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Ansaripour H, Ferguson S, Flohr M. In-vitro Biomechanics of the Cervical Spine: a Systematic Review. J Biomech Eng 2022; 144:1140519. [PMID: 35482019 DOI: 10.1115/1.4054439] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Indexed: 11/08/2022]
Abstract
In-vitro testing has been conducted to provide a comprehensive understanding of the biomechanics of the cervical spine. This has allowed a characterization of the stability of the spine as influenced by the intrinsic properties of its tissue constituents and the severity of degeneration or injury. This also enables the pre-clinical estimation of spinal implant functionality and the success of operative procedures. The purpose of this review paper was to compile methodologies and results from various studies addressing spinal kinematics in pre- and post-operative conditions so that they could be compared. The reviewed literature was evaluated to provide suggestions for a better approach for future studies, to reduce the uncertainties and facilitate comparisons among various results. The overview is presented in a way to inform various disciplines, such as experimental testing, design development, and clinical treatment. The biomechanical characteristics of the cervical spine, mainly the segmental range of motion (ROM), intradiscal pressure (IDP), and facet joint load (FJL), have been assessed by testing functional spinal units (FSUs). The relative effects of pathologies including disc degeneration, muscle dysfunction, and ligamentous transection have been studied by imposing on the specimen complex load scenarios imitating physiological conditions. The biomechanical response is strongly influenced by specimen type, test condition, and the different types of implants utilized in the different experimental groups.
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Affiliation(s)
- Hossein Ansaripour
- CeramTec GmbH, Plochingen, Germany; Institute for Biomechanics, D-HEST, ETH, Zurich, Switzerland, CeramTec GmbH, CeramTec-Platz 1-9, 73207 Plochingen, Germany
| | - Stephen Ferguson
- Institute for Biomechanics, D-HEST, ETH, Zurich, Switzerland, Hönggerbergring 64, HPP O-22, 8093 Zurich, Switzerland
| | - Markus Flohr
- CeramTec GmbH, Plochingen, Germany, CeramTec GmbH, CeramTec-Platz 1-9, 73207 Plochingen, Germany
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Jin C, Wang Z, Liu P, Liu Y, Wang Z, Xie N. A biomechanical analysis of anterior cervical discectomy and fusion alone or combined cervical fixations in treating compression-extension injury with unilateral facet joint fracture: a finite element study. BMC Musculoskelet Disord 2021; 22:938. [PMID: 34758793 PMCID: PMC8582196 DOI: 10.1186/s12891-021-04814-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 10/21/2021] [Indexed: 11/12/2022] Open
Abstract
Background Compression-extension injury with unilateral facet joint fracture is one of the most devastating injuries of subaxial cervical spine. However, it is not yet clear which fixation technique represents the optimal choice in surgical management. This study aims to assess the construct stability at the operative level (C4/C5 cervical spine) following anterior cervical discectomy and fusion (ACDF) alone and combined fixation techniques (posterior-anterior fixations). Methods A previously validated three-dimensional C2-T1 finite element model were modified to simulate surgical procedures via the anterior-only approach (ACDF) and combined cervical approach [(transarticular screw, lateral mass screw, unilateral pedicle screw, bilateral pedicle screw) + ACDF, respectively] for treating compression-extension injury with unilateral facet joint fracture at C4/C5 level. Construct stability (range of rotation, axial compression displacement and anterior shear displacement) at the operative level was comparatively analyzed. Results In comparison with combined fixation techniques, a wider range of motion and a higher maximum von Mises stress was found in single ACDF. There was no obvious difference in range of motion among transarticular screw and other posterior fixations in the presence of anterior fixation. In addition, the screws inserted by transarticular screw technique had high stress concentration at the middle part of the screw but much less than 500 MPa under different conditions. Furthermore, the variability of von Mises stress in the transarticular screw fixation device was significantly lower than ACDF but no obvious difference compared with other posterior fixations. Conclusions Of the five fixation techniques, ACDF has proven poor stability and high structural stress. Compared with lateral and pedicle screw, transarticular screw technique was not worse biomechanically and less technically demanding to acquire in clinical practice. Therefore, our study suggested that combined fixation technique (transarticular screw + ACDF) would be a reasonable treatment option to acquire an immediate stabilization in the management of compression-extension injury with unilateral facet joint fracture. However, clinical aspects must also be regarded when choosing a reconstruction method for a specific patient.
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Affiliation(s)
- Chen Jin
- Division of Spine Surgery, Department of Orthopedics, Tongji Hospital, Tongji University School of Medicine, 389 Xincun Road, Putuo District, Shanghai, 200065, China
| | - Zhong Wang
- Division of Spine Surgery, Department of Orthopedics, Daping Hospital of Army Medical University, Chongqing, China
| | - Peng Liu
- Division of Spine Surgery, Department of Orthopedics, Daping Hospital of Army Medical University, Chongqing, China.,State Key Laboratory of Trauma: Burns & Combined Wound, Institute for Traffic Medicine of Army Medical University, Chongqing, China
| | - Yaoyao Liu
- Division of Spine Surgery, Department of Orthopedics, Daping Hospital of Army Medical University, Chongqing, China
| | - Zhanwei Wang
- Division of Spine Surgery, Department of Orthopedics, Tongji Hospital, Tongji University School of Medicine, 389 Xincun Road, Putuo District, Shanghai, 200065, China
| | - Ning Xie
- Division of Spine Surgery, Department of Orthopedics, Tongji Hospital, Tongji University School of Medicine, 389 Xincun Road, Putuo District, Shanghai, 200065, China.
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Hah RJ, Alluri R, Anderson PA. Biomechanical Analysis of an Anterior Cervical Discectomy and Fusion Pseudarthrosis Model Revised With Machined Interfacet Allograft Spacers. Global Spine J 2020; 10:973-981. [PMID: 32875821 PMCID: PMC7645080 DOI: 10.1177/2192568219884265] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
STUDY DESIGN Biomechanics study. OBJECTIVES To evaluate the biomechanical advantage of interfacet allograft spacers in an unstable single-level and 2-level anterior cervical discectomy and fusion (ACDF) pseudoarthrosis model. METHODS Nine single-level and 8 two-level ACDF constructs were tested. Range of motion in flexion-extension (FE), lateral bending (LB), and axial rotation (AR) at 1.5 N m were collected in 4 testing configurations: (1) intact spine, (2) ACDF with interbody graft and plate/screw, (3) ACDF with interbody graft and plate/loosened screws (loose condition), and (4) ACDF with interbody graft and plate/loosened screws supplemented with interfacet allograft spacers (rescue condition). RESULTS All fixation configurations resulted in statistically significant decreases in range of motion in all bending planes compared with the intact spine (P < .05). One Level. Performing ACDF with interbody graft and plate on the intact spine reduced FE, LB, and AR 60.0%, 64.9%, and 72.9%, respectively. Loosening the ACDF screws decreased these reductions to 40.9%, 44.6%, and 52.1%. The addition of interfacet allograft spacers to the loose condition increased these reductions to 74.0%, 84.1%, and 82.1%. Two Level. Performing ACDF with interbody graft and plate on the intact spine reduced FE, LB, and AR 72.0%, 71.1%, and 71.2%, respectively. Loosening the ACDF screws decreased these reductions to 55.4%, 55.3%, and 51.3%. The addition of interfacet allograft spacers to the loose condition significantly increased these reductions to 82.6%, 91.2%, and 89.3% (P < .05). CONCLUSIONS Supplementation of a loose ACDF construct (pseudarthrosis model) with interfacet allograft spacers significantly increases stability and has potential applications in treating cervical pseudarthrosis.
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Affiliation(s)
- Raymond J. Hah
- University of Southern California, Los Angeles, CA, USA,Raymond J. Hah, Department of Orthopaedic Surgery, Keck School of Medicine, University of Southern California, USC Spine Center, 1420 San Pablo St, Ste 5400, Los Angeles, CA 90033, USA.
| | - Ram Alluri
- University of Southern California, Los Angeles, CA, USA
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Voronov LI, Siemionow KB, Havey RM, Carandang G, Patwardhan AG. Biomechanical evaluation of DTRAX(®) posterior cervical cage stabilization with and without lateral mass fixation. MEDICAL DEVICES-EVIDENCE AND RESEARCH 2016; 9:285-90. [PMID: 27601934 PMCID: PMC5003555 DOI: 10.2147/mder.s111031] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Introduction Lateral mass screw (LMS) fixation with plates or rods is the current standard procedure for posterior cervical fusion. Recently, implants placed between the facet joints have become available as an alternative to LMS or transfacet screws for patients with cervical spondylotic radiculopathy. The purpose of this study was to evaluate the biomechanical stability of the DTRAX® cervical cage for single- and two-level fusion and compare this to the stability achieved with LMS fixation with rods in a two-level construct. Methods Six cadaveric cervical spine (C3–C7) specimens were tested in flexion–extension, lateral bending, and axial rotation to ±1.5 Nm moment without preload (0 N) in the following conditions: 1) intact (C3–C7), 2) LMS and rods at C4–C5 and C5–C6, 3) removal of all rods (LMS retained) and placement of bilateral posterior cages at C5–C6, 4) bilateral posterior cages at C4–C5 and C5–C6 (without LMS and rods), and 5) C4–C5 and C5–C6 bilateral posterior cages at C4–C5 and C5–C6 with rods reinserted. Results Bilateral posterior cervical cages significantly reduced range of motion in all tested directions in both single- and multilevel constructs (P<0.05). Similar stability was achieved with bilateral posterior cages and LMS in a two-level construct: 0.6°±0.3° vs 1.2°±0.4° in flexion–extension (P=0.001), (5.0°±2.6° vs 3.1°±1.3°) in lateral bending (P=0.053), (1.3°±1.0° vs 2.2°±0.9°) in axial rotation (P=0.091) for posterior cages and LMS, respectively. Posterior cages, when placed as an adjunct to LMS, further reduced range of motion in a multilevel construct (P<0.05). Conclusion Bilateral posterior cages provide similar cervical segmental stability compared with a LMS and rod construct and may be an alternative surgical option for select patients. Furthermore, supplementation of a lateral mass construct with posterior cages increases cervical spine stability in single- and multilevel conditions.
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Affiliation(s)
- Leonard I Voronov
- Department of Orthopaedic Surgery and Rehabilitation, Loyola University Chicago, Maywood; Musculoskeletal Biomechanics Laboratory, Edward Hines Jr. VA Hospital, Hines
| | - Krzysztof B Siemionow
- Department of Orthopaedics, University of Illinois College of Medicine at Chicago, Chicago, IL, USA
| | - Robert M Havey
- Department of Orthopaedic Surgery and Rehabilitation, Loyola University Chicago, Maywood; Musculoskeletal Biomechanics Laboratory, Edward Hines Jr. VA Hospital, Hines
| | - Gerard Carandang
- Musculoskeletal Biomechanics Laboratory, Edward Hines Jr. VA Hospital, Hines
| | - Avinash G Patwardhan
- Department of Orthopaedic Surgery and Rehabilitation, Loyola University Chicago, Maywood; Musculoskeletal Biomechanics Laboratory, Edward Hines Jr. VA Hospital, Hines
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Voronov LI, Siemionow KB, Havey RM, Carandang G, Phillips FM, Patwardhan AG. Bilateral posterior cervical cages provide biomechanical stability: assessment of stand-alone and supplemental fixation for anterior cervical discectomy and fusion. MEDICAL DEVICES-EVIDENCE AND RESEARCH 2016; 9:223-30. [PMID: 27471414 PMCID: PMC4948702 DOI: 10.2147/mder.s109588] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Introduction Supplemental posterior instrumentation has been widely used to enhance stability and improve fusion rates in higher risk patients undergoing anterior cervical discectomy and fusion (ACDF). These typically involve posterior lateral mass or pedicle screw fixation with significant inherent risks and morbidities. More recently, cervical cages placed bilaterally between the facet joints (posterior cervical cages) have been used as a less disruptive alternative for posterior fixation. The purpose of this study was to compare the stability achieved by both posterior cages and ACDF at a single motion segment and determine the stability achieved with posterior cervical cages used as an adjunct to single- and multilevel ACDF. Methods Seven cadaveric cervical spine (C2–T1) specimens were tested in the following sequence: intact, C5–C6 bilateral posterior cages, C6–C7 plated ACDF with and without posterior cages, and C3–C5 plated ACDF with and without posterior cages. Range of motion in flexion–extension, lateral bending, and axial rotation was measured for each condition under moment loading up to ±1.5 Nm. Results All fusion constructs significantly reduced the range of motion compared to intact in flexion–extension, lateral bending, and axial rotation (P<0.05). Similar stability was achieved with bilateral posterior cages and plated ACDF at a single level. Posterior cages, when placed as an adjunct to ACDF, further reduced range of motion in both single- and multilevel constructs (P<0.05). Conclusion The biomechanical effectiveness of bilateral posterior cages in limiting cervical segmental motion is comparable to single-level plated ACDF. Furthermore, supplementation of single- and multilevel ACDF with posterior cervical cages provided a significant increase in stability and therefore may be a potential, minimally disruptive option for supplemental fixation for improving ACDF fusion rates.
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Affiliation(s)
- Leonard I Voronov
- Musculoskeletal Biomechanics Laboratory, Department of Research, Edward Hines Jr VA Hospital, Hines, IL, USA; Department of Orthopaedic Surgery and Rehabilitation, Loyola University Chicago, Maywood, IL, USA
| | | | - Robert M Havey
- Musculoskeletal Biomechanics Laboratory, Department of Research, Edward Hines Jr VA Hospital, Hines, IL, USA; Department of Orthopaedic Surgery and Rehabilitation, Loyola University Chicago, Maywood, IL, USA
| | - Gerard Carandang
- Musculoskeletal Biomechanics Laboratory, Department of Research, Edward Hines Jr VA Hospital, Hines, IL, USA; Department of Orthopaedic Surgery and Rehabilitation, Loyola University Chicago, Maywood, IL, USA
| | - Frank M Phillips
- Midwest Orthopedics at Rush, Rush University Medical Center, Chicago, IL, USA
| | - Avinash G Patwardhan
- Musculoskeletal Biomechanics Laboratory, Department of Research, Edward Hines Jr VA Hospital, Hines, IL, USA; Department of Orthopaedic Surgery and Rehabilitation, Loyola University Chicago, Maywood, IL, USA
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Tong J, Ji W, Zhou R, Huang Z, Liu S, Zhu Q. Biomechanical comparison of transfacet screws to lateral mass screw-rod constructs in the lower cervical spine. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2015; 25:1787-93. [PMID: 26530298 DOI: 10.1007/s00586-015-4305-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Revised: 10/20/2015] [Accepted: 10/21/2015] [Indexed: 10/22/2022]
Abstract
PURPOSE Transfacet screws have been used as an alternative posterior fixation in the cervical spine. There is lack of spinal stability of the transfacet screws either as stand-along constructs or combined with anterior plate. This study was designed to evaluate spinal stability of transfacet screws following posterior ligamentous injury and combined with anterior plate, respectively, and compare transfacet screws to lateral mass screw-rod constructs. METHODS Flexibility tests were conducted on eight cadaveric specimens in an intact and injury, and instrumented with the transfacet screw fixation and lateral mass screw-rod construct at C5-C7 levels either after section of the posterior ligamentous complex or combined with an anterior plate and a mesh cage for C6 corpectomy reconstruction. A pure moment of ±2.0 Nm was applied to the specimen in flexion-extension, lateral bending, and axial rotation. Ranges of motion (ROM) were calculated for the C5-C7 segment. RESULTS ROM with the transfacet screws was 22 % of intact in flexion-extension, 9 % in lateral bending and 11 % in axial rotation, while ROM with the lateral mass screw-rod construct was 9 % in flexion-extension, 8 % in lateral bending and 22 % in axial rotation. The only significant difference between two constructs was seen in flexion-extension (5.8 ± 4.2° vs. 2.4 ± 1.2°, P = 0.002). When combined with an anterior plate and mesh cage, the transfacet screw fixation reduced ROM to 3.0° in flexion-extension, 1.2° in lateral bending, and 1.1° in axial rotation, which was similar to the lateral mass screw-rod construct. CONCLUSIONS This study identified the transfacet screw fixation, as stand-alone posterior fixation, was equivalent to the lateral mass screw-rod constructs in axial rotation and lateral bending except in flexion-extension. When combined with an anterior plate, the transfacet screw fixation was similar to the lateral mass screw-rod construct in motion constraint. The results suggested the transfacet screw fixation a biomechanically effective way as supplementation of anterior fixation.
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Affiliation(s)
- Jie Tong
- Department of Spine Surgery, Nanfang Hospital, Southern Medical University, 1838 N. Guangzhou Ave, Guangzhou, 510515, Guangdong, People's Republic of China.,Department of Spine Surgery, The First People's Hospital of Chenzhou, Chenzhou, Hunan, People's Republic of China
| | - Wei Ji
- Department of Spine Surgery, Nanfang Hospital, Southern Medical University, 1838 N. Guangzhou Ave, Guangzhou, 510515, Guangdong, People's Republic of China
| | - Ruozhou Zhou
- Department of Spine Surgery, Nanfang Hospital, Southern Medical University, 1838 N. Guangzhou Ave, Guangzhou, 510515, Guangdong, People's Republic of China.,Department of Spine Surgery, The First People's Hospital of Chenzhou, Chenzhou, Hunan, People's Republic of China
| | - Zhiping Huang
- Department of Spine Surgery, Nanfang Hospital, Southern Medical University, 1838 N. Guangzhou Ave, Guangzhou, 510515, Guangdong, People's Republic of China
| | - Sheting Liu
- Department of Spine Surgery, The First People's Hospital of Chenzhou, Chenzhou, Hunan, People's Republic of China
| | - Qingan Zhu
- Department of Spine Surgery, Nanfang Hospital, Southern Medical University, 1838 N. Guangzhou Ave, Guangzhou, 510515, Guangdong, People's Republic of China.
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Santoni B, Cabezas AF, Cook DJ, Yeager MS, Billys JB, Whiting B, Cheng BC. Comparison of Intervertebral ROM in Multi-Level Cadaveric Lumbar Spines Using Distinct Pure Moment Loading Approaches. Int J Spine Surg 2015; 9:32. [PMID: 26273550 DOI: 10.14444/2032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Pure-moment loading is the test method of choice for spinal implant evaluation. However, the apparatuses and boundary conditions employed by laboratories in performing spine flexibility testing vary. The purpose of this study was to quantify the differences, if they exist, in intervertebral range of motion (ROM) resulting from different pure-moment loading apparatuses used in two laboratories. METHODS Twenty-four (laboratory A) and forty-two (laboratory B) intact L1-S1 specimens were loaded using pure moments (±7.5 Nm) in flexion-extension (FE), lateral bending (LB) and axial torsion (AT). At laboratory A, pure moments were applied using a system of cables, pulleys and suspended weights in 1.5 Nm increments. At laboratory B, specimens were loaded in a pneumatic biaxial test frame mounted with counteracting stepper-motor-driven biaxial gimbals. ROM was obtained in both labs using identical optoelectronic systems and compared. RESULTS In FE, total L1-L5 ROM was similar, on average, between the two laboratories (lab A: 37.4° ± 9.1°; lab B: 35.0° ± 8.9°, p=0.289). Larger apparent differences, on average, were noted between labs in AT (lab A: 19.4° ± 7.3°; lab B: 15.7° ± 7.1°, p=0.074), and this finding was significant for combined right and left LB (lab A: 45.5° ± 11.4°; lab B: 35.3° ± 8.5°, p < 0.001). CONCLUSIONS To our knowledge, this is the first study comparing ROM of multi-segment lumbar spines between laboratories utilizing different apparatuses. The results of this study show that intervertebral ROM in multi-segment lumbar spine constructs are markedly similar in FE loading. Differences in boundary conditions are likely the source of small and sometimes statistically significant differences between the two techniques in LB and AT ROM. The relative merits of each testing strategy with regard to the physiologic conditions that are to be simulated should be considered in the design of a study including LB and AT modes of loading. An understanding of these differences also serves as important information when comparing study results across different laboratories.
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Affiliation(s)
| | | | - Daniel J Cook
- Allegheny Health Network, Department of Neurosurgery, Pittsburgh, PA
| | - Matthew S Yeager
- Allegheny Health Network, Department of Neurosurgery, Pittsburgh, PA
| | - James B Billys
- Allegheny Health Network, Department of Neurosurgery, Pittsburgh, PA
| | - Benjamin Whiting
- Allegheny Health Network, Department of Neurosurgery, Pittsburgh, PA
| | - Boyle C Cheng
- Allegheny Health Network, Department of Neurosurgery, Pittsburgh, PA
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