Current Insights On Custom And Prefabricated Foot Orthoses
Q: How do you evaluate a patient for foot orthotic devices?
A: All three panelists will perform a gait analysis. Russell Volpe, DPM, begins by assessing what he wants the orthosis to accomplish once he decides a CFO is indicated. If control of motion is needed, he will tailor material selection and many of the plaster modifications and prescription items to help accomplish that goal. If Dr. Volpe’s desired goal is accommodation, soft-tissue supplementation or assistance with motion, he will gear material selection and prescription features toward those goals. He also considers other factors like the patient’s weight, the activity or activities the device will be used for and the shoe the device will be worn in, all of which impact device selection and design.
Initially, Howard Kimmel, DPM, will attempt a subjective evaluation. He notes the importance of asking patients what their expectations are for the orthoses, especially if they are being used to prevent the worsening of a current structural deformity like a bunion or hammertoe. Dr. Kimmel tries to make orthoses for the shoes that the patients wear the most but emphasizes patient education on expectations.
“The patients need to know that the orthoses are not going to correct their deformity,” says Dr. Kimmel.
Dr. Kimmel notes that he always asks patients to bring a worn pair of shoes so he can evaluate the wear pattern. He says this helps to correlate his biomechanical exam.
Scott Spencer, DPM, will obtain several measurements: neutral calcaneal stance position, relaxed calcaneal stance position, subtalar joint (STJ) range of motion, ankle joint dorsiflexion in STJ neutral, first metatarsophalangeal joint (MPJ) dorsiflexion with the joint unloaded and forefoot to rearfoot frontal plane measurement with the forefoot maximally loaded under the lateral forefoot and the STJ in neutral position. As he says, this combination helps him obtain a good foundation for the orthotic prescription. He has been starting to use the STJ axis location exam and says it has improved his orthotic prescriptions by better addressing rearfoot control.
In regard to whether a CFO is indicated based upon the chief complaint, Dr. Volpe bases his clinical decision on the history of the complaint and what other treatments or devices the patient has already received. All patients who are candidates for CFOs undergo a full biomechanical static evaluation and dynamic observational gait examination. Dr. Volpe says this helps determine the biomechanical deficits or pathologies that the device must attempt to neutralize or accommodate.
“When I do prescribe CFOs, I make every effort to include them as part of a comprehensive treatment plan that should feature other components and modalities to assist the patients with symptoms and management of the condition,” says Dr. Volpe. “I prefer to use orthoses to return and maintain feet to a more optimal position to prevent recurrence or exacerbation after acute symptomatology has been relieved or is receiving ongoing treatment.”
Q: What are your thoughts on OTC foot orthotic devices?
A: Dr. Kimmel cites several brands that “have done a good job in trying to make an orthotic for the masses.” He says Powerstep’s line has different levels of rigidity and has taken the average measurements of a large number of patients to come up with the arch height and posting. Spenco’s orthotic lines have a plastic bottom and are moldable to a degree using hot water, and Dr. Kimmel says patients have tolerated them very well. Although there is a line of OTC orthoses with an interchangeable metatarsal pad, Dr. Kimmel says most of his patients cannot tolerate them. Dynasteps (Dr. Scholl) are “not a bad device for patients on a budget,” adds Dr. Kimmel. “I always tell my patients that it is like buying glasses over the counter. They might help but it is not their prescription.”
Dr. Spencer will use OTC orthoses but not all types. He prefers devices that incorporate a shell with some motion control. He also prefers an OTC orthosis with a thermoplastic shell, saying the shell permits him more control over adjusting and augmenting the OTC device to best suit the patient.
Over-the-counter orthoses “have a place,” says Dr. Volpe. He says they can be helpful as trial devices to see if the patient will benefit from mechanical support or control. However, Dr. Volpe notes that a failed effort with an OTC device “surely does not always mean that a custom device, with all of its inherent benefits, will not benefit the patient.” He prefers using a weight-dispersive strapping as a trial or temporary therapy to ascertain whether repositioning the foot will help reduce symptoms. For patients who need soft tissue supplementation or accommodation, he notes that a well-cushioned OTC device can be a good first line of treatment.
Dr. Spencer notes that OTC orthotics are not useful for all patients but patients can greatly benefit from them if they need some control of foot function or may have financial restrictions that prevent them from utilizing prescription orthoses. In the same vein, Dr. Volpe reserves OTC devices as an option for patients when custom devices are cost-prohibitive. He notes that many orthotic labs have “semi-custom” lines that match a cast to a line of prefabricated shells that one can customize somewhat.
“These devices are a nice compromise between OTC and fully custom devices, and serve as a nice bridge in lowering the cost while still providing the patient with a quality device,” says Dr. Volpe. “In addition, the quality of OTC devices offered by some labs has also improved dramatically so they are able to function as controlling devices when indicated.”
Q: In your opinion, what would make a good OTC foot orthotic device?
A: Using a thermoplastic shell as a basis for design is the key for a quality OTC device, according to Dr. Spencer. He recalls seeing less than optimal results with OTC inserts that provide poor motion control to the foot.
“Regrettably, I think many patients who use OTC inserts do so before speaking with a podiatrist and end up with something that does not help them,” notes Dr. Spencer.
If one desires motion control, Dr. Volpe says the material must be moderately non-conforming, maintaining its shape and offering support under loads. Further, he notes that an adequate height to the arch is beneficial and the plantar surface of the device should not rock when one places it in the shoe. In a generic device, Dr. Volpe notes the advantage of a soft tissue supplement at the foot-orthotic interface for comfort.
In cases in which shock absorption or accommodation is the issue, Dr. Volpe prefers to use a laminated device with materials of different densities that work together to optimize outcomes. He prefers having a lower durometer or a more accommodating material closer to the foot-orthotic interface. Dr. Volpe adds that one may layer a higher durometer material beneath it to add some body or support to the device. The top cover should be appropriate for the patient’s activity, according to Dr. Volpe. He suggests nylene or Spenco materials as useful in reducing friction while vinyl is helpful if orthoses have to be cleaned frequently.
“I would also add that one has to be careful sometimes that an OTC device does not distract a patient from the potential benefits of moving on to a custom device over time. If one uses only symptoms to gauge results with an orthosis, a given patient may have a relief of symptoms with an OTC device that may prove to be temporary,” maintains Dr. Volpe.
In some cases, Dr. Volpe says moving the patient to custom-level therapy may be the difference between short-term and long-term benefits. He adds that a superior custom device may also help prevent other compensations and maintain neutral position function of the foot, which may have other lasting benefits for the musculoskeletal position over time.
As Dr. Kimmel advises, there must be some level of customization, whether the device is heat moldable to the patient’s foot or there is the ability to add some degree of posting. If an OTC device were sold with pads so the patient could add an accommodation or post, he feels that would help significantly.
“Unfortunately, I have seen patients go to ‘national chain foot stores’ that are owned by either an orthotist or pedorthotist, stand on a pedigraph and come out with a supposed ‘custom’ made device,” recalls Dr. Kimmel. “These devices are expensive and sometimes hinder our ability to make a custom-made device because of patient misconceptions.”
Q: Is there an area of the foot that you feel requires more influence from a foot orthotic device than perhaps other areas?
A: Dr. Volpe notes the importance of all components of a custom foot orthosis. That said, he notes that in motion-controlling devices, critical components are the conformity of the shell to the heel, arch and midfoot. The heel cup, especially with added intrinsic plaster modifications, is a key component that aids the device’s ability to control or modify subtalar joint function, according to Dr. Volpe. He says these features will contribute to a shell that will produce a more medial orthotic reaction force (ORF) to the subtalar joint axis, which leads to a net supinatory effect. Furthermore, he says an extrinsic rearfoot post can be an important addition to the device. Dr. Volpe adds that this can help stabilize the device in the shoe and help decelerate pronation after heel contact when necessary.
As Dr. Volpe says, the stage for midfoot and forefoot pathology, including metatarsophalangeal (MPJ) deformities, is often set by rearfoot dysfunction. He notes one of the keys to improving the function of the distal segments of the foot is adequate influence on the proximal segment.
Dr. Kimmel feels if one does not control the motion in the rearfoot (subtalar) joint, the device is nothing more than an accommodative device as opposed to a functional device. He explains that controlling any excess motion in the rearfoot will influence the midfoot and the rest of the foot. He likes to have his patients wear a device that is extrinsically posted in the rearfoot with a little deeper heel cup.
Unfortunately, Dr. Kimmel says most patients cannot get these orthotics in traditional dress shoes like loafers or wingtips. Although intrinsically posted orthotics are easier to fit in most shoes and have a better compliance, Dr. Kimmel notes a loss of functionality.
Dr. Spencer does not believe that he must focus on one specific area to create a foot orthotic that will properly serve the patient. He stresses the importance of getting a clear idea of what all the areas of the foot are doing during function, and addressing those areas with the orthosis.
Dr. Spencer also emphasizes having a strong understanding of the implications that the rearfoot, midtarsal joint, lesser tarsus, lesser metatarsals, the first ray and the lesser digits will have on overall foot function. After getting an idea of what these areas are capable of and seeing what they are actually doing during gait, he says one can successfully prescribe a foot orthotic to address these areas.
Q: How do you see foot orthotic therapy evolving in the next five to 10 years?
A: Dr. Kimmel recalls starting his practice at the tail end of the Rohadur era and the beginning of the graphite era. He thinks new materials are going to come out that allow clinicians easy adjustment of devices in the office and still provide some of the benefits of Rohadur. Polydur, a material that is similar to Rohadur, does not have the same number of benefits, according to Dr. Kimmel. Dr. Kimmel also feels new computerized casting techniques might allow a practitioner to cast and make an orthotic in the office in a short period of time.
Dr. Spencer sees more use of pressure measurement systems in the prescribing and adjusting of orthotic devices. He employs the F-Scan system (F-Scan) to assess plantar foot pressure and the timing of pressure distribution, and equalizing this pressure pattern and timing between both feet. As Dr. Spencer points out, this is one area that DPMs cannot analyze via measurements or watching the patient walk.
“I have seen incredible positive effects to patient function, not just foot function but overall gait function of the body, when timing and distribution are balanced,” says Dr. Spencer. He cites the example of a patient with drastically asymmetric arm swing that was corrected by influencing the pressure distribution and the timing of pressure distribution, which created more symmetry in foot function.
Dr. Volpe foresees continued production upgrades at laboratories, including material advancements that will enable DPMs to prescribe thinner, more versatile devices for numerous clinical circumstances and shoe gear requirements. Over time, he feels techniques for casting, fabrication and device design should continue to improve.
Dr. Volpe says he would like to see an increased emphasis on orthoses prescribed for children to help reduce chronic problems that may emerge when they become adults. He notes additional outcomes studies are needed to verify the positive effects of CFOs, particularly in the pediatric population.
“It is hoped that health insurance reimbursement for this critical therapeutic modality will continue to improve so more and more patients who might benefit from CFO therapy will be able to avail themselves of it without financial obstacles,” says Dr. Volpe. “The aforementioned outcome studies should help with this cause and would also contribute to wider acknowledgement of the benefits of this therapy across the medical community.”
