Influence of cement-augmented pedicle screw instrumentation in an osteoporotic lumbosacral spine over the adjacent segments: a 3D finite element study

Abstract

To compare the effect of conventional pedicle screw (CPS) and cement-augmented pedicle screw instrumentation (CAPSI) on adjacent segment degeneration (ASD). Methods: A normal male volunteer without a history of spinal disease was selected, lumbar CT data was collected, an intact L3-S1 three-dimensional finite element model was created by software including Mimics, Geomagic, and SolidWorks, and the fixation methods were performed accordingly. A common pedicle screw model and a cementaugmented pedicle screw model of L4-L5 with fusion and internal fixation were constructed. With ANSYS Workbench 17.0, a 500 N load was applied to the upper surface of L3 to simulate the weight of a human body, and a 7.5 N m moment was applied at the neutral point to simulate flexion, extension, left/right bending, left/right rotation of the spine. The peak von Mises stress of intervertebral disc and the range of motion (ROM) on the adjacent segments (L3-4 and L5-S1) were compared. Results: The validity of the intact model shows that the ROM of the model is similar to that of a cadaveric study. Compared with the intact model, CPS model and CAPSI model in all motion patterns increased the ROM of adjacent segments. The intervertebral disc stress and the ROM of adjacent segments were found to be higher in the CAPSI model than in the CPS model, especially in L3-4. Conclusion: In general, the biomechanical analysis of an osteoporotic lumbar spine showed that both CPS and CAPSI can increase the ROM and disc stresses of osteoporotic lumbar models, and compared with CPS, CAPSI is more likely to increase the potential risk of adjacent segment degeneration.

Surgical Outcome Prediction Using a Four-Dimensional Planning Simulation System With Finite Element Analysis Incorporating Pre-bent Rods in Adolescent Idiopathic Scoliosis: Simulation for Spatiotemporal Anatomical Correction Technique

“…The collected raw data in the DICOM format were imported into Mimics research 19.0 (Materialize, Leuven, Belgium) to generate 3D vertebral models in a standard triangle language (STL). Subsequently, the STL data generated were imported into ANSYS 19.2 in the form of solid 3D structure ( Peng et al, 2020 ; Zhou et al, 2020 ), which was built of 10-node tetrahedral element meshes ( Ulrich et al, 1998 ). Screws were positioned and oriented in the desired locations.…”

“…Spinal rods were modeled with a cross-sectional diameter of 5.5 mm, Young’s modulus of 420 GPa, and Poisson’s ratio of 0.3 according to CoCr alloy properties ( Yamada et al, 2020 ). The screws were modeled as cylinders with a length of 30 mm, cross-sectional diameter of 5.5 mm, Young’s modulus of 5,000 MPa, and Poisson’s ratio of 0.3 ( Zhou et al, 2020 ). Rods and screws were modeled with materials of isotropic elastic linear material properties.…”

Biomechanical modelling of the facet joints: a review of methods and validation processes in finite element analysis

“…( 2020 ) Friction coefficient of 0.1 Linear elastic: , = 0.4 Zhou et al. ( 2020 ) Friction coefficient of 0.2 Linear elastic: , = 0.3 Ayturk and Puttlitz ( 2011 ); Du et al. ( 2016a ) Frictionless Neo Hooke Holzapfel and Stadler ( 2006 ) Friction coefficient of 0.06 Neo Hooke Schmidt et al.…”

Evaluation of S2 alar and traditional S1 pedicle fixation for severe lumbar spondylolisthesis in different bone mineral densities: a finite element analysis

“…A 1 mm bony end plate was simulated on either end of each vertebra (Fig. 2) [13] . The material properties of the various spinal components were derived from the literature [16][17][18][19] , as speci ed in Table 1.…”

“…Finite element analysis (FEA) is a numerical method simulating and analyzing the behavior or mechanism of structures or components, which is initially developed in the 1950s in the aircraft industry [10] . FEA has already been applied to characterize the complex biomechanical properties of the lumbar vertebrae in previous studies [11][12][13][14][15] . Nevertheless, to the best of our knowledge, few studies have illustrated the detailed biomechanical mechanisms of L5-S1 and L5-S2 alar xation in spondylolisthesis patients with osteoporosis.…”