Study About Foot Stress Of 3D Printed Orthopedic Insole Based On Finite Element Analysis Model In Flatfoot

BackgroundFlatfoot is a common deformity with collapse of the medial arch.Orthopedic insole is widely used in the treatment of flatfeet,for the advantages of non-invasive and continuous intervention.The orthopedic insole in clinical is mainly hand-made by orthopedists,while the process is complicated and there are no fixed parameters for manufacturing,then the quality of orthopedic insoles depend on the experience of orthopedist.In addition,hand-made insoles are accompanied by harsh manufacturing conditions and serious waste of materials.It is necessary to explore a better method of making orthopedic insoles.ObjectiveTo explore the feasibility of manufacturing orthopedic insoles by computer-aided design and 3D printing technology for the flatfoot,and compare the effect of orthopedic insoles through finite element analysis,then optimize the design and manufacture of flatfoot orthopedic insole.MethodA patient with stage Ⅱ flatfoot was recruited by using a plantar laser scanner.Orthopedic insole was designed according to his bipedal data.Collect the CT data of the patient’s left foot,extract the image information through computer software,and reconstruct it into a three-dimensional geometric model.Based on the finite element analysis,a foot-insole model to simulate the patient in still standing is established.According to the left foot stress analysis outcomes,the orthopedic insole model was modified and made by 3D printing.Compare the plantar pressure before and after orthopedic insole intervention.ResultsEstablished a flatfoot-orthopedic insole-ground finite element model including whole soft tissue,bones,main articular cartilage,main ankle-foot ligaments and fascia,insoles(flat insoles,type I,II)and ground support.The model includes a total of 212813 nodes,1068660 solid elements,and 86 truss elements;In the foot-insole model,the shape of the foot stress contour obtained by flat insole was similar to that of barefoot,but the pressure peak was smaller than that of barefoot;Type I changed the stress distribution of the foot,but also increased plantar stress of arch and stress of the fifth metatarsalia;type II redistributed the stress of the foot than type I,and the peak internal and external stress of the foot was significantly reduced when compared with barefoot.The component and quality of 3D printed orthopedic insoles were checked,no formaldehyde and phthalates were detected,and it was resistant to twists and turns.The predicted plantar stress peak value and the pressure distribution area is the similar to the actual outcomes.The results of horizontal ground walking test before and after wearing the 3D printed orthopedic insoles were compared,the overall pressure of the patient tended to be redistributed,and the plantar stress peak value was reduced,but the patient still felt uncomfotable in the foot arch.ConclusionIt is feasible to customize flatfoot orthopedic insoles by computer-aided design technology combined with 3D printing technology.The finite element analysis can be used to compare the influence of different insoles on the foot stress of patients with flat foot when standing still.After wearing the 3D printed orthopedic insole,the peak pressure of the sole of the subjects decreased,the pressure distribution tended to be uniform,and the comfort of the forefoot increased.