CAD-CAM Technology for Diabetic Footwear

DESCRIPTION (provided by applicant): Over 15% of diabetic patients will experience a foot ulcer. Foot ulcers are expensive both in terms of cost of care and work productivity lost. Foot ulcers are also the dominant contributory cause to the more than 80,000 amputations performed in the US each year in diabetic patients. In order to prevent ulcerations and amputations, at-risk patients must use special footwear for life as part of a comprehensive care and self-care program. Currently the design and manufacture of therapeutic footwear is largely based on subjective criteria. Successful shoes are usually made by experienced craftspeople and much iteration is often required. Several attempts have been made to put the design process for the critical shoe-foot interface (insole) on a quantitative basis. These products appear to have not been particularly successful because of the lack of a well-defined algorithm to translate patient attributes into insole design. We will develop an entire therapeutic shoe system for at risk DM patients that will incorporate: data collection; automatic algorithm for insole design; CAD-CAM system for manufacture; and system for shoe selection including outsole modifications. The final product will also include a means for provider and patient education and products to promote appropriate care and self-care. Phase I preliminary studies have demonstrated success in data acquisition in the areas of plantar pressure, foot shape and arch shape. Algorithms for shoe sizing and alignment of the pressure and shape data with the shoe template have been developed. A method for reproducible design of insole modifications on the computer screen, based on the shape and pressure data, now exists and virtually designed insoles can now be milled using the CAD-CAM system. A data set from patients staying healed has been acquired that for the first time provides guidance for the identification of an in-shoe pressure ulceration threshold. We have also demonstrated feasibility of the whole process by utilizing the method to reduce in-shoe pressure below threshold in a group of neuropathic high-risk feet with high pressure at the first metatarsal head. We now see a clear path toward further automation of the system and to a consideration of other "at-risk" regions of the foot.