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Defending Root: Is The New Study By Jarvis And Colleagues All It Is Cracked Up To Be?

Doug Richie Jr. DPM FACFAS FAAPSM

04/28/2017

When Root, Weed and Orien published their seminal text, Normal and Abnormal Function of the Foot in 1977, I was a second-year student at the California College of Podiatric Medicine (CCPM).¹ For the students at CCPM, this textbook was a pivotal part of our education as it provided a comprehensive description of all that we were learning in our biomechanics courses. It was a welcome and usable resource since all we had prior to this book were our lecture notes and handouts from a sum total of five courses in biomechanics.

The “Root Theory” is based on much more than this single publication. Prior to the 1977 publication, Root, Orien and Weed had already published their examination techniques and their “criteria for normalcy” of the human foot.² It was this publication that proposed a nomenclature that all professions could recognize as well as a starting point reference of alignment known as the neutral position of the subtalar joint. Even before that, Root had been teaching his techniques for neutral suspension casting and fabrication of “functional foot orthoses” that were being implemented around the country with widespread acceptance by the time of the 1977 publication. Root shared his insights and techniques with all competing foot orthotic labs in the United States without claiming any proprietary interest.³

Therefore, the book Normal and Abnormal Function of the Foot expanded on previous work but also provided a comprehensive view of lower extremity function that reflected the body of scientific knowledge at that time.¹ The most valuable and enduring parts of this book are the sections on gait, muscle function and pathomechanics of common foot disorders. Interestingly, few of these specific sections of the book have faced challenges to any significant degree since the date of publication. Instead, researchers and clinicians have continued to question Root and colleagues’ definition of “normalcy,” the relevance of subtalar neutral position and whether static measurements can predict “abnormal” foot function.

The fact that 40 years later the observations and theories of Root, Weed and Orien are still being debated and challenged validates the monumental impact these three teachers have had on our profession and on many practitioners around the world. No collection of published work from our profession has had such a profound effect over such a long period of time.

When Merton Root, DPM, was first challenged on some of his observations and conclusions about normal and abnormal foot function, he speculated that much of the content of his teachings and writings would be tested and then either validated or disproven.⁴ He encouraged that process. Indeed, it was not long after 1977 that modern gait laboratories using breakthrough technologies and measurement techniques began examining and testing various parts of the “Root Theory” to determine if the conclusions were accurate.

Many students of Root and coworkers also began questioning the importance of measuring forefoot to rearfoot relationships. In the clinic, we would see a patient with a high degree of forefoot valgus who walked with severe pronation, the opposite of what we would expect. John Weed, DPM, and other attendings would address this dilemma by asking us to examine other parameters such as femoral position and we would quickly appreciate that rearfoot alignment could be easily influenced by factors more proximal up the kinetic chain.

We also struggled with our own accuracy and reproducibility of measurements as we learned from the faculty at CCPM, who were all trained by Root and colleagues. We would all measure the same patient in the clinic and come up with different measurements. However, when we watched the patient walk, we would usually agree with what we saw. Root, Orien and Weed always put the greatest emphasis on gait analysis in detecting pathology and measuring success of foot orthotic therapy.

What The Recent Study Says About Root Theory And Tissue Stress Theory

In a recently published paper (https://jfootankleres.biomedcentral.com/articles/10.1186/s13047-017-0189-2 ), Jarvis and colleagues do an excellent job of summarizing all of the key research articles published over the past 30 years that cast doubt or actually refute several key components of the “Root Theory.”⁵ In fact, each and every static measurement advocated by Root to determine “normalcy” of the human foot and tested by Jarvis and coworkers had already been refuted by several quality published studies in the past. The key finding of the study by Jarvis and coworkers was summarized by their statement: “It is important to understand why static measures are so poorly related to dynamic foot kinematics, which is an outcome of this (study) but also other literature.” The authors cite four previous studies that had drawn this same conclusion, all published between 1999 and 2015.^3-7

This poses the question: “Is there anything new here which should change the way we treat our patients?”

Critics of the “Root Theory” have been recently embracing the so-called “Tissue Stress Theory” of orthotic therapy. This theory was originally described by McPoil and Hunt, who advocated a new strategy for foot orthotic intervention based solely upon anecdotal evidence.⁸ Others have used this notion to validate their own orthotic outcomes but no one has actually conducted clinical trials to test the efficacy of this type of orthotic strategy intervention.^9-11

This notion of “Tissue Stress Intervention” was again propagated by Jarvis and colleagues, who state “It follows that orthotic prescriptions might target changing stresses in specific (painful or at risk) structures rather than achievement of seemingly erroneous skeletal alignments.”⁵ However, these authors do not cite any credible references that validate this approach to foot orthotic therapy. That is because there are no such studies.

It is ironic that many of the terms used by tissue stress advocates and the evaluation and interventions to relieve tissue stress in the lower extremity actually began with Root’s work. Tissue stress relieving orthotic therapy has not faced testing in any randomized controlled trials. Suggestions about using certain orthotic designs to relieve stress on a specific anatomic structure are predicated upon pure speculation. I would challenge any proponent of tissue stress orthotic therapy to explain what forces cause plantar fasciopathy and what specific orthotic design reliably mitigates those stresses or forces. Many high quality laboratory studies have explored that question and the answer today still remains elusive.

So while the study by Jarvis and colleagues only validated previous works that refute the Root notion of static measurements to predict dynamic foot function, the disturbing message in this paper was the almost spiteful conclusion stated by the authors: “We recommend that clinicians stop using the Root et al. biomechanical examination protocol.”⁵ They further state: “Based on the results here and the related literature over the last twenty years, we believe that the assessment protocol advocated by Root et al. is no longer a suitable basis for professional practice.”

Should We Abandon Root Theory For Other Evaluation Methods?

If we are to stop evaluating patients with techniques that have worked for us over the past 40 years, what evaluation method should we now embrace? What method does Jarvis and coworkers find “suitable” in their own clinical practices? Tissue stress?

With all due respect to Jarvis and colleagues, many of the teachings of Root, Orien and Weed have been accepted in various forms and have become essential components of treatment of lower extremity pathologies by a wide range of specialties around the world. The assessment of the human foot, the terminology to describe the relationships of the component parts of the lower extremity and the perception of what types of stresses that deforming forces will impose on the structures of the lower extremity as originally taught by Root and colleagues permeates all the major textbooks and teaching manuals in the fields of orthopedics, podiatry, pedorthics and rehabilitative medicine.

Consider the fourth edition of McGlamry’s Comprehensive Text Book of Foot and Ankle Surgery as well as the ninth edition of Mann’s Surgery of the Foot and Ankle, both of which were published in 2013.^12,13 Throughout both of these gold standard surgical textbooks, written from the orthopedic and podiatric professions, the terms forefoot varus, forefoot valgus, rearfoot varus, plantarflexed first ray and neutral rearfoot position are present. Furthermore, the authors describe and advocate surgical procedures to correct these deformities. These textbooks universally accept that a forefoot deformity such as an acquired supinatus or forefoot varus, as one would observe with adult-acquired flatfoot, will cause pronation compensation in the rearfoot. The textbook authors also advocate that a plantarflexed first ray, as one would note in cases of a cavus deformity, will cause rearfoot supination compensation. Cavus foot surgery approaches the forefoot primarily to correct rearfoot alignment.

Surgical procedures to correct foot deformities such as the adult-acquired flatfoot follow the Root principle of aligning the rearfoot perpendicular to the ground and reducing any acquired forefoot varus. The deforming force of the gastroc-soleus on flatfoot deformity is universally accepted and procedures such as the gastrocnemius recession are mainstays in flatfoot surgery.

Accordingly, the surgical community has accepted the influence of forefoot to rearfoot deformities in the development of pathologies in the lower extremity. The notion of restoring the alignment of the foot to an optimal position with surgical procedures follows the Root theory in almost every regard. Furthermore, the pre-surgical assessment of our patients still requires some type of static examination, including static radiographic measurements. On the operating table, we measure range of motion of the first metatarsophalangeal joint, the degree of stiffness or “hypermobility” of the first ray, the alignment of the calcaneus after an osteotomy and the range of ankle joint dorsiflexion after a gastroc recession.

Are we to immediately “stop using” these measurements and assessments in clinical practice just because a group of researchers tell us so? Are we to switch to some other type of theory or measurement technique which has yet to be validated in clinical trials?

In spite of a relatively small group of critics, the mainstream of lower extremity clinicians embodies and implements many parts of the “Root Theory” in everyday practice. They do so because their treatment protocols seem to work. Whether using foot orthotic therapy or surgical procedures, we do not keep implementing treatments that do not work. We implement procedures and treatments that reliably work for us and our patients. The fact that the foot orthotic industry has grown exponentially since Root first taught his principles 40 years ago must validate that something was right about his proposed treatments.

Keep in mind that the study published by Jarvis and colleagues did not measure efficacy of foot orthotic therapy as Root taught us. It only tested static measures of the foot and ankle, and the value of these measures to predict alignment of the foot during gait. Although Jarvis and coworkers took the liberty to challenge how we decide which patients should receive foot orthotic therapy, their study did not directly measure or test this intervention.

As far as measuring the efficacy of “Root functional orthoses," there are many published studies showing favorable treatment outcomes and improvements in lower extremity function.^14-18 There is nothing in the study by Jarvis and coworkers to substantiate any assertion that we should abandon the casting technique, fabrication technique and prescription criteria for foot orthotic therapy taught by Root and colleagues. Foot orthotic therapy has been and will continue to be the mainstay of non-operative interventions in podiatric practice for years to come.

Why The Study Is Off Base On Orthotics And Correcting Deformities

This leads to the most troubling pronouncement made by Jarvis and coworkers in their discussion of their findings.⁵ They make the unfounded assertion that the so-called “deformities” described by Root have “no clinical relevance.” Tell this to a patient with Charcot-Marie-Tooth disease with 20 degrees of forefoot valgus and is forced to walk on the side of the foot. Tell this to a patient with 20 degrees of acquired forefoot supinatus and a stage 3 adult-acquired flatfoot deformity who walks with severe sinus tarsi pain. Yes, Jarvis and colleagues only measured kinematic variables related to foot deformities and ignored the far more significant kinetic forces that arise from these malalignments.

Furthermore, Jarvis and colleagues suggest that since the “deformities” defined by Root do not cause symptoms, then one should not treat the deformities.⁵ They state: “if the deformities described by Root et al are the basis for prescribing some foot orthoses, then evidence that the so-called deformities have no functional relevance is perhaps evidence that foot orthoses should not be used in the absence of symptoms and simply to ‘correct’ deformities.”

Any student of Root or his colleagues could verify that they learned never to intervene with foot orthotic therapy simply to “correct deformities.” To attribute such an irresponsible abuse of orthotic treatment to Root and colleagues demonstrates a total lack of respect for the integrity of these pioneers of podiatric biomechanics. Anyone who studied under Root and his co-authors would know that such a flagrant misuse of foot orthotic therapy would have been condemned by these stellar professionals. To suggest that such an abuse of a valid therapy was ever advocated by Root and coworkers casts a cloud of uncertainty regarding the motives of Jarvis and coworkers in the conduction of their study and the formulation of their conclusions.

Yes, this study of self-reported healthy individuals age 18 to 45 could measure no correlation with static measurements and predicted gait patterns as originally advocated by Root and colleagues.⁵ A single assessor performed all of the static measurements of the patients and this assessor presumably had no bias against Root and colleagues. Yet the sweeping condemnation of Root by the authors in areas far beyond the findings of this study leaves the reader with many questions about the true motivation of the study.

In Conclusion

This study by Jarvis and colleagues by no means invalidates the entirety of what Root contributed to our knowledge and clinical practice today. For that, we should all be grateful and respectful as we provide commentary and suggestions for improvement in all aspects of podiatric care.

References

Root M, Weed J, Orien W. Normal and Abnormal Function of the Foot, First Edition. Clinical Biomechanics Corp., Los Angeles, 1977.  
Root ML, Weed JH, Orien WP. Neutral Position Casting Techniques. Clinical Biomechanics Corp., Los Angeles, 1971.
Root ML, Orien WP, Weed JH, Hughes RJ. Biomechanical Examination of the Foot, Volume 1. Clinical Biomechanics Corporation, Los Angeles, 1971.
Root ML. How was the Root functional orthotic developed? Podiatry Arts Lab Newsletter, Pekin, Illinois, Fall 1981.
Jarvis H, Nester C, Bowden PD, Jones RK. Challenging the foundations of the clinical model of foot function: further evidence the root model assessments fail to appropriately classify foot function. J Foot Ankle Res. 2017; 10(7).
Buldt AK, Murley GS, Levinger P, Menz HB, Nester CJ, Landorf KB. Are clinical measures of foot posture and mobility associated with foot kinematics when walking? J Foot Ankle Res. 2015;8:63.
Buldt AK, Murley GS, Butterworth P, Levinger P, Menz HB, Landorf KB. The relationship between foot posture and lower limb kinematics during walking: a systematic review. Gait Posture. 2013;38(3):363–72.
McPoil TG, Hunt GC. Evaluation and management of foot and ankle disorders: present problems and future directions. J Orthop Sports Phys Ther. 1995;21(6):381-8.
McPoil T, Cornwall MW. Relationship between neutral subtalar joint position and pattern of rearfoot motion during walking. Foot Ankle Int. 1994;15(3):141–5.
Cornwall MW, McPoil TG. Effect of ankle dorsiflexion range of motion on rearfoot motion during walking. J Am Podiatr Med Assoc. 1999;89(6):272–7.
Harradine P, Bevan L. A review of the theoretical unified approach to podiatric biomechanics in relation to foot orthoses therapy. J Am Podiatr Med Assoc. 2009; 99(4):317-325.
Southerland J, Alder D, Boberg J, et al (eds). McGlamry’s Comprehensive Text Book of Foot and Ankle Surgery, Fourth Edition. Lippincott, Williams and Wilkins, Philadelphia, 2013.
Coughlin MJ, Saltzman CL, Anderson RB (eds). Mann’s Surgery of the Foot and Ankle, Ninth Edition. Mosby, St. Louis, 2013.
Woodburn J, Barker S, Helliwell PS. A randomized controlled trial of foot orthoses in rheumatoid arthritis. J Rheum. 2002; 29(7):1377-1383.
Gross MT, Byers JM, Krafft JL, et al. The impact of custom semirigid foot orthotics on pain and disability for individuals with plantar fasciitis. J Ortho Sp Phys Ther. 2002; 32(4):149-157.
Hertel J, Denegar CR, Buckley WE, Sharkey NA, Stokes WL. Effect of rearfoot orthotics on postural control in healthy subjects. J Sport Rehabil. 2001; 10:36-47.
MacLean C, Davis IM, Hamill J. Influence of a custom foot intervention on lower extremity dynamics in healthy runners. Clin Biomech. 2006; 21(6):621-630.
MacLean CL, Davis IS, Hamill J. Short and long-term influences of a custom foot orthotic intervention on lower extremity dynamics. Clin J Sport Med. 2008; 18(4):338-343.