Lower extremity amputation in people with diabetes continues to be a major public health problem. More than 65,000 amputations are performed annually on diabetic patients in the US and, despite recent efforts, this number is increasing. Ulceration in the neuropathic foot is a major precursor of amputation and therapeutic footwear has been shown to be an important component of ulcer prevention. Unfortunately, there are still no overall guidelines to help with the prescription and construction of such shoes. The investigators believe that a comprehensive understanding of the problem of matching a given """"""""at risk"""""""" neuropathic foot to a given therapeutic footwear intervention is unlikely flow just from human experimental work. Based on encouraging pilot results, they therefore propose in this application to develop in ABAQUS a series of increasingly complex finite element models of the forefoot based upon individual high resolution MRI images. The models will include the action of the flexor tendons, the plantar fascia, the transverse tarsal ligament, the major joints of the forefoot and a sliding interface between the foot and the ground or the footwear. A number of mechanical tests are proposed to develop material properties and model boundary conditions. The models will be validated using both a unique cadaver model and by measurements of pressure and plantar tissue thickness in walking human subjects. Once accurate predictions are achieved under these simple conditions, a series of typical footwear modifications will be examined. These will include insoles of different thickness and stiffness, """"""""plugs"""""""" for local stress relief, metatarsal pads, and insoles with a molded forefoot. These results will again be validated against cadaver and human subject measurements. This work should result in significant advances in the modeling of the foot, and should provide. a detailed understanding of the design principles for footwear interventions that can reduce plantar pressure under the forefoot
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