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Eremina G, Smolin A, Xie J, Syrkashev V. Development of a Computational Model of the Mechanical Behavior of the L4-L5 Lumbar Spine: Application to Disc Degeneration. MATERIALS (BASEL, SWITZERLAND) 2022; 15:6684. [PMID: 36234026 PMCID: PMC9572952 DOI: 10.3390/ma15196684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 09/22/2022] [Accepted: 09/23/2022] [Indexed: 06/16/2023]
Abstract
Degenerative changes in the lumbar spine significantly reduce the quality of life of people. In order to fully understand the biomechanics of the affected spine, it is crucial to consider the biomechanical alterations caused by degeneration of the intervertebral disc (IVD). Therefore, this study is aimed at the development of a discrete element model of the mechanical behavior of the L4-L5 spinal motion segment, which covers all the degeneration grades from healthy IVD to its severe degeneration, and numerical study of the influence of the IVD degeneration on stress state and biomechanics of the spine. In order to analyze the effects of IVD degeneration on spine biomechanics, we simulated physiological loading conditions using compressive forces. The results of modeling showed that at the initial stages of degenerative changes, an increase in the amplitude and area of maximum compressive stresses in the disc is observed. At the late stages of disc degradation, a decrease in the value of intradiscal pressure and a shift in the maximum compressive stresses in the dorsal direction is observed. Such an influence of the degradation of the geometric and mechanical parameters of the tissues of the disc leads to the effect of bulging, which in turn leads to the formation of an intervertebral hernia.
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Affiliation(s)
- Galina Eremina
- Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Sciences, Pr. Akademicheskii, 2/4, 634055 Tomsk, Russia
| | - Alexey Smolin
- Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Sciences, Pr. Akademicheskii, 2/4, 634055 Tomsk, Russia
| | - Jing Xie
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China
| | - Vladimir Syrkashev
- Department of General Medicine, Siberian State Medical University, Moskovsky Trakt, 2, 634050 Tomsk, Russia
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Megías R, Vercher-Martínez A, Belda R, Peris JL, Larrainzar-Garijo R, Giner E, Fuenmayor FJ. Numerical modelling of cancellous bone damage using an orthotropic failure criterion and tissue elastic properties as a function of the mineral content and microporosity. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022; 219:106764. [PMID: 35366593 DOI: 10.1016/j.cmpb.2022.106764] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 03/07/2022] [Accepted: 03/18/2022] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND OBJECTIVE Elastic and strength properties of lamellar tissue are essential to analyze the mechanical behaviour of bone at the meso- or macro-scale. Although many efforts have been made to model the architecture of cancellous bone, in general, isotropic elastic constants are assumed for tissue modelling, neglecting its non-isotropic behaviour. Therefore, isotropic damage laws are often used to estimate the bone failure. The main goals of this work are: (1) to present a new model for the estimation of the elastic properties of lamellar tissue which includes the bone mineral density (BMD) and the microporosity, (2) to address the numerical modelling of cancellous bone damage using an orthotropic failure criterion and a discrete damage mechanics analysis, including the novel approach for the tissue elastic properties aforementioned. METHODS Numerical homogenization has been used to estimate the elastic properties of lamellar bone considering BMD and microporosity. Microcomputed Tomography (μ-CT) scans have been performed to obtain the micro-finite element (μ-FE) model of cancellous bone from a vertebra of swine. In this model, lamellar tissue is orientated by considering a unidirectional layer pattern being the mineralized collagen fibrils aligned with the most representative geometrical feature of the trabeculae network. We have considered the Hashin's failure criterion and the Material Property Degradation (MPDG) method for simulating the onset and evolution of bone damage. RESULTS The terms of the stiffness matrix for lamellar tissue are derived as functions of the BMD and microporosity at tissue scale. Results obtained for the apparent yield strain values agree with experimental values found in the literature. The influence of the damage parameters on the bone mechanics behaviour is also presented. CONCLUSIONS Stiffness matrix of lamellar tissue depends on both BMD and microporosity. The new approach presented in this work enables to analyze the influence of the BMD and porosity on the mechanical response of bone. Lamellar tissue orientation has to be considered in the mechanical analysis of the cancellous bone. An orthotropic failure criterion can be used to analyze the bone failure onset instead of isotropic criteria. The elastic property degradation method is an efficient procedure to analyze the failure propagation in a 3D numerical model.
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Affiliation(s)
- Raquel Megías
- Dept. de Ingeniería Mecánica y de Materiales. Instituto de Ingeniería Mecánica y Biomecánica de Valencia - I2MB, Universitat Politècnica de València, Camino de Vera, Building 5E-9C, Valencia 46022, Spain
| | - Ana Vercher-Martínez
- Dept. de Ingeniería Mecánica y de Materiales. Instituto de Ingeniería Mecánica y Biomecánica de Valencia - I2MB, Universitat Politècnica de València, Camino de Vera, Building 5E-9C, Valencia 46022, Spain.
| | - Ricardo Belda
- Dept. de Ingeniería Mecánica y de Materiales. Instituto de Ingeniería Mecánica y Biomecánica de Valencia - I2MB, Universitat Politècnica de València, Camino de Vera, Building 5E-9C, Valencia 46022, Spain
| | - José Luis Peris
- Instituto de Ingeniería Mecánica y Biomecánica de Valencia - I2MB, Healthcare Technology Group (GTS-IBV), Universitat Politècnica de València, Camino de Vera, Building 5E-9C, Valencia 46022, Spain
| | - Ricardo Larrainzar-Garijo
- Orthopedic and Trauma Department, Hospital Universitario Infanta Leonor, Medical School, Universidad Complutense Madrid, Spain
| | - Eugenio Giner
- Dept. de Ingeniería Mecánica y de Materiales. Instituto de Ingeniería Mecánica y Biomecánica de Valencia - I2MB, Universitat Politècnica de València, Camino de Vera, Building 5E-9C, Valencia 46022, Spain
| | - F Javier Fuenmayor
- Dept. de Ingeniería Mecánica y de Materiales. Instituto de Ingeniería Mecánica y Biomecánica de Valencia - I2MB, Universitat Politècnica de València, Camino de Vera, Building 5E-9C, Valencia 46022, Spain
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Tian T, Huang HY, Wang W, Shi B, Zheng Q, Li CH. Three-dimensional finite element analysis of the effect of alveolar cleft bone graft on the maxillofacial biomechanical stabilities of unilateral complete cleft lip and palate. Biomed Eng Online 2022; 21:31. [PMID: 35596229 PMCID: PMC9123812 DOI: 10.1186/s12938-022-01000-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 05/16/2022] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND The objective is to clarify the effect of alveolar cleft bone graft on maxillofacial biomechanical stabilities, the key areas when bone grafting and in which should be supplemented with bone graft once bone resorption occurred in UCCLP (unilateral complete cleft lip and palate). METHODS Maxillofacial CAD (computer aided design) models of non-bone graft and full maxilla cleft, full alveolar cleft bone graft, bone graft in other sites of the alveolar cleft were acquired by processing the UCCLP maxillofacial CT data in three-dimensional modeling software. The maxillofacial bone EQV (equivalent) stresses and bone suture EQV strains under occlusal states were obtained in the finite element analysis software. RESULTS Under corresponding occlusal states, the EQV stresses of maxilla, pterygoid process of sphenoid bone on the corresponding side and anterior alveolar arch on the non-cleft side were higher than other maxillofacial bones, the EQV strains of nasomaxillary, zygomaticomaxillary and pterygomaxillary suture on the corresponding side were higher than other maxillofacial bone sutures. The mean EQV strains of nasal raphe, the maximum EQV stresses of posterior alveolar arch on the non-cleft side, the mean and maximum EQV strains of nasomaxillary suture on the non-cleft side in full alveolar cleft bone graft model were all significantly lower than those in non-bone graft model. The mean EQV stresses of bilateral anterior alveolar arches, the maximum EQV stresses of maxilla and its alveolar arch on the cleft side in the model with bone graft in lower 1/3 of the alveolar cleft were significantly higher than those in full alveolar cleft bone graft model. CONCLUSIONS For UCCLP, bilateral maxillae, pterygoid processes of sphenoid bones and bilateral nasomaxillary, zygomaticomaxillary, pterygomaxillary sutures, anterior alveolar arch on the non-cleft side are the main occlusal load-bearing structures before and after alveolar cleft bone graft. Alveolar cleft bone graft mainly affects biomechanical stabilities of nasal raphe and posterior alveolar arch, nasomaxillary suture on the non-cleft side. The areas near nasal floor and in the middle of the alveolar cleft are the key sites when bone grafting, and should be supplemented with bone graft when the bone resorbed in these areas.
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Affiliation(s)
- Tao Tian
- West China School of Stomatology, Sichuan University, Chengdu, 610041, Sichuan Province, The People's Republic of China
| | - Han-Yao Huang
- West China School of Stomatology, Sichuan University, Chengdu, 610041, Sichuan Province, The People's Republic of China.,West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, Sichuan Province, The People's Republic of China
| | - Wei Wang
- Urumql DW Innovation InfoTech Co., Ltd., Urumqi, 830000, Xinjiang Uygur Autonomous Region, The People's Republic of China
| | - Bing Shi
- West China School of Stomatology, Sichuan University, Chengdu, 610041, Sichuan Province, The People's Republic of China.,West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, Sichuan Province, The People's Republic of China
| | - Qian Zheng
- West China School of Stomatology, Sichuan University, Chengdu, 610041, Sichuan Province, The People's Republic of China. .,West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, Sichuan Province, The People's Republic of China.
| | - Cheng-Hao Li
- West China School of Stomatology, Sichuan University, Chengdu, 610041, Sichuan Province, The People's Republic of China. .,West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, Sichuan Province, The People's Republic of China.
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Distribution of Young's modulus at various sampling points in a human lumbar spine vertebral body. Spine J 2020; 20:1861-1875. [PMID: 32592901 DOI: 10.1016/j.spinee.2020.06.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 06/17/2020] [Accepted: 06/17/2020] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Mathematical modeling for creating computer spine models is one of the basic methods underlying many scientific publications. The accuracy of strength parameters of tissues introduced into such models translates directly into the reliability of obtained results. Experimental determination of Young's modulus (E) in various areas of spongy bone tissue seems to be crucial for creating a reliable spine model without excessive simplifications in the form of a single E value for the whole vertebral body. PURPOSE The aim of the study was to determine Young's modulus in different parts of the lumbar vertebral column for samples subjected to compression and bending. STUDY DESIGN Cylindrical spongy bone tissue samples were subjected to bending and compression strength tests. METHODS The study included 975 pathologically unchanged samples of spongy bone tissue harvested from the lumbar vertebrae of 15 male donors. The samples were subjected to compression or bending strength tests and then Young's modulus was determined for each sample depending on its location in the vertebral body. The samples were tested differently between given locations within one vertebra as well as between vertebrae. RESULTS Compressed specimens are characterized by highly significantly different Young's modulus values depending on the location in the vertebral body. Samples No. 7 and No. 9 in the anterior part of the vertebral body have highly significantly higher Young's modulus values compared to those in the posterior part of the vertebral body for all lumbar vertebrae. Samples subjected to bending showed significant differences (p<.05) between samples located closer to the vertebral canal (No.16, No.17) and samples located further away (No.14, No.15) with higher values for the samples located in the posterior part of the vertebral body. CONCLUSIONS Accommodating the anisotropic structure of spongy bone in computer models and the application of different Young's module values for areas within one vertebral body will allow one to obtain realistic results of computer simulations used. CLINICAL SIGNIFICANCE Determining the exact strength parameters of spongy bone tissue within one vertebra and changes in these properties in subsequent vertebrae will allow to create more accurate computer models of the lumbar spine and the whole spine. This, in turn, will translate into more reliable computer simulations used, among others, to determine the risk of fractures or osteoporotic changes, or simulation of the procedure of spinal fusion.
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