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Biomechanics of spinal trauma
Published in Youlian Hong, Roger Bartlett, Routledge Handbook of Biomechanics and Human Movement Science, 2008
Brian D. Stemper, Narayan Yoganandan
Several ligaments interconnect each vertebral segment. Ligaments are elastic bands made up of collagen and elastin fibres arranged in parallel (Nachemson et al., 1968). Five primary ligaments interconnect each segmental level: anterior and posterior longitudinal ligaments, ligamentum flavum, interspinous ligament, and facet joint capsular ligament. The longitudinal ligaments run continuously along anterior and posterior vertebral body surfaces from cervical to lumbosacral regions. The anterior longitudinal ligament is a broad ligament covering most of the vertebral body anterior surface. The posterior longitudinal ligament is similar to its anterior counterpart, although about one-third as wide. Individual deep fibers of these liagments traverse a single disc and superficial fibers may traverse several segments. The ligamentum flavum, or yellow ligament, spans between adjacent laminae. The thickness of the ligamentum flavum increases inferiorly. The interspinous ligament spans between spinous processes of adjacent levels. The ligamentum flavum and interspinous ligaments are not continuous as fibers connect opposing surfaces of adjacent vertebrae. Capsular ligaments along with synovial membranes and synovial fluid form the facet joints. These synovial joints consist of fluid between the adjacent articular processes. The synovial membrane contains the fluid, and the capsular ligament forms a band around the membrane. The membrane and ligament are collectively known as the joint capsule. Posterior to the spinous processes is the supraspinous ligament in thoracic and lumbar regions and the ligamentum nuchae in the cervical region. The nuchae extends from the occipital bone of the cranium to the posterior extents of cervical spinous processes. The thin supraspinous ligament runs continuously along the posterior extents of spinous processes from C7 to the sacral region.
Analysis of stress and stabilization in adolescent with osteoporotic idiopathic scoliosis: finite element method
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Qiaolin Zhang, Yan Zhang, Teo. Ee Chon, Julien S. Baker, Yaodong Gu
Ligaments play an important role in the biomechanics of the spine because they provide stability to the joints during rest and movement. In this work, we considered the seven most important ligaments in the lumbar spine, as shown below. They are: posterior longitudinal ligament, anterior longitudinal ligament, transverse ligament, ligamentum flavum, capsular ligament, supraspinous ligament and intraspinous ligament. Ligaments restrict the movement of lumbar vertebrae by stretching cones. In Ansys Workbench 19.0 (ANSYS, Inc., Canonsburg, United States), we use springs to simulate the tension of ligaments. We insert the spring on the surface of the cone according to the anatomical structure, as shown in Figure 4. The ligament structure of spinal functional units is stimulated by linear tension springs, which is defined as：
Finite element mechanics analysis of lumbar spine with normal and varying degrees of herniated lesions under different working conditions and material properties
Published in Mechanics of Advanced Materials and Structures, 2022
Yu Hui, Ze-xun Zhou, Jing Du, Bo Wu, Wei Huang
Through observation, it can be seen that under various working conditions of the normal model, the compressive stress of the facet joints under lateral bending is basically larger, followed by flexion and extension. When the left or right sides of the spine are bent, the compressive stress of the opposite facet joint will increase, which is consistent with the clinical manifestations. From the comparison of the compressive stress of the facet joints in flexion and extension states, we can find that the compressive stress of the facet joints in the flexion state is larger and stress distribution is wider. It can be interpreted as: When the vertebra body is doing forward flexion, it is pulled by the ligaments of the posterior longitudinal ligament, supraspina, interspinous, and ligamentum flavum. In the spatial position, the vertebral body approximately takes the bone facet joint as the support point, and rotates in the longitudinal direction; the extension movement is mainly only affected by the traction of the anterior longitudinal ligament, and the compressive stress of the facet joint as the support point is smaller than that of the flexion state.
Biomechanical modeling of spinal ligaments: finite element analysis of L4-L5 spinal segment
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Shabnam Hamidrad, Masoud Abdollahi, Vahid Badali, Mohammad Nikkhoo, Sadegh Naserkhaki
Ligaments included anterior longitudinal ligament (ALL), posterior longitudinal ligament (PLL), capsular ligament (CL), intertransverse ligament (ITL), ligamentum flavum (LF), supraspinous ligament (SSL), and interspinous ligament (ISL). Four different approaches were utilized to model the ligaments resulting in four different models as summarized in Table 2 and depicted in Figure 1. Uniaxial truss elements were used in three of the models and 2 D shell element was used in one of them. In the 3 D model, space trusses were structured in longitudinal, anteroposterior, mediolateral and diagonal directions which were connected together in space joints three dimensionally (Figure 1(d)). Initially two layers of parallel longitudinal trusses were constructed between two vertebrae at the position of each ligament. Then, they were divided to approximately 1 mm elements. Finally, diagonal and transverse elements were generated between every two adjacent joints of these elements.