A Novel Porous Structural Design of the Orthotic Insole for Diabetic Foot

Diabetic foot is a common complication of diabetes with a significant symptom of excessive plantar pressure. Studies have shown that reducing plantar pressure can effectively lower the incidence of diabetic foot. In this work, a new design method is proposed to reduce plantar pressure by dividing the orthotic insole into two areas. Support area is under the midfoot and shares a part of plantar pressure compared to flat structure. Soft area helps in decreasing the plantar pressure of the forefoot region and rearfoot region by low young's modulus structure. Honeycomb structure and auxetic structure are applied in the novel porous insole. The orthotic insoles were manufactured by fused-deposition modeling. Finite element analyses show that the auxetic structure of soft area enhances larger deformation than ordinary flat structure by 18% under pressure. Results show that the support area reduces the pressure of the forefoot region and rearfoot region by 30% during upright position. The scene of wearing orthotic insoles with pressure sensors is explored. Consequently, the novel porous insoles can be used to bring better plantar pressure reduction for the treatment of diabetic foot.