Study On Stress Distribution Of Femur And Its Union Under Longitudinal And Transverse Loading

The femur is an important part of the body.Excessive loads,accidental shocks,fatigue,etc.may cause fracture damage to the femur.Femoral neck cracking and fracture is a typical,high incidence of injury,at this point the need for artificial prosthesis instead of damaged part of the femur.In order to make the prosthesis and femur binding performance close to the original femur,it is necessary to study the stress distribution of the femur.The aseptic loosening of the prosthesis is one of the most prominent problems,excessive contact stress,is one important aspect of osteolysis caused due to loosening of the prosthesis.After the prosthesis implantation,a greater reduction of the stress level of the femur will lead to the so-called stress shielding,affecting the growth of bone tissue,leading to local bone loss,osteoporosis and so on.Therefore,the ideal combination of prosthesis and femur is very important,but the biomechanical experiment of prosthesis and femur joint is limited by structural complexity and technical factors,most of which are based on the finite element numerical simulation results.The intact femur and implant metal femoral prosthesis related project based on the vertical pressure,lateral bending stress,torsional couple point under the action of stress measurement,finite element numerical analysis.Using CT scanning data based on femoral,using precise 3D geometry model of MIMICS software for reconstruction of femoral,finite element analysis was then transferred into ANSYS software unit,get the intact femur and implant prosthesis femoral stress distribution results.The application of finite element numerical methods make the femoral biomechanical model from 2D to 3D,especially the application of CT data acquisition and reconstruction technology,make the femoral entity model and the calculation precision is improved greatly.The numerical analysis based on the test results more reliable.The main research contents include the following three parts:(1)Analysis of the stress distribution characteristics of the femur under longitudinal compression.Longitudinal compression is the main form of the external effect of the femur Respectively for intact femur and implant metal femoral prosthesis,based on longitudinal compression multiple key points(including femoral neck)test results of stress,finite element analysis,calculated the stress distribution and the values of key points,comparison of calculation and test the consistency of the main results,and then study the stress distribution and its variation with external force,complete medial femoral upper femoral shaft has a large stress area,medial and lateral femoral neck stress is large,the lateral femoral neck tensile stress will easily lead to injury of femoral bone fracture;The metal prosthesis implantation of femur after stress distribution was changed greatly,stress can increase the contact of femur and femoral shaft shoulder junction,easily lead to the loosening of the prosthesis,the stress of femoral prosthesis at the front end of the middle are smaller,drop in stress level of the so-called stress shielding,will lead to the loss of bone mass.Therefore,artificial an appropriate prosthesis combination,optimization is very important for rehabilitation and health of the femur.(2)The end of femur and the combination of stress distribution in the transverse force.At the end of the transverse bending force is subjected to external effects(such as femoral impact)is another important form.Similar to the above,respectively for intact femur and implant prosthesis of femur,the lateral force at key points of the test based on the results of stress,the stress distribution and the stress of the key points were calculated by finite element numerical analysis.The consistency between the calculated results and the test results was compared,and then the stress distribution and its variation with the external force were studied,get the complete medial femoral femoral upper part has a large stress area,medial and lateral femoral neck stress is large,easily lead to fracture of femur;Femoral prosthesis after implantation of metal stress distribution also changed greatly,and the rear end of femur prosthesis contact stress increases,the middle femoral prosthesis at the front end of stress reduced.(3)With the end of femur and its stress distribution.The torsion couple end torsion couple is hit by another form of action of femur.Similarly,respectively for intact femur and femoral prosthesis implantation of metal,by when the key points of the torsional couple stress testing based on the results of finite element analysis,calculated the stress distribution and the key points of the stress value of the consistency of comparison between calculation and test results,and then study the stress distribution and its variation with force and get similar results,complete medial femoral femoral upper part of greater stress,the metal prosthesis implantation after femoral stress distribution also changed greatly,but the stress direction changes.In conclusion,the results of finite element numerical analysis of intact femur and implanted femur under several typical stress conditions are in good agreement with the experimental results,and the results are in good agreement,the results show that the reliability of the finite element analysis results;The femoral vulnerable area and fracture risk area are the femoral neck,which is consistent with the actual situation;The stress of the contact area between the posterior end of the prosthesis and the femur is large and concentrated,which leads to the loosening of the prosthesis,while the stress at the front of the prosthesis in the middle part of the femoral shaft decreases,indicating the existence of stress shielding and bone loss in the prosthesis and the femur joint.