For people with traumatic lower limb injuries, a custom composite
ankle-foot orthosis can often salvage the limb and return the wearer to his or
her previously active lifestyle. However, these devices are labor-intensive,
requiring specialized tools and knowledge to fabricate, and often come with a
high price tag.
Hoping to remedy this problem, John Gillespie, PhD and
Shridhar Yarlagadda, PhD, the director and assistant director at the
University of Delaware Center for Composite Materials, respectively, received a
3-year, $3 million grant from the Defense Advanced Research Projects Agency to
develop an accelerated process for creating composite AFOs using 3-D
technologies.
“Our overarching goal is to create a methodology to build
high-performance composite devices that can be customized for a particular
individual quickly, and hopefully, cheaply,” Yarlagadda told O&P
Business News. “We want to find out, if the orthotist has all of the
equipment needed to build a device, can it be done in a matter of days?”
Yarlagadda and Gillespie will be working in collaboration with Steven
Stanhope, PhD, the director of the BADER Consortium, which is a University
of Delaware network of rehabilitation facilities and hospitals that focuses on
recovering from extremity traumas. Stanhope has already developed a process for
manufacturing polymer passive dynamic AFOs through additive manufacturing. The
process involves using a digital scan of a patient’s foot to design an
orthotic device, which is then printed using a 3-D printer. However,
Stanhope’s patent-pending process is limited to polymer materials.
“Dr. Stanhope came to us about 2 or 3 years ago, but one of the
issues we noticed was that polymer is bulky and doesn’t have the
properties necessary to make devices light or thin.” Yarlagadda said.
“So we started looking at other options in terms of materials, design
approaches and manufacturing of these devices.”
Phase one
Yarlagadda and his colleagues are focusing on combining the rapid
production of additive manufacturing with the high-performance, lightweight
benefits afforded by composite materials. The study will occur in two phases,
each lasting 18 months, and the first phase will revolve around research and
development.
The first thing Yarlagadda and his colleagues hope to do is modify the
casting process and reduce the time it takes for an orthosis to be fabricated.
“Customizability is the first thing we want to address. Normally,
an orthotist has to get the geometry of the foot with a cast, prescribe a
device, send the cast to someone else for fabrication and wait for the finished
product to be shipped back,” Yarlagadda said. “We want to automate
the process and give the orthotist all of the tools he needs to scan the
patient’s foot, decide what type of device to build, run it through the
computer and pop out the device. We’re trying to get the entire process to
below a week.”
They are also looking at the how composite materials can be tuned to fit
the needs of the individual patient, as well as investigating how the orthosis
could adjust as the patient’s needs change.
“One of the issues with most materials is that once you build it,
it has a fixed property. But composite materials have unique features, such as
tunable properties,” Yarlagadda said. “If a patient walks at a
certain velocity, a certain stiffness may be best, but walking faster, or
running, would require a different stiffness. So we want to be able to tune the
stiffness or the response of the device based on the activity that we want it
to do.”
The same idea applies to rehabilitation devices, which need to adapt as
a patient gets stronger. Yarlagadda hopes that by using tunable materials, they
can eliminate the need to remake a new device as the patient’s rehab
progresses.
Phase two
Yarlagadda and his colleagues plan to have at least six orthotic devices
built at the completion of phase one in order to begin clinical testing. They
will work with Stanhope and the BADER Consortium to test the devices on wounded
soldiers and veterans.
“We want to try to make at least one device with each of the
processes that we are investigating,” Yarlagadda said. “At the end of
the first phase, we hope to have a clear idea of what the right manufacturing
process, or processes are, so in phase two, we will be able to show that we
have all of the tools in place to build the devices and start collecting
clinical data.”
At the end of the second phase, Yarlagadda said they plan on finalizing
the cost for developing the devices.
“Cost is not something we’ve put too much thought into yet
because the bulk of the cost of modeling work will come later as it will be
dependent on the manufacturing processes,” Yarlagadda said. “But we
are very conscious of it, so we will be looking at the cost of the existing
devices on the market and hopefully beat them. We want to make this as
affordable as possible.”
The study began only a few weeks ago, and although a finalized product
is still several years away, their work could have a significant impact on the
orthotic industry.
“Creating devices with this type of performance is a new area that
I don’t think many people have looked at yet,” Yarlagadda said.
“And if we can create this system and actually shorten the time it takes
for people to get their devices and start rehab, it will hopefully trickle down
in terms of rehab time and application to other devices as well.” —
by Megan Gilbride
Disclosure: The researchers received grant monies from the Defense
Advanced Research Projects Agency.
