The Effects of Plastazote® and Aliplast®/Plastazote® Orthoses on Plantar Pressures in Elderly Persons With Diabetic Neuropathy

Abstract

High plantar pressures often lead to ulcers and amputation in persons with diabetic neuropathy. Orthoses, worn with diabetic shoes, are prescribed to decrease plantar pressures. The purpose of this study was to determine the effect of Plastazote® and Aliplast®/Plastazote® orthoses in decreasing plantar pressures. Eight men and eight women (mean age, 68 ± 6 years), with diabetic neuropathy were separated into two groups of eight, matched by body mass index and history of or current foot ulceration. One group wore custom Plastazote orthoses, the other, custom Aliplast/Plastazote orthoses, for 3 months. Plantar pressures were measured during walking with and without orthoses at predetermined velocity immediately after orthosis fabrication, at 1 month, after orthosis adjustment deemed necessary by the orthotist, and after 3 months of wear. Plantar pressure variables were recorded for six plantar regions of the foot: heel, medial midfoot, lateral midfoot, metatarsal one and big toe, metatarsals two and three and corresponding toes, and metatarsals four and five and corresponding toes. Repeated measures ANOVAs identified significant differences in peak pressure, maximum mean pressure, pressure time integral, mean force, and contact area between groups and orthosis condition (with vs. without) immediately after fabrication. Separate repeated measures ANOVAs identified significant differences in the same variables for group, orthosis condition, and time between 1 and 3 months. Walking with shoes and either orthosis significantly decreased all plantar pressure variables and increased contact areas compared with walking with shoes without orthoses under the big toe and metatarsals two and three immediately after fabrication. Peak pressure under the big toe decreased 27% and that under metatarsals two and three decreased 41% when wearing orthoses. Peak pressure also significantly decreased under the heel and metatarsals four and five (25% and 35%, respectively). No variables differed between orthosis groups or with time wearing orthoses. Wearing custom-made orthoses reduced plantar pressures by increasing contact area. Plastazote alone and Aliplast/Plastazote are equally effective in decreasing pressures at time of fabrication, at 1 month after 9 of 16 pairs of orthoses were adjusted for wear, and after orthoses wear for an additional 2 months.