Insensate Feet Research Articles

The effect of insoles in therapeutic footwear—A finite element approach

Current practice in the prevention of recurrence of neuropathic foot ulcers is to prescribe accommodative in-shoe orthoses or insoles which reduce plantar pressure levels at locations of bony prominences, particularly under the metatarsal heads. To date, design of these orthoses has largely been a trial and error process. There is little quantitative information available regarding the effects of thickness and the influence of soft tissue characteristics on the cushioning effect of such interventions. The current paper investigated alterations in pressure under the second metatarsal head as a function of insole thickness and tissue thickness. Both experimental and quasi-static plane strain finite element approaches were employed. The orthoses chosen reduced plantar pressure by a maximum of approximately 30% and were more effective (on a percentage basis) in the setting of reduced sub-metatarsal tissue thickness. Peak normal stresses predicted by the FE models were, on average, within 5.9% of experimentally measured values for the normal tissue case and 8.1% for the reduced tissue case. The techniques presented represent a promising approach to understanding plantar cushioning and the principles involved in the design of therapeutic footwear for insensate feet.

The use of running shoes to reduce plantar pressures in patients who have diabetes.

We compared the plantar pressures generated by walking in leather-soled Oxford-style shoes and by walking in inexpensive running shoes with those generated by walking in thin socks on a hard surface for thirty-nine individuals (thirteen who had diabetes and neuropathy, and thirteen who had diabetes without neuropathy, and thirteen who had neither diabetes nor neuropathy [controls]). Except for two anatomical regions, the plantar pressure associated with the Oxford-style shoes were not different from those associated with walking without shoes. In comparison, the inexpensive running shoes relieved plantar pressure in the forefoot and heel by a mean (and standard deviation) of 31 +/- 9.1 per cent, with the most relief occurring in the feet that had the highest pressures when they were unshod. There were significant reductions in pressure in all regions of the foot except for the midfoot (p < 0.01), and there were no significant differences between the groups. Individuals who have insensate feet should be discouraged from wearing leather-soled Oxford-style shoes because of the risk of ulceration due to elevated plantar pressures. Inexpensive running shoes should be viewed as the very minimally acceptable choice for footwear for these individuals if the feet are free of deformity.

Poster 164 Prevention of plantar ulceration's recurrence in insensate feet: Marta Imamura, MD (Hospital das Clinicas/Sao Paulo University, Sao Paulo, Brazil); Osny Salomão, MD

Poster 164 Prevention of plantar ulceration's recurrence in insensate feet: Marta Imamura, MD (Hospital das Clinicas/Sao Paulo University, Sao Paulo, Brazil); Osny Salomão, MD