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Sep 12, 2023

Practice Perfect 878
Stop Doing a “Biomechanical”
Exam and Do an Exam

  Jarrod Shapiro, DPM, FACFAS, FACPM, FFPM, RCPS Glasg

PRACTICE PERFECT   September 12, 2023

In light of this past weekend’s excellent online PRESENT Biomechanics and Surgery Conference (I hope you didn’t miss it!), I couldn’t help but think about the biomechanical examination. So, this one is for all you learners out there, students and residents alike, who seem to think of the lower extremity biomechanical examination as something to be avoided or something you’ll never understand. I have heard for years about residents who don’t log enough biomechanical cases, how biomechanics is “biomagic” because they don’t understand what their preceptors and teachers are looking at, and the lamentations of many an older podiatrist about how you have to know biomechanics to make surgical decisions. I also speak to students and residents all the time who can’t answer my simple “why” question when I ask, “Why, does this patient have X diagnosis? What biomechanical factors are involved?”

I hope to spend a few minutes demystifying the exam and to help you understand that this is simply another part of being a caregiver of the lower extremity. I’d like to take the next few weeks following today’s editorial to discuss each of the components of the examination in a bit more detail to show you it’s not magic, and it’s not as hard as you think. Today, let’s talk generalities.

Featured Lecture
First MTP Joint Fusions: Biomechanical Considerations
Jarrod Shapiro DPM,  FACFAS,  FACPM,  FFPM,  RCPS Glasg
First MTP Joint Fusions: Biomechanical Considerations

Jarrod Shapiro, DPM, FACFAS, FACPM discusses the importance and utility of the 1st MTP joint arthrodesis, covering fundamental biomechanical principles, and surgical techniques. Mechanical effects of this procedure will be reviewed as well as an emphasis on target populations.

Available Credits: CPME 0.5

It’s Not a Biomechanical Exam – It’s a Physical Exam

The first shift we have to make is to understand that there’s really no such thing as a “biomechanical” examination. This is an artificial construct created over the years to organize a set of principles. I’m not historian enough to tell you who first coined the phrase “biomechanical examination”, but in my own experience, like many in school, I was exposed to this via “Root” biomechanics – whatever that is. Root gave us a set of terminologies and ways to describe the foot (forefoot varus/valgus, for example), and with this comes an examination to determine important factors. But this is just another part of any physical examination. When you look at/touch/palpate/percuss/manipulate a foot, you’re examining it to understand how that specific foot/ankle/leg functions. What is it about that foot that is causing the patient’s pain?

When you palpate for pulses, are you intimidated? Of course not. You’re learned where to put your fingers, how to feel for the pulse, and how to grade whatever it is you feel. Can’t feel a pulse? That tells you something. Feel a bounding pulse? That tells you something else. Examining a foot for “biomechanical” factors is no different. Looking at the foot, you find that a patient has a fixed forefoot varus. This means something in terms of how the patient functions. Looking at another foot you see a forefoot supinatus. That means something else.

You’re not doing a “vascular” exam or a “biomechanical” exam. You’re doing an exam. If you had a patient with shoulder pain, while on an orthopedics rotation, you wouldn’t think you’re doing a shoulder biomechanical examination – you’re just doing a shoulder exam. The Empty Can Test tells you something about shoulder impingement, while the Speed’s Test tells you something else about the biceps tendon. These aren’t magical tests that are part of a “biomechanical exam” but are simply maneuvers that are part of the physical exam to help you understand what part of your patient’s body is damaged. So, for the rest of this editorial, I will no longer use the phrase “biomechanical exam” and instead simply say physical exam.

The Physical Exam Takes Practice

Like every part of the physical exam, it takes practice to become proficient. Don’t avoid practicing because something seems difficult or even obscure. It’s best to practice slowly at first to hone those examination skills, but there’s never a better time than the present. Do this as a workshop so you can take the time in a pressure-free environment to think about what you’re doing. Come in with a simplified approach to consider the major parts of the examination rather than trying to cover everything. I like the examination suggestion documents published by some leaders and organizations, but they can be a bit overwhelming, even to those who have been around for a while. I can promise you that I do not do every part of any published examination. We simply don’t have time to do one-hour examinations on our patients. Focus instead on gathering information that will be useful to you. How do you determine what is useful? That involves the next step.

Organize Yourself

It’s important to have an organizing framework to focus your thoughts and your examination. As a simple example, most podiatrists will not choose to do a Coleman Block Test on a patient with flatfoot because that’s generally for a patient with a pes cavus. Immediately, you can see a simple organizing principle to help you to make the decision when to do this test: pes planus versus pes cavus foot type. Granted, this is a simple example, but it brings the point home that you need a mental model in which to organize yourself. I’ve written about this several times and even spoken at several conferences on an organizational model that I call the Kineticokinematic Approach (or KK Approach) (Practice Perfect 667)The Making Practice Perfect Decisions Series - Practice Perfect 823-834. The name doesn’t matter, but the model simplifies the approach to patient problems and gives us a framework in which to base treatment decisions. Here it is in summary:

  1. Determine the painful/damaged anatomy. 
  2. Appreciate the underlying mechanics. 
  3. Treat the underlying mechanics.

Now, I know it looks simple, but that’s why it’s powerful. We need low complexity models to be useful in real life situations. The KK Approach is simply a model very similar to the tissue stress theory that lets one simplify their thought process. This will also help guide your examination. Palpate a painful great toe joint dorsally and you immediately start thinking “hallux limitus/rigidus”. This leads you to the second step, figuring out why they have this set of symptoms and signs. Maybe the medial column has excessive mobility, the foot is flat (the subtalar joint is pronated), and the heel is everted. You know a lot more about the foot, now, and can begin to plan treatment by focusing on those factors. Your foot orthotic prescription would attempt to modify those factors to decrease the patient’s pain. Your surgical approach would do exactly the same thing.

You can also organize yourself while doing the examination. I included a slide from a prior lecture that organizes the examination in a very common and simplified manner (Figure 1). As with any examination, having an organized and somewhat standard approach will be very helpful.

Figure 1. A method to organize the mind when doing a lower extremity physical examination.

In future editorials about this topic, I will break the examination into these four primary parts. Like anything complicated, it’s always beneficial to deconstruct it to keep it from becoming overwhelming. Every time I see a patient, I go through the combination of the three steps I described above plus the examination in this order: nonweightbearing → stance → special tests → gait. My reason for this is simple: when I first walk into the examination room the patient is already seated, so it is more efficient to start with the nonweightbearing exam (after obtaining a history). There’s nothing wrong with starting in a different order; it’s just more efficient for me this way.

Final Thoughts: Read!

As in every single topic in all of medicine, there is something to read to gain further understanding. Behind much of the lower extremity physical examination are a number of topics and principles that are often helpful. You should NOT think of these written sources as gospel, however. Just because someone writes something doesn’t mean it is correct. But it can expand your understanding and help you to help your patients. One small example is the calcaneopedal unit concept (see The Twisted Plate: A Simple but Useful Biomechanical Model Practice Perfect 876 for discussion). Without going into details, this relates that the talus is actually part of the leg rather than the foot. The end practical result of this model is to realize that the description of subtalar motion we learned in school is inaccurate. It’s not the talus moving but rather the foot moving around the talus. It’s not talar plantarflexion and adduction as part of closed kinetic chain subtalar pronation but rather calcaneal eversion, forefoot abduction and eversion around a fixed talus. Not sure if this is applicable? Try to move the talus during your next triple arthrodesis, and you’ll see that just doesn’t work. Instead, focus on bringing the foot back underneath the talus, and you’ll achieve much more successful results.

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Desert Foot 2023

Everything you read will increase your understanding of the very complex machine that we treat. It will also create more questions to ask! Not sure what to read? Here’s a bibliography of various materials we previously studied to help get you started.

Best wishes.

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

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