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Reduction and Fixation of Sacroiliac joint Dislocation by the Combined Use of S1 Pedicle Screws and an Iliac Rod
Published in Kai-Uwe Lewandrowski, Donald L. Wise, Debra J. Trantolo, Michael J. Yaszemski, Augustus A. White, Advances in Spinal Fusion, 2003
Kai-Uwe Lewandrowski, Donald L. Wise, Debra J. Trantolo, Michael J. Yaszemski, Augustus A. White
When the neck is flexed and extended, the spinal cord moves cranially and caudally in the spinal canal [31]. During hyperextension, the ligamenta flava bulge, thereby compressing the spinal cord dorsally [32]. Bulging ligamenta flava compress the posterior and lateral columns and the dorsal root entry zone. During extension, the cross-sectional area of the cervical spinal cord has been found to enlarge [33]. These findings may explain the occasional exacerbation of symptoms and the clinical improvement often observed when the neck is immobilized with a collar [34]. Symptoms and signs may also be exacerbated by neck flexion. The spinal cord is then injured as it is stretched over a ventral osteophytic wall. Quick or slow anteflexion (rarely extension) is a maneuver provoking Lhermitte’s sign (a shock-like sensation in the trunk or limbs). CLINICAL FEATURES
Application of the ‘Surgical GPS’ to posterior spinal fusion procedures for scoliosis correction
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2022
Austin Tapp, James Bennett, Michel. A. Audette
A third validation measure involved the use of synthetic image data. Synthetic images were formed for the cervical, thoracic, and lumbar spine regions and contained most soft tissues and ligaments surrounding a vertebra, including interspinous ligaments, intertransverse ligaments, ligamenta flava, vertebral articular surfaces and zygapophyseal joint capsules. Some additional soft tissues are present for synthetic thoracic images; these soft tissues include intraarticular ligaments, lateral costotransverse ligaments and radiate ligaments. The synthetic images were created using a data augmentation generator that produces a somewhat similar but notably different median image, which is neither the sum of nor the exact match to the multiple images used (Cates et al. 2017). For example, a synthetic lumbar image was created by aggregating all lumbar vertebrae, 1 through 5, and mapping the features of those aggregated images into a single composite image. A total of 15 synthetic images, 5 for each region of the spine, were produced. CAD templates were then deformed to match the synthetic images, instead of CT or MRIs, and the template that displayed the best agreement with a synthetic image after that template’s deformation was recorded (Figure 8) (Table 1, Table 2). The same DSC and Hausdorff distance validation metrics used for vertebrae and IVD agreement were also used to quantify the agreement between a deformed CAD template and its associated synthetic image.
Biomechanical analysis of lumbar interbody fusion cages with various lordotic angles: a finite element study
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2018
Zhenjun Zhang, Guy R. Fogel, Zhenhua Liao, Yitao Sun, Weiqiang Liu
Figure 1 displayed the FE model of the intact lumbar spine. Each vertebra was divided into three parts: cancellous bone, cortical bone, and posterior bone. Each intervertebral disc was divided into two parts: annulus fibrosus and nucleus pulposus. 7 kinds of ligaments were included in the FE mode: anterior longitudinal ligament (ALL), posterior longitudinal ligament (PLL), ligamenta flava (LF), interspinal ligament (ISL), supraspinal ligament (SSL), intertransverse ligament (ITL), and capsular ligament (CL). The thickness of cortical bone was 1.0 mm, and the thickness of bone endplate was 0.5 mm (Ambati et al. 2015). All kinds of ligaments were modeled as truss elements (T3D2) which had the property of tension-only. The 3D tetrahedral elements were employed to mesh the FE model except for the ligaments. 195,533 nodes and 841,038 elements were contained in the intact FE model, which could effectively eliminate the influence of meshing on the accuracy of the calculation.
Fatigue damage prediction in the annulus of cervical spine intervertebral discs using finite element analysis
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2020
Adhitya V. Subramani, Phillip E. Whitley, Harsha T. Garimella, Reuben H. Kraft
Then, five classes of spinal ligaments were added to the cervical spine mesh according to the study of cervical spine ligaments by Yoganandan et al. (2000). Each functional spine unit contains one anterior longitudinal ligament (ALL), one posterior longitudinal ligament (PLL), two facet capsules (FC), two ligamenta flava (LF) and one interspinous ligament (ISL). The ALL, PLL, LF and ISL were modelled with discrete-beam cable elements because they only resist tensile deformation and do not resist compressive deformation (El-Rich et al. 2009). The facet capsules, however, were modelled with truss elements because they offer resistance to both tension and compression (El-Rich et al. 2009).