems, and an interactive "virtual arm"-brainchild of the
Institute's associate director, Kevin Englehart, PhD, PEng.
A computer-generated model of the prosthesis and its environment
can be simulated in order to evaluate control strategies prior to
fabrication of the definitive prosthesis. The system allows
researchers to evaluate how well a control configuration works for
a patient, and to fine-tune it before actually making the costly
limb.
The system may be a valuable aid in rehab therapy, as well,
allowing new amputees the opportunity to learn to control the
various functions of the on-screen virtual arm, thus getting a head
start on training prior to being fitted with the prosthesis.
"We will be able to have the client doing active, daily living
tasks in this virtual space," said Englehart in Alignment. "We'll
also have the ability to explore things you'd never be able to test
on existing prosthetic devices."
The virtual arm prototype already exists, and the system should
be ready for widespread use within a year, Hudgins anticipates.
The Institute's latest developments will be examined at the
Myoelectric Controls and Powered Prosthetics Symposium (MEC 2002),
hosted by the University of New Brunswick August 18-23. For further
information, visit www.unb.ca/bio-med
Judith Otto is a freelance writer based in Holly Springs,
Mississippi. 
Table Of Contents - August 2002
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