Finite Element Analysis Of The Effect Of Intertrochanteric Fracture Reduction Mode On Intramedullary Nailing

Background:Intertrochanteric fractures,a common type of fracture,are the most common type of hip fracture,most common in older age.With the aging of China’s population,the incidence of intertrochanteric fracture is increasing year by year.Because of its high morbidity,high mortality,difficult nursing and expensive hospitalization,it is often referred to as "the last fracture of life",and its treatment puts forward high requirements for clinicians.Special anatomical structure makes it hard for fractures with closed between rotor reach anatomical reduction,so the inside of the cortex reset support has become necessary choice,and the research proves that the medial cortical support reset is an effective and efficient treatment of femoral fractures between rotor,but the current study only stay in qualitative research,lack of quantitative research.Objective:Three-dimensional finite element analysis was used to establish 25 internal fixation models of intramedullary nail for intertrochanteric fracture of femur with different reduction modes in anteroposterior and lateral positions respectively.Different loads were applied to simulate the stress state of femur when patients stood,walked and went downstairs after surgery.Got femur under different motion state of stress,and the size of the stress exerted on it when the intramedullary nail,and fracture as a result,the size of the displacement analysis of the rationality of the stress and displacement,different reset mode to discuss the pros and cons of each model,in addition to find a anatomical repositioning of the other one or more of the following can be easily implemented and can meet the curative effect of reduction method,and provide theoretical support for clinical work.Methods:The femoral CT of healthy volunteers was saved in DICOM format and processed by Mimics and Geomagic software respectively to obtain the femoral model for analysis.Moreover,25 models of different reduction modes were obtained by Solid Works software for fracture manufacturing,fracture displacement and internal fixation assembly.Finally,different loads were loaded by ANSYS software to simulate the representative movements of patients after fracture surgery,such as standing,walking,downstairs and so on,and the stress of femur and intramedullary nail and the displacement of fracture end were obtained.Finally,the obtained data were calculated by SPSS statistical software,and the experimental results and statistical results were discussed and analyzed.Results:Models 1a,2a,5c,5d,3e,4e,and 5e will have stress concentration on the femur,which exceeds the yield strength of the bone,and local bone yield collapse will occur,resulting in microfractures and bone fractures at the stress concentration.Absorption,etc.,so that the stress is dispersed,which leads to the unstable fixation of the fracture,the loosening of the internal fixation device,which leads to loss of reduction,delayed fracture healing,non-union,and failure of the internal fixator.From the perspective of the reduction mode of internal and external displacement,the stress of the femur and the intramedullary nail are all within a reasonable range,and there is no consistent difference.Increase the distance of displacement of the fractured end,which is more prominent in complex movements such as walking and going downstairs.From the perspective of the reduction mode of anterior and posterior displacement,the head and neck mass that is moved forward without displacement will increase the stress of the femur and the intramedullary nail,which is particularly prominent in the downstairs state.But will not exceed the yield strength of the femur and intramedullary nail.By analyzing the displacement of the fracture end,it was found that the displacement of the fracture end in the forward one cortex group（group e）was significantly greater than that in the backward displacement group（group a,b）,so the stability of the fracture fixation in the forward one cortex group was not good.Conclusion:In A1.2 intertrochanteric fractures,the recommended reduction patterns are 3a,1b,2b,3b,1c,2c,3c,followed by 1d,2d,3d.Combining clinical research and actual situation,it is concluded that when the femoral intertrochanteric fracture is difficult to reduce,the recommended alternative reduction modes are 1c and 2c,that is,the positive support of the medial cortex,followed by 1d,2d,and 3d,that is,the front of the head and neck fracture.Shift the anteromedial cortical support and medial cortical support of the hemicortex.