NEW YORK (Reuters Health) – Custom therapeutic insoles enhance plantar pressure relief in high-pressure areas under the forefoot, according to a report in the May issue of Diabetes Care.

“Not all insoles are equal,” Dr. Georgeanne Botek from Cleveland Clinic in Ohio told Reuters Health. “With increased numbers of sites making insoles and dispensing shoes, researching who has a special interest in preventing foot ulceration and preserving ambulation and function is important. Pre-fabricated devices, store-bought insoles, and even orthotic laboratory ‘customized’ insoles vary depending on the prescription and lab.”

Dr. Botek and colleagues investigated whether combining the foot shape measurement with the placement of offloading features, on the basis of quantitative measurements, led to an insole design that achieves better off-loading than the current shape-based approach.

The design based on foot shape and plantar pressure measurements achieved superior unloading compared with two designs based on foot shape alone, the authors report, both with flexible shoes and with rocker shoes.

The insoles developed using the new design approach relieved peak pressure at the regions of interest by 21% to 37% more than insoles made with the current design approach.

In the flexible shoe, the new insoles significantly increased peak pressure and force-time integral in the midfoot, the investigators say, whereas they significantly increased only the force-time integral in the rocker shoe.

“Larger metatarsal pads or bars can transfer more of the load to the midfoot,” Dr. Botek explained. “Also, rocker soles are more effective at offloading high pressure points.”

“Technology is advancing” and computer-based software holds the promise of “having orthotics made at the point of service, using equipment that can translate patient information to a distant site that can create a more specific, customized insole more efficiently and effectively than stepping in a foam box and mailing to a distant orthotics laboratory,” Dr. Botek said.

“We have a registry of patients who have ulcerated within the past year,” Dr. Botek added. “I hope to have a randomized trial with resolved ulcers, having one group of patients fitted with custom molded insoles based on foot shape, and the other group of patients fitted with the shape and pressure based insoles. We can then look at re-ulceration rates of both groups.”

Diabetes Care 2008;31:839-844.

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