Discoveries Found Along the Road of Research

I do not recall the name of the prosthetist, but I remember exactly what
he said. I was a graduate student in biomedical engineering at Ohio State
University in 1996, taking a class in prosthetics and orthotics with the
medical residents. It was an evening class in a small, cramped room in one of
those back halls of the hospital that I didn’t know existed. The topic was
prosthetic feet, and the prosthetist was describing the brief history of
“so-called energy storing feet.” He spoke of Delrin and carbon fiber,
and of uncertainty. “Many patients love these feet,” he said,
“but there are some researchers who have found that they don’t
actually return enough energy to be effective. We don’t really know
who’s right.”

For me, a dissertation was born.

I was a National Science Foundation Graduate Fellow, which afforded me a
degree of latitude in the selection of a research project. I had settled on
biomechanics and gait analysis, and had studied ACLs and total hip
arthroplasty, but remained uncertain about my dissertation project. The
prospect was daunting, because I knew the choice might define my research
emphasis for my career. As that prosthetist spoke, I found my project. I was
naïve and overconfident, and I decided that evening to go ahead and settle
the issue on how these fancy new feet work.


Every discipline has a native nomenclature, so I had much to learn about
the meaning of terms like dynamic alignment and the differences among socks,
sleeves and liners. I also quickly discovered that for a student of
biomechanics, prosthetics requires a most thorough understanding of the most
subtle elements of human motion. With every article I read, I peppered the med
school fellows across the hall with questions, expanding my mechanical
engineering knowledge with the “bio” part of biomechanics. I found
that their knowledge was also limited when it came to prosthetic components.
They did not know a SAFE foot from a Seattle foot, and I could not understand
what I read without such knowledge. In a time before Google, I needed help.

Herein lies the first lesson I’ve learned.

Researchers and clinicians need each other

As I read those articles, I had a particular orange highlighter I used
to emphasize every term or concept I did not understand. When the stack of
pumpkin-colored pages got too large, I knew I needed assistance, but I did not
know whom to call. Believe it or not, I actually looked up
“Prosthetics” in the Yellow Pages. The first listing was for American
Orthopedics, so I made a call.

This time, I do remember the name of the prosthetists. I was blessed to
encounter two very patient and knowledgeable mentors in Zach Ruhl and Ron Kidd.
They answered my questions, but they also helped me appreciate the marriage of
art and science in clinical care. I don’t know that I was of any benefit
to them, but they were an invaluable resource for me, and I am convinced that
there are lots of young researchers in the same position today: drawn to the
talisman of O&P research, but hindered by the clinical learning curve.
Compared with larger fields like orthopedics and physical therapy, O&P has
relatively few clinicians who are also researchers, so it’s imperative
that our researchers and clinicians are willing to help each other and learn
from each other.


Mark Geil

Mark Geil

I finished my classes and launched into my dissertation research, ready
to figure out these feet once and for all, and make my mighty contribution to
the state of the science. I quickly learned, once again, that I had much to

I have much to learn and always will

I found that the discrepancy in clinical and research opinions on the
function of energy storage and return feet rested in the biomechanical models
used by the researchers. The assumptions inherent in standard inverse dynamics
models of lower limb kinetics are reasonable for an anatomical limb, but
largely unreasonable for a prosthetic limb. I could not address the applied
clinical question without addressing the modeling issue.

In the end, I wrote a very different dissertation than the one I
imagined when I started, and if I shed any light, it was cast not on
definitively explaining how energy storage and return feet work, but instead on
the inadequacies of kinematic models. It was what we call basic research
instead of applied research, but it was useful, if only for me. I don’t
believe I could have properly conducted much of the applied research that has
followed without these origins in basic research. This is another lesson that I
might pass along to the field’s few but important funding agencies.

There is a place for both basic and applied research

Dissertation complete, I dove into my first faculty position at Georgia
Tech in Atlanta. There are certain very important elements of academia that,
unfortunately, graduate school does very little to prepare one for, teaching
not the least. Nonetheless, I was enamored with teaching, and worked hard to
ascend the steep learning curve. At the same time I was starting my first
independent research and writing grant proposals, and my next lesson was

Academia is a supremely challenging balancing act

I suppose just about every profession requires juggling and
multitasking, and I have become keenly aware of the varied time-consuming
requirements of clinical practice, but I don’t think I fully appreciated
the similar rigors of being an assistant professor. While I was writing
lectures for my next class (and prepared overhead transparencies, if you
remember what those were), no grants were being written. While I was writing
grants, no research was being conducted in the lab. And then there were
committees, student recruitment and admissions, curriculum, lab management,
graduate student supervision, advising, and more. It was all new to me, but I
loved it, and still do.

Discoveries Found Along  the Road of Research



Part of the joy of laboratory research was the opportunity to pursue
whatever questions I wanted to answer, within the limits of budget and
resources. My first project used a VA grant to assess material properties of
prosthetic feet and develop an iterative algorithm for a way to independently
characterize the elasticity and hysteresis of any prosthetic foot in three
simple numbers. I liked it and wondered if it would catch on and become the new
“code” that practitioners could use when deciding which foot is most
appropriate for a given individual. Needless to say, it did not catch on.

I also started a line of research in prosthetic alignment, which led to
one of my most interesting and enjoyable evenings in the lab. I decided it
would be fun to try something I’d never seen before. I called a bunch of
local prosthetists, brought them all to the lab along with a disassembled
prosthesis, and let each have a go at dynamic alignment of a transfemoral
prosthesis for a fellow practitioner. After each alignment, I conducted a gait
analysis and measured the results. I was fascinated by the idea, the results
and the implications, and I realized something. Despite the challenges and
frustrations of scrounging for funding, recruiting subjects and obtaining human
subjects review board approval, I realized the next lesson.

In its purest form, research is about answering questions

And that’s fun.

Since that time, I have moved 3 miles down the road to direct the
biomechanics laboratory at Georgia State University. I’ve added a focus on
pediatric prosthetics, and, thanks to funding from the Orthotic and Prosthetic
Education Research Foundation, I’ve even crossed over to the orthotics
side to study idiopathic toe walking. And that brings me to one final lesson
learned, this one aimed at my fellow researchers.

Don’t forget orthotics

Prosthetics research may be more glamorous, and it might be easier to
obtain funding for it, and it’s even simpler to explain to people, but
I’ve found orthotics research to be just as fulfilling. The needs are
great and the volume (and potential impact) greater. The area is also
challenging what I know about gait, and after a decade and a half, that’s
a good thing.

So, after three universities, five laboratories, and more than 15 years
of research, I owe a debt of gratitude to many: collaborators, mentors,
funders, subjects, students, and more. I am comforted and encouraged in the
knowledge that O&P has many bright and dedicated researchers who, with
patients in mind and with ideas far more impressive than mine, will continue
the extraordinary advancement in the science of the field. Research in
prosthetics and orthotics has been engaging and rewarding for me, and I remain
grateful and humbled that I get to do this job every day.


For More Information:

Mark Geil has a bachelor’s degree in mechanical engineering from North Carolina State University and a doctorate in biomedical engineering from the Ohio State University. He is currently associate professor and director of the biomechanics laboratory at Georgia State University in Atlanta, and is an honorary member of the American Academy of Orthotists & Prosthetists. He is also a member of the O&P Business News Practitioner Advisory Council.

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