Modeling And Simulation Of Secondary Fracture Healing Process Under Dynamic Loading

With the gradual development of computer technology,people can use the powerful computing power of computer to deal with a large number of data,which makes a series of biological processes can be described by computer simulation technology.In the medical field,the simulation of fracture healing based on biological cascade reaction of human body has become an important application of computer simulation technology.Through this multidisciplinary approach,which combines medicine,material mechanics,computer science and mechanical engineering,people can simulate and predict various biological behaviors in the process of fracture healing,deeply understand the process of fracture healing,and provide reliable theoretical basis for the determination of clinical treatment plan.Fracture healing is a complex tissue repair process,which is affected by many factors.In this paper,a fracture healing simulation model was established to describe the effects of loading frequency and size on cell concentration and tissue differentiation in the process of fracture healing.The mechanical properties of several hyperelastic models were analyzed,and the model fitting parameters were calculated according to the experimental data.The neo-Hooken model was used to establish the hyperelastic model of fracture healing site.Based on the hyperelastic model established,the geometric model of fracture site was established according to the experiment of transverse fracture of femur in rats.A mechanical model was established for the transport of cells and growth factors by tissue stress changes and interstitial fluid flow under dynamic loading.Combined with the mechanical model,the influence of mechanical stimulation on mesenchymal stem cell differentiation and tissue,as well as the biological interaction between growth factors and different tissues,A model of secondary fracture healing process was established based on the interaction of mechanics and biology under dynamic loading.COMSOL simulation software was used to solve the established second-stage fracture healing model,and the results were compared with relevant experimental data and simulation data to verify the feasibility of the simulation experiment in this paper.The sensitivity analysis of the three initial conditions of the simulation model,namely the concentration of mesenchymal stem cells,bone growth factor and cartilage growth factor,was carried out to verify the stability of the model and preliminatively analyze the influence of the initial conditions of the simulation model on bone and cartilage tissue.Dynamic loading strategies of 5% strain,10% strain and 15% strain at 1Hz strain frequency and dynamic loading strategies of 0.01 Hz frequency,0.1h frequency and 10 Hz frequency at 10% strain frequency were used to influence the concentration changes of different tissues during fracture healing.Simulation results show that dynamic loading enhances the transport of mesenchymal stem cells and growth factors.Fracture healing process under the dynamic load and no load under dynamic loading,compared to the fracture healing process under the dynamic load of fracture healing process can significantly increase the bone fracture in the regional concentration of mesenchymal stem cells,increase the callus of cortical bone area and periosteal area of the cartilage growth factors,and find a best load mechanism of dynamic load significantly promote the fracture healing process,10% strain at 1Hz strain frequency is the best dynamic loading mechanism to promote fracture healing process.