| Purpose:This experiment intends to use the finite element method to verify the influence of the medial and lateral defects of femoral intertrochanteric fracture on fracture stability.Analyze the stress and displacement distribution of unstable intertrochanteric fractures in postoperative rehabilitation under different stress modes.Evaluate the influence of inner and outer support on stability.And then to evaluate whether the postoperative rehabilitation activities can be completed in the absence of medial and lateral support after intramedullary fixation of femoral intertrochanteric fractures.Materials and Methods : Four kinds of stress models of proximal femur were established by simulating the stress mode of proximal femur in daily life.Based on the sectional CT images,the three-dimensional model of femur was established by mimics software and Geomagic Studio software,and the internal fixation model was established by solidworks2019 software.The finite element analysis model of femur was established.On this basis,three models of medial defect,lateral defect and medial and lateral defect of intertrochanteric fracture were simulated and fixed with proximal femoral anti-rotation intramedullary nail system and combined compression interlocking intramedullary nail system.The model is imported into the finite element analysis software Abaqus to apply constraints and loads to simulate four different stress states of the proximal femur in daily life,and to compare the displacement and stress distribution of the internal fixation mode.Results:In the case of a medial defect,the maximum displacement and maximum stress of the proximal femoral anti-rotation intramedullary nail and interlocking intramedullary nail are 3.51mm/473 MPa and 2.80mm/588 MPa.Under the condition of lateral defect,the corresponding values are 2.55mm/288 MPa and 2.10mm/307 MPa.In the case of internal and external defects,the corresponding values are 3.84mm/653 MPa and3.44mm/641 MPa.Conclusion:Compared with the lateral support,the medial support has a greater impact on the postoperative stability.In the case of the posterior medial defect,the intramedullary fixation system can meet the needs of early low-intensity rehabilitation exercises,and the application of interlocking nails compared with anti-rotation nails can reduce Risk of varus and stress concentration;in the case of lateral wall defects,the intramedullary fixation system can meet the needs of higher-intensity rehabilitation exercises,and even restore to the preoperative state,and the application of interlocking nails can also reduce varus and stress Concentrated risk.In the case of internal and external defects,the use of intramedullary system alone for fixation cannot meet the requirements of early functional exercise. |
