How Current Orthotic Thinking Influences Orthotic Prescription
Which paradigms, teachings and studies influence podiatric physicians who prescribe orthotics? These expert panelists enumerate what factors come into play when they dispense orthoses.
Q:
Which of the more current paradigms for foot function have the most influence in your practice?
A:
“Time devoted to evaluating a patient in regard to his or her function as well as the biomechanical problem prior to prescribing the orthotic device will result in greater success with the completed orthotic device,” advises Ronald Valmassy, DPM.
In the same vein, Ray Fritz, DPM, is among the many DPMs who have been influenced by the Root theory and The Biomechanics of the Foot and Ankle, a text he says was his “bible for biomechanics” in podiatry school in the 1980s.
“I think much of this dogma still influences my thinking at times but I have drifted to a more simplistic approach to my orthotic prescription,” adds Dr. Fritz.
Presently, Dr. Fritz is giving more consideration to supporting the medial column and the arch of the foot, pointing out that midfoot function and control affect the rest of the foot. He is no longer exclusively concerned about function but concentrates on the contour, shape and specific individual characteristics of each foot. The individual deficiency or disease process also affects foot function, according to Dr. Fritz.
Lawrence Huppin, DPM, says he evaluates the literature and follows an evidence-based approach to orthotic therapy. He also voices suspicion about emerging “paradigms” for orthotic therapy.
“I’m disturbed by the proliferation of new ‘orthotic paradigms’ that have been propagated by several orthotic labs,” asserts Dr. Huppin. “From my perspective, these new paradigms are simply a marketing ploy designed to increase sales at a particular lab.”
Dr. Huppin elaborates that as one accepts a particular “paradigm,” he or she is required to use the lab that is promoting that new paradigm. Anytime a new treatment of any sort requires the physician to use a particular commercial entity in order to use that treatment, he says this is an indication that the treatment is “more of a sales tool than a legitimate new therapy.” By following an evidence-based approach to orthotic therapy, Dr. Huppin notes one could use any of at least a dozen high quality orthotic labs.
Q:
What factors influence your orthotic prescription?
A:
Several studies have influenced Dr. Huppin’s method of prescribing orthoses. He cites a 1999 study by Kogler and colleagues, who demonstrated that valgus forefoot wedging decreases plantar fascial strain while varus forefoot wedging increases strain.1 Based on that study, he is “much more aggressive” in ensuring that the orthotic shell incorporates full valgus correction and will often incorporate a valgus forefoot extension in cases of plantar fasciitis.
Dr. Huppin says another example of incorporating evidence-based medicine into orthotic therapy involves prescribing orthoses for metatarsalgia. In 2000, Chalmers and Busby demonstrated that in patients with rheumatoid arthritis and metatarsalgia, semi-rigid orthoses are a much more effective treatment than soft orthoses.2 Dr. Huppin also cites a study showing that a total contact insert with a metatarsal pad was the most effective way to offload a metatarsal head.3 A 2003 study stated that one should place the highest point of a metatarsal pad between 6 mm and 10 mm behind the point of maximum pressure on the metatarsal head.4
Using this information, his preferred prescription for metatarsalgia is to use a semi-rigid polypropylene orthosis with a minimum cast fill. Dr. Huppin confirms that the orthosis conforms tightly to the arch of the foot. He also uses a wide orthotic plate, a cushioned topcover that he leaves unglued on the front half of the orthosis and a metatarsal pad. He suggests adjusting the metatarsal pad in the office so the highest point sits about 8 mm behind the painful metatarsal head.
When it comes to casting, Dr. Fritz’s greatest concern is about the neutral cast he sends to the lab as well as the way the lab applies the plaster additions to the positive mold of the patient’s foot. In particular, he focuses on the negative impression. He says his experiences as a lab technician have taught him that “all cast impressions are not created equal” and he has seen “appalling” foot impressions.
Dr. Fritz still uses a plaster mold of the foot, calling it the most accurate and reproducible casting method. Although casting techniques vary, he prefers the supine position with the STJ in neutral and the midtarsal joint loaded. However, he does note that the profession is taking casting short cuts, namely having assistants take cast impressions and using foam boxes to eliminate clean-up. In addition, Dr. Fritz says computerized casting techniques raise questions regarding reliability and accuracy. He notes that the positioning of a patient’s foot on a digital scanner, mass production and possible lack of quality controls all affect the final positive mold.
A perfect impression takes into account all prominences and individual idiosyncrasies of the foot, notes Dr. Fritz. He will personally take all positive molds and the lab he uses makes an “individualized, truly handmade” custom orthosis.
For Dr. Valmassy, gait evaluation plays a large role in his dispensation of orthoses. During his initial evaluation for consideration of an orthotic device, he will spend a moderate amount of time evaluating the gait of his patient. If the patient has a fairly normal gait pattern, he might be less inclined initially to prescribe a functional foot orthosis or may proceed with other diagnostic or treatment considerations.
As Dr. Valmassy notes, the patient’s gait becomes more consistent and easier to appreciate the more the patient walks. For example, he says patients will typically walk in a fairly awkward fashion initially so he allows them to walk up and down the hallway repeatedly so their normal gait pattern will emerge.
In addition, Dr. Valmassy cites the importance of low-Dye taping, which he will apply at the initial visit when considering functional foot orthoses. He also gives the patient instructions on how to reapply the taping as well as materials so they may duplicate the tape a second or third time if necessary.
If there are minimal levels of improvement from the initial taping and none with the subsequent taping, Dr. Valmassy may have concerns in regard to proceeding with the orthotic device. On the other hand, if there is some success, generally a 50 percent or greater relief of symptoms, he proceeds with the functional foot orthotic device.
As for the device itself, choosing materials will also affect the clinical result, according to Dr. Fritz. He notes the importance of communication with the patient and advocating realistic expectations of style and footwear. Dr. Fritz suggests asking the patient how much he or she is willing to change the footwear in order to fit an orthotic.
Dr. Fritz notes the prescription needs to be realistic for each patient. He notes he will direct his attention to where the patient places the greatest load on the foot. His more involved discussions with the patient result in more requests for a second orthotic. Dr Fritz notes that a provider who spends the time discussing activities and footwear will have better adherence and outcomes. Before completing an orthotic prescription, he always discusses patients’ footwear and at times their willingness to compromise.
Dr. Fritz practices at Allentown Family Foot Care in Allentown, Pa. He is a Fellow of the American College of Foot and Ankle Surgeons.
Dr. Huppin is the Medical Director for ProLab Orthotics/USA and is in private practice in Seattle.
Dr. Valmassy is a Past Professor and Past Chairman of the Department of Podiatric Biomechanics at the California College of Podiatric Medicine. He is a staff podiatrist at the Center for Sports Medicine at St. Francis Memorial Hospital in San Francisco.
Dr. Spencer is an Associate Professor of Orthopedics/Biomechanics at the Ohio College of Podiatric Medicine. He is also a Diplomate of the American Board of Orthopedics and Primary Podiatric Medicine.
References:
1. Kogler G, Veer FB, Solomonidis SE. The influence of medial and lateral placement of orthotic wedges on loading of the plantar aponeurosis. J Bone Joint Surg 1999; 81A:1403-1413 2. Chalmers AC, Busby C. Metatarsalgia and rheumatoid arthritis--a randomized, single blind, sequential trial comparing 2 types of foot orthoses and supportive shoes. J Rheumatol. 2000 Jul;27(7):1643-7. 3. Mueller MJ, Lott DJ, Hastings M. Efficacy and mechanism of orthotic devices to unload metatarsal heads in people with diabetes and a history of plantar ulcers. Phys Ther. 2006 Jun;86(6):833-42. 4. Hastings MK, Commean PK. Aligning anatomical structure from spiral X-ray computed tomography with plantar pressure data. Clin Biomech 2003 Nov;18(9):877-82. Additional Reference 5. Fritz R, Anderson AC. Update in pedorthics and orthotics designs, advance in materials. Curr Opin Orthop 2007; 18:145-152.
