Addressing Recent Controversies And Developments In Orthotic Therapy

Expert panelists offer insights on recent controversies over Root theory, pedorthists becoming more involved in producing or modifying custom shoes, and whether computer-aided design/computer-aided manufacturing (CAD/CAM) has improved orthoses.

Q:

Many people are advocating discarding the “Root paradigm” in light of many articles that call into question the reliability of measurements and the relationship of static measurements with function. What parts of the Root paradigm should we keep and what parts should we discard? What post-Root principles have you added to your regimen of treating patients?

A:

Jarrod Shapiro, DPM, clarifies that the “Root paradigm” is somewhat of a misnomer, saying the majority of concepts codified by Root and colleagues derive from various other sources.

“What was so fundamental and important about what Root did was organizing the knowledge of the time into a coherent system,” says Dr. Shapiro. “He also created a systematic examination and classification based on morphology, and created a methodology for consistent foot orthosis manufacture.”

Dr. Shapiro asserts that what researchers knew at the time was a result of weak research methodology, which he says has improved somewhat over time. However, he maintains that “significant limitations” to current research methods remain and no study to date has definitively eliminated any aspect of the Root model. As a result of this lack of consensus, Dr. Shapiro has not eliminated any major aspect of the Root paradigm from his practice of lower extremity biomechanics.

For example, Dr. Shapiro says it is likely true that most humans do not ambulate near the subtalar neutral position but he asserts that improving foot posture remains an appropriate goal of orthosis therapy. For example, a patient with a symptomatic, flat, pronated foot will benefit from placing the subtalar joint in a position closer to the neutral position, notes Dr. Shapiro. He adds that one may “reword” this to fit into Kirby’s subtalar joint axis location rotational equilibrium (SALRE) model as moving a medially deviated subtalar joint axis to a more lateral location by increasing the orthosis reaction force medial to the subtalar joint axis.¹  

“It makes little sense to ignore the idea of improving foot posture closer to ideal positions described by Root,” says Dr. Shapiro. “Though it may be true that people do not function near the neutral position, it is ridiculous to suggest that a patient with symptoms resulting from increased pronatory issues would see improvement by leaving the foot excessively pronated and not trying to improve foot position. It may be ‘normal’ for humans to function away from the neutral position but that does not make it ‘ideal.’”

Scott Spencer, DPM, does not necessarily agree that the profession should toss the Root paradigm for function.

“I think it serves as a great way to introduce students to foot function and pro-vides a good means of starting to visualize what the foot does during gait as long as students go on to read and incorporate new findings based on sound research,” maintains Dr. Spencer.

Dr. Spencer agrees that static measurements as a stand-alone factor are not necessarily predictive of function or how to optimize function. He does still obtain resting calcaneal stance position, neutral calcaneal stance position, forefoot to rearfoot relationship, first metatarsophalangeal joint dorsiflexion and ankle joint range of motion specifically with the subtalar joint maintained around neutral.

Robert Eckles, DPM, calls himself “somewhat of a traditionalist” in regard to Root biomechanics, having been directly instructed by Dr. Root and his colleagues “uncounted years ago.” However, in at least two instances, authors have presented complementary paradigms that he says appear to be valid extensions of “Root” theory.^2-5 “Sagittal plane models as well as tissue stress theory-based models do not supplant Root but augment it with needed detail,” says Dr. Eckles.

In Dr. Eckles’ experience, success with orthoses in general does not consistently depend upon the device creating a functional position around “neutral.” As he notes, this may well be the case because of tissue stress reduction. While he believes the concept of neutral is an important academic perspective, Dr. Eckles notes it is clear based on large population studies of foot posture that the pronated foot, operating far from what one could call “neutral,” dominates as the norm, making “neutral” a goal one may not attain with even the best prescription.^6-8

From an examination standpoint, Dr. Shapiro says the literature seems reasonably clear that there is significant inter-observer and intra-observer variability with the Root measurement system. As a result, he has discontinued making numerical measurements during the biomechanical examination. For example, Dr. Shapiro does not attempt to measure the number of degrees of calcaneal inversion and eversion, or the exact forefoot to rearfoot relationship. Instead, he will do a more subjective examination, determining the amount of rearfoot motion and whether the forefoot is in varus, valgus or perpendicular to the rearfoot.

Dr. Shapiro’s current practice method is to incorporate several of the major theories into one hybrid model depending on the pathology and needs of the patient. He tends to place most of his thought process around Root theory for eliminating or accommodating compensation, and a combined tissue stress theory/rotational equilibrium approach. Instead of always separating these ideas out as if they are mutually exclusive, he will combine them into one approach.

As an example, Dr. Shapiro says in the stage 2 adult-acquired flatfoot with pos-terior tibial tendon dysfunction, the symptoms may be due to increased stress on the posterior tibial tendon with etiology from the flexible flatfoot. He would increase subtalar supination and lateralize the subtalar axis with orthosis modifications such as a wide shell, deep heel cup, medial heel skive, minimal cast fill and a medial flange. He uses a forefoot valgus post to assist the midtarsal joint locking mechanism. Dr. Shapiro says he might also prescribe a Richie Brace to help control tibial rotation. This prescription does improve foot position but he says it also increases supinatory torque medial to the subtalar axis.

Dr. Shapiro says all of the aforementioned orthotic prescriptions together reduce stress on the posterior tibial tendon, allow for improved gait function and reduce pain. Regardless of what name a particular theory has, he notes the end result is still applying functional biomechanics of the lower extremity.

“I have frankly never understood the need of our profession to attach to one idea. I prefer to take all information and use what makes sense and works, and toss what does not,” says Dr. Spencer.

Q:

What are the advantages of pedorthists taking over the custom shoe orthotic market? What are the disadvantages? Should podiatry students learn how to make custom foot orthotics?

A:

One advantage of pedorthists in podiatric practice, says Dr. Spencer, is that prescribing custom shoes is something they do every day. He opines that podiatrists are not fully trained to prescribe and modify shoes to the level of pedorthists.

Dr. Spencer will refer patients to pedorthists if he is comfortable with their knowledge and abilities. He cites the importance of the pedorthist being willing to consider his feedback and input into the patient’s care. Dr. Spencer also thinks podiatry students should know the process involved in orthotic manufacturing in order to prescribe the best foot orthotic device for patients.

Dr. Shapiro does not see a particular advantage of pedorthists taking over the market for shoe modifications or construction specifically. The majority of podiatrists “appear to have long ago moved away from making major shoe modifications,” notes Dr. Shapiro. “This is unfortunate but does not seem to have hurt the profession to a great extent.”

When pedorthists prescribe and/or construct “custom” foot orthoses, Dr. Eckles says it is because podiatrists have “walked away from this area of practice and have ceded it to the pedorthists.

“With due respect to (pedorthists) and I have known many and appreciate a depth of understanding and clinical skill, I feel that application of prescription orthotic remedies requires the whole of the DPM education,” adds Dr. Eckles.

While Dr. Eckles is comfortable consulting with pedorthists on cases and relying on them for custom shoegear builds and modifications, he feels DPMs have to “own orthosis prescription” although podiatry students are “rather adrift from this skill.” Calling the manual application of theory “important beyond measure,” he says this has become mostly lost to other parts of the DPM curriculum.

“At a minimum and it is a bare minimum, students must personally see the process of orthosis design and fabrication in order to be capable practitioners,” says Dr. Eckles.

When it comes to foot orthoses, Dr. Shapiro sees no advantages to podiatrists losing this part of practice to pedorthists.

“It helps neither the podiatric profession nor our patients to have other specialists who obtain less education and training than we do take over this aspect of our practices. It remains up to the podiatric profession to reestablish our credentials as the experts of the foot and ankle,” says Dr. Shapiro.

Dr. Shapiro suggests increasing the amount of biomechanics education students receive, focusing more on biomechanics in residency and increasing research and fellowship opportunities.

“Without these steps, other specialties will fill the void just as podiatrists filled the void in foot and ankle surgery when the orthopedists did not want it,” comments Dr. Shapiro.

Q:

Has the introduction of CAD/CAM improved the expertise of the podiatrist in treating nonsurgical-mechanical abnormalities of the feet? Why or why not?

A:

Dr. Eckles calls the potential of CAD and 3D scanning technology, in combination with new materials, “extraordinary.” He cites enhanced speed, effective capture of contour and necessary modification of digital images with the best non-weightbearing scanners. Dr. Eckles says CAD/CAM can lower costs on the laboratory end and deliver a usable device more quickly than in the “analog” days. However, although 3D printed devices may offer some benefit, Dr. Eckles says, so far, he has been less than impressed with the products and the algorithms associated with their production.

In contrast, Dr. Shapiro does not think CAD has improved podiatric expertise. He maintains the more traditional methods of foot casting are still effective methods to capture pedal deformity. In addition, Dr. Shapiro says traditional methods force the clinician to become more intimately knowledgeable about each patient’s pathology and thus facilitate better long-term outcomes.

Dr. Spencer is not sure that CAD/CAM has improved expertise in treating non-surgical-mechanical foot abnormalities. He notes that CAD/CAM is simply a tool labs utilize to make more precise and reproducible foot orthotic devices. Dr. Spencer thinks the same level of knowledge and ability as always are required of the podiatric physician.

“CAD/CAM does not make gold out of lead,” says Dr. Spencer. “If your prescription is poor, the orthotic will be poor for the patient.”

Dr. Eckles is the Dean of Clinical Studies and an Associate Professor in the Department of Orthopedics and Pediatrics at the New York College of Podiatric Medicine.

Dr. Shapiro is an Associate Professor with the College of Podiatric Medicine at the Western University of Health Sciences in Pomona, Calif. He is the Director of the Chino Valley Medical Center PMSR/RRA Podiatric Residency in Pomona, Calif.

Dr. Spencer is an Associate Professor Surgery/Biomechanics at the Kent State University College of Podiatric Medicine. He is a Fellow of the American College of Foot and Ankle Orthopedics and Medicine.

Dr. Phillips is affiliated with the Orlando Veterans Affairs Medical Center in Orlando, Fla. He is a Diplomate of the American Board of Foot and Ankle Surgery, and the American Board of Podiatric Medicine. Dr. Phillips is a Professor of Podiatric Medicine with the College of Medicine at the University of Central Florida. He is also a member of the American Society of Biomechanics.

References

1. Kirby KA. Subtalar joint axis location and rotational equilibrium theory of foot function. J Am Podiatr Med Assoc. 2001; 91(9):465-488.
2. Dananberg HJ. Sagittal plane biomechanics. J Am Podiatr Med Assoc. 2000; 90(1):47-50.
3. Dananberg HJ. Sagittal Plane Biomechanics. In Subotnick SI (ed.), Sports Medicine of the Lower Extremity. Churchill Livingstone, New York, 1999, pp. 137-156
4. Payne CB. Past, present and future directions for podiatric biomechanics. J Am Podiatr Med Assoc. 1998; 88(2):53-63.
5. Kirby KA. Foot and Lower Extremity Biomechanics II: Precision Intricast Newsletters, 1997-2002. Precision Intricast, Inc., Payson, AZ, 2002, pp. 11-18.
6. Hagedorn, TJ, Dufour AB, Riskowski JL, Hillstrom HJ, Menz HB, Casey VA, Hannan MT. Foot disorders, foot posture, and foot function: The Framingham Foot Study. PLoS One. 2013; 8(9):e74364.
7. Riskowski JL, Dufour AB, Hagedorn, TJ, Hillstrom HJ, Menz HB, Casey VA, Hannan MT. Associations of foot posture and function to lower extremity pain: The Framingham Foot Study. Arthritis Care Res (Hoboken). 2013; 65(11): 1804–1812.
8. Hilstrom H, Song J, Neary M, Brechue W, Zifchock RA, Svoboda S, Hannan MT. Foot type symmetry and change of foot structures from sitting to standing conditions. J Foot Ankle Res. 2014; 7(Suppl 1): A34.

For further reading, see “What A Recent Study Gets Right And Wrong About Root Biomechanics” in the June 2017 issue of Podiatry Today at https://tinyurl.com/y6w9totu, “Prescribing Orthoses: Has Tissue Stress Theory Supplanted Root Theory?” in the April 2015 issue, “3D Orthotic Printing: Fad Or Game Changer?” in the December 2016 issue or the June 2014 DPM Blog “Should Podiatric Physicians Surrender AFO Therapy To Pedorthists?” by Doug Richie, Jr., DPM at https://tinyurl.com/ngtvczh.