Effect of osteoporosis on internal fixation after spinal osteotomy: A finite element analysis

Wang, Tianhao; Zhao, Yongfei; Cai, Zhihua; Wang, Wei; Xia, Yunxia; Zheng, Guoyan; Yan, Liang; Wang, Yan

doi:10.1016/j.clinbiomech.2019.07.032

Cited by 29 publications

(27 citation statements)

References 25 publications

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“…The existing pedicle screw-rod systems have increased the success rate and practicality of the fusion procedure. But it also has become apparent that there are limitations and failures in certain challenging situations [5][6][7][8][9].…”

Section: Discussionmentioning

confidence: 99%

“…Notwithstanding the popularity of the polyaxial head screw-rod systems now in use, they have several drawbacks, including a less than optimal rigidity and a reduced bony surface available for fusion, which might necessitate the inclusion of additional spinal levels or anterior interbody fusion in the final construct. The screw-rod constructs have an appreciable failure rate in patients with a poor bony quality or multiple revisions [5][6][7][8][9]. Construct revision or extension for an adjacent-level disease is another disadvantage of the screw-rod systems because they typically require the removal of the rods with some fused bone.…”

Section: Introductionmentioning

confidence: 99%

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A Novel Plate-Based System (UNIMAX) for Posterior Instrumented Spinal Fusion

Pisharodi

Aljuboori

Goel

et al. 2020

Cureus

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The polyaxial head pedicle screw-rod system is a commonly used spinal instrumentation technique to achieve stabilization, deformity correction, and bony fusion. We present a novel plate-based pedicle screw system (UNIMAX TM) that can be used for multi-level instrumentation with potential advantages for selected applications. Methods Bilateral titanium monoaxial pedicle screws are linked at each level by robust transversely oriented cross plates forming ring constructs capable of rigid triangulation at each level. The cross plates are then interconnected by sagittally oriented rigid plates situated medial to the screw heads. Biomechanically, the construct was tested for quasi-static torsion and fatigue in axial compression. The system is approved by the Food and Drug Administration (FDA). The system and case examples are presented showing its potential advantages. Results The quasi-static torsion, the mean for the angular displacement, torsional stiffness, and torsional ultimate strength was 2.5 degrees (SD ± 0.8), 5.3 N-m/mm (SD ± 0.7), and 21.6 N-m (SD ± 4.4). For the fatigue in axial compression, the closed ring construct failed when the applied load and bending moment were ≥ 1500 N and ≥ 60 N.m. This system maximizes the construct rigidity, allows easy extension to adjacent levels, and can be incorporated intuitively into practice. The ring construct with triangulation at each level, together with its biomechanical robustness, predicts a high pullout resistance. It requires an open posterior approach incompatible with minimally invasive techniques. Conclusion This system may have advantages over the screw-rod systems in carefully selected situations requiring extra rigidity and high pull-out strength for complex reconstructions, sagittal and/or coronal correction, patients with poor bone quality, revisions, and/or extension to adjacent levels.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Novel Plate-Based System (UNIMAX) for Posterior Instrumented Spinal Fusion

Pisharodi

Aljuboori

Goel

et al. 2020

Cureus

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“…The mesh model generated in SolidWorks 2017CAD was imported into ANSYS Workbench 17.0 (ANSYS, Ltd., Canonsburg, PA, USA), and previous literature was referenced to set the cortical bone (osteoporosis), cancellous bone (osteoporosis), articular cartilage, endplates, annulus fibrosus, nucleus pulposus, bone cement, cages, and internal fixation ( Table 1). The ligaments were simulated using spring elements that were only stressed by pulling force (one ligament stimulated by one spring) [17][18][19][20]. The contact type between the models was defined in the connection, where in the facet joint contact type was frictional and the frictional coefficient was 0.2 [21]; the remaining contact types were set to be the bonded mode [20,22].…”

Section: Materials Properties and Biomechanical Evaluationmentioning

confidence: 99%

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

Zhou

Zeng

et al. 2020

J Orthop Surg Res

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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.

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“…The mesh model generated in SolidWorks 2017CAD was imported into ANSYS Workbench 17.0 (ANSYS, Ltd., Canonsburg, Pennsylvania, USA ), and previous literature was referenced to set the cortical bone (osteoporosis), cancellous bone (osteoporosis), articular cartilage, endplates, annulus fibrosus, nucleus pulposus, cages, bone cement, and internal fixation (Table 1) [10,12,13]. The ligaments were simulated using spring elements that were only stressed by pulling force [14]. The contact type between the models was defined in the connection, where the facet joint contact type was "frictional" and the frictional coefficient was 0.2; the remaining contact types were set to be the "bonded" mode [11].…”

Section: Materials Properties Boundary and Loading Conditionsmentioning

confidence: 99%

Influence of cement-augmented pedicle screws with different volumes of polymethylmethacrylate in osteoporotic lumbar vertebrae over the adjacent segments: A 3D finite element analysis

Zhang

Guo

et al. 2020

Preprint

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Background: Polymethylmethacrylate (PMMA) is commonly used for cement-augmented pedicle screw instrumentation (CAPSI) to improve the fixation stability and reduce the risk of screw loosening in the osteoporotic thoracolumbar spine. Biomechanical researches have shown that various dose of cement (1-3ml) can be injected to enhance screw stability. To date, there have been no studies on the relationship between adjacent segment degeneration and the volume of PMMA. This study aimed to explore the influence of CAPSI with different volumes of PMMA in osteoporotic lumbar vertebrae over adjacent segments by using finite element analysis.Methods: Seven different finite element models were reconstructed and simulated under different loading conditions, including (1) an intact model, (2) three single-level CAPSI models with different volumes of PMMA (1, 1.73, and 2.5 ml), and (3) three double-level CAPSI models with different volumes of PMMA (1, 1.73, and 2.5 ml). To improve the accuracy of the finite element analysis, the models of the injectable pedicle screw and bone cement were created by using a three-dimensional scanning machine and the CAPSI patient’s CT data, respectively. The range of motion (ROM), the stress of intervertebral discs, and the stress of facet in the adjacent segment were comparatively analysed among the different models.Results: The ROMs of the different segments were compared with experimental data, with good agreement under the different load conditions. Compared with the intact model, the ROM, disc stresses, and facet stress in adjacent segments were found to be higher in the six operative models. Otherwise, with a larger volume of PMMA injected, the ROM, disc stresses, and facet stress slightly increased at the adjacent segment. However, the differences among the augmented models were insignificant for all loading cases.Conclusions: CAPSI could increase the incidence of disk degeneration in the adjacent segment, while within a certain range, different volumes of PMMA provided an approximate impact over the adjacent segment degeneration.

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Effect of osteoporosis on internal fixation after spinal osteotomy: A finite element analysis

Cited by 29 publications

References 25 publications

A Novel Plate-Based System (UNIMAX) for Posterior Instrumented Spinal Fusion

A Novel Plate-Based System (UNIMAX) for Posterior Instrumented Spinal Fusion

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

Influence of cement-augmented pedicle screws with different volumes of polymethylmethacrylate in osteoporotic lumbar vertebrae over the adjacent segments: A 3D finite element analysis

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