A question I hear often is, “How do you come up with different topics to write about?” It’s often a random process with ideas sometimes coming unbidden. However, for this week’s topic, someone else dropped the idea right in my lap.

I was driving to work last week listening to a podcast. With a sometimes one hour drive to work, it’s helpful to keep myself entertained and informed, and podcasts are a great way to do that. I was listening to a particular podcast in which a theoretical physicist was being interviewed. He made a comment about the utility of the science he studied, stating, “I haven’t done a practical thing in my life.”

I found this statement profoundly interesting. So much so that when I stopped to fill the car up with gas, I had to pull out my computer and start writing! It was such a unique thought – not doing anything practical at all in one’s professional life. You see I, like everyone who practices the various forms and specialties of medicine, live in a world of practicality. Treating patients successfully can’t be done by theory or best intentions. There is very little leeway with other peoples’ health. Successfully resolving patients’ illnesses requires correctly diagnosing and actually treating their problems. If we fail, then it’s not “too bad, better luck next time.” If we fail, another human being will suffer. There appears to be no room for theory here.

When I teach new students in clinic, I will often ask them to give me a diagnosis. These new students will look at me blankly at first, and then state some outlandish diagnosis that might make sense in theory but in practice is incredibly unlikely. Take forefoot pain, as an example. After examining a patient with generalized plantar forefoot pain, a trainee recently answered my “what’s your diagnosis” question with, “intermetatarsal neuromas of the second and third spaces.” Now, although this is theoretically possible, it’s highly improbable, and therefore, not practical. First of all, second intermetatarsal neuromas are vanishingly rare. Second, to have neuromas of two adjacent intermetatarsal spaces is even rarer yet.

Sure enough, when I examined the patient, I found a dysfunctional medial column, hallux valgus, and lesser metatarsophalangeal joint findings consistent with capsulitis and predislocation syndrome – a much more likely and therefore, practical set of diagnoses.

When we speak about evidence-based medicine and practice we, most of the time, are thinking in terms of the best research evidence to support a particular treatment method combined with patients’ needs and values. However, the other part of this is having the evidence that our diagnoses make sense. A logical thought process that links the patient’s history and physical examinations to reveal the correct diagnosis is the first step to success. Theoretical answers are worthless in these situations.

Now, on the other hand, a theory is highly important to move our conceptual understanding further. We may not be aware at the time what practical applications a particular theory might have, and time will often tell. Take, for example, Einstein’s special theory of relativity. It was a theory with an, at the time, unknown practical application. With time, of course, we now understand the incredibly important and practical results of this theory, including satellites and many other technological advances.

Similarly, theories sometimes help move us from an initial understanding of a concept to a more accurate and comprehensive knowledge. This is the idea of an effective theory. An effective theory is one in which its ideas are correct for a certain set of parameters but does not describe the entire story. As an example, let’s stick with the physics world and use Newton’s laws. If we maintain a regime of the “typical” (what we are used to experiencing), Newton’s laws hold true. However, for speeds nearing that of light, these laws break down and must be replaced with Einstein’s special theory of relativity. Similarly, at sizes of the incredibly small, quantum mechanics takes over. As a result, we don’t say Newton was wrong, but that he was correct within a certain set of parameters.

Along a similar vein, several aspects of Root biomechanics of foot function loosely make up an effective theory. It is useful to help us understand the general ways in which the foot works, but in reality, there are other details we have since learned that limit its effectiveness as a theory in all situations. For example, it is well known that the joints of the foot do not actually function as hinges with a fixed range of motion but rather as a composite set of movements, a bundled set of axes that change based on the movement of particular bones. Similarly, we know now that the talus doesn’t simply rotate around a fixed axis but rather moves in a way similar to a screw, sliding anteriorly as it everts and plantarflexes (pronation) and posteriorly as it supinates. Yet, starting with hinged axes is helpful to eventually understand the helical axis idea.

Root’s concepts also help us understand the importance of the balance between theory and practice. One of the powerful aspects of Root’s work was the bridging of theory with practice. He and his colleagues created a useful paradigm that could be applied to patients with systematic terminology and the construction of functional foot orthoses. Whether you agree or disagree with Root’s original concepts, his effective theory created the environment to move into more modern approaches to biomechanics.

We become so much more intellectually mature when we learn to exploit the balance between theory and practice. Applying both together gives us the power to be creative while also being maximally effective for our patients.