Key Insights On Orthotic Fabrication And Replacement

Guest Clinical Editor: David Levine, DPM, CPed


Why do some patients prefer OTC devices to custom orthotics?


Dr. Firestone points out that patients often prefer OTC orthotics as a first-line treatment because they are more cost-effective than custom-molded devices. In addition, he says many patients present with acute situations, such as posterior tibial tendinitis and plantar fasciitis, that require immediate support. Lastly, many of his patients are runners who are currently training for a race and are in need of an orthotic on the spot.

   “Since no two feet are identical in terms of structural imperfections and lower extremity influences, not only from patient-to-patient but from right to left, an OTC device can never provide individualized alignment and function for anyone,” notes Dr. D’Amico.

   Since the majority of podiatric patients present with a chief complaint that has been precipitated, perpetuated or aggravated by pedal pathomechanics, Dr. D’Amico says it is not only inappropriate but also inadequate to merely treat symptoms without addressing the underlying pathology. He has found there is nothing more tolerable or preferred by the patient than a properly prescribed custom foot orthotic that addresses the underlying cause of the presenting concern.

   In regard to orthotic efficacy, a factor that DPMs often overlook is the type of shoe in which the patient is using the device, notes Dr. Levine. As he explains, if one is placing a rigid device into a motion control shoe, there may be too much control and limitation of motion, making the feet, ankle and legs uncomfortable. Take the same device and place it into a more neutral shoe, and it will feel totally different, notes Dr. Levine.

   Consider standing on a rigid orthotic as standing on top of a pillow, says Dr. Levine. He notes that no matter how much control the orthotic device has, there will still be instability. Do the same thing with the orthotic device on top of a book and he says the device will feel much more supportive.

   “Just like glasses, there are over-the-counter reading glasses that work well for many but if there is asymmetry or they just are not quite right, then prescription glasses are necessary. The same is true with feet and the need for prescription orthotic devices,” says Dr. Levine.


How do you determine the type of orthotic device to make for your patients?


One should start with a thorough biomechanical examination when determining what orthosis to make, suggests Dr. Levine, noting that determining the mechanical characteristics of the lower extremities will start the process. For instance, he says in a foot with ligamentous laxity, a more rigid device is necessary in comparison to a foot post-triple arthrodesis. He notes the material selection depends upon the flexibility of the foot and the need for biomechanical control.

   After selecting material, Dr. Levine turns his attention to casting technique. He says neutral suspension plaster, digital and foam box impressions will provide different types of devices, and different pathomechanical conditions require different approaches. Dr. Levine cautions that there is more than one type of successful device for each patient and successful devices require attention to detail, including the amount of posting and control of the foot desired. As he notes, heel and forefoot posting rely upon findings from the biomechanical exam and the goal of the treatment that one is trying to provide. Other considerations are topcover materials and orthotic width.

   Dr. Firestone will generally stick with carbon fiber orthotics when he is looking for a lightweight, durable orthotic, which is important in runners who are looking to keep their running shoes as light as possible. He will also use carbon fiber for dress orthotics since that material is generally lower profile. Dr. Firestone uses polypropylene orthotics for severe overpronators, patients who need better accommodation in the shell and those he feels may need a future adjustment to the shell. He prefers full-length orthotics for athletic shoes and three-quarter length orthotics for dress shoes. Dr. Firestone will fabricate a tri-laminate orthotic with a combination of polyethylene, PPT, ethylene vinyl acetate (EVA) and Plastazote when he is looking for better accommodation.

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