Fundamentals
Clare E. Milner in Functional Anatomy for Sport and Exercise, 2019
Ligaments are soft tissue structures which connect bone to bone at a joint. They are generally inelastic, and their major role is to prevent excessive joint motion. When the ligament is pulled tight by movement of the bones, it prevents further movement. In this way ligaments contribute to joint stability. Although they cannot be stretched much, ligaments are flexible. They can be thought of as a short piece of string connecting two bones, which can move with the bones until it is pulled tight, when it resists further movement in that direction. Ligaments are composed mainly of collagen fibres, which are inelastic. Other components include water, fibroblast cells, ground substance and elastin. Most ligaments contain only a very small amount of elastin, which is an elastic fibre. However, there is a spinal ligament with special elastic properties which contains twice as much elastin as collagen. This yellow-coloured ligament is called the ligamentum flavum and it runs the length of the vertebral column. It plays an important role in spinal stability. This ligament is stretched when the trunk is flexed and recoils when the trunk extends from the flexed position. This elastic recoil assists with the extension movement of the trunk (see thoracic region – ligaments).
Ligament Reconstruction with Reference to the Anterior Cruciate Ligament of the Knee
Verna Wright, Eric L. Radin in Mechanics of Human Joints, 2020
Ligaments are band or cordlike structures of dense, highly oriented connective tissue that link bones in the vicinity of every synovial joint. They consist mainly of pure type I collagen, with the fibers arranged along the length of the ligament, that is, in the direction of the load acting. In the resting state the collagen fiber bundles have a wavy appearance; they are crimped. This feature explains the characteristic response of ligamentous structure to load. The elongation of a ligament is large for a small increment of load at the initial stages of loading, and once the crimped fiber bundles have straightened under load, it also stiffens. Subsequently, increments in load produce smaller corresponding elongations of the structure to the point of failure. The load-elongation relationship follows a typical nonlinear J curve.
Orthopaedics and Trauma, including Neurosurgery
Kaji Sritharan, Samia Ijaz, Neil Russell, Tim Allen-Mersh in 300 Essentials SBAs in Surgery, 2017
A 32-year-old man attends the orthopaedic clinic following an injury sustained while paying football. He is complaining of pain and swelling of his left knee and of not being able to straighten it. He sustained the injury when changing direction. The pain was instantaneous but the swelling did not develop immediately. Since the injury, he has been unable to straighten his knee, as he feels it is locking. You examine his knee and find a moderate-sized effusion. He has full flexion but is unable to extend his knee actively or passively. All the ligaments are intact. What is the definitive treatment for this injury? MRI of the kneeCT of the kneeX-ray of the kneeArthroscopyAspiration of the effusion
A comparison of intervertebral ligament properties utilized in a thoracic spine functional unit through kinematic evaluation
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Michael Polanco, Stacie Ringleb, Michel Audette, Rumit Kakar, Sebastian Bawab
Ligaments are fibrous bands of tissue that bind vertebral bodies and intervertebral discs together within a spinal column, restricting motion along the axial, coronal, and sagittal planes. The understanding of load distribution throughout the spinal column can assist clinicians in planning for treatment of musculoskeletal disorders. Surgical procedures such as the Ponte osteotomy (Samdani et al. 2015), involving the removal and re-sectioning of ligaments and facet joints, have gained interest in their ability to offer increased spinal column correction for kyphosis and scoliosis. Finite Element (FE) modeling can be utilized to answer clinical questions that cannot be easily answered from in vitro experimentation or clinical practice. A model’s ability to assist in surgical planning is contingent upon accurate characterization of ligaments and their benchmark with experimental data.
Parameter identification for the simulation of the periodontal ligament during the initial phase of orthodontic tooth movement
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Albert Heinrich Kaiser, Ludger Keilig, Reinhard Klein, Christoph Bourauel
In general, a ligament is a soft tissue that connects bone to bone and its mechanical function is to guide and restrict relative motion of joints. For an introduction refer to the textbook of Cowin and Doty (2007). Tensile tests of ligaments are typically done with specimens, where collagen fibre axes are aligned with the load direction. The stress strain curve observed depicts a progressive behaviour and is typically divided into three regions (e.g., Holzapfel 2001): At first, in the toe region, small force levels are necessary to elongate the tissue initially. Then, in the heel region, with increased load a progressively increased force is observed. The crimped collagen fibres gradually line up with load direction and at the end of the heel region, when collagen fibres are straightened, a transition into the linear region is observed. Here the stress strain curve is dominated by the straightened collagen fibres. At the end of the linear region, with gradual failure of highly stretched fibre bundles, drops in the stress strain curve and ultimate failure is observed. When subject to dynamic loads ligaments show viscoelastic behaviour. This could be due to the shear interaction of the interfibre matrix, that is, the interaction of the collagen fibres with the ground substance proteoglycans.
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:
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