How To Maximize The Efficacy Of Orthotic Prescriptions

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Q: What is your feeling regarding OTC foot orthotic devices and prescription orthotic devices?
A:
In Dr. Wernick’s opinion, OTC orthoses work well as temporary devices or in cases in which the patient has a minimal degree of pathology. However, he cautions DPMs to ensure that the device’s medial architecture matches the foot’s medial architecture. “(A failed match) is the main reason that these devices do not work,” explains Dr. Wernick.

Both OTC foot orthoses and prescription foot orthoses “serve valuable purposes” in Dr. Kirby’s practice. He notes that OTC orthoses are readily available to the patient and one may easily mold them in the office to improve the patient’s function and comfort.

Prescription orthoses are more durable and deform less quickly than OTC devices, according to Dr. Kirby. Furthermore, Dr. Kirby says prescription orthoses are much better than OTC orthoses when it comes to conforming exactly to the foot and one may modify the prescription devices “in nearly infinite ways” for optimal function and comfort. He points out that most of those who receive prescription foot orthoses in his practice have already failed OTC orthosis therapy and need “the much greater potential therapeutic benefits” of prescription foot orthoses.

Dr. Spencer notes some people may only need nominal orthotic control for foot function and do very well with OTC inserts. Some OTC inserts may be useful for pediatric patients who need some control of foot function and he says they will outgrow a prescribed foot orthotic device quickly. The efficacy of an OTC orthosis depends on the device itself, according to Dr. Spencer, who says they are not all created equal. Since cost is a factor with orthoses, Dr. Spencer feels one must offer patients a cost-effective alternative and he feels a well-made OTC orthotic can meet that need.

Here is a medial heel skive. Dr. Kirby has used this device to facilitate more effective treatment of symptoms and pathologies caused by excessive subtalar joint pronation moments. (Photo courtesy of Paul R. Scherer, DPM)
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Author(s): 
Guest Clinical Editor: Scott Spencer, DPM

     Dr. Wernick thinks orthoses are under-prescribed. “There are so many over-the-counter (OTC) or prefabricated devices available today that, too often, people use them when a functional device would be a better choice,” he says. “You can buy glasses at a pharmacy but are they of any benefit to you?” As he emphasizes, orthotics are not arch supports but are specifically designed devices to control the joints and architecture of the lower extremity rather than just the foot.

     Q: When prescribing foot orthotic devices in general, do you lean more toward accommodation or control?

     A: Dr. Kirby says all of the prescription foot orthoses he makes for his patients are functional in that he designs them to reduce the magnitude of pathological internal loading forces within the foot and lower extremity. He emphasizes these orthoses also improve the patient’s abnormal gait function and accordingly relieve symptoms and restore more normal gait function. If one requires accommodation to reduce the magnitude of pathological external loading forces acting on isolated plantar areas, Dr. Kirby says one may easily modify the functional orthoses to improve their therapeutic benefit for the patient.

     If the patient has an adequate range of motion in the joints one is attempting to control, Dr. Wernick notes you can influence the joints with a functional device. He does emphasize caution when it comes to determining the direction and amplitude of motion. If a patient’s deformity cannot tolerate functional control, one should use an accommodative device, according to Dr. Wernick.

     When prescribing orthotic devices, Dr. Spencer tends to emphasize motion and function control rather than accommodation. As far as control goes, he does lean toward decreased control, particularly in those who have never worn orthoses. With the vast majority of his prescribed orthoses, Dr. Spencer still uses a shell of variable rigidity. He does not use an accommodative device unless his goal is even distribution of pressure across the plantar aspect of the foot as would be the case for diabetic patients with peripheral neuropathy and a gait that is primarily apropulsive.

     Q: Are there any “tricks” you have found that enhance the effectiveness of your prescription orthoses?

     A: For 16 years, Dr. Kirby has used a medial heel skive to selectively increase the subtalar joint supination moment from foot orthoses for more effective treatment of those with symptoms and pathologies caused by excessive subtalar joint pronation moments. He also commonly uses a lateral heel skive to treat symptoms such as peroneal tendonitis and chronic lateral ankle instability, as well as lateral midfoot and forefoot symptoms caused by excessive subtalar joint supination moments. Dr. Kirby notes that adding 3 to 6 mm heel lifts to orthoses frequently abates plantar arch irritation from orthoses and permits resupination of the foot to occur earlier during gait.

     Dr. Kirby also says having the anterior edge of the orthosis 5 to 6 mm thick, as opposed to skived thin, frequently leads to great improvements with metatarsalgia and other metatarsal head symptoms. Not only do plantar fascial accommodations make orthoses more comfortable but Dr. Kirby emphasizes the accommodations’ importance in improving the orthoses’ therapeutic effectiveness for various pathologies.

     Dr. Wernick cites the “trick” of viewing the position of the hallux in relation to the first metatarsal shaft. He says the normal resting position should be 15 degrees of dorsiflexion of the hallux. If the angle is diminished or the toe is directly aligned with the metatarsal, this indicates that the first metatarsal is dorsally dislocated, according to Dr. Wernick.

     When casting the orthotic devices, Dr. Wernick advises one to dorsiflex the hallux to approximately 15 degrees. He says one can do this by dorsiflexing the toe while plantarflexing the metatarsal.

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