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Buchweitz N, Sun Y, Cisewski Porto S, Kelley J, Niu Y, Wang S, Meng Z, Reitman C, Slate E, Yao H, Wu Y. Regional structure-function relationships of lumbar cartilage endplates. J Biomech 2024; 169:112131. [PMID: 38739987 PMCID: PMC11182561 DOI: 10.1016/j.jbiomech.2024.112131] [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: 03/01/2024] [Revised: 04/17/2024] [Accepted: 05/02/2024] [Indexed: 05/16/2024]
Abstract
Cartilage endplates (CEPs) act as protective mechanical barriers for intervertebral discs (IVDs), yet their heterogeneous structure-function relationships are poorly understood. This study addressed this gap by characterizing and correlating the regional biphasic mechanical properties and biochemical composition of human lumbar CEPs. Samples from central, lateral, anterior, and posterior portions of the disc (n = 8/region) were mechanically tested under confined compression to quantify swelling pressure, equilibrium aggregate modulus, and hydraulic permeability. These properties were correlated with CEP porosity and glycosaminoglycan (s-GAG) content, which were obtained by biochemical assays of the same specimens. Both swelling pressure (142.79 ± 85.89 kPa) and aggregate modulus (1864.10 ± 1240.99 kPa) were found to be regionally dependent (p = 0.0001 and p = 0.0067, respectively) in the CEP and trended lowest in the central location. No significant regional dependence was observed for CEP permeability (1.35 ± 0.97 * 10-16 m4/Ns). Porosity measurements correlated significantly with swelling pressure (r = -0.40, p = 0.0227), aggregate modulus (r = -0.49, p = 0.0046), and permeability (r = 0.36, p = 0.0421), and appeared to be the primary indicator of CEP biphasic mechanical properties. Second harmonic generation microscopy also revealed regional patterns of collagen fiber anchoring, with fibers inserting the CEP perpendicularly in the central region and at off-axial directions in peripheral regions. These results suggest that CEP tissue has regionally dependent mechanical properties which are likely due to the regional variation in porosity and matrix structure. This work advances our understanding of healthy baseline endplate biomechanics and lays a groundwork for further understanding the role of CEPs in IVD degeneration.
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Affiliation(s)
- Nathan Buchweitz
- Department of Bioengineering, Clemson University, Clemson, SC, USA.
| | - Yi Sun
- Department of Orthopaedics, The 2nd Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Sarah Cisewski Porto
- Department of Bioengineering, Clemson University, Clemson, SC, USA; School of Health Sciences, College of Charleston, Charleston, SC, USA.
| | - Joshua Kelley
- Department of Bioengineering, Clemson University, Clemson, SC, USA.
| | - Yipeng Niu
- College of Art and Science, New York University, New York City, NY, USA.
| | - Shangping Wang
- Department of Bioengineering, Clemson University, Clemson, SC, USA.
| | - Zhaoxu Meng
- Department of Mechanical Engineering, Clemson University, Clemson, SC, USA.
| | - Charles Reitman
- Department of Orthopaedics and Physical Medicine, Medical University of South Carolina, Charleston, SC, USA.
| | - Elizabeth Slate
- Department of Statistics, Florida State University, Tallahassee, FL, USA.
| | - Hai Yao
- Department of Bioengineering, Clemson University, Clemson, SC, USA; Department of Orthopaedics and Physical Medicine, Medical University of South Carolina, Charleston, SC, USA.
| | - Yongren Wu
- Department of Bioengineering, Clemson University, Clemson, SC, USA; Department of Orthopaedics and Physical Medicine, Medical University of South Carolina, Charleston, SC, USA.
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Muhayudin NA, Basaruddin KS, Ijaz MF, Daud R. Finite Element Modelling of a Synthetic Paediatric Spine for Biomechanical Investigation. MATERIALS (BASEL, SWITZERLAND) 2023; 16:4514. [PMID: 37444827 DOI: 10.3390/ma16134514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 05/31/2023] [Accepted: 06/09/2023] [Indexed: 07/15/2023]
Abstract
Studies on paediatric spines commonly use human adult or immature porcine spines as specimens, because it is difficult to obtain actual paediatric specimens. There are quite obvious differences, such as geometry, size, bone morphology, and orientation of facet joint for these specimens, compared to paediatric spine. Hence, development of synthetic models that can behave similarly to actual paediatric spines, particularly in term of range of motion (ROM), could provide a significant contribution for paediatric spine research. This study aims to develop a synthetic paediatric spine using finite element modelling and evaluate the reliability of the model by comparing it with the experimental data under certain load conditions. The ROM of the paediatric spine was measured using a validated FE model at ±0.5 Nm moment in order to determine the moment required by the synthetic spine to achieve the same ROM. The results showed that the synthetic spine required two moments, ±2 Nm for lateral-bending and axial rotation, and ±3 Nm for flexion-extension, to obtain the paediatric ROM. The synthetic spine was shown to be stiffer in flexion-extension but more flexible in lateral bending than the paediatric FE model, possibly as a result of the intervertebral disc's simplified shape and the disc's weak bonding with the vertebrae. Nevertheless, the synthetic paediatric spine has promising potential in the future as an alternative paediatric spine model for biomechanical investigation of paediatric cases.
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Affiliation(s)
- Nor Amalina Muhayudin
- Faculty of Mechanical Engineering Technology, Universiti Malaysia Perlis, Pauh Putra Campus, Arau 02600, Malaysia
| | - Khairul Salleh Basaruddin
- Faculty of Mechanical Engineering Technology, Universiti Malaysia Perlis, Pauh Putra Campus, Arau 02600, Malaysia
- Sports Engineering Research Centre (SERC), Universiti Malaysia Perlis, Arau 02600, Malaysia
| | - Muhammad Farzik Ijaz
- Mechanical Engineering Department, College of Engineering, King Saud University, Riyadh 11421, Saudi Arabia
- King Salman Center for Disability Research, Riyadh 11614, Saudi Arabia
| | - Ruslizam Daud
- Faculty of Mechanical Engineering Technology, Universiti Malaysia Perlis, Pauh Putra Campus, Arau 02600, Malaysia
- Sports Engineering Research Centre (SERC), Universiti Malaysia Perlis, Arau 02600, Malaysia
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Hedlund J, Ekström L, Thoreson O. Porcine Functional Spine Unit in orthopedic research, a systematic scoping review of the methodology. J Exp Orthop 2022; 9:54. [PMID: 35678892 PMCID: PMC9184692 DOI: 10.1186/s40634-022-00488-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 05/16/2022] [Indexed: 11/20/2022] Open
Abstract
Purpose The aim of this study was to conduct a systematic scoping review of previous in vitro spine studies that used pig functional spinal units (FSU) as a model to gain an understanding of how different experimental methods are presented in the literature. Research guidelines are often used to achieve high quality in methods, results, and reports, but no research guidelines are available regarding in vitro biomechanical spinal studies. Methods A systematic scoping review approach and protocol was used for the study with a systematic search in several data bases combined with an extra author search. The articles were examined in multiple stages by two different authors in a blinded manner. Data was extracted from the included articles and inserted into a previously crafted matrix with multiple variables. The data was analyzed to evaluate study methods and quality and included 70 studies. Results The results display that there is a lack of consensus regarding how the material, methods and results are presented. Load type, duration and magnitude were heterogeneous among the studies, but sixty-seven studies (96%) did include compressive load or tension in the testing protocol. Conclusions This study concludes that an improvement of reported data in the present field of research is needed. A protocol, modified from the ARRIVE guidelines, regarding enhanced report-structure, that would enable comparison between studies and improve the method quality is presented in the current study. There is also a clear need for a validated quality-assessment template for experimental animal studies.
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Affiliation(s)
- Jacob Hedlund
- Department of Orthopedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Lars Ekström
- Orthopaedic Research Unit, Sahlgrenska University Hospital, Mölndal, Sweden
| | - Olof Thoreson
- Department of Orthopedics, Institute of Clinical Sciences at Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. .,Research and Development Primary Health Care, R&D Centre Gothenburg and Södra Bohuslän, Gothenburg, Sweden.
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Chepurin D, Chamoli U, Diwan AD. Bony Stress and Its Association With Intervertebral Disc Degeneration in the Lumbar Spine: A Systematic Review of Clinical and Basic Science Studies. Global Spine J 2022; 12:964-979. [PMID: 34018442 PMCID: PMC9344512 DOI: 10.1177/21925682211008837] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
STUDY DESIGN Translational review encompassing basic science and clinical evidence. OBJECTIVES Multiple components of the lumbar spine interact during its normal and pathological function. Bony stress in the lumbar spine is recognized as a factor in the development of pars interarticularis defect and stress fractures, but its relationship with intervertebral disc (IVD) degeneration is not well understood. Therefore, we conducted a systematic review to examine the relationship between bony stress and IVD degeneration. METHODS Online databases Scopus, PubMed and MEDLINE via OVID were searched for relevant studies published between January 1980-February 2020, using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines. Two authors independently analyzed the data, noting characteristics and biases in various studies. RESULTS Thirty-two articles were included in the review: 8 clinical studies, 9 finite element modeling studies, 3 in-vivo biomechanical testing studies, and 12 in-vitro biomechanical testing studies. Of the 32 articles, 19 supported, 4 rejected and 9 made no conclusion on the hypothesis that there is a positive associative relationship between IVD degeneration and bony stress. However, sufficient evidence was not available to confirm or reject a causal relationship. CONCLUSIONS Most studies suggest that the prevalence of IVD degeneration increases in the presence of bony stress; whether a causal relationship exists is unclear. The literature recommends early diagnosis and clinical suspicion of IVD degeneration and bony stress. Longitudinal studies are required to explore causal relationships between IVD degeneration and bony stress.
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Affiliation(s)
- Daniel Chepurin
- Department of Orthopaedic Surgery,
Spine Service, St. George & Sutherland Clinical School, University of New South
Wales Australia, Kogarah, Sydney, New South Wales, Australia,Department of Medicine, Faculty of Medicine Nursing & Health
Sciences, Monash University, Clayton, Melbourne, Victoria, Australia
| | - Uphar Chamoli
- Department of Orthopaedic Surgery,
Spine Service, St. George & Sutherland Clinical School, University of New South
Wales Australia, Kogarah, Sydney, New South Wales, Australia,School of Biomedical Engineering,
Faculty of Engineering & Information Technology, University of Technology
Sydney, Ultimo, Sydney, New South Wales, Australia,Uphar Chamoli, Spine Service, L5, Suite 16,
St. George Private Hospital, Kogarah, NSW 2217, Australia.
| | - Ashish D. Diwan
- Department of Orthopaedic Surgery,
Spine Service, St. George & Sutherland Clinical School, University of New South
Wales Australia, Kogarah, Sydney, New South Wales, Australia
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LIU FANG, ZHU ZHIWEN. NONLINEAR DYNAMIC CHARACTERISTICS OF LUMBAR DISC SUBJECTED TO STOCHASTIC EXCITATION. J MECH MED BIOL 2021. [DOI: 10.1142/s021951942140056x] [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
The lumbar disc has complex structure and material properties, and if it develops disease, it cannot heal itself. Therefore, prevention of lumbar disc herniation is very important. In this paper, the model of lumbar disc is built, and the nonlinear dynamic response of the system is researched. A modified Van der Pol model is imported to describe the stress–strain curves of the lumbar disc. The system’s dynamic model is set up, and harmonic balance method is applied to revise the natural frequency of the system. The product of numerical simulation reveals that the lumbar disc has complex dynamic characteristics, including balance point, limit cycle bifurcation and stochastic Hopf bifurcation. By changing the parameters, we can avoid large-scale periodic movement of the lumbar disc which causes lumbar disc herniation. These results contribute to the prevention of lumbar disc herniation.
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Affiliation(s)
- FANG LIU
- School of Mechanical Engineering, Tianjin University, Tianjin 300350, P. R. China
| | - ZHI-WEN ZHU
- Tianjin Key Laboratory of Nonlinear Dynamics and Control, Tianjin University, Tianjin 300350, P. R. China
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Mirzaali MJ, Libonati F, Ferrario D, Rinaudo L, Messina C, Ulivieri FM, Cesana BM, Strano M, Vergani L. Determinants of bone damage: An ex-vivo study on porcine vertebrae. PLoS One 2018; 13:e0202210. [PMID: 30114229 PMCID: PMC6095531 DOI: 10.1371/journal.pone.0202210] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 07/29/2018] [Indexed: 02/07/2023] Open
Abstract
Bone's resistance to fracture depends on several factors, such as bone mass, microarchitecture, and tissue material properties. The clinical assessment of bone strength is generally performed by Dual-X Ray Photon Absorptiometry (DXA), measuring bone mineral density (BMD) and trabecular bone score (TBS). Although it is considered the major predictor of bone strength, BMD only accounts for about 70% of fragility fractures, while the remaining 30% could be described by bone "quality" impairment parameters, mainly related to tissue microarchitecture. The assessment of bone microarchitecture generally requires more invasive techniques, which are not applicable in routine clinical practice, or X-Ray based imaging techniques, requiring a longer post-processing. Another important aspect is the presence of local damage in the bony tissue that may also affect the prediction of bone strength and fracture risk. To provide a more comprehensive analysis of bone quality and quantity, and to assess the effect of damage, here we adopt a framework that includes clinical, morphological, and mechanical analyses, carried out by means of DXA, μCT and mechanical compressive testing, respectively. This study has been carried out on trabecular bones, taken from porcine trabecular vertebrae, for the similarity with human lumbar spine. This study confirms that no single method can provide a complete characterization of bone tissue, and the combination of complementary characterization techniques is required for an accurate and exhaustive description of bone status. BMD and TBS have shown to be complementary parameters to assess bone strength, the former assessing the bone quantity and resistance to damage, and the latter the bone quality and the presence of damage accumulation without being able to predict the risk of fracture.
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Affiliation(s)
| | - Flavia Libonati
- Department of Mechanical Engineering, Politecnico di Milano, Milan, Italy
| | - Davide Ferrario
- Department of Mechanical Engineering, Politecnico di Milano, Milan, Italy
| | - Luca Rinaudo
- TECHNOLOGIC S.r.l. Hologic Italia, Torino, Italy
| | - Carmelo Messina
- Istituto Ortopedico Galeazzi IRCCS, Radiodiagnostic Unit, Milan, Italy
| | - Fabio M. Ulivieri
- Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Nuclear Medicine-Bone Metabolic Unit, Milan, Italy
| | - Bruno M. Cesana
- Department of Clinical Sciences and Community Health, Unit of Medical Statistics, Biometry and Bioinformatics "Giulio A. Maccacaro", Faculty of Medicine and Surgery, University of Milan, Milan, Italy
| | - Matteo Strano
- Department of Mechanical Engineering, Politecnico di Milano, Milan, Italy
| | - Laura Vergani
- Department of Mechanical Engineering, Politecnico di Milano, Milan, Italy
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Funabashi M, Nougarou F, Descarreaux M, Prasad N, Kawchuk GN. Does the application site of spinal manipulative therapy alter spinal tissues loading? Spine J 2018; 18:1041-1052. [PMID: 29355792 DOI: 10.1016/j.spinee.2018.01.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 12/04/2017] [Accepted: 01/10/2018] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Previous studies found that the intervertebral disc (IVD) experiences the greatest loads during spinal manipulation therapy (SMT). PURPOSE Based on that, this study aimed to determine if loads experienced by spinal tissues are significantly altered when the application site of SMT is changed. STUDY DESIGN A biomechanical robotic serial dissection study. SAMPLE Thirteen porcine cadaveric motion segments. OUTCOME MEASURES Forces experienced by lumbar spinal tissues. METHODS A servo-controlled linear actuator provided standardized 300 N SMT simulations to six different cutaneous locations of the porcine lumbar spine: L2-L3 and L3-L4 facet joints (FJ), L3 and L4 transverse processes (TVP), and the space between the FJs and the TVPs (BTW). Vertebral kinematics were tracked optically using indwelling bone pins; the motion segment was removed and mounted in a parallel robot equipped with a six-axis load cell. Movements of each SMT application at each site were replayed by the robot with the intact specimen and following the sequential removal of spinal ligaments, FJs and IVD. Forces induced by SMT were recorded, and specific axes were analyzed using linear mixed models. RESULTS Analyses yielded a significant difference (p<.05) in spinal structures loads as a function of the application site. Spinal manipulative therapy application at the L3 vertebra caused vertebral movements and forces between L3 and L4 spinal segment in the opposite direction to when SMT was applied at L4 vertebra. Additionally, SMT applications over the soft tissue between adjacent vertebrae significantly decreased spinal structure loads. CONCLUSION Applying SMT with a constant force at different spinal levels creates different relative kinetics of the spinal segments and load spinal tissues in significantly different magnitudes.
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Affiliation(s)
- Martha Funabashi
- Department of Physical Therapy, University of Alberta, 8205 114 Street, University of Alberta, Edmonton, Alberta, T6G 2G4, Canada.
| | - François Nougarou
- Département de génie électrique et informatique, Université du Québec à Trois-Rivières, Léon-Provancher Pavillion, 3351, boul. des Forges, Trois-Rivières, Québec, G8Z 4M3, Canada
| | - Martin Descarreaux
- Département des sciences de l'activité physique, Université du Québec à Trois-Rivières, Albert-Tessier Pavillion, 3351, boul. des Forges, Trois-Rivières, Québec, G8Z 4M3, Canada
| | - Narasimha Prasad
- Department of Mathematical and Statistical Sciences, University of Alberta, CAB 632, University of Alberta, Edmonton, Alberta, T6G 2G1, Canada
| | - Gregory N Kawchuk
- Department of Physical Therapy, University of Alberta, 8205 114 Street, University of Alberta, Edmonton, Alberta, T6G 2G4, Canada
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Porcine spine finite element model: a complementary tool to experimental scoliosis fusionless instrumentation. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2017; 26:1610-1617. [DOI: 10.1007/s00586-016-4940-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 12/21/2016] [Accepted: 12/25/2016] [Indexed: 10/20/2022]
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Determination of the mechanical properties of lumbar porcine vertebrae with 2D digital image correlation. J Appl Biomater Funct Mater 2015; 13:e195-200. [PMID: 26350348 DOI: 10.5301/jabfm.5000175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/29/2013] [Indexed: 11/20/2022] Open
Abstract
PURPOSE To evaluate the strain fields and to calculate the modulus of elasticity and Poisson's ratio of trabecular bone of the 6 lumbar vertebrae of the porcine spine by a 2-dimensional digital image correlation (2D DIC). METHODS This study was performed through a 2D DIC technique and the specimens were tested under compression. The resulting images were analyzed numerically by 2D DIC. Then, representative regions of interest were examined. The strain fields were determined and stress-strain curves were obtained. RESULTS The full field measurement of the strain in the lumbar bone spine was evaluated and with this data, the Young's modulus and Poisson's ratio were determined. CONCLUSIONS This research highlights the potential applications of noninvasive acquisition techniques in biomechanical analysis. This is useful in the mechanical characterization of bony structures and in the design of prostheses.
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Liu Q, Wang TY, Yang XP, Li K, Gao LL, Zhang CQ, Guo YH. Strain distribution in the intervertebral disc under unconfined compression and tension load by the optimized digital image correlation technique. Proc Inst Mech Eng H 2014; 228:486-493. [DOI: 10.1177/0954411914529756] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The unconfined compression and tension experiments of the intervertebral disc were conducted by applying an optimized digital image correlation technique, and the internal strain distribution was analysed for the disc. It was found that the axial strain values of different positions increased obviously with the increase in loads, while inner annulus fibrosus and posterior annulus fibrosus experienced higher axial strains than the outer annulus fibrosus and anterior annulus fibrosus. Deep annulus fibrosus exhibited higher compressive and tensile axial strains than superficial annulus fibrosus for the anterior region, while there was an opposite result for the posterior region. It was noted that all samples demonstrated a nonlinear stress–strain profile in the process of deforming, and an elastic region was shown once the sample was deformed beyond its toe region.
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Affiliation(s)
- Qing Liu
- Tianjin Key Laboratory for Control Theory & Applications in Complicated Industry Systems, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, P.R. China
| | - Tai-Yong Wang
- School of Mechanical Engineering, Tianjin University, Tianjin, P.R. China
| | - Xiu-Ping Yang
- Tianjin Key Laboratory for Control Theory & Applications in Complicated Industry Systems, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, P.R. China
| | - Kun Li
- School of Electronic Information Engineering, Tianjin University of Technology, Tianjin, P.R. China
| | - Li-Lan Gao
- Tianjin Key Laboratory for Control Theory & Applications in Complicated Industry Systems, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, P.R. China
| | - Chun-Qiu Zhang
- Tianjin Key Laboratory for Control Theory & Applications in Complicated Industry Systems, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, P.R. China
| | - Yue-Hong Guo
- Tianjin Key Laboratory for Control Theory & Applications in Complicated Industry Systems, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, P.R. China
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Remodelling of vertebral endplate subchondral bone in scoliosis: a micro-CT analysis in a porcine model. Clin Biomech (Bristol, Avon) 2010; 25:636-41. [PMID: 20605291 DOI: 10.1016/j.clinbiomech.2010.04.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Revised: 04/27/2010] [Accepted: 04/27/2010] [Indexed: 02/07/2023]
Abstract
BACKGROUND Disc degeneration has been correlated with alteration of bone density of adjacent vertebral bodies. Abnormal mechanical loading appears in scoliosis as compared to normal spines. How vertebral endplate was remodelled in scoliosis is not well understood. METHODS We conducted a micro-CT analysis of subchondral bone of the vertebral endplate at the curve apex in a porcine scoliosis model. Two adjacent thoracic T(5)-T(6) and lumbar L(1)-L(2) levels were instrumented in six four-week-old pigs with a custom offset implant connected by a flexible stainless steel wire. Two months after implantation, three cylindrical specimens were harvested into the vertebral endplate of each of the scoliosis levels: centre, convexity and concavity, and from the dorsal T(9)-T(10) vertebral units obtained from nine three-month-old non-instrumented pigs used as controls. Micro-CT analysis was carried out on each specimen. FINDINGS In the concavity of the scoliotic spine, bone volume fraction, trabecular thickness, and trabecular separation significantly increased whereas in the convexity, only trabecular separation increased. Connectivity index and trabecular number decreased significantly. INTERPRETATION This was the first micro-CT study of subchondral bone microarchitecture of the scoliotic vertebral end plate. At the curve apex, increased compression in the concavity induced an osteogenic process. In the convexity, diminished compression caused an osteolytic process with a local resorption. Clinically, the unbalanced tissue remodelling could play a role in the convective and diffusive transports into the end plate, which is of prime importance for the segment homeostasis in scoliosis treatment with or without surgery.
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