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

In various prior editorials I've advocated – reasonably strongly – a critical approach to everything we do in medicine. I've argued for the use of the research literature to support what we do, and I've asked for more and higher quality research coming from our community. This week, though, I've had the metaphorical rug pulled out from under me by something I found in the literature. As a result of this slightly mind-blowing gem, I question even further many of our foundational concepts.

A quick digression to set the scene…

Figure 1. The Silfverskiold test demonstrating a gastrocnemius equinus.

We're all trained to evaluate patients for ankle equinus. We're taught the Silfverskiold test in which one dorsiflexes the foot on the ankle with the knee extended and then with the knee bent. If there is less than 10 degrees of dorsiflexion with the knee extended the patient has equinus, and if that motion increases to greater than 10 degrees with the knee flexed the patient has a gastrocnemius equinus. If no change and a spongy end range of motion, then it's a gastrocnemius-soleus equinus, right? If there's a hard end to the motion then it's likely an osseous equinus. We're taught to apply this foundational piece of information to many pathological processes, including the diabetic foot (equinus increases plantar pressures) and the pathological flatfoot (subtalar pronation is one form of compensation for equinus). This is all basic biomechanics, right? Many of us choose surgical procedures according to this test, whether it's a tendoachilles lengthening or some form of gastrocnemius recession.

		Tonight's Premier Lecture is The Non Compliant Wound Patient: Pitfalls, Advice, and Evidence Kathleen Satterfield, DPM

What would you think if I told you this test was not created to evaluate the majority of patients we treat?

During an online literature search for an unrelated subject, I came across a study discussing the "reverse Silfverskiold" test for Achilles rupture diagnosis.¹   A quick glance at the study had me thinking, "What did Silfverskiold's original paper say about this test?" I've made it a habit over the last couple of years to look up the original description of various tests and procedures, such as Evan's osteotomy and the Koutsogiannis procedure. In this vein I found the original 1924 paper by Nils Silfverskiöld, MD, who, interestingly, worked under Patrik Haglund, MD – yes, THAT Haglund.²

Ok, here comes the earthquake – for me this one's about a 6 on the Richter scale. Dr. Silfverskiold described his now famous test in relation to SPASTIC conditions. Nowhere does he mention this is a test for nonspastic equinus. He mentions it, not in relation to flatfoot conditions or diabetes, but to spastic hemi- and di-plegic disorders. Now, from a historical perspective, this is understandable. When he wrote his article, diabetes was not a chronic disease yet that would have required the treatment of complications that we have today. As such, there would have been no reason for the application of this clinical test to diabetic patients or to others such as pronatory deformities, which are the two most common pathologies in which equinus is implicated.

You may or may not be impressed by this, but if you read his entire paper, he actually undermines to some extent our current thought process on equinus. This might take a little explaining, which I will address in part 2 of our discussion.

I'll leave you with a few thoughts. First, if the test is for spastic conditions, and we now more commonly use it for nonspastic conditions, what does it say about the legitimacy of the test? Perhaps this is part of the reason for the controversy over equinus, because we are not able to either A. define it or B. measure it clinically in a repeatable, accurate manner. What we are looking for when we examine our patients is something completely different from what Silfverskiold was looking for when he developed this test. I think that makes our use of his test questionable. The test is meant to look at the extent of spasticity, rather than nonspastic tightness.  We definitely need new research to "prove" the applicability of this test to nonspastic conditions.

Second, does this make you wonder about some of our other clinical tests? Would it strike you as interesting that the Tinel sign was originally characterized for carpal tunnel syndrome, and we've adapted it to the foot and ankle? The ankle is not a wrist, is it? What does that mean for this test? How about the capillary refill time? Would you be surprised to know that this test was originally described to determine dehydration in pediatric patients and NOT peripheral arterial disease? How many peds patients have PAD?

What other tests do we use under questionable conditions? These tests might all be valid and useful for us. It's pretty clear, for example, that equinus is an important process to be considered in the diabetic foot. But does our acceptance of these tests at face value have greater implications? You be the judge….

Best wishes.

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

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