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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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Park JS, Goh TS, Lee JS, Lee C. Analyzing isolated degeneration of lumbar facet joints: implications for degenerative instability and lumbar biomechanics using finite element analysis. Front Bioeng Biotechnol 2024; 12:1294658. [PMID: 38600941 PMCID: PMC11005061 DOI: 10.3389/fbioe.2024.1294658] [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: 09/15/2023] [Accepted: 02/26/2024] [Indexed: 04/12/2024] Open
Abstract
The facet joint contributes to lumbar spine stability as it supports the weight of body along with the intervertebral discs. However, most studies on the causes of degenerative lumbar diseases focus on the intervertebral discs and often overlook the facet joints. This study aimed to investigate the impact of facet joint degeneration on the degenerative changes and diseases of the lumbar spine. A finite element model of the lumbar spine (L1-S1) was fabricated and validated to study the biomechanical characteristics of the facet joints. To simulate degeneration of the facet joint, the model was divided into four grades based on the number of degenerative segments (L4-L5 or L4-S1) and the contact condition between the facet joint surfaces. Finite element analysis was performed on four spine motions: flexion, extension, lateral bending, and axial torsion, by applying a pure moment to the upper surface of L1. Important parameters that could be used to confirm the effect of facet joint degeneration on the lumbar spine were calculated, including the range of motion (ROM) of the lumbar segments, maximum von Mises stress on the intervertebral discs, and reaction force at the facet joint. Facet joint degeneration affected the biomechanical characteristics of the lumbar spine depending on the movements of the spine. When analyzed by dividing it into degenerative onset and onset-adjacent segments, lumbar ROM and the maximum von Mises stress of the intervertebral discs decreased as the degree of degeneration increased in the degenerative onset segments. The reaction force at the facet joint decreased with flexion and increased with lateral bending and axial torsion. In contrast, lumbar ROM of the onset-adjacent segments remained almost unchanged despite severe degeneration of the facet joint, and the maximum von Mises stress of the intervertebral discs increased with flexion and extension but decreased with lateral bending and axial torsion. Additionally, the facet joint reaction force increased with extension, lateral bending, and axial rotation. This analysis, which combined the ROM of the lumbar segment, maximum von Mises stress on the intervertebral disc, and facet joint reaction force, confirmed the biomechanical changes in the lumbar spine due to the degeneration of isolated facet joints under the load of spinal motion. In the degenerative onset segment, spinal instability decreased, whereas in the onset-adjacent segment, a greater load was applied than in the intact state. When conducting biomechanical studies on the lumbar spine, considering facet joint degeneration is important since it can lead to degenerative spinal diseases, including adjacent segment diseases.
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Affiliation(s)
- Jun Sung Park
- Department of Biomedical Engineering, Graduate School, Pusan National University, Busan, Republic of Korea
| | - Tae Sik Goh
- Department of Orthopaedic Surgery, School of Medicine, Pusan National University, Busan, Republic of Korea
- Biomedical Research Institute, Pusan National University Hospital, Busan, Republic of Korea
| | - Jung Sub Lee
- Department of Orthopaedic Surgery, School of Medicine, Pusan National University, Busan, Republic of Korea
- Biomedical Research Institute, Pusan National University Hospital, Busan, Republic of Korea
| | - Chiseung Lee
- Biomedical Research Institute, Pusan National University Hospital, Busan, Republic of Korea
- Department of Biomedical Engineering, School of Medicine, Pusan National University, Busan, Republic of Korea
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Yang X, Zhang S, Su J, Guo S, Ibrahim Y, Zhang K, Tian Y, Wang L, Yuan S, Liu X. Comparison of Clinical and Radiographic Outcomes Between Transforaminal Endoscopic Lumbar Discectomy and Microdiscectomy: A Follow-up Exceeding 5 Years. Neurospine 2024; 21:303-313. [PMID: 38317550 PMCID: PMC10992631 DOI: 10.14245/ns.2347026.513] [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: 10/05/2023] [Revised: 01/04/2024] [Accepted: 01/08/2024] [Indexed: 02/07/2024] Open
Abstract
OBJECTIVE To compare the long-term clinical and radiographic outcomes of transforaminal endoscopic lumbar discectomy (TELD) versus microdiscectomy (MD). METHODS The data of 154 patients with lumbar disc herniation (LDH) who underwent TELD (n = 89) or MD (n = 65) were retrospectively analyzed. The patients' clinical outcomes were evaluated using visual analogue scales for leg and low back pain, the Japanese Orthopaedic Association (JOA) score, and the Oswestry Disability Index (ODI). The evolution of radiographic manifestations was observed during follow-up. Potential risk factors for a poor clinical outcome were investigated. RESULTS During a mean follow-up of 5.5 years (range, 5-7 years), the recurrence rate was 4.49% in the TELD group and 1.54% in the MD group. All scores significantly improved from preoperatively to postoperatively in both groups (p < 0.01). The improvement in the ODI and JOA scores was significantly greater in the TELD than MD group (p < 0.05). Forty-seven patients (52.8%) in the TELD group and 32 (49.2%) in the MD group had Modic changes before surgery, most of which showed no changes at the last follow-up. The degeneration grades of 292 discs (71.0%) were unchanged at the last follow-up, while 86 (20.9%) showed improvement, mostly at the upper adjacent segment. No significant difference was observed in the intervertebral height index or paraspinal muscle-disc ratio. CONCLUSION Both TELD and MD provide generally satisfactory long-term clinical outcomes for patients with LDH. TELD can be used as a reliable alternative to MD with less surgical trauma. Modic type II changes, decreased preoperative intervertebral height, and a high body mass index are predictors of a poor prognosis.
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Affiliation(s)
- Xinyu Yang
- Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, China
- Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Shijun Zhang
- Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, China
| | - Junxiao Su
- Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, China
- Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Sai Guo
- Photography Department, School of Journalism and Communication, Tianjin Normal University, Tianjin, China
| | - Yakubu Ibrahim
- Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, China
- Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Kai Zhang
- Department of Orthopedics, The Ninth People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yonghao Tian
- Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, China
| | - Lianlei Wang
- Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, China
| | - Suomao Yuan
- Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, China
| | - Xinyu Liu
- Department of Orthopedics, Qilu Hospital of Shandong University, Jinan, China
- Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
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Zheng LD, Cao YT, Yang YT, Xu ML, Zeng HZ, Zhu SJ, Candito A, Chen Y, Zhu R, Cheng LM. Biomechanical response of lumbar intervertebral disc in daily sitting postures: a poroelastic finite element analysis. Comput Methods Biomech Biomed Engin 2023; 26:1941-1950. [PMID: 36576174 DOI: 10.1080/10255842.2022.2159760] [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: 10/25/2022] [Revised: 12/07/2022] [Accepted: 12/13/2022] [Indexed: 12/29/2022]
Abstract
This study aims to establish and validate a poroelastic L4-L5 finite element model to evaluate the effect of different sitting postures and their durations on the mechanical responses of the disc. During the sustained loading conditions, the height loss, fluid loss and von-Mises stress gradually increased, but the intradiscal pressure decreased. The varying rates of aforementioned parameters were more significant at the initial loading stage and less so at the end. The predicted values in the flexed sitting posture were significantly greater than other postures. The extended sitting posture caused an obvious von-Mises stress concentration in the posterior region of the inter-lamellar matrix. From the biomechanical perspective, prolonged sitting may pose a high risk of lumbar disc degeneration, and therefore adjusting the posture properly in the early stage of sitting time may be useful to mitigate that. Additionally, upright sitting is a safer posture, while flexed sitting posture is more harmful.
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Affiliation(s)
- Liang-Dong Zheng
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Tongji Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Yu-Ting Cao
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Tongji Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Yi-Ting Yang
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Tongji Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Meng-Lei Xu
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Tongji Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Hui-Zi Zeng
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Tongji Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Shi-Jie Zhu
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Tongji Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Antonio Candito
- Institute of Mechanical, Process and Energy Engineering, School of Engineering and Physical Sciences, Heriot-Watt University, Scotland, UK
| | - Yuhang Chen
- Institute of Mechanical, Process and Energy Engineering, School of Engineering and Physical Sciences, Heriot-Watt University, Scotland, UK
| | - Rui Zhu
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Tongji Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Li-Ming Cheng
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Tongji Hospital, School of Medicine, Tongji University, Shanghai, China
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Fan R, Liu J, Liu J. Prediction of the natural frequencies of different degrees of degenerated human lumbar segments L2-L3 using dynamic finite element analysis. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2021; 209:106352. [PMID: 34419755 DOI: 10.1016/j.cmpb.2021.106352] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Accepted: 08/05/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND AND OBJECTIVE Chronic exposure to resonant environment may cause more serious injuries to human lumbar spine than other vibrations. On the condition that the natural frequency of human lumbar spine is known, excitation frequency from an external vibration source can be optimized to keep away from the natural frequency and thus avoid lumbar resonance. Therefore, this study aimed to present an approach to predict the natural frequency of the human lumbar spine. METHODS Four poroelastic finite element models of human L2-L3 spinal motion segments with different degrees of degeneration were established. Dynamic finite element analyses of these models during 1 h of vibration were then conducted. The mechanical parameters of these models under vibrations at different excitation frequencies were predicted. The excitation frequencies that resulted in the greatest changes in the lumbar mechanical parameters were identified as the natural frequencies of the established L2-L3 spinal motion segments. RESULTS Simulation results showed that the natural frequencies of the healthy and mildly degenerated L2-L3 spinal motion segments, moderately degenerated L2-L3 spinal motion segments, and seriously degenerated L2-L3 spinal motion segments were in the range of 5-7, 3-5, and 1-3 Hz, respectively. CONCLUSIONS The predicted results indicated that the natural frequencies of the human L2-L3 spinal motion segments gradually decreased with the severity of degeneration. These phenomena may be related to changes in the lumbar structures and materials because of degeneration. This study provided a feasible method to predict the lumbar natural frequencies for different populations, which may be helpful in optimizing external vibration sources to avoid lumbar resonance.
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Affiliation(s)
- Ruoxun Fan
- Department of Automotive Engineering, Jilin Institute of Chemical Technology, Jilin 132022, China.
| | - Jie Liu
- Department of Automotive Engineering, Jilin Institute of Chemical Technology, Jilin 132022, China
| | - Jun Liu
- Second Hospital of Jilin University, Jilin University, Changchun 130025, China
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Son S, Lee SG, Kim WK, Ahn Y, Jung JM. Disc height discrepancy between supine and standing positions as a screening metric for discogenic back pain in patients with disc degeneration. Spine J 2021; 21:71-79. [PMID: 32687982 DOI: 10.1016/j.spinee.2020.07.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 07/14/2020] [Accepted: 07/14/2020] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT The diagnosis of discogenic low back pain (LBP) from disc degeneration of the lumbar spine is often evaluated with discography. Noninvasive, simple screening methods other than invasive discography are useful, as evidence supporting clinical findings and magnetic resonance imaging (MRI) have come to the forefront. PURPOSE To investigate disc height (DH) discrepancy between supine and standing positions on simple radiography to clarify its clinical screening value in individuals with discogenic LBP. STUDY DESIGN/SETTINGS Retrospective matched cohort design. PATIENT SAMPLE Ninety-two patients with early to middle stage disc degeneration (Pfirrmann grade II, III, or IV). OUTCOME MEASURES Each subject underwent simple radiographs and MRI. Baseline characteristics, including demographic data and MRI findings, and radiological findings, including DH discrepancy, segmental angle, and sagittal balance, were analyzed. DH discrepancy ratio was calculated as (1 - [calibrated DH on standing radiography/calibrated DH on supine radiography]) × 100%. METHODS We matched LBP group of 46 patients with intractable discogenic pain (≥7 of visual analog scale scores) confirmed by discography with control group of 46 patients with similar stage disc degeneration with mild LBP (≤4 of visual analog scale scores). Binary regression analysis, receiver operating characteristic curve analysis, and cut-off value for diagnosis were used to evaluate and clarify diagnostic value of various factors. RESULTS There was no significant difference between the two groups in terms of baseline characteristics, including age, sex, body mass index, pathological level, and magnetic resonance findings such as disc degeneration, high intensity zone, and para-spinal muscle volume. Among the various radiological findings, the calibrated mean DH in the standing position (20.87±5.65 [LBP group] vs. 26.95±3.02 [control group], p<.001) and the DH discrepancy ratio (14.55±6.13% [LBP group] vs. 1.47±0.75% [control group], p=.007) were significantly different between the two groups. The cut-off value for DH discrepancy ratio to screen discogenic LBP was ≥6.04%. Additionally, as a compensation for pain, sagittal vertical axis (3.43±2.03 cm [LBP group] vs. -0.54±3.05 cm [control group], p=.002) and pelvic incidence (54.74±6.76° [LBP group] vs. 43.98±8.67° [control group]; p=.006) were different between the two groups. CONCLUSIONS The results suggest that DH discrepancy between the supine and standing positions could be a screening metric for discogenic LBP in early to middle stage disc degeneration of the lumbar spine.
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Affiliation(s)
- Seong Son
- Department of Neurosurgery, Gil Medical Center, Gachon University College of Medicine, Nadong-Gu, Incheon, 21565, South Korea.
| | - Sang Gu Lee
- Department of Neurosurgery, Gil Medical Center, Gachon University College of Medicine, Nadong-Gu, Incheon, 21565, South Korea
| | - Woo Kyung Kim
- Department of Neurosurgery, Gil Medical Center, Gachon University College of Medicine, Nadong-Gu, Incheon, 21565, South Korea
| | - Yong Ahn
- Department of Neurosurgery, Gil Medical Center, Gachon University College of Medicine, Nadong-Gu, Incheon, 21565, South Korea
| | - Jong Myung Jung
- Department of Neurosurgery, Gil Medical Center, Gachon University College of Medicine, Nadong-Gu, Incheon, 21565, South Korea
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Castro APG, Alves JL. Numerical implementation of an osmo-poro-visco-hyperelastic finite element solver: application to the intervertebral disc. Comput Methods Biomech Biomed Engin 2020; 24:538-550. [PMID: 33111576 DOI: 10.1080/10255842.2020.1839059] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
This work deals with the finite element (FE) implementation of a biphasic poroelastic formulation specifically developed to address the intricate behaviour of the Intervertebral Disc (IVD) and other highly hydrated soft tissues. This formulation is implemented in custom FE solver V-Biomech, being the validation performed with a lumbar IVD model, which was compared against the analogous FE model of Williams et al. and the experiments of Tyrrell et al. Good agreement with these benchmarks was achieved, meaning that V-Biomech and its novel poroelastic formulation are a viable alternative for simulation of biphasic soft tissues.
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Affiliation(s)
- A P G Castro
- IDMEC - Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - J L Alves
- CMEMs, Department of Mechanical Engineering, Universidade do Minho, Guimarães, Portugal
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Fan R, Liu J, Liu J. Finite element investigation on the dynamic mechanical properties of low-frequency vibrations on human L2-L3 spinal motion segments with different degrees of degeneration. Med Biol Eng Comput 2020; 58:3003-3016. [PMID: 33064234 DOI: 10.1007/s11517-020-02263-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 08/29/2020] [Indexed: 11/26/2022]
Abstract
Exposure to low-frequency vibration is harmful to human lumbar health. However, the dynamic mechanical properties of lumbar spines with varying degrees of degeneration during time-dependent vibration remain incompletely understood. In this study, four poroelastic finite element models of human L2-L3 spinal motion segments, including the non-degeneration and the mild, moderate, and serious degeneration, were established. One-hour low-frequency vibrations with different frequencies were applied. Then, the dynamic mechanical properties of different degenerated lumbar models under the same vibration and the same lumbar model under vibrations at different frequencies were investigated. The results indicated and implied that the negative influences of 1-h vibration on the dynamic mechanical properties of the non-degenerated and mildly degenerated models were similar, but became obvious for the moderately and seriously degenerated models with time. Therefore, the damage caused by low-frequency vibration on the degenerated spinal motion segments was more serious compared with that on the healthy one. Meanwhile, the dynamic mechanical properties of the same lumbar model under vibrations at different frequencies expressed the negligible differences when the vibration frequency was not close to the lumbar natural frequency. Thus, the effects of the 1-h vibrations at different frequencies on one spinal motion segment were similar. Vibration frequency sensitivity analysis on the dynamic characteristics of human L2-L3 spinal motion segments with different degrees of degeneration.
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Affiliation(s)
- Ruoxun Fan
- Department of Automotive Engineering, Jilin Institute of Chemical Technology, Jilin, 132022, China.
| | - Jie Liu
- Department of Automotive Engineering, Jilin Institute of Chemical Technology, Jilin, 132022, China
| | - Jun Liu
- Second Hospital of Jilin University, Jilin University, Changchun, 130025, China
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Presentation of an Approach on Determination of the Natural Frequency of Human Lumbar Spine Using Dynamic Finite Element Analysis. Appl Bionics Biomech 2019; 2019:5473891. [PMID: 30719072 PMCID: PMC6334357 DOI: 10.1155/2019/5473891] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 10/25/2018] [Accepted: 11/06/2018] [Indexed: 11/18/2022] Open
Abstract
Occurring resonance may negatively affect the health of the human lumbar spine. Hence, vibration generated in working and living environments should be optimized to avoid resonance when identifying the natural frequency of the human lumbar spine. The range of the natural frequency of the human lumbar spine has been investigated, but its specific numerical value has not been determined yet. This study aimed at presenting an approach based on resonance for predicting the specific numerical value of the natural frequency of the human lumbar spine. The changes in the numerical fluctuation amplitudes and the cycles of lumbar mechanical parameters during resonance are greater than those during nonresonant vibration. Given that the range of the natural frequency has been identified, vibrations at different excitation frequencies within this range can be applied in a human lumbar finite element model for dynamic finite element analysis. When the excitation frequency is close to the natural frequency, resonance occurs, causing great changes in the numerical fluctuation amplitudes and the cycles of lumbar mechanical parameters. Therefore, the natural frequency of the lumbar finite element model could be back-calculated. Results showed that the natural frequency of the established model was 3.5 Hz. Meanwhile, the closer the excitation frequency was to the natural frequency, the greater the changes in the numerical fluctuation amplitudes and cycles in the parameters would be. This study presented an approach for predicting the specific numerical value of the natural frequency of the human lumbar spine. Identifying the natural frequency assists in finding preventive measures for lumbar injury caused by vibration and in designing the vibration source in working and living environments to avoid approximating to the natural frequency of the human lumbar spine.
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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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Li L, Shen T, Li YK. A Finite Element Analysis of Stress Distribution and Disk Displacement in Response to Lumbar Rotation Manipulation in the Sitting and Side-Lying Positions. J Manipulative Physiol Ther 2018; 40:580-586. [PMID: 29187309 DOI: 10.1016/j.jmpt.2017.07.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 06/30/2017] [Accepted: 07/20/2017] [Indexed: 11/27/2022]
Abstract
OBJECTIVE This study aimed to investigate stress distribution and disk displacement in healthy and degenerated intervertebral disks during simulated lumbar rotation manipulation (LRM) in the sitting and side-lying positions. METHODS Three-dimensional (3D) finite element models of healthy, mildly degenerated and moderately degenerated L4/5 spinal units were reconstructed. Lumbar rotation manipulation in the sitting and side-lying positions were simulated, and alterations in stress distribution and disk displacement in the lumbar disks were observed. RESULTS The application of LRM in the sitting or side-lying position resulted in a similar stress distribution in healthy, mildly degenerated, and moderately degenerated disks. Stress was concentrated at the anterior right side of the annulus. In all disks, intradiskal pressure (IDP) and maximum von Mises stress were higher during LRM in the sitting position than during LRM in the side-lying position. During these manipulations, Intradiskal pressure and stress in the annulus of moderately degenerated disks were higher than in mildly degenerated disks. Displacement was most obvious in healthy disks. CONCLUSIONS Mildly and moderately degenerated lumbar disks were subject to higher stress during LRM in the sitting position than during LRM in the side-lying position. Intradiskal pressure and the maximum von Mises stress in the annulus of moderately degenerated disks increased, suggesting the need for caution when treating patients with moderately compromised disks. Although our results are in accordance with previously published data, they are simulated and preliminary and do not necessarily replicate the clinical condition.
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Affiliation(s)
- Li Li
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, Guangdong Province, China; Department of Rehabilitation Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong Province, China.
| | - Tong Shen
- Department of Rehabilitation Medicine, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong Province, China
| | - Yi-Kai Li
- School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, Guangdong Province, China
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