A New Finite Element Analysis Of A New Spinal Correction System With Muscle Model

Objective:Based on the construction of a complete new finite element analysis model of a normal adult healthy male with muscle,the experiment simulated the posterior internal fixation of the traditional pedicle screw rod system and the improved new spinal correction hook rod system under the effect of stress,and then analyzed the biomechanical characteristics of the three models under different stresses.On the basis of previous analysis,the influence of muscle model data on clinical application was analyzed.Methods:Through finite element analysis software,various organizational attributes were added to generate A 3D model with stress nephogram.On this basis,muscle parameters were added to establish a complete 3D finite element model A.The model B and the improved new hook rod system were simulated.The stress distribution of the three models is analyzed.Anteflexion(AF),Back extension(BE),Lateral bending(lateral bending),lateral bending(Lateral bending,lateral bending,Axial rotation(AR)and Axial Rotation(LB)demonstrate changes in stress distribution,stiffness and angular displacement of models B and C undergoing corrective surgery.Finally,the influence of such changes is compared with that of muscle-free models in previous experiments.Results:(1)The intervertebral disc stress in model C was higher than that in model B during the vertebra flexion and extension.However,when the vertebral body underwent left bending and left rotation,the two stresses were relatively close,and the stress of model B was slightly larger than that of model C.Compared with the model without muscle addition,the stress on the intervertebral disc in model B and Model C was higher when the vertebra of the model with muscle was bent forward.The stress of muscle model B on L1/2 vertebra was small when the vertebra was extended backward.The stress of muscle models B and C on L1/2 of the intervertebral disc was low during lateral bending,but the stress on L2/3 was opposite.The intervertebral disc stress of muscle model was high during rotation.(2)The stress of model B on the L1 vertebra was slightly greater than that of model C,and the stress of model B on the L1 vertebra was less than that of model C in the non-muscular model only when the vertebra was flexed forward.The stress of model B on L2 vertebral body was significantly smaller than that of model C under different motion states.The same goes for muscle-free models.The maximum stress of L3 vertebrae is B>C during forward bending,backward extension and left bending.The reverse is true when rotated to the left.The maximum stress of the model with muscle was larger or smaller than that of the model without muscle,and the difference did not affect the overall data.(3)The stress shielding rate of intervertebral disc L1/2,L2/3 and intermediate vertebral L2 during flexion and extension was significantly lower in the modified spinal correction system C than in the pedicle screw system B.The stress shielding ratio of intervertebral disc L1/2,L2/3 and intermediate vertebral body L2 was basically the same in lateral bending.In terms of rotation,disc L1/2and intermediate vertebral L2 stress shielding rates were slightly higher in modified spinal correction system C than in pedicle screw system B,while the stress shielding rates were almost equal in disc L2/3.The stress shielding ratio of model B with muscle model was higher in L1/2,L2/3 and the middle vertebra than in model B without muscle model,while the stress shielding ratio of model C with muscle model was lower in the other motion directions except forward flexion.(4)When the vertebra is bent forward and extended,its angular displacement is A>C>B from large to small,while the bending stiffness is just the opposite: B>C>A.In the case of lateral bending and rotation,the angular displacement and stiffness of B and C L1-L3 are close,smaller than that of normal model A in the case of lateral bending and larger than that of normal model A in the case of rotation.In the muscle-free experiment,the vertebra was smaller than normal model A in both lateral bending and rotation.(5)The maximum displacement of model B is basically close to model C,and model B is slightly less than model C.Results of pedicle nails and modified spinal correction systems were very similar in the muscle-free model of lateral curvature.However,the maximum displacement of the horizontal rotation modified spinal correction system model C was greater than that of the pedicle screw system model B.Conclusion:Compared with the traditional pedicle screw system,the modified spinal correction system has a similar rigid internal fixation effect,and can effectively reduce the stress occlusion rate between the intervertebral discs,and effectively improve the postoperative complications of vertebral degeneration and vertebral instability.Moreover,the finite element analysis model with muscle model is different from the finite element analysis model without muscle model in terms of internal fixation strength and correction strength,which further verifies the possibility and effectiveness of the improved new spinal correction system in clinical application.