Research On Biomechanics And Bionic Orthotics Of The Arch System Of Flatfoot

Flatfoot is a common foot deformity that often causes series of lower extremity problems that serious ly affect the quality of life.Abnormal structural changes of the arch system of flat foot often lead to changes in its biomechanical properties,resulting in abnormal distribution of plantar pressure,which in turn leads to local pain and even fractures.T herefore,this paper focuses on the in-depth analysis of the biomechanical characteristics of the arch system of flat foot,and on this basis,we conduct researches on the bionic ortho sis for flatfoot,in order to provide an important biomechanical basis and technical reference for the innovation of treatments for flatfoot.In this paper,we investigated the characteristics of pressure distribution under different motion states and the material mechanical properties of plantar fascia in flatfoot based on plantar pressure measurement,two-dimensional ultrasound and shear wave elastography,respectively.On this basis,the structure design and parameter optimization of the bionic orthosis for flatfoot were performed combined with the finite element model.The bionic insoles were prepared by 3D printing technology,and on this basis,the performance test was carried out.The main research contents and conclusions of this paper are as follows:(1)Research on plantar pressure distribution at different speeds.The platform plantar pressure measurement system was used to analyze the plantar pressure distribution characteristics of flat foot under slow,normal and fast walking conditions.Th is study found that with the increase of walking speed,the contact area of each area showed a decreasing trend,while the maximum force,peak pressure and average pressure gradually increased,suggesting that when patients with flatfoot walk fast,the probability o f foot injury increases,and then the distribution law of plantar pressure of flexible flat foot at different walking speeds is analyzed,which provides a biomechanical basis for lateral research and the prevention and treatment of flatfoot injuries.(2)Research on the distribution of thickness and mechanical elastic modulus of plantar fascia in flatfoot.The thickness and Young's modulus of the plantar fascia at different locations were evaluated based on B-mode ultrasound and SWE.Th is study found that the thickness and Young's modulus of the second and third branches of the five distal branches of plantar fascia were larger than those of the other three branches;In addition,the thickness and Young's modulus of plantar fascia graduall y decreased from the insertion end of calcaneal to the distal end,showing a certain spatial gradient.Th ese spatial distribution feature s(different Young's modulus in different regions)help to define more precise material properties for the finite element model of flexible flatfoot,resulting in more meaningful simulation results.At the same time,it provides a certain basis for the in-depth study of the biomechanics of the arch system in flatfoot.(3)Noninvasive identification and analysis of flatfoot in vivo based on plantar fascia angle.Based on the study of the changes in the spatial orientation of the plantar fascia with B-mode ultrasound,a new concept of plantar fascia angle was proposed,and a non-invasive identification of flatfoot was studied in vivo based on the plantar fascia angle.The study found a good correlation between the plantar fascia angle and the calcaneal pitch angle.Taking the diagnostic results of the calcaneal pitch angle as the gold standard,the area under the ROC curv e for the diagnosis of flat foot by the plantar fascia angle was 0.973,and the diagnostic sensitivity and specificity based on the diagnostic cut-off value(9.8°)were 97.7% and94.1%,respectively.It indicates that the parameter of plantar fascial angle proposed in this paper is an excellent and effective method for non-invasive diagnosis of flat foot in vivo.(4)Establishment and validation of finite element model of flatfoot.With Mimics,Geomagic,Solid Works and other software systems,a n anatomy-based 3D solid model was constructed.A total of 30 bones,35 cartilages,plantar fascia,soft tissues,and 8 7 ligaments were included in the model.Based on the 3D solid model,the simulation calculation of static plantar pressure was carried out.The simulation results were compared with the results of the plantar pressure measurement,and the results show ed that the simulation calculation results of the foot model were in good agreement with the experimental test.The 3D solid model constructed was reasonable,effective,and could be used for the prediction and auxiliary analysis of related parameters.(5)Design,preparation and performance study of bio nic insoles for flatfoot.Based on the arch characteristics of the 3D model of a healthy foot,a bionic insole model for flatfoot was designed,and the effectiveness of the bionic insole was verified by the finite element simulation results.Based on the arch charact eristics of the 3D model of a healthy foot,parameters optimized for the design of the insole were selected.Through the orthogonal experimental design,the experimental scheme was optimized,and the main factors for improving the pressure distribution of the bionic insole were analyzed based on the simulation results,and the optimal combination of the parameters for insole preparation was determined.Finally,bionic orthopedic insoles were prepared based on 3D printing technology.The results of the perfotmance test showed that the bionic insoles for flatfoot can effectively reduce the maximum force,peak pressure and average pressure of the forefoot and heel.At the same time,it plays a certain role in improving the center of pressure excursion caused by flatfoot,and in turn affirms the therapeutic effect of the bio nic inshoes.