Can Orthotics Prevent Re-Ulceration In Patients With Diabetes?
By Brian McCurdy, Senior Editor
Patients with diabetes can be at risk for re-ulceration, making prevention a top priority. A recent study in the Journal of the American Podiatric Medical Association notes that custom orthotics can reduce plantar pressures and prevent subsequent ulcers.
The authors focused on 117 patients with a history of diabetic foot ulcers who received prescription insoles after having never before worn orthotics. After two years of wearing insoles, the re-ulceration rate decreased from 79 percent to 15 percent and the amputation rate declined from 54 percent to 6 percent.
As Kevin Kirby, DPM, notes, the literature indicates foot orthoses are very effective at not only reducing peak plantar pressures in patients with diabetes but also at facilitating the healing of existing ulcerations. He cites a study in Diabetic Medicine in which orthoses caused a 30 percent reduction in maximum peak pressure in 81 patients with type II diabetes.
As Dr. Kirby advises, the degree of neuropathy and presence of existing ulcerations or pre-ulcerations should spur concern about not only the foot orthosis design and construction but the patient’s shoes as well. He notes that in patients with significant neuropathy, softer and thicker topcovers, which can help reduce peak pressures and shearing forces, can be the difference in preventing ulcers. If the patient already has a plantar ulcer or has a high risk of ulcer recurrence, Dr. Kirby suggests that shoes may need the addition of rocker soles or sole accommodations.
There is “very little doubt” that high pressures contribute to the development of diabetic foot ulcers in people with diabetes with and without neuropathy, according to David G. Armstrong, DPM, PhD, MD, the Director of the Southern Arizona Limb Salvage Alliance in Tucson, Ariz.
“Reduced pressure should be a priority for anybody working to prevent these problems,” he says.
Dr. Armstrong concurs with Dr. Kirby about research showing the benefits of orthoses in reducing pressures. He hopes to develop a model to measure normal and shear stress before and after shoe prescription.
“The bottom line is that neuropathic patients do not have the ability to sense high pressure spots on their plantar skin either with or without foot orthoses under their feet,” notes Dr. Kirby, an Adjunct Associate Professor within the Department of Applied Biomechanics at the California School of Podiatric Medicine at Samuel Merritt University in Oakland, Calif. “The podiatrist must therefore monitor these high-risk patients accordingly with more careful, frequent orthosis follow-ups and adjustments than what they otherwise schedule for their non-neuropathic patients.”
If the goal of foot orthosis therapy for patients with diabetic neuropathy is the reduction in pressures at high pressure areas on the plantar foot, Dr. Kirby suggests designing the orthosis with a biomechanical knowledge of how to reduce plantar pressures without causing other pathologies. To reduce plantar pressures effectively with an orthosis, the orthosis must cause a reaction force in areas of the plantar foot other than existing high pressure areas. However, Dr. Kirby cautions that this redistribution of orthosis reaction force to other areas of the plantar foot must not cause pathologic magnitudes of compression or shear forces, which could potentially cause ulceration in other areas of the foot.
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