Biomechanical modeling of metal screw loadings on the human vertebra  

作　　者：Leonardo Molinari Cristina Falcinelli Alessio Gizzi Alberto Di Martino 

机构地区：[1]Department of Engineering,Campus Bio-Medico University of Rome,Via A.del Portillo 21,Rome 00128,Italy [2]Department of Biomedical and Neuromotor Science DIBINEM,University of Bologna,Bologna,Italy [3]1st Orthopaedic and Traumatologic Clinic,IRCCS Istituto Ortopedico Rizzoli,Bologna,Italy

出　　处：《Acta Mechanica Sinica》2021年第2期307-320,共14页力学学报（英文版）

基　　金：The authors acknowledge the support of the Italian National Group for Mathematical Physics(GNFM-INdAM).

摘　　要：During spinal fusion surgery,angled screw insertion can provide a more favorable stress distribution reducing failure events(screw breakage and loosening).Finite element(FE)analysis can be employed for identifying the optimal insertion path,preventing stress concentrations,and ensuring a lower failure incidence.In this work,a patient-specific FE model of L4 vertebra,virtually implanted with two pedicle screws,was obtained from diagnostic images and numerically investigated.Linearly elastic,inhomogeneous,and isotropic material properties were assigned to bone based on density distributions reconstructed from the medical images.The mechanical response of the screws-vertebra system was analyzed through a progressive damage procedure,considering a stress-based criterion.Different screws insertion angles were simulated,as well as physiological loading conditions.In each loading case,screw orientation influences the fracture mechanism(i.e.,brittle or ductile one),as well as the fracture pattern and load.Besides,stresses in trabecular bone and pedicle screws are significantly affected by the screw configuration.The caudomedial trajectory indicates the most safe case,significantly reducing the stress concentrations in both trabecular bone and screws.Our findings aim to furnish a useful indication to surgeons regarding the screws insertion angle,further reducing the failure risk and improving the clinical outcome of the fixation procedure.

关 键 词：Fracture mechanics Patient-specific FE modeling Vertebra mechanics Screw orientation Stress analysis 

分 类 号：O3[理学—力学]