【摘 要】
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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 str
【机 构】
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Department of Engineering,Campus Bio-Medico University of Rome,Via A.del Portillo 21,Rome 00128,Ital
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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.
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