Intramedullary Nailing In Femoral Intertrochanteric Fracture Healing Process Of Biomechanical Evaluation

Objective:This paper uses the effective after intramedullary nail fixation of femoral three-dimensional entity model and finite element model of intertrochanteric fracture based medical image processing software Mimics, the reverse engineering software Geomagic Studio, three-dimensional entity modeling software Solidworks, the threedimensional finite element analysis of large scale software ANSYS, to calculate the model, obtain the intramedullary nail fracture the model in the healing process of stress field, displacement field; analysis of stress distribution of the femur fracture after the removal of the characteristics of healing after intramedullary nail, and the artificial femoral intramedullary nail rough measurement experiment data to discover the regulation of electricity than, intertrochanteric fracture, and provide the basis and guidance for the clinical application of biomechanics. Method: First, Adopt the method of 3 d printing and precision casting preparation of artificial femoral model of high precision, and ensure that the material properties of the femur and femoral maximum close to human body, plaster device such as a fixed after intramedullary nailing in the femur model, remove the intramedullary nail, and manufacturing of intertrochanteric fracture, and then the artificial femoral intramedullary nail and to assemble, stick a strain gauge in the corresponding position, strain gauge and the static and dynamic resistance strain test and analysis system for connection, and then in WDW—10 on the microcomputer control electron universal testing load, namely to artificial femoral intramedullary nailing intertrochanteric fractures electrical measuring experiment, record the experiment data, analysis data, make the load- micro strain data graph; Second, the artificial femoral intramedullary nailing intertrochanteric fracture experiment model scanned into CT data, using Mimics, Geomagic Studio, Solidworks software to scan CT data into a complete femoral three-dimensional entity model is set up, according to the parameters of intramedullary nail with Solidworks established main nail, proximal cross-bolting, distal locking of the three-dimensional entity model, and the three-dimensional entity model and the femoral intramedullary nailing assembly three-dimensional entity model, is the artificial femoral intramedullary nailing intertrochanteric fracture model preparation into a 3 d finite element model, save as X_T format file, and then the X_T format file into ANSYS, with Boolean operation, create fractures, to change the material parameters, simulation of the fracture healing process, establish a complete artificial femoral intramedullary nailing intertrochanteric fracture three-dimensional finite element model, numbered in sequence, in setting unit properties, boundary conditions, material properties, division of grid, according to 600 N in the process of fracture healing normal walking slowly feet on the ground when the maximal peak value of numerical simulation of hip, and loading and solving, intramedullary nail model was obtained by the stress and the stress distribution characteristics, the stress of the fracture line, the broken end clearance changes characteristics, sort out stick strain data of strain gauge position, and compared with the experimental data, found the law; Mainly through the other gives different elastic modulus of fractures to simulate the healing phase femur biomechanical influence to human body, and unit and function by using ANSYS to simulate the stress distribution law of withdraw after femoral nail, artificial femoral stress and strain change rules. Results:(1) Comparing the results of numerical calculation and experimental results shows that the numerical simulation results coincide well with experimental results.(2) The cause of numerical simulation and experimental data is error could be obtained from 3D reconstruction of the femur why someone for operating entity model, femur model has some difference with the experiment, numerical simulation and the experimental boundary conditions may have some difference.(3) To complete the simulation of femoral intramedullary nailing intertrochanteric fracture healing process, and compared with the experimental results and analysis, get the healing process of observation regularity of strain gauge. Conclusion:(1) To make the entity model, artificial femoral intertrochanteric fracture model consists of a fracture, a proximal fracture model and a distal fracture model, with intramedullary nail fixation of intertrochanteric fracture model, and select 10 reference points on the model strain gauge, the artificial femoral intramedullary nailing intertrochanteric fracture model under physiological load of electrical measuring experiment, the measured artificial femoral intramedullary nailing intertrochanteric fracture three-dimensional entity model of the different parts of the strain data, obtained the artificial femoral intramedullary nailing intertrochanteric fractures distribution regularity of 10 points.(2) According to the artificial femoral intramedullary nailing intertrochanteric fractures entity model CT scan data, using three dimensional modelling software Mimics completed the initial point cloud processing, application of reverse engineering software Geomagic studio and Solidworks software, the successful build out of the artificial femoral intramedullary nailing intertrochanteric fracture three-dimensional entity model.(3) The ANSYS numerical simulation software in the artificial femoral intramedullary nailing intertrochanteric fracture model under physiological load numerical simulation analysis, the main analysis of the influence of the displacement field and stress field. To give different elastic modulus of fractures healing process simulation, studied the healing process for fracture of artificial femoral intramedullary nailing intertrochanteric fracture model under physiological load load displacement field and stress field, the influence of the numerical simulation results show that the experimental results coincide with the results of numerical simulation.(4) Compares the results of numerical simulation and experimental results of analysis, demonstrates the experiment method and the correctness of the numerical simulation method, for the next step for clinical intramedullary nail fixation of intertrochanteric fractures in application to provide biomechanical basis and guidance.