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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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Zhou M, Theologis AA, O’Connell GD. Understanding the etiopathogenesis of lumbar intervertebral disc herniation: From clinical evidence to basic scientific research. JOR Spine 2024; 7:e1289. [PMID: 38222810 PMCID: PMC10782075 DOI: 10.1002/jsp2.1289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 08/01/2023] [Accepted: 09/20/2023] [Indexed: 01/16/2024] Open
Abstract
Lumbar intervertebral disc herniation, as a leading cause of low back pain, productivity loss, and disability, is a common musculoskeletal disorder that results in significant socioeconomic burdens. Despite extensive clinical and basic scientific research efforts, herniation etiopathogenesis, particularly its initiation and progression, is not well understood. Understanding herniation etiopathogenesis is essential for developing effective preventive measures and therapeutic interventions. Thus, this review seeks to provide a thorough overview of the advances in herniation-oriented research, with a discussion on ongoing challenges and potential future directions for clinical, translational, and basic scientific investigations to facilitate innovative interdisciplinary research aimed at understanding herniation etiopathogenesis. Specifically, risk factors for herniation are identified and summarized, including familial predisposition, obesity, diabetes mellitus, smoking tobacco, selected cardiovascular diseases, disc degeneration, and occupational risks. Basic scientific experimental and computational research that aims to understand the link between excessive mechanical load, catabolic tissue remodeling due to inflammation or insufficient nutrient supply, and herniation, are also reviewed. Potential future directions to address the current challenges in herniation-oriented research are explored by combining known progressive development in existing research techniques with ongoing technological advances. More research on the relationship between occupational risk factors and herniation, as well as the relationship between degeneration and herniation, is needed to develop preventive measures for working-age individuals. Notably, researchers should explore using or modifying existing degeneration animal models to study herniation etiopathogenesis, as such models may allow for a better understanding of how to prevent mild-to-moderately degenerated discs from herniating.
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Affiliation(s)
- Minhao Zhou
- Department of Mechanical EngineeringUniversity of California, Berkeley (UC Berkeley)BerkeleyCaliforniaUSA
| | - Alekos A. Theologis
- Department of Orthopaedic SurgeryUniversity of California, San Francisco (UCSF)San FranciscoCaliforniaUSA
| | - Grace D. O’Connell
- Department of Mechanical EngineeringUniversity of California, Berkeley (UC Berkeley)BerkeleyCaliforniaUSA
- Department of Orthopaedic SurgeryUniversity of California, San Francisco (UCSF)San FranciscoCaliforniaUSA
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3
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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; 142:1074128. [DOI: 10.1115/1.4046186] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Indexed: 12/25/2022]
Abstract
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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Gao X, Zhu Q, Gu W. An anisotropic multiphysics damage model with application to annulus fibrosus. J Biomech 2017; 61:88-93. [PMID: 28764957 DOI: 10.1016/j.jbiomech.2017.07.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 06/07/2017] [Accepted: 07/10/2017] [Indexed: 10/19/2022]
Abstract
An anisotropic multiphysics damage model is developed to characterize the couplings among multiple physical fields within soft tissues and the tissue damage based on thermodynamic principles. This anisotropic multiphysics damage model integrates the continuum mixture theory and a continuum damage model, and the anisotropic damage is considered by evolution of internal damage variables governing the anisotropic mechanical behaviors of tissues. The energy dissipation associated with the transport of fluid and ions is generally related to tissue damage. The anisotropic multiphysics damage model is applied to simulate a case of annulus fibrosus (AF) damage in an isolated intervertebral disc under compression, to understand the damage initiation and propagation. It is found that, for this case (with 1000N/s of compression rate and neglected ground matrix damage), the damage initiated in the outer and middle posterior regions of AF at about 700N of axial compression. The region-dependent yield stretch ratio predicted by this model is consistent with experimental findings. A sensitive study on the damage parameters is also presented. This study provides an additional insight into AF damage in the isolated disc under mechanical compression.
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Affiliation(s)
- Xin Gao
- Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, FL, USA
| | - Qiaoqiao Zhu
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA
| | - Weiyong Gu
- Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, FL, USA; Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA.
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Zhu Q, Gao X, Brown MD, Temple HT, Gu W. Simulation of water content distributions in degenerated human intervertebral discs. J Orthop Res 2017; 35:147-153. [PMID: 27153106 PMCID: PMC5097704 DOI: 10.1002/jor.23284] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 04/29/2016] [Indexed: 02/04/2023]
Abstract
The objective of this study was to investigate the spatial and temporal variations of water content in intervertebral discs during degeneration and repair processes. We hypothesized that the patterns of water content distribution in the discs are related to the intensity patterns observed in T2-weighted MRI images. Water content distributions in the mildly (e.g., 80% viable cells in the disc, 2.3% decrease in disc height) and moderately (e.g., 40% viable cells in the disc, 9.3% decrease in disc height) degenerated discs were predicted using a finite element model. The variation of water content in the degenerated discs treated with three biological therapies (i.e., increasing the cell density in the nucleus pulposus [Case I], increasing glycosaminoglycan synthesis rate in the nucleus pulposus [Case II], and decreasing glycosaminoglycan degradation rate in the nucleus pulposus [Case III]) were also predicted. It was found that two patterns of water content distributions, a horizontal region with lower water content at the mid-axial plane of nucleus pulposus and a spot with higher water content at the posterior region, were shown during the degeneration progress for the disc simulated in this study. These two patterns disappeared after treatment in Case I, but in Case II and Case III. The implication of these patterns for the horizontal gray band and high intensity zone in T2-weighted MRI images was discussed. This study provided new guidance to develop a novel method for diagnosing disc degeneration and assessing outcomes of biological therapies with MRI techniques. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:147-153, 2017.
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Affiliation(s)
- Qiaoqiao Zhu
- Dept. of Biomedical Engineering, University of Miami, Miami, FL
| | - Xin Gao
- Dept. of Mechanical and Aerospace Engineering, University of Miami, Miami, FL
| | - Mark D. Brown
- Dept. of Orthopaedics, University of Miami, Miami, FL
| | - H. Thomas Temple
- Dept. of Orthopaedic Surgery, NOVA Southeastern University, Fort Lauderdale, FL
| | - Weiyong Gu
- Dept. of Biomedical Engineering, University of Miami, Miami, FL,Dept. of Mechanical and Aerospace Engineering, University of Miami, Miami, FL,Corresponding author: Weiyong Gu, PhD, 1251 Memorial Drive, MEB206, Coral Gables, FL 33124-0624, 305-284-8553, 305-284-2580 (Fax),
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Gao X, Zhu Q, Gu W. Prediction of glycosaminoglycan synthesis in intervertebral disc under mechanical loading. J Biomech 2016; 49:2655-2661. [PMID: 27288332 PMCID: PMC5056134 DOI: 10.1016/j.jbiomech.2016.05.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 05/23/2016] [Accepted: 05/25/2016] [Indexed: 01/07/2023]
Abstract
The loss of glycosaminoglycan (GAG) content is a major biochemical change during intervertebral disc (IVD) degeneration. Abnormal mechanical loading is one of the major factors causing disc degeneration. In this study, a multiscale mathematical model was developed to quantify the effect of mechanical loading on GAG synthesis. This model was based on a recently developed cell volume dependent GAG synthesis theory that predicts the variation of GAG synthesis rate of a cell under the influence of mechanical stimuli, and the biphasic theory that describes the deformation of IVD under mechanical loading. The GAG synthesis (at the cell level) was coupled with the mechanical loading (at the tissue level) via a cell-matrix unit approach which established a relationship between the variation of cell dilatation and the local tissue dilatation. This multiscale mathematical model was used to predict the effect of static load (creep load) on GAG synthesis in bovine tail discs. The predicted results are in the range of experimental results. This model was also used to investigate the effect of static (0.2MPa) and diurnal loads (0.1/0.3MPa and 0.15/0.25MPa in 12/12 hours shift with an average of 0.2MPa over a cycle) on GAG synthesis. It was found that static load and diurnal loads have different effects on GAG synthesis in a diurnal cycle, and the diurnal load effects depend on the amplitude of the load. The model is important to understand the effect of mechanical loading at the tissue level on GAG synthesis at the cellular level, as well as to optimize the mechanical loading in growing engineered tissue.
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Affiliation(s)
- Xin Gao
- Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, FL, USA
| | - Qiaoqiao Zhu
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA
| | - Weiyong Gu
- Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, FL, USA; Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA
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