Jarrod Shapiro, DPM
Practice Perfect Editor
Assistant Professor,
Dept. of Podiatric Medicine,
Surgery & Biomechanics
College of Podiatric Medicine Western University of Health Sciences,
St, Pomona, CA

Biomechanics and Surgery:
Never the Twain Shall Meet?

During my time as a podiatrist, from student to resident, to private practice, and now to educator, the fields of biomechanics and surgery have often been presented as separate specialties, often diametrically opposed, to each other. I learned podiatric biomechanics in med school essentially in a vacuum, as an alternative to surgery. In fact the idea of applying biomechanics to surgery never came up during my time at CSPM. Rather, the biomechanical examination was a means to the end of prescribing a pair of custom foot orthotics. I argue below that although this may be the current state of affairs for many of us practicing modern podiatry, it is not only unnecessary but also detrimental to our profession.

The History

I can understand the reason for this state of affairs. It appears from my surface understanding of the history of podiatry that lower extremity biomechanics developed with a distinctly nonsurgical bent. For example, if one reads Normal and Abnormal Function of the Foot by Root, et al.,¹ unarguably the sine qua non of modern podiatric biomechanics, one is hard pressed to find even one section of this fascinating book devoted to surgical biomechanics. The same was true in my experience with biomechanics as a student at CSPM, the original think-tank where our beloved biomechanics was born. As a student, I was taught by Dr. Paul Scherer, one of podiatry’s biomechanics gems. Dr. Scherer’s class was the first time I felt like I was being given the tools to modify the foot in ways that would help my patients. Unfortunately, after creating my first pair of orthotics, the application side of these teachings ended, and the biomechanics I learned was never related to surgery.

BioMagicians are Different

Perhaps the reason for this comes from another part of podiatry’s history: the corporate orthotic laboratory. How many of our biomechanics experts either own an orthotic lab or consult for one? I don’t think I need to point out the conflict of interest here, at least as it relates to joining these two portions of our specialty. These physicians with expertise in foot function and biomechanics spend their time developing orthotics and there has been a lack of integration of their knowledge into the surgical realm. In fact, those who “specialized” in biomechanics tended to be those who weren't particularly interested in surgery. I mean, it’s not called the American Board of Podiatric Orthopedics and Primary Podiatric Medicine and Surgery.

So are Foot Surgeons

We can’t put all this on the biomechanists. As podiatric surgery has blossomed, it has tried to become increasingly “orthopedic surgical” in nature. Our surgical procedures have become ever more complex and specialized as our scope of practice becomes ever broader. Just think about the complexity of Charcot reconstructions or revisional ankle fusions. But as these procedures grow in complexity, well beyond the “lump and bump” surgery of our forbearers, is there a true consideration about the biomechanical effect their reconstructions create? How will the reconstructed foot support the body and respond to the pull of muscles around it ? How will it affect balance, cadence and propulsion ? Isn’t there more to the concept of a “plantigrade foot” as the goal of Charcot reconstruction than just a foot without the bump on the bottom? What do our biomechanists and surgeons say about the functional consequences of these complex surgeries? We’re trying so hard to be orthopedists that we surgeons (present company included) easily forget about function. Not convinced of this? Look at our residencies, becoming ever more orthopedically oriented with decreasing attention to biomechanics. What’s the board called? The American College of Foot and Ankle Surgeons and Biomechanists? I don’t think so.

There Have Been Some Meetings of the Minds

Luckily this isn’t true across the board. Consider flatfoot surgery. Previously, the choice of procedures was dictated by one’s knowledge of prior eponymous procedures – Koutsogiannis, Cotton, Strayer, etc. In modern times, we now have the biomechanically oriented concepts of planal dominance and CORA (center of rotational angulation) to determine procedure choice.² Similarly, an interesting paper advocated the use of the subtalar joint axis palpation technique intraoperatively to determine the appropriate correction when performing a medial calcaneal displacement osteotomy.³ Excellent work using biomechanical principles intraoperatively.

Early signs of biomechanical considerations are now showing up with the first ray. I would direct the interested reader to the work of Johnson and Christensen, et al who published an excellent biomechanically oriented cadaveric series of investigations on first ray function that has important ramifications on surgery of the first ray.⁴

This is the kind of work we need that combines biomechanics and surgery into a healthy integrated whole. But we need more. More research. And more mixing of the biomechanists and the surgeons. When that happens, we and our patients will benefit greatly.

Vultus dictum muneris - Form Dictates Function

Biomechanical principles (form) should dictate how we treat our patients surgically (function). The same is true for our profession: form- combined or separate - will dictate function – success or failure. Best wishes all you biomechanical surgeons and surgical biomechanists.

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References

Root, et al. Normal and Abnormal Function of the Foot. 1977. Clinical Biomechanics Corporation pub.
Labovitz J. The Algorithmic Approach to Pediatric Flexible pes Planovalgus. Clinics in Podiatric Medicine and Surgery, Jan 2006; 23(1): 57-76.
Roukis T and Kirby K. A Simple Intraoperative Technique To Accurately Align the Rearfoot Complex. Journal of the American Podiatric Medical Association, Sep 2005; 95(5): 505-507.
Johnson C and Christensen J. Biomechanics of the First Ray Part 1. The Effects of Peroneus Longus Function: A Three Dimensional Kinematic Study on a Cadaver Model. Journal of Foot and Ankle Surgery, Sept 1999; 38(5): 313-321.

Keep writing in with your thoughts and comments. Better yet, post them in our eTalk forum. Best wishes.

Jarrod Shapiro, DPM
PRESENT Practice Perfect Editor
[email protected]