Internal Fixation And Biomechanical Study Of Pauwels Ⅲ Type Neck Of Femur Fracture Based On Finite Element Method

With the rapid growth of the global population,it is estimated that by2025,the number of hip fracture patients worldwide will increase to about 2.6million,and neck of femur fracture accounts for about half of hip fractures,especially the current trend of young patients.Young people mainly use internal fixation to treat neck of femur fractures.Pauwels type III neck of femur fractures have complex fracture types and high shear force,leading to a high failure rate of internal fixation treatment.The causes of failure include insufficient strong internal fixation,stress shielding,affecting bone healing,etc.At the same time,the current research on internal fixation of neck of femur fractures lacks experimental analysis of dynamic loads of human activities.This article proposes solutions to the above problems and verifies them through finite element simulation.First of all,this paper selects the load data of human hip joint under 9kinds of daily activities as the load conditions for the finite element experiment of Pauwels III type neck of femur fracture internal fixation model.The research results systematically demonstrate the mechanical effects of 9 types of activity loads on the femur and implants.Among them,the stability of internal fixation is less affected when the legs are moving,and the risk of internal fixation failure is very low.The peak stress of the internal fixation during walking is the smallest,while the peak stress and strain of the femur and implants during jogging are huge,with a high risk of failure.For patients undergoing internal fixation treatment,double leg movements can be performed appropriately during the recovery process,while single leg movements should be treated with caution.Secondly,aiming at the problem of difficult rigid internal fixation,this paper established six kinds of internal fixation models for Pauwels Ⅲ type neck of femur fracture,and conducted a comprehensive and systematic biomechanical evaluation of the six kinds of internal fixation models.The results indicate that the failure risk of dynamic hip screws(DHS)is the highest,and the combined performance of DHS,double anti rotation screws(DHS+BS),and three hollow compression screws(CSs)is superior.Both the anti rotation screws and the inner support plate show the effect of dispersing the stress of the tension screw,enhancing the ability to resist high shear forces.Through comprehensive assessment,DHS+BS is suitable for the rigid internal fixation of neck of femur fracture of Pauwels III in more complex situations,and the neck of femur system(FNS)has excellent comprehensive mechanical properties under ordinary Pauwels III fracture.Finally,in view of the problem of implant and femoral stress shielding,this paper selects four kinds of current materials for internal fixation of neck of femur fracture as the research object,and compares the stress shielding and their mechanical properties of implant and femur under various materials through experiments.The results showed that as the elastic modulus of the material increased,the stress shielding effect between the implant and the femur became more obvious.The bone screw contact interface under stainless steel and titanium alloy materials produced a huge stress shielding effect.Poly ether ether ketone(PEEK)material can effectively eliminate the stress shielding effect,but the strength of the material itself is insufficient.The combined material model is similar to the results under PEEK material.The internal fixation model made of magnesium alloy material not only ensures strong internal fixation but also weakens the stress shielding effect,making it the most suitable choice among the four materials to solve the stress shielding problem.