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Knapik GG, Mendel E, Bourekas E, Marras WS. Computational lumbar spine models: A literature review. Clin Biomech (Bristol, Avon) 2022; 100:105816. [PMID: 36435080 DOI: 10.1016/j.clinbiomech.2022.105816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 10/26/2022] [Accepted: 11/08/2022] [Indexed: 11/15/2022]
Abstract
BACKGROUND Computational spine models of various types have been employed to understand spine function, assess the risk that different activities pose to the spine, and evaluate techniques to prevent injury. The areas in which these models are applied has expanded greatly, potentially beyond the appropriate scope of each, given their capabilities. A comprehensive understanding of the components of these models provides insight into their current capabilities and limitations. METHODS The objective of this review was to provide a critical assessment of the different characteristics of model elements employed across the spectrum of lumbar spine modeling and in newer combined methodologies to help better evaluate existing studies and delineate areas for future research and refinement. FINDINGS A total of 155 studies met selection criteria and were included in this review. Most current studies use either highly detailed Finite Element models or simpler Musculoskeletal models driven with in vivo data. Many models feature significant geometric or loading simplifications that limit their realism and validity. Frequently, studies only create a single model and thus can't account for the impact of subject variability. The lack of model representation for certain subject cohorts leaves significant gaps in spine knowledge. Combining features from both types of modeling could result in more accurate and predictive models. INTERPRETATION Development of integrated models combining elements from different model types in a framework that enables the evaluation of larger populations of subjects could address existing voids and enable more realistic representation of the biomechanics of the lumbar spine.
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Affiliation(s)
- Gregory G Knapik
- Spine Research Institute, The Ohio State University, 210 Baker Systems, 1971 Neil Avenue, Columbus, OH 43210, USA.
| | - Ehud Mendel
- Department of Neurosurgery, Yale University, New Haven, CT 06510, USA
| | - Eric Bourekas
- Department of Radiology, The Ohio State University, Columbus, OH 43210, USA
| | - William S Marras
- Spine Research Institute, The Ohio State University, 210 Baker Systems, 1971 Neil Avenue, Columbus, OH 43210, USA
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Sengul E, Ozmen R, Yaman ME, Demir T. Influence of posterior pedicle screw fixation at L4-L5 level on biomechanics of the lumbar spine with and without fusion: a finite element method. Biomed Eng Online 2021; 20:98. [PMID: 34620170 PMCID: PMC8499536 DOI: 10.1186/s12938-021-00940-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 09/24/2021] [Indexed: 12/27/2022] Open
Abstract
Background Posterior pedicle screw (PS) fixation, a common treatment method for widespread low-back pain problems, has many uncertain aspects including stress concentration levels, effects on adjacent segments, and relationships with physiological motions. A better understanding of how posterior PS fixation affects the biomechanics of the lumbar spine is needed. For this purpose, a finite element (FE) model of a lumbar spine with posterior PS fixation at the L4–L5 segment level was developed by partially removing facet joints (FJs) to imitate an actual surgical procedure. This FE study aimed to investigate the influence of the posterior PS fixation system on the biomechanics of the lumbar spine before and after fusion by determining which physiological motions have the most increase in posterior instrumentation (PI) stresses and FJ loading. Results It was determined that posterior PS fixation increased FJ loading by approximately 35% and 23% at the L3–L4 adjacent level with extension and lateral bending motion, respectively. This increase in FJ loading at the adjacent level could point to the possibility that adjacent segment disease has developed or progressed after posterior lumbar interbody fusion. Furthermore, analyses of peak von Mises stresses on PI showed that the maximum PI stresses of 272.1 MPa and 263.7 MPa occurred in lateral bending and flexion motion before fusion, respectively. Conclusions The effects of a posterior PS fixation system on the biomechanics of the lumbar spine before and after fusion were investigated for all physiological motions. This model could be used as a fundamental tool for further studies, providing a better understanding of the effects of posterior PS fixation by clearing up uncertain aspects.
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Affiliation(s)
- Emre Sengul
- Department of Mechanical Engineering, TOBB University of Economics and Technology, Çankaya, Ankara, Turkey. .,Mechanical Engineer, Roketsan Inc., Lalahan, 06852, Ankara, Turkey.
| | - Ramazan Ozmen
- Department of Mechanical Engineering, Karabük University, Merkez, Karabük, Turkey
| | - Mesut Emre Yaman
- Department of Neurosurgery, Gazi University School of Medicine, Ankara, Turkey
| | - Teyfik Demir
- Department of Mechanical Engineering, TOBB University of Economics and Technology, Çankaya, Ankara, Turkey
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Jain P, Khan MR. Selection of suitable pedicle screw for degenerated cortical and cancellous bone of human lumbar spine: A finite element study. Int J Artif Organs 2020; 44:361-366. [PMID: 33045876 DOI: 10.1177/0391398820964483] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Pedicular arthrodesis is the traditional procedure in terms of increase in the biomechanical stability with higher fixation rate. The current work aims to identify the effect of three spinal pedicle screws considering cortical and cancellous degeneracy condition. Lumbar section L2-L3 is utilized and various load and moment conditions were applied to depict the various biomechanical parameters for selection of suitable screw. Three dimensional model is considered in finite element analysis to identify the various responses of pedicle screw at bone screw juncture. Computed tomography (CT) images of a healthy male were considered to generate the finite element vertebral model. Generated intact model was further utilized to develop the other implanted models of degenerated cortical and cancellous bone models. The three fused instrumented models with different cortical and cancellous degeneracy conditions were analyzed in finite element analysis. The results were obtained as stress pattern at bone screw boundary and intervertebral disc stress. FE simulated results represents significant changes in the von Mises stress due to various load and moment conditions on degenerated bones during different body movement conditions. Results have shown that among all pedicle screws, the 6.0 mm diameter screw reflects very less stress values at the juncture. Multiple results on biomechanical aspects obtained during the FE study can be considered to design a new stabilization device and may be helpful to plan surgery of critical sections.
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Affiliation(s)
- Pushpdant Jain
- School of Mechanical Engineering, VIT Bhopal University, Madhya Pradesh, India
| | - Mohammed Rajik Khan
- Department of Industrial Design, National Institute of Technology Rourkela, Odisha, India
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Demir E, Eltes P, Castro AP, Lacroix D, Toktaş İ. Finite element modelling of hybrid stabilization systems for the human lumbar spine. Proc Inst Mech Eng H 2020; 234:1409-1420. [PMID: 32811288 DOI: 10.1177/0954411920946636] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Intersomatic fusion is a very popular treatment for spinal diseases associated with intervertebral disc degeneration. The effects of three different hybrid stabilization systems on both range of motion and intradiscal pressure were investigated, as there is no consensus in the literature about the efficiency of these systems. Finite element simulations were designed to predict the variations of range of motion and intradiscal pressure from intact to implanted situations. After hybrid stabilization system implantation, L4-L5 level did not lose its motion completely, while L5-S1 had no mobility as a consequence of disc removal and fusion process. BalanC hybrid stabilization system represented higher mobility at the index level, reduced intradiscal pressure of adjacent level, but caused to increment in range of motion by 20% under axial rotation. Higher tendency by 93% to the failure was also detected under axial rotation. Dynesys hybrid stabilization system represented more restricted motion than BalanC, and negligible effects to the adjacent level. B-DYN hybrid stabilization system was the most rigid one among all three systems. It reduced intradiscal pressure and range of motion at the adjacent level except from motion under axial rotation being increased by 13%. Fracture risk of B-DYN and Dynesys Transition Optima components was low when compared with BalanC. Mobility of the adjacent level around axial direction should be taken into account in case of implantation with BalanC and B-DYN systems, as well as on the development of new designs. Having these findings in mind, it is clear that hybrid systems need to be further tested, both clinically and numerically, before being considered for common use.
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Affiliation(s)
- Eylül Demir
- Mechanical Engineering Department, Faculty of Engineering and Natural Sciences, Ankara Yildirim Beyazit University, Ankara, Turkey
| | - Peter Eltes
- National Center for Spinal Disorders, Budapest, Hungary
| | - Andre Pg Castro
- IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
| | - Damien Lacroix
- INSIGNEO Institute for in Silico Medicine, The University of Sheffield, Sheffield, UK
| | - İhsan Toktaş
- Mechanical Engineering Department, Faculty of Engineering and Natural Sciences, Ankara Yildirim Beyazit University, Ankara, Turkey
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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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Comparison of Biomechanical Performance of Five Different Treatment Approaches for Fixing Posterior Pelvic Ring Injury. JOURNAL OF HEALTHCARE ENGINEERING 2020; 2020:5379593. [PMID: 32076495 PMCID: PMC6996702 DOI: 10.1155/2020/5379593] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 11/18/2019] [Accepted: 01/06/2020] [Indexed: 12/03/2022]
Abstract
Background A large number of pelvic injuries are seriously unstable, with mortality rates reaching 19%. Approximately 60% of pelvic injuries are related to the posterior pelvic ring. However, the selection of a fixation method for a posterior pelvic ring injury remains a challenging problem for orthopedic surgeons. The aim of the present study is to investigate the biomechanical performance of five different fixation approaches for posterior pelvic ring injury and thus provide guidance on the choice of treatment approach in a clinical setting. Methods A finite element (FE) model, including the L3-L5 lumbar vertebrae, sacrum, and full pelvis, was created from CT images of a healthy adult. Tile B and Tile C types of pelvic fractures were created in the model. Five different fixation methods for fixing the posterior ring injury (PRI) were simulated: TA1 (conservative treatment), TA2 (S1 screw fixation), TA3 (S1 + S2 screw fixation), TA4 (plate fixation), and TA5 (modified triangular osteosynthesis). Based on the fixation status (fixed or nonfixed) of the anterior ring and the fixation method for PRI, 20 different FE models were created. An upright standing loading scenario was simulated, and the resultant displacements at the sacroiliac joint were compared between different models. Results When TA5 was applied, the resultant displacements at the sacroiliac joint were the smallest (1.5 mm, 1.6 mm, 1.6 mm, and 1.7 mm) for all the injury cases. The displacements induced by TA3 and TA2 were similar to those induced by TA5. TA4 led to larger displacements at the sacroiliac joint (2.3 mm, 2.4 mm, 4.8 mm, and 4.9 mm), and TA1 was the worst case (3.1 mm, 3.2 mm, 6.3 mm, and 6.5 mm). Conclusions The best internal fixation method for PRI is the triangular osteosynthesis approach (TA5), followed by S1 + S2 screw fixation (TA3), S1 screw fixation (TA2), and plate fixation (TA4).
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Fan W, Guo LX, Zhao D. Stress analysis of the implants in transforaminal lumbar interbody fusion under static and vibration loadings: a comparison between pedicle screw fixation system with rigid and flexible rods. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2019; 30:118. [PMID: 31628540 DOI: 10.1007/s10856-019-6320-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Accepted: 10/08/2019] [Indexed: 06/10/2023]
Abstract
The use of a pedicle screw fixation system with rods made of more compliant materials has become increasingly popular for spine fusion surgery in recent years. The aim of this study was to compare stress responses of the implants in transforaminal lumbar interbody fusion (TLIF) when using flexible and conventional rigid posterior fixation systems. A previously validated intact L1-S1 finite element model was modified to simulate single-level (L4-L5) TLIF with bilateral pedicle screw fixation using two types of connecting rod (rigid and flexible rods). The von Mises stresses in the implants (including TLIF cage, pedicle screws and rods) for the rigid and flexible fixations were analyzed under static and vibration loadings. The results showed that compared with the rigid fixation, the use of flexible fixation decreased the maximum stress in the pedicle screws, but increased the maximum stress in the cage and the ratio of maximum stress in the rods to the yield stress. It was also found that with decreasing diameter of the flexible rod (i.e. increasing flexibility of the rod), the maximum stress was decreased in the pedicle screws but increased in the cage and the rods. The findings imply that compared with the rigid rod, application of the flexible rod in the pedicle screw fixation system for the TLIF might decrease the breakage risk of pedicle screws but increase the risk of cage subsidence and rod breakage. Moreover, flexibility of the rod in the flexible fixation system should be carefully determined.
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Affiliation(s)
- Wei Fan
- School of Mechanical Engineering and Automation, Northeastern University, No. 3-11, Wenhua Road, Heping District, Shenyang, 110819, China.
| | - Li-Xin Guo
- School of Mechanical Engineering and Automation, Northeastern University, No. 3-11, Wenhua Road, Heping District, Shenyang, 110819, China
| | - Dan Zhao
- Liaoning University of Traditional Chinese Medicine, Shenyang, China
- Liaoning Special Education Teachers College, Shenyang, China
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Zhou C, Cha T, Li G. An upper bound computational model for investigation of fusion effects on adjacent segment biomechanics of the lumbar spine. Comput Methods Biomech Biomed Engin 2019; 22:1126-1134. [PMID: 31294608 DOI: 10.1080/10255842.2019.1639047] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Prediction of the biomechanical effects of fusion surgery on adjacent segments is a challenge in computational biomechanics of the spine. In this study, a two-segment L3-L4-L5 computational model was developed to simulate the effects of spinal fusion on adjacent segment biomechanical responses under a follower load condition. The interaction between the degenerative segment (L4-5) and the adjacent segment (L3-4) was simulated using an equivalent follower spring. The spring stiffness was calibrated using a rigid fusion of a completely degenerated disc model at the L4-5 level, resulting in an upper bound response at the adjacent (L3-4) segment. The obtained upper bound equivalent follower spring was used to simulate the upper bound biomechanical responses of fusion of the disc with different degeneration grades. It was predicted that as the disc degeneration grade at the degenerative segment decreased, the effect on the adjacent segment responses decreased accordingly after fusion. The data indicated that the upper bound computational model can be a useful computational tool for evaluation of the interaction between segments and for investigation of the biomechanical mechanisms of adjacent segment degeneration after fusion.
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Affiliation(s)
- Chaochao Zhou
- Orthopaedic Bioengineering Research Center , Newton-Wellesley Hospital, Harvard Medical School , Newton , MA , USA.,Department of Mechanical Engineering , State University of New York at Binghamton , Binghamton , NY , USA.,Department of Orthopaedic Surgery , Massachusetts General Hospital, Harvard Medical School , Boston , MA , USA
| | - Thomas Cha
- Department of Orthopaedic Surgery , Massachusetts General Hospital, Harvard Medical School , Boston , MA , USA
| | - Guoan Li
- Orthopaedic Bioengineering Research Center , Newton-Wellesley Hospital, Harvard Medical School , Newton , MA , USA.,Department of Orthopaedic Surgery , Massachusetts General Hospital, Harvard Medical School , Boston , MA , USA
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Jain P, Khan MR. Prediction of biomechanical behavior of lumbar vertebrae using a novel semi-rigid stabilization device. Proc Inst Mech Eng H 2019; 233:849-857. [PMID: 31203751 DOI: 10.1177/0954411919856497] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The work investigates the effect of proposed novel semi-rigid stabilization device on lumbar segment L2-L3 so as to preserve motion at vertebral level. Here, the biomechanical behavior of intact spine with three instrumented spinal models (semi-rigid stabilization device, rigid implant and dynamic stabilization system NFlex) have been compared under the motion conditions of flexion, extension, bending and twist. Three-dimensional non-linear finite models of intact spine, semi-rigid stabilization device, rigid implant and dynamic stabilization system NFlex were developed in the present study. All the four models were subjected to a combined load of 400 N in axial compression along with 2, 4, 6, 8 and 10 N m as bending moment individually. Dynamic stabilization system NFlex shows the maximum variation in motion and reflects range of motion as 89.7% during lateral bending, 53.4% in flexion, 34.6% in twist and 28.0% in extension with respect to intact spine. However, semi-rigid stabilization device and rigid implant shows the range of motion of 60%, 48.7%, 32% and 21.8% and 60%, 32.3%, 22.3% and 21.7% of intact, respectively, during bending, flexion, twist and extension. Finite element simulation results reveal that semi-rigid stabilization device shows comparatively lower values than dynamic stabilization system NFlex and higher as compared to rigid implant for measured intradiscal pressure and von Mises strain at intervertebral disc-23.
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Affiliation(s)
- Pushpdant Jain
- Department of Industrial Design, National Institute of Technology Rourkela, Rourkela, India
| | - Mohammed Rajik Khan
- Department of Industrial Design, National Institute of Technology Rourkela, Rourkela, India
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Más Y, Gracia L, Ibarz E, Gabarre S, Peña D, Herrera A. Finite element simulation and clinical follow-up of lumbar spine biomechanics with dynamic fixations. PLoS One 2017; 12:e0188328. [PMID: 29186157 PMCID: PMC5706716 DOI: 10.1371/journal.pone.0188328] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 11/03/2017] [Indexed: 12/16/2022] Open
Abstract
Arthrodesis is a recommended treatment in advanced stages of degenerative disc disease. Despite dynamic fixations were designed to prevent abnormal motions with better physiological load transmission, improving lumbar pain and reducing stress on adjacent segments, contradictory results have been obtained. This study was designed to compare differences in the biomechanical behaviour between the healthy lumbar spine and the spine with DYNESYS and DIAM fixation, respectively, at L4-L5 level. Behaviour under flexion, extension, lateral bending and axial rotation are compared using healthy lumbar spine as reference. Three 3D finite element models of lumbar spine (healthy, DYNESYS and DIAM implemented, respectively) were developed, together a clinical follow-up of 58 patients operated on for degenerative disc disease. DYNESYS produced higher variations of motion with a maximum value for lateral bending, decreasing intradiscal pressure and facet joint forces at instrumented level, whereas screw insertion zones concentrated stress. DIAM increased movement during flexion, decreased it in another three movements, and produced stress concentration at the apophyses at instrumented level. Dynamic systems, used as single systems without vertebral fusion, could be a good alternative to degenerative disc disease for grade II and grade III of Pfirrmann.
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Affiliation(s)
- Yolanda Más
- Department of Mechanical Engineering, University of Zaragoza, Zaragoza, Spain
| | - Luis Gracia
- Department of Mechanical Engineering, University of Zaragoza, Zaragoza, Spain
- Aragón Institute of Engineering Research, Zaragoza, Spain
| | - Elena Ibarz
- Department of Mechanical Engineering, University of Zaragoza, Zaragoza, Spain
- Aragón Institute of Engineering Research, Zaragoza, Spain
| | - Sergio Gabarre
- Department of Mechanical Engineering, University of Zaragoza, Zaragoza, Spain
| | - Diego Peña
- Spine Unit, Department of Orthopaedic Surgery and Traumatology, Miguel Servet University Hospital, Zaragoza, Spain
- Aragón Health Research Institute, Zaragoza, Spain
| | - Antonio Herrera
- Aragón Institute of Engineering Research, Zaragoza, Spain
- Aragón Health Research Institute, Zaragoza, Spain
- Department of Surgery, School of Medicine, University of Zaragoza, Zaragoza, Spain
- * E-mail:
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Biomechanical Study of Fused Lumbar Spine Considering Bone Degeneracy Using FEA. ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2017. [DOI: 10.1007/s13369-017-2848-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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