Medical Design Briefs - March 2024 - 36

erate assistive forces in tandem with
muscle movement.
The effect was instantaneous. Without
any special training, the patient was able
to walk without any freezing indoors and
with only occasional episodes outdoors.
He was also able to walk and talk without
freezing, a rarity without the device.
" Our team was really excited to see the
impact of the technology on the participant's
walking, " says Jinsoo Kim, former
PhD student at SEAS and co-lead author
on the study.
During the study visits, the participant
told researchers: " The suit helps
me take longer steps and when it is not
active, I notice I drag my feet much
more. It has really helped me, and I
feel it is a positive step forward. It could
help me to walk longer and maintain
the quality of my life. "
" Our study participants who volunteer
their time are real partners, " says
Walsh. " Because mobility is difficult, it
was a real challenge for this individual
to even come into the lab, but we benefited
so much from his perspective and
feedback. "
The device could also be used to better
understand the mechanisms of gait
freezing, which is poorly understood.
" Because we don't really understand
freezing, we don't really know
why this approach works so well, " says
Ellis. " But this work suggests the potential
benefits of a 'bottom-up' rather
than 'top-down' solution to treating
gait freezing. We see that restoring almost-normal
biomechanics alters the
peripheral dynamics of gait and may
influence the central processing of
gait control. "
The research was co-authored by Jinsoo
Kim, Franchino Porciuncula, Hee Doo
Yang, Nicholas Wendel, Teresa Baker and
Andrew Chin. Asa Eckert-Erdheim and
Dorothy Orzel also contributed to the
design of the technology, as well as Ada
Huang, and Sarah Sullivan managed the
clinical research. It was supported by the
National Science Foundation under grant
CMMI-1925085; the National Institutes of
Health under grant NIH U01 TR002775;
and the Massachusetts Technology Collaborative,
Collaborative Research and Development
Matching Grant.
This article was written by Leah Burrows,
Harvard University. For more information,
contact Conor Walsh at 617-4964269
or visit https://seas. harvard.edu.
A video of the technology is available
at https://www.youtube.com/watch?v
=pAWrypkeDXM.
Infection-Resistant, 3D Printed Metals Developed
for Implants
The implant kills 87
percent of bacteria that
cause staph infections.
Washington State University
Pullman, WA
A novel surgical implant developed by
Washington State University researchers
was able to kill 87 percent of the bacteria
that cause staph infections in laboratory
tests, while remaining strong and compatible
with surrounding tissue like current
implants.
The work, reported in the International
Journal of Extreme Manufacturing, could
someday lead to better infection control
in many common surgeries, such as hip
and knee replacements, that are performed
daily around the world. Bacterial
colonization of the implants is one of the
leading causes of their failure and bad
outcomes after surgery.
" Infection is a problem for which we
do not have a solution, " says Amit Bandyopadhyay,
corresponding author on
the paper and Boeing Distinguished Professor
in WSU's School of Mechanical
and Materials Engineering. " In most cases,
the implant has no defensive power
from the infection. We need to find
something where the device material it36
self
offers some inherent resistance -
more than just providing drug-based infection
control. Here we're saying, why
not change the material itself and have
inherent antibacterial response from the
material itself? "
Titanium materials used for hip and
knee replacements and other surgical
implants were developed more than 50
years ago and are not well suited to overcoming
infections. Although surgeons
often treat preemptively with antibiotics,
life-threatening infection can occur
right after surgery or weeks or months
later as a secondary infection. Once an
infection sets in as a fuzzy, fine film on an
implant, doctors try to treat it with systemic
antibiotics. In about 7 percent of
implant surgery cases, though, doctors
have to perform a revision surgery, removing
the implant, cleaning the area,
adding antibiotics and putting in another
implant.
Using 3D printing technology, the
WSU researchers added 10 percent tantalum,
a corrosion-resistant metal, and 3
percent copper to the titanium alloy typically
used in implants. When bacteria
come into contact with the material's
copper surface, almost all of their cell
walls rupture. Meanwhile, the tantalum
encourages healthy cell growth with surwww.medicaldesignbriefs.com
rounding
bone and tissue leading to expedited
healing for the patient. The researchers
spent three years on a
comprehensive study of their implant,
assessing its mechanical properties, biology
and antibacterial response both in
the lab and in animal models. They also
studied its wear to make sure that metal
ions from the implant won't wear off and
move into nearby tissue causing toxicity.
" The biggest advantage for this type of
multifunctional device is that one can
use it for infection control as well as for
good bone tissue integration, " says coauthor
Susmita Bose, Westinghouse Distinguished
Professor in the school. " Because
infection is such a big issue in
today's surgical world, if any multifunctional
device can do both things, there's
nothing like it. "
The researchers are continuing the
work, hoping to improve the bacterial
death rate to the standard of more than
99 percent without compromising tissue
integration. They also want to make sure
that the materials offer good performance
under real-world loading conditions
that patients might use, such as for
hiking in the case of a knee replacement.
The researchers are working with
WSU's Office of Commercialization and
have filed a provisional patent. The work
Medical Design Briefs, March 2024
https://seas.�harvard.edu https://www.youtube.com/watch?v=pAWrypkeDXM https://www.youtube.com/watch?v=pAWrypkeDXM http://www.medicaldesignbriefs.com
Medical Design Briefs - March 2024

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