Adjusting Orthoses: Simple Solutions To Common Complaints

Author(s): 
Larry Huppin, DPM

Troubleshooting orthoses is a vital skill when a patient returns with a complaint about the prescribed device. This author presents a guide to remediating common problems, including addressing arch irritation, how to add valgus extensions and keys to adjusting orthoses for shoe fit.

There are several skill sets that are required for an accomplished practitioner of orthotic therapy. Those include the ability to analyze a patient’s biomechanics in a manner that allows for the determination of proper mechanical therapy; the ability to write an orthosis prescription that addresses the patient’s issues; and the ability to take a proper cast or image of the foot. The final critical skill set, and the one that I will address in this article, is the ability to troubleshoot and adjust orthoses.

   Over the past decades, there has been a decreased emphasis in podiatric schools and residencies on orthotic therapy education, including education focused on orthotic troubleshooting, modifications and adjustments. In addition, most podiatric continuing education programs poorly address orthotic therapy.

   Practitioners who wish to advance their orthotic therapy practice have several options to enhance their skills. One of the most effective and easiest methods is to use orthotic labs that have podiatric consultants on staff. Look for labs that have a podiatrist available for consultation every business day and then use them. At least initially, request a consult on every patient for whom you prescribe orthoses. Not only will you likely write a more effective prescription but you will be learning at the same time. The best labs will have consultants who closely follow the literature pertaining to orthotic therapy. Also, look for labs that encourage you to send pictures and videos of your patients to the consultants.

   Other methods to enhance skills include visiting the offices of podiatrists who specialize in orthotic therapy and, if you can find them, attending seminars that incorporate an orthotic therapy component.

What Basic Troubleshooting Skills Should You Have?

There are a few basic troubleshooting skills that every orthotic practitioner should be able to easily perform in the office. These include adjusting for arch height in cases of arch irritation or when the patient feels the orthosis is pushing them too far laterally; adding covers and cushioning; adding modifications such as metatarsal pads and heel lifts; and adding forefoot extensions such as reverse Morton’s extensions.

   In order to perform these adjustments, there are a few basic pieces of equipment and materials that every orthotic practitioner should have in the office. This includes a grinder and a method to polish orthoses after grinding. A gluing station, preferably with a hood, is necessary. Practitioners will also need materials to add cushion and accommodation. Most offices should be able to get by with the following accommodation materials:

• Korex for Morton’s/reverse Morton’s extensions, varus/valgus extensions, aperture
• Poron for cushioning
• Self stick metatarsal pads
• Self stick wedges

   Talk to the podiatric consultants at your orthotic lab about the most useful equipment and materials to use in the office for orthotic modifications. If you have the option, a visit to an orthotic lab can provide a useful lesson on orthotic adjustments.

When Orthotic Adjustments Are Needed

There are several general categories that require one to make an adjustment to an orthosis.

   Direct discomfort. In this situation, patients find that the orthosis causes pain when they wear the devices. This occurs commonly in the arch (for example, the arch feels too high) but can occur at any point where the orthosis makes contact with the foot.

   Continued symptoms. In these cases, the patient may find the orthosis comfortable but continues to have symptoms. If there are orthotic adjustments that might further reduce symptoms, then an orthosis adjustment is called for.

   New symptoms. In this situation, patients may not notice any direct irritation from the orthoses and they may have had resolution of their original symptoms, but they now have developed new symptoms. For example, patients may develop knee pain when they wear a new orthosis they received for treatment of plantar fasciitis.

   Shoe fit. Either due to poor shoe choices or poor communication, patients may find that their orthoses will not fit in the shoes they plan to wear.

How To Make Adjustments For Direct Discomfort

Arch irritation is the most common direct discomfort issue that requires adjustment and these adjustments may be required more often when orthotic prescriptions are based on evidence in the literature. Studies over the past decades have shown that for many of the most common pathologies for which we prescribe orthotics, orthoses that conform closer to the arch of the foot are more effective than those that gap from the arch of the foot. These include studies that give guidance to how one should write orthotic prescriptions for the treatment of plantar fasciitis, metatarsalgia and hallux limitus.

   In a 1996 cadaveric study, researchers demonstrated that orthoses that conform closely to the arch of the foot more effectively reduce plantar fascia tension.1

   Another study focused on the effect of a total contact insert and a metatarsal pad on metatarsal head peak plantar pressures and pressure-time integrals.2 The study authors concluded that the total contact insert and metatarsal pad led to substantial and additive pressure decreases under the metatarsal heads. By increasing the contact area of weightbearing forces, the total contact insert lowers excessive pressures at the metatarsal heads.

   Roukis and colleagues concluded that preventing first ray plantarflexion led to hallux limitus.3 The authors also found that when the first ray could plantarflex, there was an increase in available first metatarsophalangeal joint (MPJ) dorsiflexion. This study shows that orthotic devices that conform close to the arch, thus preventing first ray dorsiflexion, will enhance windlass function.

   Harradine found that increasing heel eversion, which dorsiflexes the first ray as the medial forefoot is forced into the supporting surface, reduces the first MPJ’s available dorsiflexion.4

   These studies indicate that orthoses that prevent first ray dorsiflexion — usually devices that conform close to the arch when the first ray is dorsiflexed — enhance hallux dorsiflexion.

   Although there is evidence that “total contact” orthoses can be more effective for plantar fasciitis, metatarsalgia and hallux limitus, these higher arched orthoses also lead to more potential for direct arch irritation by the orthosis. Accordingly, in order to provide patients with the best possible clinical outcomes, it is imperative that orthotic therapy practitioners be adept at adjusting for this issue.

   The most effective method to adjust for arch irritation depends on the orthotic’s material.

   Polypropylene and other plastics. Arch irritation occurs when there is more force on the foot than the patient finds comfortable. To easily decrease this force on a polypropylene orthosis, grind the orthosis from the bottom to make it thinner and more flexible. One great advantage of this technique is that one can localize the adjustment to the portion of the orthosis that is causing irritation. Another advantage is that clinicians can address the force without changing the shape of the orthosis.

   A recommended technique is to mark the bottom of the orthosis where the patient is feeling excessive pressure. A Sharpie pen works well for this. Then simply grind the orthosis from the bottom just enough to remove the pen mark. This is usually enough to increase the flexibility of the orthosis slightly. Then let the patient try the orthosis. If the patient is comfortable, then you are done. If he or she still feels too much pressure, repeat the procedure until the orthosis feels comfortable. This technique allows a gradual increase in flexibility and helps prevent an overly flexible orthosis.

   Carbon fiber. Carbon fiber orthoses (often called “graphite”) are more difficult to adjust as one cannot grind them thinner without the risk of the device fracturing. Clinicians can heat adjust most of the carbon fiber materials. With this material, this is the most effective method to decrease orthosis arch irritation. The disadvantage of heat adjustment, however, is the risk of losing the shape of the arch. This is a primary reason that I prefer polypropylene orthoses over carbon fiber.

Pertinent Insights On Adjusting Orthoses For Continued Symptoms

Another common reason to adjust orthoses is to accentuate the clinical effectiveness of the orthosis in a situation in which the patient does not achieve adequate relief of his or her symptoms. Let’s look at how we might accentuate orthosis function for the plantar fasciitis and metatarsalgia.

   A 1999 study by Kogler found that valgus forefoot wedging decreased tension on the plantar fascia while varus wedging increased tension.5 Kogler stated that the most effective way to decrease strain on the plantar fascia was to evert the forefoot.

   An easy method to adjust an orthosis in a manner that everts the forefoot so as to decrease plantar fascia tension is to add a valgus extension to the orthosis. One can accomplish this by cutting a piece of 3 mm Korex to fit under the second through the fifth metatarsal heads. Bevel the Korex so it retains full thickness laterally and is paper thin medially. Glue it to the bottom of the topcover under the metatarsal heads.

   In the same George Washington University study noted above, researchers noted that metatarsal pads act by compressing the soft tissues proximal to the metatarsal heads and relieving compression at the metatarsal heads.2 A 2003 study looked at where to place metatarsal pads for the most effective reduction of pressure at a metatarsal head.6 These authors found that one should place the metatarsal pad between 6 mm and 10.6 mm proximal to the metatarsal head.

   These studies indicate that metatarsal pads can be an effective modification to add to a foot orthosis for patients suffering from sub-metatarsal pain, calluses and ulcers. Practitioners can make the addition of metatarsal pads simple by initially prescribing their orthoses and leaving the cover unglued on the anterior portion of the orthosis. This allows placement and modification of the metatarsal pad to ensure patient comfort. Although the study above indicates the general area to place the pad for optimum pressure reduction, there is still a subjective component and the patient will tell you where the pad is most comfortable. Let the patients move the pad (they can tape it in place) until they find the most comfortable placement. Only then should one glue the pad to the orthosis and glue the cover anteriorly.

When Patients Return With New Symptoms

The third category that might require adjustment of their orthoses is patients who develop new symptoms when they begin to wear their orthoses. The most common new symptoms I see are pain affecting the knee, hip and/or back when patients are initially wearing their orthoses. The most common cause seems to be orthoses that we prescribe to reduce excessive pronation but do so in a manner that they apply more supinatory torque then the patient can tolerate.

   Several studies, for example, have demonstrated that valgus wedging of the heel can reduce varus torque within the knee and symptoms associated with medial compartment osteoarthritis.7,8 Conversely, however, varus wedging may act to increase torque in the medial knee and symptoms associated with medial compartment osteoarthritis. Since in most cases a functional orthosis acts as least partially as a varus wedge, there is certainly risk for increasing medial knee pain with the use of functional orthoses.

   The goal when adjusting these orthoses is to decrease the “varus wedge” function. To look at it another way, we want to reduce the supinatory torque that the orthoses are applying around the subtalar joint axis or let the patient pronate a bit more. One of the easier techniques to accomplish this is to increase the flexibility of the devices by grinding them thinner in the arch as I have described above. Other options include removing the rearfoot post and/or adding a valgus extension to the orthosis.

How To Adjust The Orthotic For Shoe Fit

Finally, a skilled orthotic practitioner must be able to adjust for shoe fit. Listed below are a few of many modifications that one can make to allow for improved shoe fit.

   Narrowing the orthosis. One should narrow the orthosis only from the medial aspect. If the clinician narrows the device laterally, this allows the entire orthosis to slide laterally in the shoe and the arch of the orthosis will not match the arch of the foot.

   Lowering the heel cup. Since a heel cup gets wider as it gets higher, the heel cup width is often the limiting factor in allowing an orthosis to fit into the most posterior portion of the shoe. Be aware that after you lower the heel cup, you must often make the posterior wall of the heel cup thinner.

   Thinning the heel contact. If a patient feels that the heel is pistoning out of the shoe, thinning the heel contact point of the orthosis allows the orthosis to sit lower in the shoe and in many shoes will eliminate the pistoning.

In Conclusion

To provide patients with the best orthotic therapy and optimum outcomes, podiatrists must be skilled at adjusting and troubleshooting foot orthoses.

   It is beyond the scope of this article to provide instruction on performing the majority of orthotic adjustments and modifications that podiatrists might perform regularly in a podiatric clinic. What I hope is that the article will demonstrate the importance of orthotic adjustment skills in providing patients with optimum clinical outcomes and inspire students, residents and practitioners to learn the skills necessary to provide the best possible orthotic therapy for their patients.

   Dr. Huppin is the Medical Director of ProLab Orthotics. He is in private practice in Seattle.

References
1. Kogler GF, Solomonidis SE, Paul JP. Biomechanics of longitudinal arch support mechanisms in foot orthoses and their effect on plantar aponeurosis strain. Clin Biomech. 1996; 11(5):243-252.
2. 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; 86(6):833-42.
3. Roukis TS, Scherer PR, Anderson CF. Position of the first ray and motion of the first metatarsophalangeal joint. J Am Podiatr Med Assoc. 1996; 86(11):538-46.
4. Harradine B. The effect of rearfoot eversion on maximal hallux dorsiflexion. J Am Podiatr Med Assoc. 2000; 90(8):390-3.
5. Kogler GF, Veer FB, Solomonidis SE, Paul JP. The influence of medial and lateral placement of orthotic wedges on loading of the plantar aponeurosis. J Bone Joint Surg Am. 1999; 81(10):1403-13.
6. Hastings MK, Commean PK. Aligning anatomical structure from spiral X-ray computed tomography with plantar pressure data. Clin Biomech. 2003; 18(9):877-82.
7. Kerrigan DC, Lelas JL, Goggins J, Merriman GJ, Kaplan RJ, Felson DT. Effectiveness of a lateral-wedge insole on knee varus torque in patients with knee osteoarthritis. Arch Phys Med Rehabil. 2002; 83(7):889-93.
8. Kakihana W, Akai M, Yamasaki N, Takashima T, Nakazawa K. Changes of joint moments in the gait of normal subjects wearing laterally wedged insoles. Am J Phys Med Rehabil. 2004; 83(4):273-8.

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