基于糖尿病患者步态周期足底压力的变刚度鞋垫设计

Design of variable stiffness insole based on diabetics plantar pressure during gait period

目的分析步态周期内糖尿病患者足底压力特征,探究变刚度减压鞋垫的优化设计。方法开展足底压力实验,建立包含157例受试者的数据库。分析糖尿病有神经病变、无神经病变患者和健康人的足底压力分布差异,划分鞋垫压力区域,并按照压力梯度在不同鞋垫区域填充多孔单元。构建糖尿病足-小腿-鞋垫有限元模型,分析足跟着地、动态中立和前掌推离3个姿态下足底压力和内部应力的分布特点,探究最合理的鞋垫刚度设计。结果与健康组相比,糖尿病神经病变患者左、右足足跟区峰值压力和高压百分比均有下降趋势,其中左足足跟区峰值压力减少11%(P=0.026),高压百分比减少9.8%(P=0.02)。鞋垫跖骨高压区、足跟高压区分别采用2.5 MPa和1.9 MPa的多孔单元时,能够使前掌推离、动态中立和足跟着地姿态的足底峰值压力分别降低42.4%、27.4%和26.4%,软组织峰值应力分别降低49.8%、43.6%和25.1%。结论糖尿病患者跖骨区比足跟区溃疡风险更高;基于多姿态下足底压力和内部应力优化的变刚度鞋垫,能有效降低行走时足底峰值压力和软组织峰值应力,为变刚度鞋垫设计提供参考。

Objective To analyze the characteristics of plantar pressure of diabetic patients during gait cycle,and to design a offloading insole with variable stiffness.Methods The plantar pressure experiment was carried out and a database including 157 subjects was established.The differences of plantar pressure distribution were analyzed among diabetic patients with and without peripheral neuropathy,and healthy people.The insole pressure area was divided,and porous units were filled in different insole areas according to the pressure gradient.The fed-calf-insole finite element model of diabetic patients was constructed.The simulation analysis of different insole schemes was carried out under the conditions of push-off,footheel-strike and dynamic neutrality posture,and to explore the most reasonable insole stiffness design.Results Compared with the healthy group,the percentage of peak pressure and high pressure in the left and right heel ar‐eas of diabetic neuropathy patients showed a decreasing trend,in which the left peak pressure was significantly reduced by 11%(P=0.026)and the percentage of high pressure was significantly reduced by 9.8%(P=0.02).When the porous elements of 2.5 MPa and 1.9 MPa were used in the high pressure area of the insole metatarsal and high pressure area of the heel,the peak plantar pressure of footheel-strike,dynamic neutral and push-off was reduced by 42.4%,27.4%and 26.4%,and the peak stress of the soft tissue was reduced by 49.8%,43.6%and 25.1%,respectively.Conclusion There is a higher risk of ulcer in the metatarsal region than in the heel region for diabetic patients.The variable stiffness insoles based on the optimization of plantar pressure and internal stress under multi-posture can effectively reduce the peak pressure of plantar and peak stress of soft tissue during walking,which provides a reference for the design of variable stiffness insoles.