Study Sheds New Light On Therapeutic Footwear For Patients With Diabetes
While there has been a plethora of studies in recent years that have tackled therapeutic footwear for people with diabetes, a new study reveals a dramatically lower rate of foot ulcers among those who wear therapeutic footwear and insoles. The study, which was published recently in Diabetes Care, found that 33 percent of patients who wore their own shoes had new foot lesions while approximately four percent of those who wore therapeutic footwear and insoles experienced new ulcers.
The study, which was conducted in India, tracked 241 patients with diabetes who either had previous foot ulcerations or were at risk for ulcerations. According to the study, the four study groups were divided up as follows:
• group one patients who wore sandals with 10-mm insoles of microcellular rubber and an 8-mm rubber outsole;
• group two patients who wore sandals with 5-mm polyurethane foam insoles, 5-mm microcellular rubber midsoles and 10-mm ethylene vinyl acetate outsoles;
• group three patients who wore sandals with 6-mm polyurethane insoles, 10-mm ethylene vinyl acetate outsoles and 6-mm cork midsoles; and
• group four patients who declined the prescribed sandals for economic reasons and wore their own footwear with a hard leather board insole.
Using in-shoe pressure measurements, the authors found that those who wore their own shoes had an increased foot pressure (40.7 + 20.5 kPa) in contrast to the other groups whose foot pressures ranged from 6.2 to 6.9 kPa.
Guy Pupp, DPM, says the study reinforces the importance of therapeutic footwear in preventing recurrent ulcers among high-risk patients with diabetes.
“A diabetic patient with a history of previous ulceration or amputation is at an increased risk for further ulceration, infection and subsequent amputation,” says Dr. Pupp, Clinical Director of the Southeast Michigan Surgical Hospital Foot and Ankle Clinic in Warren, Mich. He notes these conditions may be compounded further by neuropathy and peripheral vascular disease.
When patients do not wear the proper footgear, Dr. Pupp says he has seen “significant recurrence of ulcers” and has noted “catastrophic results” among patients who had previously underwent successful limb salvage surgery.
David G. Armstrong, DPM, says the study by Viswanathan, et. al., is the latest to confirm the notion that good shoes “seem to work.
“Prescriptive footwear, when appropriately constructed, can reduce peak plantar pressures and that reduction appears to have an effect on preventing wounds,” notes Dr. Armstrong, a member of the Board of Directors for the American Diabetes Association.
Tips On Choosing Materials
For Therapeutic Insoles
In the study, researchers point out that materials such as polyurethane, ethyl vinyl acetate (EVA), microcellular rubber and cork are lightweight, durable, flexible and absorb shock.
However, Nicholas Sol, DPM, CPed, says he has tried the aforementioned materials for patients with diabetes and rejected them in favor of using multi-laminates. He has had particular success with a tri-laminate material. He says he heats the material to 275º and molds it directly to the patient’s protected feet. After it has cooled, the material is easily trimmed and shaped to fit the shoe.
With this material, the softest layer is against the foot and the hardest material is against the shoe, according to Dr. Sol, who has a private practice in Colorado Springs, Colo.
“I find that this combination maintains shape and is easy to both mold and modify,” says Dr. Sol.
For David Levine, DPM, CPed, the key is to use soft materials that do not bottom out and can absorb shock. While he says there are a lot of materials to choose from, he tends to use Microcell, poron, p-lite, Spenco, cloud crepe, cork and plastazote for these patients.
In regard to the characteristics he looks for in insoles for diabetic footwear, Dr. Armstrong prefers a low durometer material over a progressively higher durometer material under that softer material, which he says you would ideally mold to the foot.