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Wang Z, Du S, Zhu H, Yi K, Tang Z, Li Q. A finite element analysis of periodontal ligament fluid mechanics response to occlusal loading based on hydro-mechanical coupling model. Arch Oral Biol 2024; 164:106008. [PMID: 38781742 DOI: 10.1016/j.archoralbio.2024.106008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 05/12/2024] [Accepted: 05/20/2024] [Indexed: 05/25/2024]
Abstract
OBJECTIVE Considering fluid stimulation is one of the essential biomechanical signals for periodontal tissues, this study aims to characterizing fluid mechanics response during occlusal loading by a hydro-mechanical coupling model for periodontal ligament. DESIGN Models simulating periodontium with normal bone height and with intraosseous defects were built with three mechanical modules: tooth, periodontal ligament and alveolar bone. Tooth was modeled as linear elastic, and periodontal ligament and alveolar bone as a hydro-mechanical coupling model. Transient analyses under dynamic occlusal loading were performed. Fluid dynamics within periodontal ligament space was simulated and visualized by post-processing module. RESULTS Reciprocating oscillatory flow occurred within the periodontal ligament under occlusal loading. Higher pore pressure and fluid velocity were observed in furcation and apical regions compared to mid-root and cervical regions. Intraosseous defects increased pore pressure and fluid velocity within the periodontal ligament, most significantly near the defect. CONCLUSION Based on the results of the hydro-mechanical coupling model, significant oscillatory fluid motion is observed within the periodontal ligament under occlusal loading. Particularly, higher fluid velocity is evident in the furcation and apical areas. Additionally, Intraosseous defects significantly enhance fluid motion within the periodontal ligament.
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Affiliation(s)
- Zhongyu Wang
- Second Clinical Division, Peking University School and Hospital of Stomatology & National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & Beijing Key Laboratory of Digital Stomatology & NHC Key Laboratory of Digital Stomatology & NMPA Key Laboratory for Dental Materials, No.22, Zhongguancun South Avenue, Haidian District, Beijing
| | - Sa Du
- Second Clinical Division, Peking University School and Hospital of Stomatology & National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & Beijing Key Laboratory of Digital Stomatology & NHC Key Laboratory of Digital Stomatology & NMPA Key Laboratory for Dental Materials, No.22, Zhongguancun South Avenue, Haidian District, Beijing
| | - Huilin Zhu
- Second Clinical Division, Peking University School and Hospital of Stomatology & National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & Beijing Key Laboratory of Digital Stomatology & NHC Key Laboratory of Digital Stomatology & NMPA Key Laboratory for Dental Materials, No.22, Zhongguancun South Avenue, Haidian District, Beijing
| | - Ke Yi
- Second Clinical Division, Peking University School and Hospital of Stomatology & National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & Beijing Key Laboratory of Digital Stomatology & NHC Key Laboratory of Digital Stomatology & NMPA Key Laboratory for Dental Materials, No.22, Zhongguancun South Avenue, Haidian District, Beijing
| | - Zhihui Tang
- Second Clinical Division, Peking University School and Hospital of Stomatology & National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & Beijing Key Laboratory of Digital Stomatology & NHC Key Laboratory of Digital Stomatology & NMPA Key Laboratory for Dental Materials, No.22, Zhongguancun South Avenue, Haidian District, Beijing.
| | - Qing Li
- Center of Digital Dentistry, Peking University School and Hospital of Stomatology & National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Research Center of Oral Biomaterials and Digital Medical Devices & Beijing Key Laboratory of Digital Stomatology & NHC Key Laboratory of Digital Stomatology & NMPA Key Laboratory for Dental Materials, No.22, Zhongguancun South Avenue, Haidian District, Beijing, PR China.
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Zheng LD, Lv HY, Yang YT, Yuan Q, Cao YT, Zhang K, Zhu R. Effect of compressive and tensile forces on glucose concentration and cell viability within the intervertebral disc: A finite element study. Med Eng Phys 2024; 129:104189. [PMID: 38906572 DOI: 10.1016/j.medengphy.2024.104189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 05/09/2024] [Accepted: 05/22/2024] [Indexed: 06/23/2024]
Abstract
Understanding the role of mechanical force on tissue nutrient transport is essential, as sustained force may affect nutrient levels within the disc and initiate disc degeneration. This study aims to evaluate the time-dependent effects of different compressive force amplitudes as well as tensile force on glucose concentration and cell viability within the disc. Based on the mechano-electrochemical mixture theory, a multiphasic finite element model of the lumbar intervertebral disc was developed. The minimum glucose concentration and minimum cell density in both normal and degenerated discs were predicted for different compressive force amplitudes, tensile force, and corresponding creep time. Under high compressive force, the minimum glucose concentration exhibited an increasing and then decreasing trend with creep time in the normal disc, whereas that of the degenerated disc increased, then decreased, and finally increased again. At steady state, a higher compressive force was accompanied by a lower glucose concentration distribution. In the degenerated disc, the minimum cell density was negatively correlated with creep time, with a greater range of affected tissue under a higher compressive force. For tensile force, the minimum glucose concentration of the degenerated disc raised over time. This study highlighted the importance of creep time, force magnitude, and force type in affecting nutrient concentration and cell viability. Sustained weight-bearing activities could deteriorate the nutrient environment of the degenerated disc, while tensile force might have a nonnegligible role in effectively improving nutrient levels within the degenerated disc.
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Affiliation(s)
- Liang-Dong Zheng
- Shanghai YangZhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), School of Medicine, Tongji University, Shanghai 200092, China
| | - Hao-Yang Lv
- Shanghai YangZhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), School of Medicine, Tongji University, Shanghai 200092, China
| | - Yi-Ting Yang
- Shanghai YangZhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), School of Medicine, Tongji University, Shanghai 200092, China
| | - Qing Yuan
- Shanghai YangZhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), School of Medicine, Tongji University, Shanghai 200092, China; School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092, China
| | - Yu-Ting Cao
- Shanghai YangZhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), School of Medicine, Tongji University, Shanghai 200092, China
| | - Kai Zhang
- School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092, China
| | - Rui Zhu
- Shanghai YangZhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), School of Medicine, Tongji University, Shanghai 200092, China.
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Xiang P, Luo ZP, Che YJ. Insights into the mechanical microenvironment within the cartilaginous endplate: An emerging role in maintaining disc homeostasis and normal function. Heliyon 2024; 10:e31162. [PMID: 38803964 PMCID: PMC11128916 DOI: 10.1016/j.heliyon.2024.e31162] [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: 12/26/2023] [Revised: 05/10/2024] [Accepted: 05/10/2024] [Indexed: 05/29/2024] Open
Abstract
Biomechanical factors are strongly linked with the emergence and development of intervertebral disc degeneration (IVDD). The intervertebral disc (IVD), as a unique enclosed biomechanical structure, exhibits distinct mechanical properties within its substructures. Damage to the mechanical performance of any substructure can disrupt the overall mechanical function of the IVD. Endplate degeneration serves as a significant precursor to IVDD. The endplate (EP) structure, especially the cartilaginous endplate (CEP), serves as a conduit for nutrient and metabolite transport in the IVD. It is inevitably influenced by its nutritional environment, mechanical loading, cytokines and extracellular components. Currently, reports on strategies targeting the CEP for the prevention and treatment of IVDD are scarce. This is due to two primary reasons: first, limited knowledge of the biomechanical microenvironment surrounding the degenerated CEP cells; and second, innovative biological treatment strategies, such as implanting active cells (disc or mesenchymal stem cells) or modulating natural cell activity through the addition of therapeutic factors or genes to treat IVDD often overlook a critical aspect-the restoration of the nutrient supply function and mechanical microenvironment of the endplate. Therefore, restoring the healthy structure of the CEP and maintaining a stable mechanical microenvironment within the EP are crucial for the prevention of IVDD and the repair of degenerated IVDs. We present a comprehensive literature review on the mechanical microenvironment characteristics of cartilage endplates and their associated mechanical signaling pathways. Our aim is to provide valuable insights into the development and implementation of strategies to prevent IVDD by delaying or reversing CEP degeneration.
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Affiliation(s)
- Pan Xiang
- Department of Orthopaedics, The First Affiliated Hospital of SooChow University, Suzhou, Jiangsu, 215000, PR China
| | - Zong-Ping Luo
- Department of Orthopaedics, The First Affiliated Hospital of SooChow University, Suzhou, Jiangsu, 215000, PR China
| | - Yan-Jun Che
- Orthopedics and Sports Medicine Center, The Affiliated Suzhou Hospital of Nanjing Medical University, 242 Guangji Road, Suzhou, Jiangsu, 215008, PR China
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Xu ML, Yang YT, Zeng HZ, Cao YT, Zheng LD, Jin C, Zhu SJ, Zhu R. Finite element modeling and analysis of effect of preexisting cervical degenerative disease on the spinal cord during flexion and extension. Med Biol Eng Comput 2024; 62:1089-1104. [PMID: 38148413 DOI: 10.1007/s11517-023-02993-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Accepted: 12/07/2023] [Indexed: 12/28/2023]
Abstract
Recent studies have emphasized the importance of dynamic activity in the development of myelopathy. However, current knowledge of how degenerative factors affect the spinal cord during motion is still limited. This study aimed to investigate the effect of various types of preexisting herniated cervical disc and the ligamentum flavum ossification on the spinal cord during cervical flexion and extension. A detailed dynamic fluid-structure interaction finite element model of the cervical spine with the spinal cord was developed and validated. The changes of von Mises stress and maximum principal strain within the spinal cord in the period of normal, hyperflexion, and hyperextension were investigated, considering various types and grades of disc herniation and ossification of the ligamentum flavum. The flexion and extension of the cervical spine with spinal canal encroachment induced high stress and strain inside the spinal cord, and this effect was also amplified by increased canal encroachments and cervical hypermobility. The spinal cord might evade lateral encroachment, leading to a reduction in the maximum stress and principal strain within the spinal cord in local-type herniation. Although the impact was limited in the case of diffuse type, the maximum stress tended to appear in the white matter near the encroachment site while compression from both ventral and dorsal was essential to make maximum stress appear in the grey matter. The existence of canal encroachment can reduce the safe range for spinal cord activities, and hypermobility activities may induce spinal cord injury. Besides, the ligamentum flavum plays an important role in the development of central canal syndrome.Significance. This model will enable researchers to have a better understanding of the influence of cervical degenerative diseases on the spinal cord during extension and flexion.
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Affiliation(s)
- Meng-Lei Xu
- Shanghai YangZhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), School of Medicine, Tongji University, Shanghai, 200092, China
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of the Ministry of Education, Tongji Hospital, School of Medicine, Tongji University, 389 Xincun Road, Shanghai, 200065, China
| | - Yi-Ting Yang
- Shanghai YangZhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), School of Medicine, Tongji University, Shanghai, 200092, China
| | - Hui-Zi Zeng
- Shanghai YangZhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), School of Medicine, Tongji University, Shanghai, 200092, China
| | - Yu-Ting Cao
- Shanghai YangZhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), School of Medicine, Tongji University, Shanghai, 200092, China
| | - Liang-Dong Zheng
- Shanghai YangZhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), School of Medicine, Tongji University, Shanghai, 200092, China
| | - Chen Jin
- Shanghai YangZhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), School of Medicine, Tongji University, Shanghai, 200092, China
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of the Ministry of Education, Tongji Hospital, School of Medicine, Tongji University, 389 Xincun Road, Shanghai, 200065, China
| | - Shi-Jie Zhu
- Shanghai YangZhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), School of Medicine, Tongji University, Shanghai, 200092, China
| | - Rui Zhu
- Shanghai YangZhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), School of Medicine, Tongji University, Shanghai, 200092, China.
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of the Ministry of Education, Tongji Hospital, School of Medicine, Tongji University, 389 Xincun Road, Shanghai, 200065, China.
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Khalaf K, Nikkhoo M, Shams S, Niu CC, Cheng CH. Impact of osteoporosis and Cement-Augmented fusion on adjacent spinal levels Post-Fusion Surgery: Patient-Specific finite element analysis. J Biomech 2024; 166:112070. [PMID: 38569456 DOI: 10.1016/j.jbiomech.2024.112070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 03/26/2024] [Accepted: 03/30/2024] [Indexed: 04/05/2024]
Abstract
Cement-augmentation is a technique commonly used during posterior lumbar instrumented fusion (PLIF) to reinforce compromised osteoporotic vertebral bone, minimize the risk of loosening screws, enhance stability, and improve overall surgical outcomes. In this study, we introduce a novel segmented vertebral body regional modeling approach to investigate the effects of osteoporosis and cement-augmented lumbar fusion on disc biomechanics at spinal levels adjacent to the fused vertebrae. Using our previously validated personalized-poroelastic-osteoligamentous FE model of the spine, fusion was simulated at L4-L5, and the biomechanics of adjacent levels were studied for 30 patients (non-osteoporotic patients (N = 15), osteoporotic patients (N = 15)). PLIF models, with and without cement-augmentation, were developed and compared after an 8 h-rest period (200 N), following a 16 h-cyclic compressive loading of 500-1000 N (40 and 20 min, respectively). Movement in different directions (flexion/ extension/ lateral bending/ axial rotation) was simulated using 10Nm moment before and after cyclic loading. The material mapping algorithm was validated by comparing the results of voxel-based and parametric models. The FE cement-augmented models, subject to daily activity loading, demonstrated significant differences in disc height loss and fluid loss as compared to non-cemented models. The calculated axial stress and fiber strain values were also significantly higher for these models. This work demonstrates that although osteoporosis does not significantly alter the time-dependent characteristics of adjacent IVDs post-surgery, cement-augmentation increases the risk of adjacent segment disease (ASD) incidence. A holistic understanding of the trade-offs and long-term complex interplay between structural reinforcement modalities, including cement augmentation, and altered biomechanics warrants further investigation.
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Affiliation(s)
- Kinda Khalaf
- College of Medicine and Health Sciences, Khalifa University of Science and Technology, and Health Engineering Innovation Center, Abu Dhabi, United Arab Emirates.
| | - Mohammad Nikkhoo
- School of Physical Therapy and Graduate Institute of Rehabilitation Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan; Bone and Joint Research Center, Chang Gung Memorial Hospital, Linkou, Taiwan; Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Shohreh Shams
- Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran
| | - Chi-Chien Niu
- Bone and Joint Research Center, Chang Gung Memorial Hospital, Linkou, Taiwan; Department of Orthopedic Surgery, Chang Gung Memorial Hospital, Linkou, Taiwan
| | - Chih-Hsiu Cheng
- School of Physical Therapy and Graduate Institute of Rehabilitation Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan; Bone and Joint Research Center, Chang Gung Memorial Hospital, Linkou, Taiwan.
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6
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Akhavanfar M, Mir-Orefice A, Uchida TK, Graham RB. An Enhanced Spine Model Validated for Simulating Dynamic Lifting Tasks in OpenSim. Ann Biomed Eng 2024; 52:259-269. [PMID: 37741902 DOI: 10.1007/s10439-023-03368-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Accepted: 09/07/2023] [Indexed: 09/25/2023]
Abstract
A fully articulated thoracolumbar spine model had been previously developed in OpenSim and had been extensively validated against experimental data during various static tasks. In the present study, we enhanced this detailed musculoskeletal model by adding the role of passive structures and adding kinematic constraints to make it suitable for dynamic tasks. We validated the spinal forces estimated by this enhanced model during nine dynamic lifting/lowering tasks. Moreover, we recently developed and evaluated five approaches in OpenSim to model the external loads applied to the hands during lifting/lowering tasks, and in the present study, we assessed which approach results in more accurate spinal forces. Regardless of the external load modeling approach, the maximum forces predicted by our enhanced spine model across all tasks, as well as the pattern of estimated spinal forces within each task, showed strong correlations (r-values and cross-correlation coefficients > 0.9) with experimental data. Given the biofidelity of our enhanced model, its accessibility via the open-source OpenSim software, and the extent to which this model has been validated, we recommend it for applications requiring estimation of spinal forces during lifting/lowering tasks using multibody-based models and inverse dynamic analyses.
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Affiliation(s)
| | - Alexandre Mir-Orefice
- School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Thomas K Uchida
- Department of Mechanical Engineering, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
- Ottawa-Carleton Institute for Biomedical Engineering, Ottawa, Canada
| | - Ryan B Graham
- School of Human Kinetics, Faculty of Health Sciences, University of Ottawa, Ottawa, ON, K1N 6N5, Canada.
- Ottawa-Carleton Institute for Biomedical Engineering, Ottawa, Canada.
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7
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Tavana S, Shek C, Rahman T, Baxan N, Newell N. The influence of geometry on intervertebral disc stiffness. J Biomech 2024; 163:111915. [PMID: 38233311 DOI: 10.1016/j.jbiomech.2023.111915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 12/05/2023] [Accepted: 12/31/2023] [Indexed: 01/19/2024]
Abstract
Geometry plays an important role in intervertebral disc (IVD) mechanics. Previous computational studies have found a link between IVD geometry and stiffness. However, few experimental studies have investigated this link, possibly due to difficulties in non-destructively quantifying internal geometric features. Recent advances in ultra-high resolution MRI provides the opportunity to visualise IVD features in unprecedented detail. This study aimed to quantify 3D human IVD geometries using 9.4 T MRIs and to investigate correlations between geometric variations and IVD stiffness. Thirty human lumbar motion segments (fourteen non-degenerate and sixteen degenerate) were scanned using a 9.4 T MRI and geometric parameters were measured. A 1kN compressive load was applied to each motion segment and stiffness was calculated. Degeneration caused a reduction (p < 0.05) in IVD height, a decreased nucleus-annulus area ratio, and a 1.6 ± 3.0 mm inward collapse of the inner annulus. The IVD height, anteroposterior (AP) width, lateral width, cross-sectional area, nucleus-annulus boundary curvature, and nucleus-annulus area ratio had a significant (p < 0.05) influence on IVD stiffness. Linear relationships (p < 0.05, r > 0.47) were observed between these geometric features and IVD compressive stiffness and a multivariate regression model was generated to enable stiffness to be predicted from features observable on clinical imaging (stiffness, N/mm = 6062 - (61.2 × AP width, mm) - (169.2 × IVD height, mm)). This study advances our understanding of disc structure-function relationships and how these change with degeneration, which can be used to both generate and validate more realistic computational models.
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Affiliation(s)
- S Tavana
- Department of Bioengineering, Imperial College London, London, UK
| | - C Shek
- Department of Bioengineering, Imperial College London, London, UK
| | - T Rahman
- Department of Bioengineering, Imperial College London, London, UK; Department of Mechanical Engineering, Imperial College London, UK
| | - N Baxan
- Biological Imaging Centre, Central Biomedical Services, Imperial College London, UK; National Heart and Lung Institute, Faculty of Medicine, Imperial College London, UK
| | - N Newell
- Department of Bioengineering, Imperial College London, London, UK.
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Crump KB, Alminnawi A, Bermudez‐Lekerika P, Compte R, Gualdi F, McSweeney T, Muñoz‐Moya E, Nüesch A, Geris L, Dudli S, Karppinen J, Noailly J, Le Maitre C, Gantenbein B. Cartilaginous endplates: A comprehensive review on a neglected structure in intervertebral disc research. JOR Spine 2023; 6:e1294. [PMID: 38156054 PMCID: PMC10751983 DOI: 10.1002/jsp2.1294] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 09/15/2023] [Accepted: 09/26/2023] [Indexed: 12/30/2023] Open
Abstract
The cartilaginous endplates (CEP) are key components of the intervertebral disc (IVD) necessary for sustaining the nutrition of the disc while distributing mechanical loads and preventing the disc from bulging into the adjacent vertebral body. The size, shape, and composition of the CEP are essential in maintaining its function, and degeneration of the CEP is considered a contributor to early IVD degeneration. In addition, the CEP is implicated in Modic changes, which are often associated with low back pain. This review aims to tackle the current knowledge of the CEP regarding its structure, composition, permeability, and mechanical role in a healthy disc, how they change with degeneration, and how they connect to IVD degeneration and low back pain. Additionally, the authors suggest a standardized naming convention regarding the CEP and bony endplate and suggest avoiding the term vertebral endplate. Currently, there is limited data on the CEP itself as reported data is often a combination of CEP and bony endplate, or the CEP is considered as articular cartilage. However, it is clear the CEP is a unique tissue type that differs from articular cartilage, bony endplate, and other IVD tissues. Thus, future research should investigate the CEP separately to fully understand its role in healthy and degenerated IVDs. Further, most IVD regeneration therapies in development failed to address, or even considered the CEP, despite its key role in nutrition and mechanical stability within the IVD. Thus, the CEP should be considered and potentially targeted for future sustainable treatments.
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Affiliation(s)
- Katherine B. Crump
- Tissue Engineering for Orthopaedics & Mechanobiology, Bone & Joint Program, Department for BioMedical Research (DBMR), Medical FacultyUniversity of BernBernSwitzerland
- Department of Orthopaedic Surgery and Traumatology, InselspitalBern University Hospital, Medical Faculty, University of BernBernSwitzerland
- Graduate School for Cellular and Biomedical Sciences (GCB)University of BernBernSwitzerland
| | - Ahmad Alminnawi
- GIGA In Silico MedicineUniversity of LiègeLiègeBelgium
- Skeletal Biology and Engineering Research Center, KU LeuvenLeuvenBelgium
- Biomechanics Research Unit, KU LeuvenLeuvenBelgium
| | - Paola Bermudez‐Lekerika
- Tissue Engineering for Orthopaedics & Mechanobiology, Bone & Joint Program, Department for BioMedical Research (DBMR), Medical FacultyUniversity of BernBernSwitzerland
- Department of Orthopaedic Surgery and Traumatology, InselspitalBern University Hospital, Medical Faculty, University of BernBernSwitzerland
- Graduate School for Cellular and Biomedical Sciences (GCB)University of BernBernSwitzerland
| | - Roger Compte
- Twin Research & Genetic EpidemiologySt. Thomas' Hospital, King's College LondonLondonUK
| | - Francesco Gualdi
- Institut Hospital del Mar d'Investigacions Mèdiques (IMIM)BarcelonaSpain
| | - Terence McSweeney
- Research Unit of Health Sciences and TechnologyUniversity of OuluOuluFinland
| | - Estefano Muñoz‐Moya
- BCN MedTech, Department of Information and Communication TechnologiesUniversitat Pompeu FabraBarcelonaSpain
| | - Andrea Nüesch
- Division of Clinical Medicine, School of Medicine and Population HealthUniversity of SheffieldSheffieldUK
| | - Liesbet Geris
- GIGA In Silico MedicineUniversity of LiègeLiègeBelgium
- Skeletal Biology and Engineering Research Center, KU LeuvenLeuvenBelgium
- Biomechanics Research Unit, KU LeuvenLeuvenBelgium
| | - Stefan Dudli
- Center of Experimental RheumatologyDepartment of Rheumatology, University Hospital Zurich, University of ZurichZurichSwitzerland
- Department of Physical Medicine and RheumatologyBalgrist University Hospital, Balgrist Campus, University of ZurichZurichSwitzerland
| | - Jaro Karppinen
- Research Unit of Health Sciences and TechnologyUniversity of OuluOuluFinland
- Finnish Institute of Occupational HealthOuluFinland
- Rehabilitation Services of South Karelia Social and Health Care DistrictLappeenrantaFinland
| | - Jérôme Noailly
- BCN MedTech, Department of Information and Communication TechnologiesUniversitat Pompeu FabraBarcelonaSpain
| | - Christine Le Maitre
- Division of Clinical Medicine, School of Medicine and Population HealthUniversity of SheffieldSheffieldUK
| | - Benjamin Gantenbein
- Tissue Engineering for Orthopaedics & Mechanobiology, Bone & Joint Program, Department for BioMedical Research (DBMR), Medical FacultyUniversity of BernBernSwitzerland
- Department of Orthopaedic Surgery and Traumatology, InselspitalBern University Hospital, Medical Faculty, University of BernBernSwitzerland
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Babcock CD, Volk VL, Zeng W, Hamilton LD, Shelburne KB, Fitzpatrick CK. Neural-driven activation of 3D muscle within a finite element framework: exploring applications in healthy and neurodegenerative simulations. Comput Methods Biomech Biomed Engin 2023:1-11. [PMID: 37966863 PMCID: PMC11093887 DOI: 10.1080/10255842.2023.2280772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 11/02/2023] [Indexed: 11/16/2023]
Abstract
This paper presents a novel computational framework for neural-driven finite element muscle models, with an application to amyotrophic lateral sclerosis (ALS). The multiscale neuromusculoskeletal (NMS) model incorporates physiologically accurate motor neurons, 3D muscle geometry, and muscle fiber recruitment. It successfully predicts healthy muscle force and tendon elongation and demonstrates a progressive decline in muscle force due to ALS, dropping from 203 N (healthy) to 155 N (120 days after ALS onset). This approach represents a preliminary step towards developing integrated neural and musculoskeletal simulations to enhance our understanding of neurodegenerative and neurodevelopmental conditions through predictive NMS models.
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Affiliation(s)
- Colton D. Babcock
- Mechanical and Biomedical Engineering, Boise State University, Boise, ID
| | - Victoria L. Volk
- Mechanical and Biomedical Engineering, Boise State University, Boise, ID
| | - Wei Zeng
- Department of Mechanical Engineering, New York Institute of Technology, New York, NY
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Cheng CH, Chiu PY, Chen HB, Niu CC, Nikkhoo M. The influence of over-distraction on biomechanical response of cervical spine post anterior interbody fusion: a comprehensive finite element study. Front Bioeng Biotechnol 2023; 11:1217274. [PMID: 37650042 PMCID: PMC10464836 DOI: 10.3389/fbioe.2023.1217274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 08/04/2023] [Indexed: 09/01/2023] Open
Abstract
Introduction: Anterior cervical discectomy and fusion (ACDF) has been considered as the gold standard surgical treatment for cervical degenerative pathologies. Some surgeons tend to use larger-sized interbody cages during ACDF to restore the index intervertebral disc height, hence, this study evaluated the effect of larger-sized interbody cages on the cervical spine with ACDF under both static and cyclic loading. Method: Twenty pre-operative personalized poro-hyperelastic finite element (FE) models were developed. ACDF post-operative models were then constructed and four clinical scenarios (i.e., 1) No-distraction; 2) 1 mm distraction; 3) 2 mm distraction; and 4) 3 mm distraction) were predicted for each patient. The biomechanical responses at adjacent spinal levels were studied subject to static and cyclic loading. Non-parametric Friedman statistical comparative tests were performed and the p values less than 0.05 were reflected as significant. Results: The calculated intersegmental range of motion (ROM) and intradiscal pressure (IDP) from 20 pre-operative FE models were within the overall ranges compared to the available data from literature. Under static loading, greater ROM, IDP, facet joint force (FJF) values were detected post ACDF, as compared with pre-op. Over-distraction induced significantly higher IDP and FJF in both upper and lower adjacent levels in extension. Higher annulus fibrosus stress and strain values, and increased disc height and fluid loss at the adjacent levels were observed in ACDF group which significantly increased for over-distraction groups. Discussion: it was concluded that using larger-sized interbody cages (the height of ≥2 mm of the index disc height) can result in remarkable variations in biomechanical responses of adjacent levels, which may indicate as risk factor for adjacent segment disease. The results of this comprehensive FE investigation using personalized modeling technique highlight the importance of selecting the appropriate height of interbody cage in ACDF surgery.
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Affiliation(s)
- Chih-Hsiu Cheng
- School of Physical Therapy and Graduate Institute of Rehabilitation Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Bone and Joint Research Center, Chang Gung Memorial Hospital, Linkou, Taiwan
| | - Ping-Yeh Chiu
- Bone and Joint Research Center, Chang Gung Memorial Hospital, Linkou, Taiwan
- Department of Orthopedic Surgery, Chang Gung Memorial Hospital, Linkou, Taiwan
| | - Hung-Bin Chen
- School of Physical Therapy and Graduate Institute of Rehabilitation Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Chi-Chien Niu
- Bone and Joint Research Center, Chang Gung Memorial Hospital, Linkou, Taiwan
- Department of Orthopedic Surgery, Chang Gung Memorial Hospital, Linkou, Taiwan
| | - Mohammad Nikkhoo
- School of Physical Therapy and Graduate Institute of Rehabilitation Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Bone and Joint Research Center, Chang Gung Memorial Hospital, Linkou, Taiwan
- Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
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11
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Biomechanical responses of the human lumbar spine to vertical whole-body vibration in normal and osteoporotic conditions. Clin Biomech (Bristol, Avon) 2023; 102:105872. [PMID: 36610268 DOI: 10.1016/j.clinbiomech.2023.105872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 12/26/2022] [Accepted: 01/02/2023] [Indexed: 01/05/2023]
Abstract
BACKGROUND The prevalence of osteoporosis is continuing to escalate with an aging population. However, it remains unclear how biomechanical behavior of the lumbar spine is affected by osteoporosis under whole-body vibration, which is considered a significant risk factor for degenerative spinal disease and is typically present when driving a car. Accordingly, the objective of this study was to compare the spine biomechanical responses to vertical whole-body vibration between normal and osteoporotic conditions. METHODS A three-dimensional finite-element model of the normal human lumbar spine-pelvis segment was developed using computed tomographic scans and was validated against experimental data. Osteoporotic condition was simulated by modifying material properties of bone tissues in the normal model. Transient dynamic analyses were conducted on the normal and osteoporotic models to compute deformation and stress in all lumbar motion segments. FINDINGS When osteoporosis occurred, vibration amplitudes of the vertebral axial displacement, disc bulge, and disc stress were increased by 32.1-45.4%, 25.7-47.1% and 23.0-42.7%, respectively. In addition, it was found that for both the normal and osteoporotic models, the response values (disc bugle and disc stress) were higher in L4-L5 and L5-S1 intervertebral discs than in other discs. INTERPRETATION Osteoporosis deteriorates the effect of whole-body vibration on lumbar spine, and the lower lumbar segments might have a higher likelihood of disc degeneration under whole-body vibration.
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12
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Huang C, Liu Z, Wei Z, Fang Z, Xi Z, Cai P, Li J. Will the adjustment of insertional pedicle screw positions affect the risk of adjacent segment diseases biomechanically? An in-silico study. Front Surg 2023; 9:1004642. [PMID: 36713678 PMCID: PMC9877423 DOI: 10.3389/fsurg.2022.1004642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 09/20/2022] [Indexed: 01/13/2023] Open
Abstract
Background The fixation-induced biomechanical deterioration will increase the risk of adjacent segment diseases (ASD) after lumbar interbody fusion with Bilateral pedicle screw (BPS) fixation. The accurate adjustment of insertional pedicle screw positions is possible, and published studies have reported its mechanical effects. However, no studies clarified that adjusting insertional screw positions would affect the postoperative biomechanical environment and the risk of ASD. The objective of this study was to identify this issue and provide theoretical references for the optimization of insertional pedicle screw position selections. Methods The oblique lumbar interbody fusion fixed by BPS with different insertional positions has been simulated in the L4-L5 segment of our previously constructed and validated lumbosacral model. Biomechanical indicators related to ASD have been computed and recorded under flexion, extension, bending, and axial rotation loading conditions. Results The change of screw insertional positions has more apparent biomechanical effects on the cranial than the caudal segment. Positive collections can be observed between the reduction of the fixation length and the alleviation of motility compensation and stress concentration on facet cartilages. By contrast, no pronounced tendency of stress distribution on the intervertebral discs can be observed with the change of screw positions. Conclusions Reducing the fixation stiffness by adjusting the insertional screw positions could alleviate the biomechanical deterioration and be an effective method to reduce the risk of ASD caused by BPS.
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Affiliation(s)
- Chenyi Huang
- Department of Orthopedics, The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, Luzhou, China
| | - Zongchao Liu
- Department of Orthopedics, The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, Luzhou, China
| | - Zhangchao Wei
- Department of Orthopedics, The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, Luzhou, China
| | - Zhongxin Fang
- Fluid and Power Machinery Key Laboratory of Ministry of Education, Xihua University, Chengdu, China
| | - Zhipeng Xi
- Department of Spine Surgery, Jiangsu Province Hospital on Integration of Chinese and Western Medicine, Nanjing, China
| | - Ping Cai
- Department of Orthopedics, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, China,Correspondence: Jingchi Li Ping Cai
| | - Jingchi Li
- Department of Orthopedics, The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, Luzhou, China,Correspondence: Jingchi Li Ping Cai
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13
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Johnson ME, Karges-Brown JR, Brismée JM, Brenza TM, Piper AK. Innovative seated vertical lumbar traction allows simultaneous computer work while inducing spinal height changes similar to supine lying. J Back Musculoskelet Rehabil 2023; 36:739-749. [PMID: 36641660 DOI: 10.3233/bmr-220202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
BACKGROUND Lumbar intervertebral disc height loss has been associated with spinal height change (SHC) and low back pain (LBP), including stenosis. Non-invasive methods to improve disc height loss require forms of lying down, which are unconducive to computer work. OBJECTIVE Intermittent vertical traction (VT) integrated with seated computer work may provide ergonomic alternatives for increasing SHC to promote LBP relief. The primary aim was to develop and introduce a safe VT prototype and dosage to induce and measure SHC. Prototype comfort and LBP ratings were exploratory secondary aims. METHODS Forty-one participants were stadiometry-measured for pre- and post-intervention SHC from seated VT at 35% body weight removed, supine lying (SL), and sitting at a computer (SIT) without VT. Pain ratings were recorded for those self-reporting LBP. VT prototype evaluations were compiled from a 3-question, 7-point Likert-style survey. RESULTS SHC increased by 3.9 ± 3.4 mm in VT, 1.7 ± 3.4 mm in SIT, and 4.3 ± 3.1 mm in SL (P< 0.000). Post hoc findings were significant between VT and SIT (P< 0.000), and SL and SIT (P< 0.000). VT and SL LBP ratings both decreased, but not SIT. CONCLUSION Intermittent seated VT is a promising alternative for postural relief during seated computer work, producing SHC similar to lying down without compromising workflow.
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Affiliation(s)
- Marit E Johnson
- Biomedical Engineering Graduate Program, South Dakota School of Mines and Technology, Rapid City, SD, USA
| | - Joy R Karges-Brown
- Department of Physical Therapy, University of South Dakota, Sanford Coyote Sports Center, Vermillion, SD, USA
| | - Jean-Michel Brismée
- Center for Rehabilitation Research, Department of Rehabilitation Sciences, Texas Tech University Health Sciences Center, Lubbock, Texas, USA
| | - Timothy M Brenza
- Biomedical Engineering Graduate Program, South Dakota School of Mines and Technology, Rapid City, SD, USA.,Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology, Rapid City, SD, USA
| | - Adam K Piper
- Biomedical Engineering Graduate Program, South Dakota School of Mines and Technology, Rapid City, SD, USA.,Department of Industrial Engineering, South Dakota School of Mines and Technology, Rapid City, SD, USA
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14
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AKINCI SALIHAZEYNEB, ARSLAN YUNUSZIYA. FINITE ELEMENT SPINE MODELS AND SPINAL INSTRUMENTS: A REVIEW. J MECH MED BIOL 2022. [DOI: 10.1142/s0219519422300010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
There is considerable biomechanics literature on finite element modeling and analysis of the spine. To accurately mimic the biomechanical behavior of the vertebral column, a generated computational model has to include anatomical structures that are consistent with physiological reality. In this review article, we focused on the finite element spine models that have been developed by various approaches in the literature. Firstly, the anatomical features of the spine and the spinal components have been briefly explained. We then focused on the modeling stages of vertebrae, ligaments, facet joints, intervertebral discs, and spinal instruments. With this paper, we expect to provide a comprehensive resource regarding the modeling preferences used in spine modeling.
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Affiliation(s)
- SALIHA ZEYNEB AKINCI
- Department of Biomedical Engineering and Bioinformatics, Graduate School of Engineering and Natural Sciences, Istanbul Medipol University, 34810 Beykoz, Istanbul, Turkey
| | - YUNUS ZIYA ARSLAN
- Department of Robotics and Intelligent Systems, Institute of Graduate Studies in Science and Engineering, Turkish-German University, Beykoz, Istanbul 34820, Turkey
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15
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McDonnell EE, Buckley CT. Consolidating and re-evaluating the human disc nutrient microenvironment. JOR Spine 2022; 5:e1192. [PMID: 35386756 PMCID: PMC8966889 DOI: 10.1002/jsp2.1192] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2021] [Revised: 12/14/2021] [Accepted: 01/07/2022] [Indexed: 12/19/2022] Open
Abstract
Background Despite exciting advances in regenerative medicine, cell‐based strategies for treating degenerative disc disease remain in their infancy. To maximize the potential for successful clinical translation, a more thorough understanding of the in vivo microenvironment is needed to better determine and predict how cell therapies will respond when administered in vivo. Aims This work aims to reflect on the in vivo nutrient microenvironment of the degenerating IVD through consolidating what has already been measured together with investigative in silico models. Materials and Methods This work uses in silico modeling, underpinned by more recent experimentally determined parameters of degeneration and nutrient transport from the literature, to re‐evaluate the current knowledge in terms of grade‐specific stages of degeneration. Results Through modeling only the metabolically active cell population, this work predicts slightly higher glucose concentrations compared to previous in silico models, while the predicted results show good agreement with previous intradiscal pH and oxygen measurements. Increasing calcification with degeneration limits nutrient transport into the IVD and initiates a build‐up of acidity; however, its effect is compensated somewhat by a reduction in diffusional distance due to decreasing disc height. Discussion This work advances in silico modeling through a strong foundation of experimentally determined grade‐specific input parameters. Taken together, pre‐existing measurements and predicted results suggest that metabolite concentrations may not be as critically low as commonly believed, with calcification not appearing to have a detrimental effect at stages of degeneration when cell therapies are an appropriate intervention. Conclusion Overall, our initiative is to provoke greater deliberation and consideration of the nutrient microenvironment when performing in vitro cell culture and cell therapy development. This work highlights urgency for robust experimental glucose measurements in healthy and degenerating IVDs, not only to validate in silico models but to significantly advance the field in fully elucidating the nutrient microenvironment and refining in vitro techniques to accelerate clinical translation.
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Affiliation(s)
- Emily E McDonnell
- Trinity Centre for Biomedical Engineering, Trinity Biomedical Sciences Institute, Trinity College Dublin The University of Dublin Dublin Ireland.,Discipline of Mechanical, Manufacturing and Biomedical Engineering, School of Engineering, Trinity College Dublin The University of Dublin Dublin Ireland
| | - Conor T Buckley
- Trinity Centre for Biomedical Engineering, Trinity Biomedical Sciences Institute, Trinity College Dublin The University of Dublin Dublin Ireland.,Discipline of Mechanical, Manufacturing and Biomedical Engineering, School of Engineering, Trinity College Dublin The University of Dublin Dublin Ireland.,Advanced Materials and Bioengineering Research (AMBER) Centre, Royal College of Surgeons in Ireland & Trinity College Dublin The University of Dublin Dublin Ireland.,Tissue Engineering Research Group, Department of Anatomy and Regenerative Medicine Royal College of Surgeons in Ireland Dublin Ireland
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16
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Fasser MR, Kuravi R, Bulla M, Snedeker JG, Farshad M, Widmer J. A novel approach for tetrahedral-element-based finite element simulations of anisotropic hyperelastic intervertebral disc behavior. Front Bioeng Biotechnol 2022; 10:1034441. [PMID: 36582835 PMCID: PMC9792499 DOI: 10.3389/fbioe.2022.1034441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 11/21/2022] [Indexed: 12/14/2022] Open
Abstract
Intervertebral discs are microstructurally complex spinal tissues that add greatly to the flexibility and mechanical strength of the human spine. Attempting to provide an adjustable basis for capturing a wide range of mechanical characteristics and to better address known challenges of numerical modeling of the disc, we present a robust finite-element-based model formulation for spinal segments in a hyperelastic framework using tetrahedral elements. We evaluate the model stability and accuracy using numerical simulations, with particular attention to the degenerated intervertebral discs and their likely skewed and narrowed geometry. To this end, 1) annulus fibrosus is modeled as a fiber-reinforced Mooney-Rivlin type solid for numerical analysis. 2) An adaptive state-variable dependent explicit time step is proposed and utilized here as a computationally efficient alternative to theoretical estimates. 3) Tetrahedral-element-based FE models for spinal segments under various loading conditions are evaluated for their use in robust numerical simulations. For flexion, extension, lateral bending, and axial rotation load cases, numerical simulations reveal that a suitable framework based on tetrahedral elements can provide greater stability and flexibility concerning geometrical meshing over commonly employed hexahedral-element-based ones for representation and study of spinal segments in various stages of degeneration.
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Affiliation(s)
- Marie-Rosa Fasser
- Spine Biomechanics, Department of Orthopedic Surgery, Balgrist University Hospital, Zurich, Switzerland.,Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Ramachandra Kuravi
- Spine Biomechanics, Department of Orthopedic Surgery, Balgrist University Hospital, Zurich, Switzerland.,Engineering Division, Lawrence Berkeley National Lab, Berkeley, CA, United States
| | | | - Jess G Snedeker
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland.,Department of Orthopedics, Balgrist University Hospital, Zurich, Switzerland
| | - Mazda Farshad
- Department of Orthopedics, Balgrist University Hospital, Zurich, Switzerland
| | - Jonas Widmer
- Spine Biomechanics, Department of Orthopedic Surgery, Balgrist University Hospital, Zurich, Switzerland.,Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
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17
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Khalaf K, Nikkhoo M. Comparative biomechanical analysis of rigid vs. flexible fixation devices for the lumbar spine: A geometrically patient-specific poroelastic finite element study. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2021; 212:106481. [PMID: 34736171 DOI: 10.1016/j.cmpb.2021.106481] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 10/13/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND AND OBJECTIVE Lumbar spinal stenosis (LSS), or the narrowing of the spinal canal, continues to be the leading preoperative diagnosis for adults older than 65 years who undergo spine surgery. Although the treatment of LSS depends on its severity, the optimal surgical technique towards decreasing the risk of adjacent segment disease (ASD) remains elusive. This study aimed to comparatively analyze spinal biomechanics with rigid and flexible fixation devices (i.e., rigid and dynamic posterolateral fusion (PLF) and interspinous process (ISP) devices) during daily activities. METHODS Using a validated parametric poroelastic finite element modeling approach, 8 subject-specific pre-operative models were developed, and their validity was evaluated. Parametric FE models of the lumbar spines were then regenerated based on post-operation images for (A) rigid PLF (B) dynamic PLF (C) rigid ISP device (Coflex) and (D) flexible ISP device (DIAM) at L4-L5 level. Biomechanical responses for instrumented and adjacent intervertebral discs (IVDs) were analyzed and compared subject to static and cyclic loading. RESULTS The preoperative models were well comparable with previous works in literature. The postoperative results for the PLF and Coflex rigid systems, demonstrated greater ROM; higher values of stress and strain in the AF region; and increased disc height and fluid loss at the adjacent levels, as compared with the pre-op models and the post-op results of the flexible systems (i.e., dynamic PLF and DIAM). The calculated forces on the facet joint were of smaller magnitude for the ISP devices as compared to the PLF, particularly during extension. CONCLUSIONS This study demonstrates that the dynamic PLF construct and DIAM implants could be effective to maintain the natural poroelastic characteristics of adjacent IVDs, which could be beneficial for enhancing long-term clinical outcomes. FEM provides clinicians with an invaluable patient-specific quantitative tool for informed surgical planning and discerning follow-up management.
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Affiliation(s)
- Kinda Khalaf
- Department of Biomedical Engineering, Khalifa University of Science and Technology, and Health Engineering Innovation Center, PO Box 127788, Abu Dhabi, United Arab Emirates.
| | - Mohammad Nikkhoo
- Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
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18
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Negative biomechanical effects of large grade nuclectomy in the transforaminal endoscopic discectomy increased the risk of adjacent segment diseases: A finite element study. J Clin Neurosci 2021; 93:141-146. [PMID: 34656238 DOI: 10.1016/j.jocn.2021.09.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 09/05/2021] [Accepted: 09/07/2021] [Indexed: 11/20/2022]
Abstract
PURPOSE The protection of articular processes (AP) in the transforaminal endoscopic discectomy (TED) was proven to optimise post-operative biomechanical environments. Published studies reported a large grade of nuclectomy leading to poor prognosis, but the underlying biomechanical mechanism was unclearly illustrated. This study aimed to investigate the changes of biomechanical environments after an in-out TED with intact AP and a large grade of nuclectomy and an out-in TED with limited foraminoplasty and a smaller grade of nuclectomy. METHODS A previously constructed and validated lumbo-sacral model was used in this study, and in-out TED with intact AP and out-in TED with limited foraminoplasty, a smaller grade of nuclectomy was simulated. Biomechanical changes in the L5-S1 segment related to the degeneration acceleration were computed under different directional loading conditions. RESULTS Post-operative biomechanical changes after the out-in TED with limited foraminoplasty were slight, except for the facet contact pressure under the extension position. By contrast, significant biomechanical deterioration, both in the adjacent disc and zygapophyseal joints, is observed under extension in the model after the in-out TED with large nuclectomy. CONCLUSION A large grade of nuclectomy is regarded as an independent risk factor of adjacent segment disease in the caudal functional spinal unit after the in-out TED.
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19
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Dixon AR, Warren JP, Culbert MP, Mengoni M, Wilcox RK. Review of in vitro mechanical testing for intervertebral disc injectable biomaterials. J Mech Behav Biomed Mater 2021; 123:104703. [PMID: 34365096 DOI: 10.1016/j.jmbbm.2021.104703] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 06/22/2021] [Accepted: 07/03/2021] [Indexed: 01/17/2023]
Abstract
Many early stage interventions for intervertebral disc degeneration are under development involving injection of a biomaterial into the affected tissue. Due to the complex mechanical behaviour of the intervertebral disc, there are challenges in comprehensively evaluating the performance of these injectable biomaterials in vitro. The aim of this review was to examine the different methods that have been developed to mechanically test injectable intervertebral disc biomaterials in an in vitro disc model. Testing methods were examined with emphasis on overall protocol, artificial degeneration method, mechanical testing regimes and injection delivery. Specifically, the effects of these factors on the evaluation of different aspects of device performance was assessed. Broad testing protocols varied between studies and enabled evaluation of different aspects of an injectable treatment. Studies employed artificial degeneration methodologies which were either on a macro scale through mechanical means or on a microscale with biochemical means. Mechanical loading regimes differed greatly across studies, with load being either held constant, ramped to failure, or applied cyclically, with large variability on all loading parameters. Evaluation of the risk of herniation was possible by utilising ramped loading, whereas cyclic loading enabled the examination of the restoration of mechanical behaviour for initial screening of biomaterials and surgical technique optimisation studies. However, there are large variations in the duration or tests, and further work is needed to define an appropriate number of cycles to standardise this type of testing. Biomaterial delivery was controlled by set volume or haptic feedback, and future investigations should generate evidence applying physiological loading during injection and normalisation of injection parameters based on disc size. Based on the reviewed articles and considering clinical risks, a series of recommendations have been made for future intervertebral disc mechanical testing.
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Affiliation(s)
- A R Dixon
- University of Leeds, Institute of Medical and Biological Engineering, Leeds, LS2 9JT, United Kingdom.
| | - J P Warren
- University of Leeds, Institute of Medical and Biological Engineering, Leeds, LS2 9JT, United Kingdom
| | - M P Culbert
- University of Leeds, Institute of Medical and Biological Engineering, Leeds, LS2 9JT, United Kingdom
| | - M Mengoni
- University of Leeds, Institute of Medical and Biological Engineering, Leeds, LS2 9JT, United Kingdom
| | - R K Wilcox
- University of Leeds, Institute of Medical and Biological Engineering, Leeds, LS2 9JT, United Kingdom.
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20
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Zhou M, Lim S, O’Connell GD. A Robust Multiscale and Multiphasic Structure-Based Modeling Framework for the Intervertebral Disc. Front Bioeng Biotechnol 2021; 9:685799. [PMID: 34164388 PMCID: PMC8215504 DOI: 10.3389/fbioe.2021.685799] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 05/10/2021] [Indexed: 12/11/2022] Open
Abstract
A comprehensive understanding of multiscale and multiphasic intervertebral disc mechanics is crucial for designing advanced tissue engineered structures aiming to recapitulate native tissue behavior. The bovine caudal disc is a commonly used human disc analog due to its availability, large disc height and area, and similarities in biochemical and mechanical properties to the human disc. Because of challenges in directly measuring subtissue-level mechanics, such as in situ fiber mechanics, finite element models have been widely employed in spinal biomechanics research. However, many previous models use homogenization theory and describe each model element as a homogenized combination of fibers and the extrafibrillar matrix while ignoring the role of water content or osmotic behavior. Thus, these models are limited in their ability in investigating subtissue-level mechanics and stress-bearing mechanisms through fluid pressure. The objective of this study was to develop and validate a structure-based bovine caudal disc model, and to evaluate multiscale and multiphasic intervertebral disc mechanics under different loading conditions and with degeneration. The structure-based model was developed based on native disc structure, where fibers and matrix in the annulus fibrosus were described as distinct materials occupying separate volumes. Model parameters were directly obtained from experimental studies without calibration. Under the multiscale validation framework, the model was validated across the joint-, tissue-, and subtissue-levels. Our model accurately predicted multiscale disc responses for 15 of 16 cases, emphasizing the accuracy of the model, as well as the effectiveness and robustness of the multiscale structure-based modeling-validation framework. The model also demonstrated the rim as a weak link for disc failure, highlighting the importance of keeping the cartilage endplate intact when evaluating disc failure mechanisms in vitro. Importantly, results from this study elucidated important fluid-based load-bearing mechanisms and fiber-matrix interactions that are important for understanding disease progression and regeneration in intervertebral discs. In conclusion, the methods presented in this study can be used in conjunction with experimental work to simultaneously investigate disc joint-, tissue-, and subtissue-level mechanics with degeneration, disease, and injury.
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Affiliation(s)
- Minhao Zhou
- Berkeley Biomechanics Laboratory, Department of Mechanical Engineering, University of California, Berkeley, Berkeley, CA, United States
| | - Shiyin Lim
- Berkeley Biomechanics Laboratory, Department of Mechanical Engineering, University of California, Berkeley, Berkeley, CA, United States
| | - Grace D. O’Connell
- Berkeley Biomechanics Laboratory, Department of Mechanical Engineering, University of California, Berkeley, Berkeley, CA, United States
- Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA, United States
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21
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Zhang S, Wang K, Zhu R, Jiang C, Niu W. Penguin Suit and Fetal Position Finite Element Model to Prevent Low Back Pain in Spaceflight. Aerosp Med Hum Perform 2021; 92:312-318. [PMID: 33875063 DOI: 10.3357/amhp.5740.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
BACKGROUND: This study aimed to investigate the biomechanical effects of different interventions on astronauts lumbar intervertebral discs in a microgravity environment during spaceflight and in a gravity environment when the astronaut returns.METHODS: A finite element model of the L4L5 lumbar segment was developed with eight loading schemes representing different interventions. The loading schemes included no intervention, wearing a penguin suit, sleeping in a fetal position, wearing a penguin suit combined with sleeping in the fetal position, reclining for 4 or 16 h/d, and maintaining upright posture for 4 or 16 h/d.RESULTS: Without intervention, the microgravity environment led to increased central pore pressure, radial displacement, and water content in the lumbar intervertebral disc. Wearing a penguin suit combined with sleeping in the fetal position can reduce disc pore pressure, axial stress, radial displacement, and water content to 0.156 MPa, 11.50 kPa, 0.538 mm, and 1.390%, respectively. When astronauts return to the gravity environment, staying upright for 4 h can reduce the pore pressure, axial stress, radial displacement, and water content of the intervertebral disc to 0.222 MPa, 10.72 kPa, 0.373 mm, and 0.219%, respectively.CONCLUSION: This study showed that wearing a penguin suit and sleeping in the fetal position both have the potential to protect the lumbar intervertebral disc from the negative effects caused by microgravity. Remaining in the upright posture for 4 h per day may help squeeze out the water in the intervertebral disc safely when astronauts return to the gravity environment.Zhang S, Wang K, Zhu R, Jiang C, Niu W. Penguin suit and fetal position finite element model to prevent low back pain in spaceflight. Aerosp Med Hum Perform. 2021; 92(5):312318.
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22
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Remus R, Lipphaus A, Neumann M, Bender B. Calibration and validation of a novel hybrid model of the lumbosacral spine in ArtiSynth-The passive structures. PLoS One 2021; 16:e0250456. [PMID: 33901222 PMCID: PMC8075237 DOI: 10.1371/journal.pone.0250456] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 04/07/2021] [Indexed: 12/04/2022] Open
Abstract
In computational biomechanics, two separate types of models have been used predominantly to enhance the understanding of the mechanisms of action of the lumbosacral spine (LSS): Finite element (FE) and musculoskeletal multibody (MB) models. To combine advantages of both models, hybrid FE-MB models are an increasingly used alternative. The aim of this paper is to develop, calibrate, and validate a novel passive hybrid FE-MB open-access simulation model of a ligamentous LSS using ArtiSynth. Based on anatomical data from the Male Visible Human Project, the LSS model is constructed from the L1-S1 rigid vertebrae interconnected with hyperelastic fiber-reinforced FE intervertebral discs, ligaments, and facet joints. A mesh convergence study, sensitivity analyses, and systematic calibration were conducted with the hybrid functional spinal unit (FSU) L4/5. The predicted mechanical responses of the FSU L4/5, the lumbar spine (L1-L5), and the LSS were validated against literature data from in vivo and in vitro measurements and in silico models. Spinal mechanical responses considered when loaded with pure moments and combined loading modes were total and intervertebral range of motions, instantaneous axes and centers of rotation, facet joint contact forces, intradiscal pressures, disc bulges, and stiffnesses. Undesirable correlations with the FE mesh were minimized, the number of crisscrossed collagen fiber rings was reduced to five, and the individual influences of specific anatomical structures were adjusted to in vitro range of motions. Including intervertebral motion couplings for axial rotation and nonlinear stiffening under increasing axial compression, the predicted kinematic and structural mechanics responses were consistent with the comparative data. The results demonstrate that the hybrid simulation model is robust and efficient in reproducing valid mechanical responses to provide a starting point for upcoming optimizations and extensions, such as with active skeletal muscles.
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Affiliation(s)
- Robin Remus
- Chair of Product Development, Department of Mechanical Engineering, Ruhr-University Bochum, Bochum, Germany
- * E-mail:
| | - Andreas Lipphaus
- Biomechanics Research Group, Chair of Product Development, Department of Mechanical Engineering, Ruhr-University Bochum, Bochum, Germany
| | - Marc Neumann
- Chair of Product Development, Department of Mechanical Engineering, Ruhr-University Bochum, Bochum, Germany
| | - Beate Bender
- Chair of Product Development, Department of Mechanical Engineering, Ruhr-University Bochum, Bochum, Germany
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Biomechanical effect of different plate-to-disc distance on surgical and adjacent segment in anterior cervical discectomy and fusion - a finite element analysis. BMC Musculoskelet Disord 2021; 22:340. [PMID: 33836709 PMCID: PMC8035773 DOI: 10.1186/s12891-021-04218-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 04/03/2021] [Indexed: 01/05/2023] Open
Abstract
Background The plate-to-disc distance (PDD) is an important factor affecting the degeneration of adjacent segments after anterior cervical discectomy and fusion (ACDF). However, the most suitable PDD is controversial. This study examined the adjacent intervertebral disc stress, bone graft stress, titanium plate stress and screw stress to evaluate the biomechanical effect of different PDD on surgical segment and adjacent segment following C5/C6 ACDF. Methods We constructed 10 preoperative finite element models of intact C4–C7 segments and validated them in the present study. We simulated ACDF surgery based on the 10 intact models in software. We designed three different distance of plate-to-disc titanium plates: long PDD (10 mm), medium PDD (5 mm) and short PDD (0 mm). The changes in C4/C5 and C6/C7 intervertebral disc stress, bone graft stress, titanium plate stress and screw stress were analyzed. Results The von Mises stress of C4/C5 and C6/C7 intervertebral discs had no significant differences (P > 0.05) in three different PDD groups. Titanium plate stress increased as the PDD decreased. The bone graft stress and screws stress decreased as the PDD decreased. The maximum stress of each part occurred was mostly in the conditions of rotation and lateral bending. Conclusions The PDD has no effect on adjacent intervertebral disc stress, but it is an important factor that affecting the bone graft stress, titanium plate stress and screws stress after ACDF. Shorter PDD plate can provide better stability to reduce stress on screws and bone graft, which may be helpful to prevent cage subsidence, pseudarthrosis and instrument failure. This can serve as a reference for clinical choice of plate.
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Nikkhoo M, Lu ML, Chen WC, Fu CJ, Niu CC, Lin YH, Cheng CH. Biomechanical Investigation Between Rigid and Semirigid Posterolateral Fixation During Daily Activities: Geometrically Parametric Poroelastic Finite Element Analyses. Front Bioeng Biotechnol 2021; 9:646079. [PMID: 33869156 PMCID: PMC8047206 DOI: 10.3389/fbioe.2021.646079] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 03/02/2021] [Indexed: 11/17/2022] Open
Abstract
While spinal fusion using rigid rods remains the gold standard treatment modality for various lumbar degenerative conditions, its adverse effects, including accelerated adjacent segment disease (ASD), are well known. In order to better understand the performance of semirigid constructs using polyetheretherketone (PEEK) in fixation surgeries, the objective of this study was to analyze the biomechanical performance of PEEK versus Ti rods using a geometrically patient-specific poroelastic finite element (FE) analyses. Ten subject-specific preoperative models were developed, and the validity of the models was evaluated with previous studies. Furthermore, FE models of those lumbar spines were regenerated based on postoperation images for posterolateral fixation at the L4–L5 level. Biomechanical responses for instrumented and adjacent intervertebral discs (IVDs) were analyzed and compared subjected to static and cyclic loading. The preoperative model results were well comparable with previous FE studies. The PEEK construct demonstrated a slightly increased range of motion (ROM) at the instrumented level, but decreased ROM at adjacent levels, as compared with the Ti. However, no significant changes were detected during axial rotation. During cyclic loading, disc height loss, fluid loss, axial stress, and collagen fiber strain in the adjacent IVDs were higher for the Ti construct when compared with the intact and PEEK models. Increased ROM, experienced stress in AF, and fiber strain at adjacent levels were observed for the Ti rod group compared with the intact and PEEK rod group, which can indicate the risk of ASD for rigid fixation. Similar to the aforementioned pattern, disc height loss and fluid loss were significantly higher at adjacent levels in the Ti rod group after cycling loading which alter the fluid–solid interaction of the adjacent IVDs. This phenomenon debilitates the damping quality, which results in disc disability in absorbing stress. Such finding may suggest the advantage of using a semirigid fixation system to decrease the chance of ASD.
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Affiliation(s)
- Mohammad Nikkhoo
- Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Meng-Ling Lu
- Bone and Joint Research Center, Chang Gung Memorial Hospital, Linkou, Taiwan.,Department of Orthopedic Surgery, Chang Gung Memorial Hospital, Kaohsiung, Taiwan
| | - Wen-Chien Chen
- Bone and Joint Research Center, Chang Gung Memorial Hospital, Linkou, Taiwan.,Department of Orthopedic Surgery, Chang Gung Memorial Hospital, Taoyuan, Taiwan
| | - Chen-Ju Fu
- Bone and Joint Research Center, Chang Gung Memorial Hospital, Linkou, Taiwan.,Division of Emergency and Critical Care Radiology, Chang Gung Memorial Hospital, Linkou, Taiwan
| | - Chi-Chien Niu
- Bone and Joint Research Center, Chang Gung Memorial Hospital, Linkou, Taiwan.,Department of Orthopedic Surgery, Chang Gung Memorial Hospital, Linkou, Taiwan
| | - Yang-Hua Lin
- School of Physical Therapy and Graduate Institute of Rehabilitation Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Chih-Hsiu Cheng
- Bone and Joint Research Center, Chang Gung Memorial Hospital, Linkou, Taiwan.,School of Physical Therapy and Graduate Institute of Rehabilitation Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan
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Castro APG. Computational Challenges in Tissue Engineering for the Spine. Bioengineering (Basel) 2021; 8:25. [PMID: 33671854 PMCID: PMC7918040 DOI: 10.3390/bioengineering8020025] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/04/2021] [Accepted: 02/13/2021] [Indexed: 12/17/2022] Open
Abstract
This paper deals with a brief review of the recent developments in computational modelling applied to innovative treatments of spine diseases. Additionally, it provides a perspective on the research directions expected for the forthcoming years. The spine is composed of distinct and complex tissues that require specific modelling approaches. With the advent of additive manufacturing and increasing computational power, patient-specific treatments have moved from being a research trend to a reality in clinical practice, but there are many issues to be addressed before such approaches become universal. Here, it is identified that the major setback resides in validation of these computational techniques prior to approval by regulatory agencies. Nevertheless, there are very promising indicators in terms of optimised scaffold modelling for both disc arthroplasty and vertebroplasty, powered by a decisive contribution from imaging methods.
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Affiliation(s)
- André P G Castro
- IDMEC, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
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26
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Wu W, Han Z, Hu B, Du C, Xing Z, Zhang C, Gao J, Shan B, Chen C. A graphical guide for constructing a finite element model of the cervical spine with digital orthopedic software. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:169. [PMID: 33569471 PMCID: PMC7867904 DOI: 10.21037/atm-20-2451] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Three-dimensional (3D) reconstruction and finite element analysis (FEA) have been extensively used to simulate cervical biomechanics. However, instructive articles providing full descriptions for operating Mimics software, Geomagic software, and FEA are rare in the literature. This omission has hindered research and development related to cervical spine biomechanics. Herein, we expound a detailed and easily understandable protocol for performing a digital biomechanics study which may facilitate a better understanding of the internal anatomy mechanics and the investigation of novel screw fixation techniques. We describe step-by-step instructions for use of Mimics and Geomagic software in FEA, along with a concise literature review. The key procedures of digital FEA stepwise instruction are presented, accompanied by a brief but complete report on the computed tomography (CT) imaging data for establishing the final finite element model. Previous publications regarding the commonly used software are also reviewed and discussed. Each piece of software performs a specific function for digital FEA establishment and each has its inherent shortcomings, making it is necessary to combine the software to leverage the advantages of each in order to best serve finite element research. For reasons of brevity, this study only provides an illustrative report on a small key part of finite element research in the cervical spine. These stepwise instructions can guide orthopedic researchers in conducting FEA studies in digital cervical biomechanics.
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Affiliation(s)
- Weidong Wu
- State Key Laboratory of Material Processing and Die and Mould Technology and School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, China.,Department of Orthopaedic Surgery, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Zhihua Han
- Trauma Center, Department of Orthopaedics and Traumatology, Shanghai General Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Bin Hu
- State Key Laboratory of Material Processing and Die and Mould Technology and School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, China
| | - Chun Du
- State Key Laboratory of Material Processing and Die and Mould Technology and School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, China
| | - Zehua Xing
- State Key Laboratory of Material Processing and Die and Mould Technology and School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, China
| | - Chao Zhang
- Department of Orthopaedic Surgery, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Jianqing Gao
- Department of Orthopaedic Surgery, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Bin Shan
- State Key Laboratory of Material Processing and Die and Mould Technology and School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, China
| | - Chun Chen
- Department of Orthopaedic Surgery, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
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Wang C, Shi Z. [Research progress in creep characteristics of lumbar intervertebral disc]. ZHONGGUO XIU FU CHONG JIAN WAI KE ZA ZHI = ZHONGGUO XIUFU CHONGJIAN WAIKE ZAZHI = CHINESE JOURNAL OF REPARATIVE AND RECONSTRUCTIVE SURGERY 2020; 34:1624-1629. [PMID: 33319547 DOI: 10.7507/1002-1892.202002167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Objective To summarize the research progress in creep characteristics of lumbar intervertebral disc. Methods The relevant literature at home and abroad was systematically searched. Then, the concept and structural basis of lumbar disc creep, the description of creep characteristics, and the latest progress of its influencing factors were summarized and analyzed. Results The intervertebral disc is viscoelastic. After loading, the deformation increases with time. However, the degree of increase is not linear with time. That is creep, which plays an important role in buffering the load generated by human activities and absorbing energy in order to maintain stable movement of the spine. Both experimental and simulation studies can well describe the creep behavior of intervertebral disc. Various models including standard linear solid model and corresponding constitutive equations can quantify and compare the creep characteristics, which can be obviously changed by the degeneration of intervertebral disc and the mode of loading stress. Conclusion Creep is an important mechanical properties of intervertebral discs, and an in-depth understanding of the creep characteristics of lumbar intervertebral discs is of great guiding significance for the intervention and treatment of low back pain.
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Affiliation(s)
- Chao Wang
- Department of Spine Surgery, Changhai Hospital Affiliated to Naval Medical University, Shanghai, 200433, P.R.China
| | - Zhicai Shi
- Department of Spine Surgery, Changhai Hospital Affiliated to Naval Medical University, Shanghai, 200433, P.R.China
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The Biomechanical Response of the Lower Cervical Spine Post Laminectomy: Geometrically-Parametric Patient-Specific Finite Element Analyses. J Med Biol Eng 2020. [DOI: 10.1007/s40846-020-00579-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Stadelmann MA, Stocker R, Maquer G, Hoppe S, Vermathen P, Alkalay RN, Zysset PK. Finite element models can reproduce the effect of nucleotomy on the multi-axial compliance of human intervertebral discs. Comput Methods Biomech Biomed Engin 2020; 23:934-944. [PMID: 32543225 DOI: 10.1080/10255842.2020.1773808] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Finite element (FE) models can unravel the link between intervertebral disc (IVD) degeneration and its mechanical behaviour. Nucleotomy may provide the data required for model verification. Three human IVDs were scanned with MRI and tested in multiple loading scenarios, prior and post nucleotomy. The resulting data was used to generate, calibrate, and verify the FE models. Nucleotomy increased the experimental range of motion by 26%, a result reproduced by the FE simulation within a 5% error. This work demonstrates the ability of FE models to reproduce the mechanical compliance of human IVDs prior and post nucleotomy.
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Affiliation(s)
- Marc A Stadelmann
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Roland Stocker
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Ghislain Maquer
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Sven Hoppe
- Department of Orthopedic Surgery, Bern University Hospital, Bern, Switzerland
| | - Peter Vermathen
- Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Ron N Alkalay
- Center for Advanced Orthopedic Studies, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | - Philippe K Zysset
- Department of Orthopedic Surgery, Bern University Hospital, Bern, Switzerland
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Mörl F, Günther M, Riede JM, Hammer M, Schmitt S. Loads distributed in vivo among vertebrae, muscles, spinal ligaments, and intervertebral discs in a passively flexed lumbar spine. Biomech Model Mechanobiol 2020; 19:2015-2047. [DOI: 10.1007/s10237-020-01322-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 03/18/2020] [Indexed: 01/09/2023]
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Internal load-sharing in the human passive lumbar spine: Review of in vitro and finite element model studies. J Biomech 2020; 102:109441. [DOI: 10.1016/j.jbiomech.2019.109441] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 10/13/2019] [Accepted: 10/14/2019] [Indexed: 01/08/2023]
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32
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Zhou M, Werbner B, O'Connell G. Historical Review of Combined Experimental and Computational Approaches for Investigating Annulus Fibrosus Mechanics. J Biomech Eng 2020; 142:030802. [PMID: 32005986 DOI: 10.1115/1.4046186] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Indexed: 07/25/2024]
Abstract
Intervertebral disc research has sought to develop a deeper understanding of spine biomechanics, the complex relationship between disc health and back pain, and the mechanisms of spinal injury and repair. To do so, many researchers have focused on characterizing tissue-level properties of the disc, where the roles of tissue subcomponents can be more systematically investigated. Unfortunately, experimental challenges often limit the ability to measure important disc tissue- and subtissue-level behaviors, including fiber-matrix interactions, transient nutrient and electrolyte transport, and damage propagation. Numerous theoretical and numerical modeling frameworks have been introduced to explain, complement, guide, and optimize experimental research efforts. The synergy of experimental and computational work has significantly advanced the field, and these two aspects have continued to develop independently and jointly. Meanwhile, the relationship between experimental and computational work has become increasingly complex and interdependent. This has made it difficult to interpret and compare results between experimental and computational studies, as well as between solely computational studies. This paper seeks to explore issues of model translatability, robustness, and efficient study design, and to propose and motivate potential future directions for experimental, computational, and combined tissue-level investigations of the intervertebral disc.
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Affiliation(s)
- Minhao Zhou
- Mechanical Engineering Department, University of California, Berkeley, 2162 Etcheverry Hall, #1740, Berkeley, CA 94720-1740
| | - Benjamin Werbner
- Mechanical Engineering Department, University of California, Berkeley, 2162 Etcheverry Hall, #1740, Berkeley, CA 94720-1740
| | - Grace O'Connell
- Mechanical Engineering Department, University of California, Berkeley, 5122 Etcheverry Hall, #1740, Berkeley, CA 94720-1740; Department of Orthopaedic Surgery, University of California, San Francisco, 513 Parnassus Ave., Suite S-1161, San Francisco, CA 94143
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Population-based design and 3D finite element analysis of transforaminal thoracic interbody fusion cages. J Orthop Translat 2020; 21:35-40. [PMID: 32071873 PMCID: PMC7013106 DOI: 10.1016/j.jot.2019.12.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Revised: 12/12/2019] [Accepted: 12/16/2019] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE To compare the biomechanical characteristics of two transforaminal thoracic interbody fusion cages based on the Chinese population thoracic anatomy. METHOD Computed tomography scans of the thoracic spine of 150 patients from our institution were collected and analysed. Two cages were designed based on the anatomical parameters of these patients. Further, we used 3D finite element analysis models to compare the stability of two cages by using Mimics 17.0 and ANSYS 15.0 software. RESULT Two kinds of thoracic cages (box and kidney-shaped) were designed. Under the displacement working condition, the two new fusion cages could achieve immediate postoperative stability, but the kidney-shaped cage was better than the box-shaped cage. Under the stress working condition, no highly focused stress area was found in either cages, but the kidney-shaped cage experienced less stress than the box-shaped cage. CONCLUSION The kidney-shaped cage is more stable and experiences lesser stress than the box-shaped cage after thoracic intervertebral fusion, and it is more suitable for Chinese transforaminal thoracic interbody fusion. THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE This article is about thoracic fusion cage design and finite element analysis (FEA) analysis based on the thoracic anatomy parameters. For there is currently no suitable thoracic fusion cage for transforaminal thoracic interbody fusion, the results in this article may have the potential of transferring the two designed cages into clinical use.
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Material properties of human lumbar intervertebral discs across strain rates. Spine J 2019; 19:2013-2024. [PMID: 31326631 DOI: 10.1016/j.spinee.2019.07.012] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2019] [Revised: 07/16/2019] [Accepted: 07/17/2019] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT The use of finite element (FE) methods to study the biomechanics of the intervertebral disc (IVD) has increased over recent decades due to their ability to quantify internal stresses and strains throughout the tissue. Their accuracy is dependent upon realistic, strain-rate dependent material properties, which are challenging to acquire. PURPOSE The aim of this study was to use the inverse FE technique to characterize the material properties of human lumbar IVDs across strain rates. STUDY DESIGN A human cadaveric experimental study coupled with an inverse finite element study. METHODS To predict the structural response of the IVD accurately, the material response of the constituent structures was required. Therefore, compressive experiments were conducted on 16 lumbar IVDs (39±19 years) to obtain the structural response. An FE model of each of these experiments was developed and then run through an inverse FE algorithm to obtain subject-specific constituent material properties, such that the structural response was accurate. RESULTS Experimentally, a log-linear relationship between IVD stiffness and strain rate was observed. The material properties obtained through the subject-specific inverse FE optimization of the annulus fibrosus (AF) fiber and AF fiber ground matrix allowed a good match between the experimental and FE response. This resulted in a Young modulus of AF fibers (-MPa) to strain rate (ε˙, /s) relationship of YMAF=31.5ln(ε˙)+435.5, and the C10 parameter of the Neo-Hookean material model of the AF ground matrix was found to be strain-rate independent with an average value of 0.68 MPa. CONCLUSIONS These material properties can be used to improve the accuracy, and therefore predictive ability of FE models of the spine that are used in a wide range of research areas and clinical applications. CLINICAL SIGNIFICANCE Finite element models can be used for many applications including investigating low back pain, spinal deformities, injury biomechanics, implant design, design of protective systems, and degenerative disc disease. The accurate material properties obtained in this study will improve the predictive ability, and therefore clinical significance of these models.
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Finite Element Based-Analysis for Pre and Post Lumbar Fusion of Adult Degenerative Scoliosis Patients. Spine Deform 2019; 7:543-552. [PMID: 31202369 DOI: 10.1016/j.jspd.2018.11.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 10/01/2018] [Accepted: 11/12/2018] [Indexed: 11/20/2022]
Abstract
STUDY DESIGN Pre-post cohort finite elements (FE). OBJECTIVES To investigate the effect of adjacent load transfer pre and post fusion surgery of lumbar scoliotic spines using FE models. SUMMARY OF BACKGROUND DATA Adult degenerative scoliosis (ADS) results from age-related changes, leading to segmental instability, deformity, and stenosis. FE study is capable of capturing the biomechanical parameters internal to the bones and connective soft tissues of the spine, which is difficult to measure by experimental approaches. Literature that describes the underlying mechanisms responsible for spinal fusion in scoliosis patients is limited, and FE study with larger subject sample size should be conducted. METHODS Twenty three-dimensional nonlinear FE models of the lumbosacral spine were created from pre (Cobb angle: 28.1° ± 10.5°) and post scoliosis surgery in vivo CT scans. During surgery, pedicle screws and rods were implanted at lumbar and sacral levels. A compressive load and six different moments (flexion, extension, right lateral bending, left lateral bending, right axial rotation, left axial rotation) were applied to the top level of each model. Outcome measures were range of motion (RoM), intradiscal pressure (IDP), and facet joint forces (FJF). Spinal fusion did alter the mechanical function of the scoliotic spine. RESULTS Scoliotic spine presented abnormal and asymmetrical kinetic and kinematic behavior. RoM: At the adjacent level, spinal fusion surgery produced a statically significantly increased left and right later bending intersegmental rotation (p < .006) in comparison to presurgical scoliosis models. At the fused level, spinal fusion surgery produced a statically significantly reduced intersegmental rotation in all the loading conditions (p = .001) in comparison to presurgical scoliosis models. IDP: At the fused level, spinal fusion surgery produced a much lower IDP in all of the loading conditions (p = .001). FJF: At the adjacent level, spinal fusion surgery produced a considerably larger left lateral rotation FJF (p = .001) in comparison to presurgical scoliosis models. At the fused level, spinal fusion surgery produced considerably lower FJF in all the loading conditions (p = .001) in comparison to presurgical scoliosis models. CONCLUSIONS This study was the first to investigate the effect of adjacent load transfer before and after fusion surgery using in vivo CT scans of 10 scoliotic spines. A posterior fusion has only a minor effect on mechanical behavior and a large effect on pressure and forces at the adjacent level. As expected, a large effect in the kinematics and kinetics was found at the fused level. LEVEL OF EVIDENCE Level 3.
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Xu M, Yang J, Lieberman IH, Haddas R. Finite element method-based study of pedicle screw–bone connection in pullout test and physiological spinal loads. Med Eng Phys 2019; 67:11-21. [PMID: 30879945 DOI: 10.1016/j.medengphy.2019.03.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 01/21/2019] [Accepted: 03/02/2019] [Indexed: 12/25/2022]
Affiliation(s)
- Ming Xu
- Human-Centric Design Research Lab, Department of Mechanical Engineering, Texas Tech University, Lubbock, TX, USA
| | - James Yang
- Human-Centric Design Research Lab, Department of Mechanical Engineering, Texas Tech University, Lubbock, TX, USA.
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Fan W, Guo LX. The influence of bilateral pedicle screw fixation on vibration response of the disc degenerated human lumbar spine: A finite element stress analysis. Technol Health Care 2019; 27:441-450. [PMID: 31033465 DOI: 10.3233/thc-181273] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Very few studies have evaluated biomechanical characteristics of the disc degenerated human lumbar spine after bilateral pedicle screw fixation (BPSF) under whole body vibration (WBV) that is typically present in vehicles. OBJECTIVE To examine the influence of BPSF on stress responses of the disc degenerated human lumbar spine to WBV using finite element (FE) method. METHODS Two previously validated L1-S1 FE models with different grades of disc degeneration (mild and moderate) at L4-L5 were employed, and the two degenerated models were instrumented with bilateral pedicle screws and rods across the L4-L5 level, respectively. Transit dynamic analyses were performed on all these models under a 400 N compressive follower preload and a 40 N sinusoidal vertical vibration load. Intradiscal pressure (IDP) and von Mises stress (VMS) of the annulus ground substance in all disc levels of the degenerated models and the corresponding implanted models were recorded and compared. RESULTS BPSF decreased maximum response values and vibration amplitudes of the IDP and annulus VMS in both the degenerated and adjacent levels of the lumbar spine. CONCLUSIONS Application of the BPSF system is helpful in prevention of further injury of the disc degenerated lumbar spine during WBV.
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Nikkhoo M, Cheng CH, Wang JL, Khoz Z, El-Rich M, Hebela N, Khalaf K. Development and validation of a geometrically personalized finite element model of the lower ligamentous cervical spine for clinical applications. Comput Biol Med 2019; 109:22-32. [PMID: 31035068 DOI: 10.1016/j.compbiomed.2019.04.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 04/14/2019] [Accepted: 04/14/2019] [Indexed: 11/17/2022]
Abstract
Epidemiological and clinical studies show that the magnitude and scope of cervical disease are on the rise, along with the world's rising aging population. From a biomechanical perspective, the cervical spine presents a wide inter-individual variability, where its motion patterns and load sharing strongly depend on the anatomy. This study aimed to first develop and validate a geometrically patient-specific model of the lower cervical spine for clinical applications, and secondly to use the model to investigate the spinal biomechanics associated with typical cervical disorders. Based on measurements of 30 parameters from X-ray radiographs, the 3D geometry of the vertebrae and intervertebral discs (IVDs) were developed, and detailed finite element models (FEMs) of the lower ligamentous cervical spine for 6 subjects were constructed and simulated. The models were then used for the investigation of different grades of IVD alteration. The multi directional range of motion (ROM) results were in alignment with the in-vitro and in-Silico studies confirming the validity of the model. Severe disc alteration (Grade 3) presented a significant decrease in the ROM and intradiscal pressure (flexion, extension, and axial rotation) on the C5-C6 and slightly increase on the adjacent levels. Maximum stress in Annulus Fibrosus (AF) and facet joint forces increased for Grade 3 for both altered and adjacent levels. The novel validated geometrically-personalized FEM presented in this study potentially offers the clinical community a valuable quantitative tool for the noninvasive analyses of the biomechanical alterations associated with cervical spine disease towards improved surgical planning and enhanced clinical outcomes.
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Affiliation(s)
- Mohammad Nikkhoo
- Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran.
| | - Chih-Hsiu Cheng
- School of Physical Therapy and Graduate Institute of Rehabilitation Science, Chang Gung University, Taoyuan, Taiwan, ROC
| | - Jaw-Lin Wang
- Institute of Biomedical Engineering, College of Medicine and Engineering, National Taiwan University, Taipei, Taiwan, ROC
| | - Zahra Khoz
- Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Marwan El-Rich
- Department of Mechanical Engineering, Khalifa University, Abu Dhabi, United Arab Emirates
| | - Nader Hebela
- Orthopaedic Spine Surgery, Neurological Institute, Cleveland Clinic Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Kinda Khalaf
- Department of Biomedical Engineering, Khalifa University of Science and Technology, Health Engineering Innovation Centre, Abu Dhabi, United Arab Emirates
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Michalek AJ. A growth-based model for the prediction of fiber angle distribution in the intervertebral disc annulus fibrosus. Biomech Model Mechanobiol 2019; 18:1363-1369. [PMID: 30980210 DOI: 10.1007/s10237-019-01150-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 04/08/2019] [Indexed: 10/27/2022]
Abstract
There is a growing interest in the development of patient-specific finite element models of the human lumbar spine for both the assessment of injury risk and the development of treatment strategies. A current challenge in implementing these models is that the outer annulus fibrosus of the disc is composed of concentric sheets of aligned collagen fibers, the helical angles of which vary spatially. In finite element models, fiber angle is typically assumed to be constant, based on average experimental measurements from a small number of locations. The present study hypothesized that the full spatial distribution of fiber angles in the annulus fibrosus may be predicted for any disc geometry by assuming growth from a thin cylinder with constant fiber angle. This hypothesis was tested by developing an analytical model of disc growth and calibrating it with fiber angle measurements of adult bovine caudal discs. The calibrated model was then run on a representative human lumbar disc geometry. The model was able to accurately predict fiber angle distributions in both the experimental bovine caudal disc measurements and literature-reported human lumbar disc measurements. Despite its theoretical basis in development, the model requires only mature state geometry, making it practical for implementation in patient-specific finite element analyses, in which disc geometry is obtained from clinical imaging.
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Affiliation(s)
- Arthur J Michalek
- Department of Mechanical and Aeronautical Engineering, Clarkson University, 8 Clarkson Ave, Box 5725, Potsdam, NY, 13699, USA.
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Yang B, Lu Y, Um C, O'Connell G. Relative Nucleus Pulposus Area and Position Alters Disc Joint Mechanics. J Biomech Eng 2019; 141:2727815. [PMID: 30835267 DOI: 10.1115/1.4043029] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Indexed: 01/08/2023]
Abstract
Aging and degeneration of the intervertebral disc are noted by changes in tissue composition and geometry, including a decrease in nucleus pulposus (NP) area. The NP centroid is positioned slightly posterior of the disc's centroid, but the effect of NP size and location on disc joint mechanics is not well understood. We evaluated the effect of NP size and centroid location on disc joint mechanics under dual-loading modalities (i.e., compression in combination with axial rotation or bending). A finite element model was developed to vary the relative NP area (NP:Disc area ratio range = 0.21 - 0.60). We also evaluated the effect of NP position by shifting the NP centroid anteriorly and posteriorly. Our results showed that compressive stiffness and average first principal strains increased with NP size. Under axial compression, stresses are distributed from the NP to the annulus, and stresses were redistributed towards the NP with axial rotation. Moreover, peak stresses were greater for discs with a smaller NP area. NP centroid location had a greater impact on intradiscal pressure during flexion and extension, where peak pressures in the posterior annulus under extension was greater for discs with a more posteriorly situated NP. In conclusion, the findings from this study highlight the importance of closely mimicking NP size and location in computational models that aim to understand stress/strain distribution during complex loading and for developing repair strategies that aim to recapitulate the mechanical behavior of healthy discs.
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Affiliation(s)
- Bo Yang
- Department of Mechanical Engineering, University of California Berkeley, Etcheverry Hall, Berkeley, CA, 94720
| | - Yintong Lu
- Department of Mathematics, University of California Berkeley, Evans Hall, Berkeley, CA, 94720
| | - Colin Um
- Department of Mechanical Engineering, University of California Berkeley, Etcheverry Hall, Berkeley, CA, 94720
| | - Grace O'Connell
- Department of Mechanical Engineering, University of California Berkeley, Etcheverry Hall, Berkeley, CA, 94720; Department of Orthopaedic Surgery, University of California, San Francisco
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Effect of impact velocity and ligament mechanical properties on lumbar spine injuries in posterior-anterior impact loading conditions: a finite element study. Med Biol Eng Comput 2019; 57:1381-1392. [DOI: 10.1007/s11517-019-01964-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 02/20/2019] [Indexed: 12/14/2022]
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Xu M, Yang J, Lieberman I, Haddas R. Stress distribution in vertebral bone and pedicle screw and screw–bone load transfers among various fixation methods for lumbar spine surgical alignment: A finite element study. Med Eng Phys 2019; 63:26-32. [DOI: 10.1016/j.medengphy.2018.10.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 08/14/2018] [Accepted: 10/08/2018] [Indexed: 10/28/2022]
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Sampson SL, Sylvia M, Fields AJ. Effects of dynamic loading on solute transport through the human cartilage endplate. J Biomech 2018; 83:273-279. [PMID: 30554819 DOI: 10.1016/j.jbiomech.2018.12.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Revised: 11/07/2018] [Accepted: 12/03/2018] [Indexed: 12/29/2022]
Abstract
Nutrient and metabolite transport through the cartilage endplate (CEP) is important for maintaining proper disc nutrition, but the mechanisms of solute transport remain unclear. One unresolved issue is the role of dynamic loading. In comparison to static loading, dynamic loading is thought to enhance transport by increasing convection. However, the CEP has a high resistance to fluid flow, which could limit solute convection. Here we measure solute transport through site-matched cadaveric human lumbar CEP tissues under static vs. dynamic loading, and we determine how the degree of transport enhancement from dynamic loading depends on CEP porosity and solute size. We found that dynamic loading significantly increased small and large solute transport through the CEP: on average, dynamic loading increased the transport of sodium fluorescein (376 Da) by a factor of 1.85 ± 0.64 and the transport of a large dextran (4000 Da) by a factor of 4.97 ± 3.05. Importantly, CEP porosity (0.65 ± 0.07; range: 0.47-0.76) strongly influenced the degree of transport enhancement. Specifically, for both solutes, transport enhancement was greater for CEPs with low porosity than for CEPs with high porosity. This is because the CEPs with low porosity were susceptible to larger improvements in fluid flow under dynamic loading. The CEP becomes less porous and less hydrated with aging and as disc degeneration progresses. Together, these findings suggest that as those changes occur, dynamic loading has a greater effect on solute transport through the CEP compared to static loading, and thus may play a larger role in disc nutrition.
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Affiliation(s)
- Sara L Sampson
- Department of Orthopaedic Surgery, University of California, San Francisco, CA, USA
| | - Meghan Sylvia
- Department of Orthopaedic Surgery, University of California, San Francisco, CA, USA
| | - Aaron J Fields
- Department of Orthopaedic Surgery, University of California, San Francisco, CA, USA.
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Finite Element Investigation of the Effects of the Low-Frequency Vibration Generated by Vehicle Driving on the Human Lumbar Mechanical Properties. BIOMED RESEARCH INTERNATIONAL 2018; 2018:7962414. [PMID: 30364013 PMCID: PMC6186348 DOI: 10.1155/2018/7962414] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 09/05/2018] [Accepted: 09/16/2018] [Indexed: 11/17/2022]
Abstract
Long-term exposure to low-frequency vibration generated by vehicle driving impairs human lumbar spine health. However, few studies have investigated how low-frequency vibration affects human lumbar mechanical properties. This study established a poroelastic finite element model of human lumbar spinal segments L2–L3 to perform time-dependent vibrational simulation analysis and investigated the effects of different vibrational frequencies generated by normal vehicle driving on the lumbar mechanical properties in one hour. Analysis results showed that vibrational load caused more injury to lumbar health than static load, and vibration at the resonant frequency generated the most serious injury. The axial effective stress and the radial displacement in the intervertebral disc, as well as the fluid loss in the nucleus pulposus, increased, whereas the pore pressure in the nucleus pulposus decreased with increased vibrational frequency under the same vibrational time, which may aggravate the injury degree of human lumbar spine. Therefore, long-term driving on a well-paved road also induces negative effects on human lumbar spine health. When driving on a nonpaved road or operating engineering machinery under poor navigating condition, the auto seat transmits relatively high vibrational frequency, which is highly detrimental to the lumbar spine health of a driver.
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Bashkuev M, Reitmaier S, Schmidt H. Effect of disc degeneration on the mechanical behavior of the human lumbar spine: a probabilistic finite element study. Spine J 2018; 18:1910-1920. [PMID: 29886164 DOI: 10.1016/j.spinee.2018.05.046] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 05/28/2018] [Accepted: 05/31/2018] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Intervertebral disc degeneration has been subject to numerous in vivo and in vitro investigations and numerical studies during recent decades, reporting partially contradictory findings. However, most of the previous studies were limited in the number of specimens investigated and, therefore, could not consider the vast variety of the specimen geometries, which are likely to strongly influence the mechanical behavior of the spine. PURPOSE To complement the understanding of the mechanical consequences of disc degeneration, whereas considering natural variations in the major spinal geometrical parameters. DESIGN/SETTING A probabilistic finite element study. METHODS A parametric finite element model of a human L4-L5 motion segment considering 40 geometrical parameters was developed. One thousand individual geometries comprising four degeneration grades were generated in a probabilistic manner, and the influence of the severity of disc degeneration on the mechanical response of the motion segment to different loading conditions was statistically evaluated. RESULTS Variations in the individual structural parameters resulted in marked variations in all evaluated parameters within each degeneration grade. Nevertheless, the effect of degeneration in almost all evaluated response values was statistically significant. With degeneration, the intradiscal pressure progressively decreased. At the same time, the facet loads increased and the ligament tension was reduced. The initially nonlinear load-deformation relationships became linear whereas the segment stiffness increased. CONCLUSIONS Results indicate significant stiffening of the motion segment with progressing degeneration and gradually increasing loading of the facets from nondegenerated to moderately degenerated conditions along with a significant reduction of the ligament tension in flexion.
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Affiliation(s)
- Maxim Bashkuev
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Julius Wolff Institut, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Sandra Reitmaier
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Julius Wolff Institut, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Hendrik Schmidt
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Julius Wolff Institut, Augustenburger Platz 1, 13353 Berlin, Germany.
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Thorpe AA, Bach FC, Tryfonidou MA, Le Maitre CL, Mwale F, Diwan AD, Ito K. Leaping the hurdles in developing regenerative treatments for the intervertebral disc from preclinical to clinical. JOR Spine 2018; 1:e1027. [PMID: 31463447 PMCID: PMC6686834 DOI: 10.1002/jsp2.1027] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 06/07/2018] [Accepted: 06/28/2018] [Indexed: 12/11/2022] Open
Abstract
Chronic back and neck pain is a prevalent disability, often caused by degeneration of the intervertebral disc. Because current treatments for this condition are less than satisfactory, a great deal of effort is being applied to develop new solutions, including regenerative strategies. However, the path from initial promising idea to clinical use is fraught with many hurdles to overcome. Many of the keys to success are not necessarily linked to science or innovation. Successful translation to clinic will also rely on planning and awareness of the hurdles. It will be essential to plan your entire path to clinic from the outset and to do this with a multidisciplinary team. Take advice early on regulatory aspects and focus on generating the proof required to satisfy regulatory approval. Scientific demonstration and societal benefits are important, but translation cannot occur without involving commercial parties, which are instrumental to support expensive clinical trials. This will only be possible when intellectual property can be protected sufficiently to support a business model. In this manner, commercial, societal, medical, and scientific partners can work together to ultimately improve patient health. Based on literature surveys and experiences of the co-authors, this opinion paper presents this pathway, highlights the most prominent issues and hopefully will aid in your own translational endeavors.
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Affiliation(s)
- Abbey A. Thorpe
- Biomolecular Sciences Research CentreSheffield Hallam UniversitySheffieldUK
| | - Frances C. Bach
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary MedicineUtrecht UniversityUtrechtthe Netherlands
| | - Marianna A. Tryfonidou
- Department of Clinical Sciences of Companion Animals, Faculty of Veterinary MedicineUtrecht UniversityUtrechtthe Netherlands
| | | | - Fackson Mwale
- Department of SurgeryMcGill UniversityMontrealCanada
| | - Ashish D. Diwan
- Spine Service, Department of Orthopaedic SurgerySt. George & Sutherland Clinical School, University of New South WalesSydneyAustralia
| | - Keita Ito
- Orthopaedic Biomechanics Division, Department of Biomedical EngineeringEindhoven University of TechnologyEindhoventhe Netherlands
- Department of OrthopedicsUniversity Medical Centre UtrechtUtrechtthe Netherlands
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Fan W, Guo LX. The Role of Posterior Screw Fixation in Single-Level Transforaminal Lumbar Interbody Fusion During Whole Body Vibration: A Finite Element Study. World Neurosurg 2018; 114:e1086-e1093. [DOI: 10.1016/j.wneu.2018.03.150] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 03/21/2018] [Accepted: 03/21/2018] [Indexed: 01/09/2023]
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Stadelmann MA, Maquer G, Voumard B, Grant A, Hackney DB, Vermathen P, Alkalay RN, Zysset PK. Integrating MRI-based geometry, composition and fiber architecture in a finite element model of the human intervertebral disc. J Mech Behav Biomed Mater 2018; 85:37-42. [PMID: 29843094 DOI: 10.1016/j.jmbbm.2018.05.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 04/18/2018] [Accepted: 05/03/2018] [Indexed: 10/16/2022]
Abstract
Intervertebral disc degeneration is a common disease that is often related to impaired mechanical function, herniations and chronic back pain. The degenerative process induces alterations of the disc's shape, composition and structure that can be visualized in vivo using magnetic resonance imaging (MRI). Numerical tools such as finite element analysis (FEA) have the potential to relate MRI-based information to the altered mechanical behavior of the disc. However, in terms of geometry, composition and fiber architecture, current FE models rely on observations made on healthy discs and might therefore not be well suited to study the degeneration process. To address the issue, we propose a new, more realistic FE methodology based on diffusion tensor imaging (DTI). For this study, a human disc joint was imaged in a high-field MR scanner with proton-density weighted (PD) and DTI sequences. The PD image was segmented and an anatomy-specific mesh was generated. Assuming accordance between local principal diffusion direction and local mean collagen fiber alignment, corresponding fiber angles were assigned to each element. Those element-wise fiber directions and PD intensities allowed the homogenized model to smoothly account for composition and fibrous structure of the disc. The disc's in vitro mechanical behavior was quantified under tension, compression, flexion, extension, lateral bending and rotation. The six resulting load-displacement curves could be replicated by the FE model, which supports our approach as a first proof of concept towards patient-specific disc modeling.
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Affiliation(s)
- Marc A Stadelmann
- Institute of Surgical Technology and Biomechanics, University of Bern, Bern, Switzerland.
| | - Ghislain Maquer
- Institute of Surgical Technology and Biomechanics, University of Bern, Bern, Switzerland
| | - Benjamin Voumard
- Institute of Surgical Technology and Biomechanics, University of Bern, Bern, Switzerland
| | - Aaron Grant
- Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, USA
| | - David B Hackney
- Department of Radiology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, USA
| | - Peter Vermathen
- Departments of Radiology and Clinical Research, Inselspital, University of Bern, Bern, Switzerland
| | - Ron N Alkalay
- Center for Advanced Orthopedic Studies, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, USA
| | - Philippe K Zysset
- Institute of Surgical Technology and Biomechanics, University of Bern, Bern, Switzerland
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Bohl MA, Mooney MA, Repp GJ, Cavallo C, Nakaji P, Chang SW, Turner JD, Kakarla UK. The Barrow Biomimetic Spine: Comparative Testing of a 3D-Printed L4-L5 Schwab Grade 2 Osteotomy Model to a Cadaveric Model. Cureus 2018; 10:e2491. [PMID: 29922532 PMCID: PMC6003793 DOI: 10.7759/cureus.2491] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Introduction The Barrow Biomimetic Spine project is an ongoing effort to develop a three-dimensional (3D)-printed synthetic spine model with high anatomical and biomechanical fidelity to human tissue. The purpose of this study was to evaluate the biomechanical performance of an L4-L5 3D-printed synthetic spine model in a lordotic correction test after Schwab grade 2 osteotomies as compared to human cadaveric spines that have undergone the same osteotomies and lordotic correction. Methods Ten different L4-L5 synthetic spine models were 3D printed. Each print varied in either the material used for the soft tissue components, the infill density of the bony and soft tissue structures, the pre-correction disc height, or the model orientation on the print bed. Each print was instrumented with pedicle screws and underwent a Schwab grade 2 osteotomy. Changes in disc height measurements and end-plate angle were compared against cadaveric data acquired using the same study method. Results A simple linear correlation analysis demonstrated that for horizontally printed models using PolyFlex (Polymaker, New York, NY, USA)(models 1-3, 8, 10), the pre-correction posterior disc height and lordotic correction were moderately correlated (r = 0.56), but this correlation did not achieve statistical significance (P = 0.12). Regression analysis demonstrated a very strong correlation between lordotic correction and change in posterior disc height (r = 0.92, P < 0.001). Models printed either vertically (models 4-6) or with low bone density and high soft tissue density (model 10) appeared to perform the most similarly to the cadaveric tissue. Discussion The 3D-printed synthetic spine models demonstrated predictable and reliable performance in a lordotic correction test based on their respective material qualities and print densities. The print variables tested further demonstrated that this model is capable of achieving high biomechanical fidelity to cadaveric tissue when subjected to the same lordotic correction test after Schwab grade 2 osteotomies.
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Affiliation(s)
- Michael A Bohl
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, USA
| | - Michael A Mooney
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, USA
| | - Garrett J Repp
- Biomedical Engineering, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, USA
| | - Claudio Cavallo
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, USA
| | - Peter Nakaji
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, USA
| | - Steve W Chang
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, USA
| | - Jay D Turner
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, USA
| | - U Kumar Kakarla
- Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, USA
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Yang B, O'Connell GD. Swelling of fiber-reinforced soft tissues is affected by fiber orientation, fiber stiffness, and lamella structure. J Mech Behav Biomed Mater 2018; 82:320-328. [PMID: 29653381 DOI: 10.1016/j.jmbbm.2018.03.039] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 03/13/2018] [Accepted: 03/29/2018] [Indexed: 01/13/2023]
Abstract
Native and engineered fiber-reinforced tissues are composites comprised of stiff collagen fibers embedded within an extrafibrillar matrix that is capable of swelling by absorbing water molecules. Tissue swelling is important for understanding stress distributions between collagen fibers and extrafibrillar matrix, as well as for understanding mechanisms of tissue failure. The swelling behavior of fiber-reinforced tissues in the musculoskeletal system has been largely attributed to the glycosaminoglycan content. Recent work demonstrated anisotropy in the swelling response of the annulus fibrosus in the intervertebral disc. It is well known that collagen fiber orientation affects elastic behavior, but the effect of collagen fiber network on tissue swelling behavior is not well understood. In this study, we developed three series of models to evaluate the effect of collagen fiber orientation, fiber network architecture (i.e., single or multi-fiber families within a layer), and fiber stiffness on bulk tissue swelling, which was simulated by describing the extrafibrillar matrix as a triphasic material, as proposed by Lai et al. Model results were within one standard deviation of reported mean values for changes in tissue volume, width, and thickness under free swelling conditions. The predicted swelling response of single-fiber family structures was highly dependent on fiber orientation and the number of lamellae in the bulk tissue. Moreover, matrix swelling resulted in tissue to twist, which reduced fiber deformations, demonstrating a balance between fiber deformation and matrix swelling. Large changes in fiber stiffness (20 × increase) had a relatively small effect on tissue swelling (~ 2% decrease in swelling). In conclusion, fiber angle, fiber architecture (defined as single- versus multiple fiber families in a layer), and the number of layers in a single fiber family structure directly affected tissue swelling behavior, including fiber stretch, fiber reorientation, and tissue deformation. These findings support the need to develop computational models that closely mimic the native architecture in order to understand mechanisms of stress distributions and tissue failure.
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Affiliation(s)
- Bo Yang
- Department of Mechanical Engineering, University of California, Berkeley, United States
| | - Grace D O'Connell
- Department of Mechanical Engineering, University of California, Berkeley, United States; Department of Orthopaedic Surgery, University of California, San Francisco, United States.
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