Subject-specific finite element modelling of the foot-shoe complex and its application in metatarsal stress research postprint

Abstract: To develop and validate a 3D comprehensive finite element(FE)coupled model of the foot-shoe complex for revealing their biomechanical interaction and providing scientific basis for running shoe design optimization and related foot injury prevention.The collected CT images were used for establishment of the subject-specific coupled FE model.Boundary and loading conditions were quantitatively defined through 3D gait measurement.Both plantar and shoe sole regions were further divided for model verification.The Bland-Altman plot,Pearson correlation analysis,and T test were used for the reliability and effectiveness analyses between methods.Based on the established model,the effects of barefoot/shoed conditions and shoe sole stiffness on metatarsal stress were further studied.Results are as follows:1)The simulated peak pressure showed great consistency with the experimental data except for forefoot regions.Statistical analysis found that there was a significant correlation between the two methods(r=0.986; P<0.001),and that all the pressure difference points were scattered in the 95% limits of agreement,and the data had no significant difference(P=0.202),indicating a great agreement between the approaches.2)The stress was mainly distributed at the 2nd and 3rd metatarsal bones,with the 3rd one being the most stressed,and it increased in most metatarsal bones while barefoot standing compared to shoed condition.3)As the sole stiffness increased,the peak stress difference between the metatarsal bones increased,and the stress tended to concentrate on the 2nd and 3rd metatarsal bones.Conclusions are as follows:1)The insufficient simulated forefoot pressure may be related to its excessive longitudinal strain,and subsequent research should consider further optimization of the constraints.2)Barefoot and increased sole stiffness can lead to abnormal changes in metatarsal stress; thus in terms of running shoe design,it is suggested to consider adding a buffer structure at the metatarsal region for optimizing the metatarsal stress distribution and further reducing any potential injury risk.