Biomechanics and sports medicine have always been of interest to me since I entered podiatry school. After my first year of surgical residency, I was fortunate to do the Biomechanics Fellowship at the California College of Podiatric Medicine (CCPM). Even though the year of my Biomechanics Fellowship was the period of my life when I probably experienced the greatest intellectual growth, I ended the year with more questions than I had answers.
I saw that all the traditional biomechanical measurements based on subtalar joint neutral that I had been trained to perform as a podiatry student did not necessarily correlate to my patients’ symptoms. Even though most patients were getting better with the orthoses that all the clinicians and myself made for them, none of our measurements of “foot deformities” exactly agreed with each other.
Toward the end of my Biomechanics Fellowship, I began reading the medical and biomechanics literature that was outside the podiatric sphere. The most influential references I remember reading from the CCPM library were a book on knee biomechanics by a Belgian orthopedic surgeon, Paul Maquet, MD, and a series of papers on foot and ankle biomechanics by John Hicks, MD, an orthopedic surgeon in England, and Benno Nigg, Dr.sc.nat., Dr.h.c., a biomechanist in Canada.
In their book and papers, Drs. Maquet, Hicks and Nigg all used an engineering approach to discuss and illustrate the internal forces and stresses within the structures of the foot and lower extremity. Their physics-based engineering approach was a revelation to me after spending years at CCPM learning how to properly measure subtalar joint neutral, measure “forefoot to rearfoot deformities” and “rearfoot deformities,” and make foot orthoses to “prevent compensations for forefoot and rearfoot deformities.”
By using easily understandable models of the foot and lower extremity, these three men effortlessly discussed what was mechanically occurring inside the foot and lower extremity during weightbearing activities. I became hooked on this idea that we, as podiatrists, could also learn more about the internal forces and stresses that each structural component of the foot and lower extremity was subject to by “thinking like an engineer.”
Upon reading more about engineering principles during my early years of practice, I began to learn more about the concepts that engineers use to build, for example, bridges, buildings, automobiles and ships. I realized that, unlike podiatrists who seemed to concentrate on static clinical measurements and static radiographic images of the foot and lower extremity, engineers focused on trying to understand the internal forces and stresses on each component of the structure they were designing in order to keep the bridge, building or machine from mechanically failing.
Now, over 28 years since I graduated from my Biomechanics Fellowship, I am even more convinced that the way forward for our profession is for all of us to think more like engineers. If our desire as a podiatry profession is to remain as the medical specialty that most fully understands the mechanically-based etiologies of the various pathologies of the foot and ankle, we need to move forward intellectually.
We must start focusing our podiatry school education and podiatry seminar content more on how abnormal stresses generate within the tissues of the foot and lower extremity, and how we can best reduce those pathological stresses to more physiologic levels, whether with stretching, strengthening, strapping, padding, bracing, foot orthoses and/or surgery. We must start focusing our energy and education more on how shoes, foot orthoses, braces and our foot and ankle surgeries affect the forces and stresses acting on and within the foot and lower extremity so our patients can heal faster and suffer fewer post-treatment sequelae. I believe this “tissue stress approach” will be the key to more effective conservative and surgical treatment for our patients, and to the continuing success and development of our profession.
Patients seek our help because of painful and disabling foot and lower extremity pathologies caused by abnormal tissue stresses, not because they have 3-degree forefoot valgus or 6-degree rearfoot varus “deformities.” Pathologies are caused by abnormal tissue stresses, not necessarily because feet are “pronated,” “supinated,” “flat-footed” or “high-arched.”
All podiatrists need to begin to think more like engineers to understand the abnormal tissue stresses that cause foot and lower extremity injury so they can all better improve the lives of their patients with the most effective conservative and/or surgical treatments. Our patients deserve it and the healthy future of our profession demands it.
Dr. Kirby is an Adjunct Associate Professor within the Department of Applied Biomechanics at the California School of Podiatric Medicine at Samuel Merritt University in Oakland, Calif. He is in private practice in Sacramento, Calif.
Dr. McCord retired from practice in 2008 at the Centralia Medical Center in Centralia, Wash.