March 2013

DIABETES: More results support use of foot orthoses to significantly decrease plantar pressures

Swedes also find low ulceration rate

By Jordana Bieze Foster

Research from Sweden and Egypt provides more evidence that foot orthoses can significantly decrease plantar pressures in patients with diabetes, theoretically reducing the risk of foot ulcers and lower extremity amputation.

Investigators from the University of Gothenberg in Sweden found that both custom and prefabricated insoles significantly reduced in-shoe plantar pressures in patients at risk of ulceration, effects that were maintained after one year. And researchers from Ain Shams University in Cairo, Egypt, also documented significant plantar pressure reductions with the use of a custom-molded foot orthosis in diabetic patients who had previously undergone first ray amputation.

The Swedish team randomized 114 diabetic patients to receive one of three types of insoles: a custom device made from 35-shore ethylene vinyl acetate (EVA), a custom insole made from 55-shore EVA, or a prefabricated device with support in the medial arch, a metatarsal pad, and a 25-shore A Poron cover. Patients wore the designated insoles with their own standard walking shoes. The researchers did not track patient compliance with insole wear.

No patient had an active foot ulcer at baseline; one patient developed an ulcer in the first six months, but that one case was the only ulcer to occur in the 12-month study period. Although the study did not include a control group, the ulceration rate of .9% was lower than most rates reported in the literature.

All three types of orthoses were associated with peak plantar pressures of less than 272 kPa after one year. Peak plantar pressures for the custom orthoses were significantly lower than for the prefabricated orthoses in the heel region only, said Ulla Tang, CPO, a doctoral student at the University of Gothenburg’s Institute of Clinical Sciences and an orthotist-prosthetist at Sahlgrenska University Hospital, who presented the findings at the ISPO World Congress in Hyderabad, India.

“All three types of inserts effectively distribute pressure under the sole in order to minimize the risk of ulcers,” Tang said.

The Egyptian group created custom foot orthoses for 20 patients with first ray amputations secondary to diabetic foot ulcers—a particularly challenging population with regard to preventing ulcer recurrence.

“Every foot after an amputation is usually abnormally shaped,” said Rana El-Hilaly, MD, a lecturer in rheumatology and rehabilitation at Ain Shams University, who presented her group’s findings in Hyderabad. “What I want is something that will fill in the defect and increase total contact area to better distribute the pressure. So I create the device for the foot as if it was a prosthetic socket, to capture the different shapes and bony prominences.”

Each custom orthosis included a 4-mm Pedillin base layer supplemented with Poron in high-pressure areas, topped with a layer of EVA and another layer of Pedillin.

El-Hilaly and colleagues assessed static and dynamic plantar pressures in the 20 patients using a pressure mat under three conditions: barefoot, with the custom orthoses, and with flat insoles. They found that, during walking, both insoles decreased peak plantar pressures in the midfoot, heel, and midmetatarsal regions, but the custom insoles decreased pressures more than the flat insoles. During standing, they found significant reduction of peak plantar pressures only with the custom insoles.

The findings were also e-published in December by The Foot.

Sources:

Tang U, Zugner R, Tranberg R. Effectiveness of insoles in preventive treatment of diabetic patients. Presented at International Society of Prosthetics and Orthotics 2013 World Congress, Hyderabad, India, February 2013.

El-Hilaly R, El-Shazly O, Amer A. The role of a total contact insole in diminishing foot pressures following first ray amputation in diabetics. Presented at International Society of Prosthetics and Orthotics 2013 World Congress, Hyderabad, India, February 2013.

El-Hilaly R, El-Shazly O, Amer A. The role of a total contact insole in diminishing foot pressures following partial first ray amputation in diabetic patients. Foot 2012 Dec 19. [Epub ahead of print]

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