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Wu T, Bonnheim NB, Pendleton MM, Emerzian SR, Keaveny TM. Radiation-induced changes in load-sharing and structure-function behavior in murine lumbar vertebrae. Comput Methods Biomech Biomed Engin 2024; 27:1278-1286. [PMID: 37504955 DOI: 10.1080/10255842.2023.2239415] [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: 04/25/2023] [Accepted: 07/12/2023] [Indexed: 07/29/2023]
Abstract
In this study, we used micro-CT-based finite element analysis to investigate the biomechanical effects of radiation on the microstructure and mechanical function of murine lumbar vertebrae. Specifically, we evaluated vertebral microstructure, whole-bone stiffness, and cortical-trabecular load sharing in the L5 vertebral body of mice exposed to ionizing radiation 11 days post exposure (5 Gy total dose; n = 13) and controls (n = 14). Our findings revealed the irradiated group exhibited reduced trabecular bone volume and microstructure (p < 0.001) compared to controls, while cortical bone volume remained unchanged (p = 0.91). Axially compressive loads in the irradiated group were diverted from the trabecular centrum and into the vertebral cortex, as evidenced by a higher cortical load-fraction (p = 0.02) and a higher proportion of cortical tissue at risk of initial failure (p < 0.01). Whole-bone stiffness was lower in the irradiated group compared to the controls, though the difference was small and non-significant (2045 ± 142 vs. 2185 ± 225 vs. N/mm, irradiated vs. control, p = 0.07). Additionally, the structure-function relationship between trabecular bone volume and trabecular load fraction differed between groups (p = 0.03), indicating a less biomechanically efficient trabecular network in the irradiated group. We conclude that radiation can decrease trabecular bone volume and result in a less biomechanically efficient trabecular structure, leading to increased reliance on the vertebral cortex to resist axially compressive loads. These findings offer biomechanical insight into the effects of radiation on structure-function behavior in murine lumbar vertebrae independent of possible tissue-level material effects.
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Affiliation(s)
- Tongge Wu
- Department of Mechanical Engineering, University of California, Berkeley, CA, USA
| | - Noah B Bonnheim
- Department of Orthopaedic Surgery, University of California, San Francisco, CA, USA
| | - Megan M Pendleton
- Department of Mechanical Engineering, University of California, Berkeley, CA, USA
| | - Shannon R Emerzian
- Department of Mechanical Engineering, University of California, Berkeley, CA, USA
| | - Tony M Keaveny
- Department of Mechanical Engineering, University of California, Berkeley, CA, USA
- Department of Bioengineering, University of California, Berkeley, CA, USA
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Yang S, Zhou B, Mo J, He R, Mei K, Zeng Z, Yang G, Chen Y, Luo M, Tang S, Xiao Z. Risk factors affecting spinal fusion: A meta-analysis of 39 cohort studies. PLoS One 2024; 19:e0304473. [PMID: 38848350 PMCID: PMC11161075 DOI: 10.1371/journal.pone.0304473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 05/13/2024] [Indexed: 06/09/2024] Open
Abstract
PURPOSE We performed a meta-analysis to identify risk factors affecting spinal fusion. METHODS We systematically searched PubMed, Embase, and the Cochrane Library from inception to January 6, 2023, for articles that report risk factors affecting spinal fusion. The pooled odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using fixed-effects models for each factor for which the interstudy heterogeneity I2 was < 50%, while random-effects models were used when the interstudy heterogeneity I2 was ≥ 50%. Using sample size, Egger's P value, and heterogeneity across studies as criteria, we categorized the quality of evidence from observational studies as high-quality (Class I), moderate-quality (Class II or III), or low-quality (Class IV). Furthermore, the trim-and-fill procedure and leave-one-out protocol were conducted to investigate potential sources of heterogeneity and verify result stability. RESULTS Of the 1,257 citations screened, 39 unique cohort studies comprising 7,145 patients were included in the data synthesis. High-quality (Class I) evidence showed that patients with a smoking habit (OR, 1.57; 95% CI, 1.11 to 2.21) and without the use of bone morphogenetic protein-2 (BMP-2) (OR, 4.42; 95% CI, 3.33 to 5.86) were at higher risk for fusion failure. Moderate-quality (Class II or III) evidence showed that fusion failure was significantly associated with vitamin D deficiency (OR, 2.46; 95% CI, 1.24 to 4.90), diabetes (OR, 3.42; 95% CI, 1.59 to 7.36), allograft (OR, 1.82; 95% CI, 1.11 to 2.96), conventional pedicle screw (CPS) fixation (OR, 4.77; 95% CI, 2.23 to 10.20) and posterolateral fusion (OR, 3.63; 95% CI, 1.25 to 10.49). CONCLUSIONS Conspicuous risk factors affecting spinal fusion include three patient-related risk factors (smoking, vitamin D deficiency, and diabetes) and four surgery-related risk factors (without the use of BMP-2, allograft, CPS fixation, and posterolateral fusion). These findings may help clinicians strengthen awareness for early intervention in patients at high risk of developing fusion failure.
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Affiliation(s)
- Shudong Yang
- Department of Orthopedic Trauma, Second Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang City, Hunan Province, China
| | - Beijun Zhou
- Hengyang Medical School, University of South China, Hengyang City, Hunan Province, China
| | - Jiaxuan Mo
- Hengyang Medical School, University of South China, Hengyang City, Hunan Province, China
| | - Ruidi He
- Hengyang Medical School, University of South China, Hengyang City, Hunan Province, China
| | - Kunbo Mei
- Hengyang Medical School, University of South China, Hengyang City, Hunan Province, China
| | - Zhi Zeng
- Hengyang Medical School, University of South China, Hengyang City, Hunan Province, China
| | - Gaigai Yang
- Hengyang Medical School, University of South China, Hengyang City, Hunan Province, China
| | - Yuwei Chen
- Hengyang Medical School, University of South China, Hengyang City, Hunan Province, China
| | - Mingjiang Luo
- Department of Spine Surgery, Lishui Hospital of Wenzhou Medical University, Lishui People’s Hospital, Lishui, Zhejiang, China
| | - Siliang Tang
- Department of Spine Surgery, Second Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang City, Hunan Province, China
| | - Zhihong Xiao
- Department of Spine Surgery, Lishui Hospital of Wenzhou Medical University, Lishui People’s Hospital, Lishui, Zhejiang, China
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Eremina GM, Smolin AY. Effect of patient-specific factors on regeneration in lumbar spine at healthy disc and total disc replacement. Computer simulation. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2024; 250:108172. [PMID: 38669718 DOI: 10.1016/j.cmpb.2024.108172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 03/27/2024] [Accepted: 04/10/2024] [Indexed: 04/28/2024]
Abstract
BACKGROUND AND OBJECTIVE Degenerative diseases of the spine have a negative impact on the quality of life of patients. This study presents the results of numerical modelling of the mechanical behaviour of the lumbar spine with patient-specific conditions at physiological loads. This paper aims to numerically study the influence of degenerative changes in the spine and the presence of an endoprosthesis on the creation of conditions for tissue regeneration. METHODS A numerical model of the mechanical behaviour of lumbar spine at healthy and after total disc replacement under low-energy impacts equivalent to physiological loads is presented. The model is based on the movable cellular automaton method (discrete elements), where the mechanical behaviour of bone tissue is described using the Biot poroelasticity accounting for the presence and transfer of interstitial biological fluid. The nutritional pathways of the intervertebral disc in cases of healthy and osteoporotic bone tissues were predicted based on the analysis of the simulation results according to the mechanobiological principles. RESULTS Simulation of total disc replacement showed that osseointegration of the artificial disc plates occurs only in healthy bone tissue. With total disc replacement in a patient with osteoporosis, there is an area of increased risk of bone resorption in the near-contact area, approximately 1 mm wide, around the fixators. Dynamic loads may improve the osseointegration of the implant in pathological conditions of the bone tissue. CONCLUSIONS The results obtained in the case of healthy spine and osteoporotic bone tissues correspond to the experimental data on biomechanics and possible methods of IVD regeneration from the position of mechanobiological principles. The results obtained with an artificial disc (with keel-type fixation) showed that the use of this type of endoprosthesis in healthy bone tissues allows to reproduce the function of the natural intervertebral disc and does not contribute to the development of neoplastic processes. In the case of an artificial disc with osteoporosis of bone tissues, there is a zone with increased risk of tissue resorption and development of neoplastic processes in the area near the contact of the implant attachment. This circumstance can be compensated by increasing the loading level.
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Affiliation(s)
- Galina M Eremina
- Institute of Strength Physics and Materials Science of SB RAS, 2/4, pr. Akademicheskii, Tomsk, 634055, Russia.
| | - Alexey Yu Smolin
- Institute of Strength Physics and Materials Science of SB RAS, 2/4, pr. Akademicheskii, Tomsk, 634055, Russia
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Xu H, Wang X, Han Y, Jiang Y, Wang J, Zhang X, Miao J. Biomechanical comparison of different prosthetic reconstructions in total en bloc spondylectomy: a finite element study. BMC Musculoskelet Disord 2022; 23:955. [PMID: 36329424 PMCID: PMC9635202 DOI: 10.1186/s12891-022-05919-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 10/26/2022] [Indexed: 11/06/2022] Open
Abstract
Objective To analyse and compare the biomechanical differences between 3D-printed prostheses, titanium mesh cages and poorly matched titanium mesh cages in total en bloc spondylectomy (TES). Methods The finite element model of T10-L2 for healthy adults was modified to make three models after T12 total spondylectomy. These models were a 3D-printed prosthesis, titanium mesh cage and prosthesis-endplate mismatched titanium mesh cage for reconstruction. The range of motion (ROM), stress distribution of the endplate and internal fixation system of three models in flexion and extension, lateral bending and axial rotation were simulated and analysed by ABAQUS. Result In flexion, due to the support of the anterior prosthesis, the fixation system showed the maximum fixation strength. The fixation strength of the 3D-printed prosthesis model was 26.73 N·m /°, that of the TMC support model was 27.20 N·m /°, and that of the poorly matched TMC model was 24.16 N·m /°. In flexion, the L1 upper endplate stress of the poorly matched TMC model was 35.5% and 49.6% higher than that of the TMC and 3D-printed prosthesis, respectively. It was 17% and 28.1% higher in extension, 39.3% and 42.5% higher in lateral bending, and 82.9% and 91.2% higher in axial rotation, respectively. The lower endplate of T11 showed a similar trend, but the magnitude of the stress change was reduced. In the stress analysis of the 3D-printed prosthesis and TMC, it was found that the maximum stress was in flexion and axial rotation, followed by left and right bending, and the least stress was in extension. However, the mismatched TMC withstood the maximum von Mises stress of 418.7 MPa (almost twice as much as the buckling state) in rotation, 3 times and 5.83 times in extension, and 1.29 and 2.85 times in lateral bending, respectively. Conclusion Different prostheses with good endplate matching after total spondylectomy can obtain effective postoperative stable support, and the reduction in contact area caused by mismatch will affect the biomechanical properties and increase the probability of internal fixation failure.
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Affiliation(s)
- Hanpeng Xu
- Tianjin Hospital, Tianjin University, Tianjin, China
| | - Xiaodong Wang
- Department of Orthopaedics, Affiliated Hospital of Hebei University, Baoding, China
| | - Ye Han
- Department of Orthopaedics, Affiliated Hospital of Hebei University, Baoding, China
| | - Yuanyuan Jiang
- Department of Anesthesiology, Affiliated Hospital of Hebei University, Baoding, China
| | - Jianzhong Wang
- Department of Orthopaedics, Affiliated Hospital of Hebei University, Baoding, China
| | - Xiong Zhang
- Department of Orthopaedics, Affiliated Hospital of Hebei University, Baoding, China
| | - Jun Miao
- Tianjin Hospital, Tianjin University, Tianjin, China. .,Tianjin Hospital, Tianjin University, Jiefangnanlu 406, Hexi District, Tianjin, 300210, China.
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The Role of Vertebral Porosity and Implant Loading Mode on Bone-Tissue Stress in the Human Vertebral Body Following Lumbar Total Disc Arthroplasty. Spine (Phila Pa 1976) 2021; 46:E1022-E1030. [PMID: 33660678 DOI: 10.1097/brs.0000000000004023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Micro-computed tomography- (micro-CT-) based finite element analysis of cadaveric human lumbar vertebrae virtually implanted with total disc arthroplasty (TDA) implants. OBJECTIVE (1) Assess the relationship between vertebral porosity and maximum levels of bone-tissue stress following TDA; (2) determine whether the implant's loading mode (axial compression vs. sagittal bending) alters the relationship between vertebral porosity and bone-tissue stress. SUMMARY OF BACKGROUND DATA Implant subsidence may be related to the bone biomechanics in the underlying vertebral body, which are poorly understood. For example, it remains unclear how the stresses that develop in the supporting bone tissue depend on the implant's loading mode or on typical inter-individual variations in vertebral morphology. METHODS Data from micro-CT scans from 12 human lumbar vertebrae (8 males, 4 females; 51-89 years of age; bone volume fraction [BV/TV] = 0.060-0.145) were used to construct high-resolution finite element models (37 μm element edge length) comprising disc-vertebra-implant motion segments. Implants were loaded to 800 N of force in axial compression, flexion-, and extension-induced impingement. For comparison, the same net loads were applied via an intact disc without an implant. Linear regression was used to assess the relationship between BV/TV, loading mode, and the specimen-specific change in stress caused by implantation. RESULTS The increase in maximum bone-tissue stress caused by implantation depended on loading mode (P < 0.001), increasing more in bending-induced impingement than axial compression (for the same applied force). The change in maximum stress was significantly associated with BV/TV (P = 0.002): higher porosity vertebrae experienced a disproportionate increase in stress compared with lower porosity vertebrae. There was a significant interaction between loading mode and BV/TV (P = 0.002), indicating that loading mode altered the relationship between BV/TV and the change in maximum bone-tissue stress. CONCLUSION Typically-sized TDA implants disproportionately increase the bone-tissue stress in more porous vertebrae; this affect is accentuated when the implant impinges in sagittal bending.Level of Evidence: N/A.
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Auger JD, Frings N, Wu Y, Marty AG, Morgan EF. Trabecular Architecture and Mechanical Heterogeneity Effects on Vertebral Body Strength. Curr Osteoporos Rep 2020; 18:716-726. [PMID: 33215364 PMCID: PMC7891914 DOI: 10.1007/s11914-020-00640-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/24/2020] [Indexed: 12/29/2022]
Abstract
PURPOSE OF REVIEW We aimed to synthesize the recent work on the intra-vertebral heterogeneity in density, trabecular architecture and mechanical properties, its implications for fracture risk, its association with degeneration of the intervertebral discs, and its implications for implant design. RECENT FINDINGS As compared to the peripheral regions of the centrum, the central region of the vertebral body exhibits lower density and more sparse microstructure. As compared to the anterior region, the posterior region shows higher density. These variations are more pronounced in vertebrae from older persons and in those adjacent to degenerated discs. Mixed results have been reported in regard to variation along the superior-inferior axis and to relationships between the heterogeneity in density and vertebral strength and fracture risk. These discrepancies highlight that, first, despite the large amount of study of the intra-vertebral heterogeneity in microstructure, direct study of that in mechanical properties has lagged, and second, more measurements of vertebral loading are needed to understand how the heterogeneity affects distributions of stress and strain in the vertebra. These future areas of study are relevant not only to the question of spine fractures but also to the design and selection of implants for spine fusion and disc replacement. The intra-vertebral heterogeneity in microstructure and mechanical properties may be a product of mechanical adaptation as well as a key determinant of the ability of the vertebral body to withstand a given type of loading.
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Affiliation(s)
- Joshua D Auger
- Department of Mechanical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA
| | - Neilesh Frings
- Department of Biomedical Engineering, Boston University, Boston, MA, 02215, USA
| | - Yuanqiao Wu
- Department of Mechanical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA
| | - Andre Gutierrez Marty
- Department of Mechanical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA
| | - Elise F Morgan
- Department of Mechanical Engineering, Boston University, 110 Cummington Mall, Boston, MA, 02215, USA.
- Department of Biomedical Engineering, Boston University, Boston, MA, 02215, USA.
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Vanaclocha-Saiz A, Atienza CM, Vanaclocha V, Belloch V, Santabarbara JM, Jordá-Gómez P, Vanaclocha L. ICR in human cadaveric specimens: An essential parameter to consider in a new lumbar disc prosthesis design. NORTH AMERICAN SPINE SOCIETY JOURNAL 2020; 2:100016. [PMID: 35141586 PMCID: PMC8820058 DOI: 10.1016/j.xnsj.2020.100016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 06/29/2020] [Accepted: 07/15/2020] [Indexed: 06/14/2023]
Abstract
STUDY DESIGN Biomechanical study in cadaveric specimens. BACKGROUND The commercially available lumbar disc prostheses do not reproduce the intact disc's Instantaneous centre of Rotation (ICR), thus inducing an overload on adjacent anatomical structures, promoting secondary degeneration. AIM To examine biomechanical testing of cadaveric lumbar spine specimens in order to evaluate and define the ICR of intact lumbar discs. MATERIAL AND METHODS Twelve cold preserved fresh human cadaveric lumbosacral spine specimens were subjected to computerized tomography (CT), magnetic resonance imaging (MRI) and biomechanical testing. Kinematic studies were performed to analyse range of movements in order to determine ICR. RESULTS Flexoextension and lateral bending tests showed a positive linear correlation between the angle rotated and the displacement of the ICR in different axes. DISCUSSION ICR has not been taken into account in any of the available literature regarding lumbar disc prosthesis. Considering our results, neither the actual ball-and-socket nor the withdrawn elastomeric nucleus models fit the biomechanics of the lumbar spine, which could at least in part explain the failure rates of the implants in terms of postoperative failed back syndrome (low back pain). It is reasonable to consider then that an implant should also adapt the equations of the movement of the intact ICR of the joint to the post-surgical ICR. CONCLUSIONS This is the first cadaveric study on the ICR of the human lumbar spine. We have shown that it is feasible to calculate and consider this parameter in order to design future prosthesis with improved clinical and biomechanical characteristics.
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Affiliation(s)
| | - Carlos M Atienza
- Instituto de Biomecánica (IBV) Universitat Politècnica de Valencia, Valencia, Spain
- Instituto de Biomecánica de Valencia-CIBER BBN, Grupo de Tecnología Sanitaria (GTS-IBV), Valencia, Spain
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Jain P, Rana M, Biswas JK, Khan MR. Biomechanics of spinal implants-a review. Biomed Phys Eng Express 2020; 6:042002. [PMID: 33444261 DOI: 10.1088/2057-1976/ab9dd2] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Spinal instrumentations have been classified as rigid fixation, total disc replacement and dynamic stabilization system for treatment of various spinal disorders. The efficacy and biomechanical suitability of any spinal implant can be measured through in vitro, in vivo experiments and numerical techniques. With the advancement in technology finite element models are making an important contribution to understand the complex structure of spinal components along with allied functionality, designing and application of spinal instrumentations at preliminary design stage. This paper aimed to review the past and recent studies to describe the biomechanical aspects of various spinal implants. The literatures were grouped and reviewed in accordance to instrumentation category and their functionality in the spinal column at respective locations.
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Affiliation(s)
- Pushpdant Jain
- School of Mechanical Engineering, VIT Bhopal University, Bhopal-Indore Highway Kothrikalan, Sehore Madhya Pradesh - 466114, India
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