Choosing the most effective type of orthotic device for a given condition can be tricky as one must consider factors that include materials, potential modifications and cost.
Accordingly, the panelists discuss possible indications for OTC orthoses, conditions that are particularly challenging to treat with orthotics and the role of functional foot orthoses in managing bunion deformities.
Q: Are all prefabricated, over-the-counter (OTC) foot support systems essentially the same? Are there unique characteristics of any of the devices which makes them better suited for certain foot problems?
A: All three panelists note the variety of OTC orthoses available. Kevin Kirby, DPM, notes that OTC orthoses are made from a variety of materials, have a large range of medial arch height and heel cup contours, and have considerable variation in cushioning, shape and shoe fit.
Dr. Kirby notes that OTC orthoses with increased medial arch height would be more appropriate for patients who have symptoms such as posterior tibial tendonitis/dysfunction related to increased subtalar joint pronation moments. He says OTC orthoses with increased heel cushioning may provide some relief from symptoms for patients who have plantar heel pain due to plantar fat pad atrophy.
One should base the recommendation for an OTC orthosis on the shape of the patient’s foot, the biomechanical etiology of the symptoms, the activities and the shoes in which the patient intends to wear the orthoses, suggests Dr. Kirby.
Michael Burns, DPM, says most prefab orthoses are made of soft material and some are composed of a material that maintains its shape independent of the shape of the shoe. He notes that most OTC orthoses are designed to cushion the foot but not stabilize it. If cushioning is the main goal, Dr. Burns notes a soft device may be adequate but he tends to use firmer (shank independent devices) orthoses to increase stability.
“Unlike custom-molded foot orthoses, OTC orthoses are not specifically designed for each foot’s unique three-dimensional plantar contours and they are not specifically designed to reduce the pathological internal and external forces that are causing a patient’s pain,” cautions Dr. Kirby.
In addition, Dr. Kirby says OTC orthoses are made of softer, less durable materials than most custom-molded foot orthoses. Accordingly, Dr. Kirby points out that OTC orthoses must be replaced and remodified every six months on average whereas more durable custom-molded foot orthoses will last an average of over 10 years. The ability to modify an OTC for a specific condition is important, according to Richard Blake, DPM. He prefers the YourSole device. Dr. Blake cites the device’s stability, deep heel cups, stable medial and lateral arches, and the fact that the orthosis is heat moldable and full length. Furthermore, he notes that the arch area is deep enough for necessary reinforcements and one can easily grind the material for accommodations.
Q: When should one utilize a prefabricated device?
A: Dr. Burns and Dr. Kirby say cost concerns can be a factor. Dr. Kirby uses prefab orthoses for patients who cannot afford the higher price of custom molded foot orthoses. He adjusts OTC orthoses in the office for these patients until the devices function as much like a custom foot orthosis as possible.
“Interestingly, when I have modified the OTC orthoses of those patients who ‘cannot afford custom foot orthoses’ so their symptoms resolve, many of them are soon able to afford custom foot orthoses so they can have a more long-lasting solution to their foot and lower extremity pain,” points out Dr. Kirby.
When orthotic control is indicated, Dr. Burns says patients frequently ask if there is an alternative to custom functional orthoses. He acknowledges the argument, often made by insurance companies, that one should try OTC supports before custom functional orthoses. For the common complaint of plantar fasciitis, Dr. Burns says it is initially reasonable to combine OTC orthoses with calf and plantar fascia stretching as well as a heel lift if indicated.
In regard to plantar fasciitis, Dr. Burns initially will use low Dye strapping with stretching. If most of the pain resolves, he suggests another week or two of taping along with continued stretching. If the patient does not respond well at first, he uses anti-inflammatory therapy. For persistent symptoms, Dr. Burns encourages patients to use custom functional orthoses. He says such devices are definitive and are an adjunct to continued treatment. Dr. Burns also says prefab devices can be effective for metatarsalgia if patients need cushioning.
Dr. Blake says one can use a prefabricated orthotic initially on all patients with biomechanical issues. He notes that DPMs can learn the right amount of canting if foot stability is a factor and if the patient has any unique sensitivities.
“OTC products are so much less durable in general than custom made plastics so they will never replace them,” explains Dr. Blake. “(Prefabs) can give reliable support for two to six months but then nosedive in stability.”
Dr. Kirby uses OTC orthoses for patients who need immediate pain relief and cannot wait for the fabrication of custom devices. However, as soon as possible, he will schedule patients for orthotic modification to facilitate better fit and reduce the abnormal external and internal forces in the foot and lower extremity that are causing symptoms.
Q: What foot problem do you personally find is the most challenging to treat with a functional foot orthosis and why is it so difficult? What specific orthotic modifications do you utilize to improve your outcome in these cases?
A: For Dr. Burns, posterior tibial tendon dysfunction (PTTD) is the most challenging condition to treat as it is a loss of the primary decelerator of pronation that typically occurs in a badly pronated foot. He says the condition almost always requires foot and leg support. Dr. Burns adds that acute cases require immobilization. In some instances of PTTD, he says a lace ankle brace over a custom orthosis may be helpful during rehabilitation. Then the patient can use the laced ankle brace for increased demand as recovery continues, according to Dr. Burns. He notes that a Richie Brace can be helpful for these patients.
Tarsal tunnel syndrome is the most challenging condition to treat with orthotic devices, according to Dr. Blake, who says the plantar nerve sensitivity makes arch support very painful. In these cases, he notes the foot that needs good support to prevent heel valgus cannot tolerate that support. Dr. Blake cites tape as a good option for many of these patients since even soft orthotics can be intolerable.
Dr. Kirby says dorsiflexion stress injuries to the lateral midfoot are challenging. He calls these injuries lateral dorsal midfoot interosseous compression syndrome (lateral DMICS) wherein the dorsal aspects of the lateral midfoot joints, such as the fourth and fifth metatarsal-cuboid joints, are painful with ambulation. The cause of these injuries is an excessive dorsiflexion moment on the lateral column joints. Dr. Kirby says this is caused by either an over-supinated foot or a foot that is at the end range of pronation of the subtalar joint. Yet there is still increased ground reaction force on the lateral metatarsals, according to Dr. Kirby.
He says these injuries are much harder to treat with orthoses since most orthosis designs tend to supinate and not pronate the foot. Dr. Kirby notes that orthotic modifications for lateral DMICS include a lateral heel skive, an everted balancing position, increased medial expansion plaster and valgus forefoot extensions. With these modifications, Dr. Kirby says one can try and evert the rearfoot, and reduce the dorsiflexion moments on the lateral column during weightbearing activities.
Another challenging case for Dr. Burns is central metatarsal overload without specific plantar plate insufficiency. In these cases, it may be difficult to pinpoint the etiology of the pain so the treatment may be less targeted. He notes the importance of exactly fitting the orthotic shell to the plantar aspect of the forefoot.
Dr. Burns adds that he often has the shell molded directly to the positive cast with only some expansion for the heel cup. Then he uses extrinsic forefoot posts, if necessary, for balancing.
An accommodating forefoot extension like Plastizote can permit dynamic molding of the extension to the forefoot, according to Dr. Burns. He says this provides some cresting and support of the toes, and helps to further reduce pressure under the metatarsophalangeal joints (MPJs). In such situations, Dr. Burns prefers using Spenco type topcovers to reduce the shear forces. He notes that a heel raise may help accommodate for equinus, either in the ankle or forefoot.
Q: What is the role of the functional foot orthosis in the management of bunion deformities?
A: Dr. Blake calls functional orthotics a “double-edged sword” when it comes to bunions. On the positive side, he notes they can shift weight laterally and proximally, unloading the first metatarsal head. On the negative side, he says functional orthoses can crowd shoes and place a dorsiflexory force on the first metatarsal, limiting propulsion and further jamming the first ray.
Sometimes, functional devices act solely as an attachment for a reverse Morton’s extension. If the foot continues to pronate on a plastic orthotic, Dr. Blake says the first ray gets jammed. In cases like these, he says full pronation support is better than 70 or 80 percent support.
When it comes to reducing joint pain associated with either hallux abducto valgus (HAV) or functional hallux limitus, Dr. Burns cites the efficacy of functional orthotic control. When the first ray is flexible, he feels it is helpful to plantarflex the ray a bit when taking the impression. As he notes, OTC supports are often not adequate and if the symptoms persist, he wants the patient to try custom functional control before deciding that orthotic control will not be adequate treatment.
“This is always a bit of a dilemma when suggesting a patient try an OTC support,” says Dr. Burns. “If the response is not adequate, I always wonder if a custom device would relieve the patient’s symptoms and I am hesitant to recommend surgical intervention until the patient has given it a try.”
As Dr. Kirby notes, functional foot orthoses may help slow down the progression of bunion deformities if the first intermetatarsal angle is not already too large. However, he says when the first intermetatarsal angle is too large, even a well designed foot orthosis will have little effect in slowing down the progression of a bunion deformity.
“I have never seen a functional foot orthosis reduce the severity of a bunion deformity,” maintains Dr. Kirby.
Q: Are functional foot orthoses more beneficial before or after corrective surgery for bunion deformities?
A: Preoperatively, Dr. Kirby says orthoses can slow the progression of the deformity and decrease pain to the first MPJ. Dr. Blake says orthoses may be crucial in helping some patients avoid bunion surgery. He emphasizes the importance of obtaining a stable pre-op orthotic as there are many pitfalls with fit and shoegear.
For example, Dr. Blake says one may discover preoperatively that the patient has nerve hypersensitivity secondary to Morton’s neuroma and cannot wear the orthotic. He points out that this finding could change the post-op choices if one notes these pre-op problems and completely addresses them.
In Dr. Burns’ experience, HAV is influenced, if not caused, by abnormal function. However, he acknowledges there is mixed literature on the subject. Therefore, if Dr. Burns repairs a bunion deformity without surgically addressing the cause of the midfoot instability, he emphasizes the importance of continuing orthotic control to reduce the deforming force from acting again on the first MPJ.
In practice, he discusses this with the patient before starting treatment and establishes orthotic control. If the midstance instability is well controlled, Dr. Burns encourages the patient to continue orthotic control after surgery. If there are remaining symptoms or significant deformity, Dr. Burns then offers surgical repair.
In regard to the common HAV repair with distal metatarsal osteotomy, Dr. Burns says the orthotic device will still fit well after surgery. Usually, he says the only adjustment necessary is shortening the device a bit to permit the slight first ray shortening that accompanies such procedures.
Dr. Burns describes the common scenario of a patient who presents with first MPJ pain that resolves with functional orthotic control. He notes that these patients may return years later with pain in the second MPJ with digital contracture and perhaps some increase in HAV deformity. As Dr. Burns maintains, this is often the precipitating event that spurs him to recommend HAV repair and continued orthotic control.
Postoperatively, Dr. Kirby says orthoses protect the first MPJ from abnormal mechanical forces and moments that may have caused the bunion deformity. He says post-op orthotics can also prevent other problems from occurring.
Dr. Blake emphasizes that post-op orthoses are “utterly mandatory” after bunion surgery. After surgery, he notes the first MPJ is very weak and good orthotic devices are normally mandated for a minimum of two years postoperatively.
Dr. Blake is the Past President of the American Academy of Podiatric Sports Medicine. He practices in San Francisco.
Dr. Burns is the CEO of Burns Lab. He is a Fellow of the American Academy of Podiatric Sports Medicine.
Dr. Kirby is an Adjunct Associate Professor in the Department of Biomechanics at the California School of Podiatric Medicine at Samuel Merritt College. He is the Director of Clinical Biomechanics at Precision Intricast Inc.
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.
For further reading, see “Exploring Orthotic Indications For Various Conditions” in the June 2006 issue of Podiatry Today or “How To Overcome Obstacles With Custom Orthoses” in the June 2007 issue. Also check out the archives at www.podiatrytoday.com.