Application Of Finite Element Analysis On The Influence Of Bone Cement Leakage On Vertebral Biomechanics After Thoracolumbar Vertebral Compression Fracture Surgery With Vertebral Fissure Syndrome Based On The Idea Of "Preventing Disease"

Purpose:Simulate the stress and maximum displacement in the vertebral body of patients with osteoporotic compression fractures and vertebral fissure syndrome under different bone cement distributions,in order to evaluate the surgical effect and provide a basis for preventing postoperative complications of bone cement surgery in clinical practice.Method:Collect the results of 320 row spiral CT examination at T10-L5 level in a patient who was excluded from spinal diseases such as vertebral fractures,deformities,and infections.Inform volunteers of this study and obtain their consent.In this experiment,the most vulnerable thoracolumbar segments T12～L2 were selected to construct a model.The CT data collected from the above CT scans were imported into the Mimics19.1 software.Bone tissue was selected,segmented,and 3D modeling was performed to establish a T12～L2 vertebral body bone model.Mark separation,hole filling,shell extraction,and Boolean operations were performed on T12,L1,and L2 vertebral bodies to obtain cancellous and cortical bone structures.Select two adjacent faces of the T12 and L1 vertebral bodies for anatomical reconstruction,Scale,and Boolean operations to establish a T12 to L1 intervertebral disc model(including upper and lower endplates,nucleus pulposus,and annulus fibrosus).Similarly,establish a L1 to L2 intervertebral disc model.Import all the above models into ANSYS Workbench19.2 software in sequence,and then use rope elements to establish a ligament model around the vertebral body,forming a T12-L2 osteoporotic vertebral body model.Then,bone cement is implanted into the vertebral body with fracture and vertebral fissure sign,forming six different working conditions:(1)bone cement just fills the fissure;(2)Bone cement fills cracks and seeps forward;(3)Bone cement fills the gaps and diffuses into the vertebral body;(4)Bone cement fills the gaps and diffuses into the vertebral body and leaks forward.And(5)non fractured osteoporotic vertebral body;(6)Fractures without bone cement surgery combined with vertebral fissure sign vertebral body.All models were meshed(1.2mm)and assigned material properties based on previous literature.Considering the influence of paravertebral muscles and abdominal pressure,fix the lower edge of the vertebral system and apply a vertical downward force on the upper edge of the upper vertebral body.On the basis of the above loads,continue to fix the lower edge of the vertebral system and apply loads on the upper edge of the upper vertebral body to simulate flexion,extension,left side flexion,and right side flexion movements.Finally,the Von Mises stress and displacement of L1 vertebral cortical bone and cancellous bone were compared among the six models.Result:1.Under various motion states,the average stress is the lightest in the normal and non fractured osteoporotic vertebral body of Group 5(17.72-27.00MPa);The heaviest stress was observed in the sixth group of patients with fractures and vertebral fractures(51.74-167.52MPa)without surgery,which was much higher than the average in the surgical group.2.In each state of motion,the fourth group had the least maximum displacement,with leakage before filling and moderate dispersion of the vertebral body(0.47-1.40mm);The maximum displacement is Group 6(0.57-1.40mm).3.Compare 6 groups,from the stress: the first group of bone cement just filled the cracks(22.16MPa),and the second group of bone cement filled the cracks and infiltrated slightly(21.59MPa);From displacement: The first group of bone cement just filled the crack(1.04mm),which is closest to the fifth group of unbroken vertebral body(1.09mm).Conclusion:1.Cementation surgery for fractured vertebral bodies can significantly reduce the maximum mises stress and displacement compared to non surgery;2.The maximum displacement of the bone cement dispersed to the surrounding cancellous bone can be significantly reduced compared to the non dispersed group,but the stress inside the vertebral body will slightly increase;3.The leakage of bone cement will slightly increase the maximum mises stress of the vertebral body,but can reduce the maximum displacement;4.Overall evaluation,the selection of bone cement surgery is very significant in improving the biomechanics of the lumbar spine;Patients with mild pain during surgery can achieve better surgical results if the physician chooses to fill the gaps with bone cement,while patients with severe pain can achieve better surgical results if they are moderately dispersed.