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Obaid N, Morioka K, Sinopoulou E, Nout-Lomas YS, Salegio E, Bresnahan JC, Beattie MS, Sparrey CJ. The biomechanical implications of neck position in cervical contusion animal models of SCI. Front Neurol 2023; 14:1152472. [PMID: 37346165 PMCID: PMC10280737 DOI: 10.3389/fneur.2023.1152472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 05/17/2023] [Indexed: 06/23/2023] Open
Abstract
Large animal contusion models of spinal cord injury are an essential precursor to developing and evaluating treatment options for human spinal cord injury. Reducing variability in these experiments has been a recent focus as it increases the sensitivity with which treatment effects can be detected while simultaneously decreasing the number of animals required in a study. Here, we conducted a detailed review to explore if head and neck positioning in a cervical contusion model of spinal cord injury could be a factor impacting the biomechanics of a spinal cord injury, and thus, the resulting outcomes. By reviewing existing literature, we found evidence that animal head/neck positioning affects the exposed level of the spinal cord, morphology of the spinal cord, tissue mechanics and as a result the biomechanics of a cervical spinal cord injury. We posited that neck position could be a hidden factor contributing to variability. Our results indicate that neck positioning is an important factor in studying biomechanics, and that reporting these values can improve inter-study consistency and comparability and that further work needs to be done to standardize positioning for cervical spinal cord contusion injury models.
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Affiliation(s)
- Numaira Obaid
- Mechatronic Systems Engineering, Simon Fraser University, Surrey, BC, Canada
- International Collaboration on Repair Discoveries (ICORD), Vancouver, BC, Canada
| | - Kazuhito Morioka
- Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA, United States
- Brain and Spinal Injury Center, Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, United States
| | - Eleni Sinopoulou
- Center for Neural Repair, University of California, San Diego, San Diego, CA, United States
| | - Yvette S. Nout-Lomas
- Department of Clinical Sciences, Colorado State University, Fort Collins, CO, United States
| | | | - Jacqueline C. Bresnahan
- Brain and Spinal Injury Center, Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, United States
| | - Michael S. Beattie
- Brain and Spinal Injury Center, Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA, United States
| | - Carolyn J. Sparrey
- Mechatronic Systems Engineering, Simon Fraser University, Surrey, BC, Canada
- International Collaboration on Repair Discoveries (ICORD), Vancouver, BC, Canada
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Dynamic changes in mechanical properties of the adult rat spinal cord after injury. Acta Biomater 2023; 155:436-448. [PMID: 36435440 DOI: 10.1016/j.actbio.2022.11.041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 11/06/2022] [Accepted: 11/18/2022] [Indexed: 11/25/2022]
Abstract
Spinal cord injury (SCI), a debilitating medical condition that can cause irreversible loss of neurons and permanent paralysis, currently has no cure. However, regenerative medicine may offer a promising treatment. Given that numerous regenerative strategies aim to deliver cells and materials in the form of tissue-engineered therapies, understanding and characterising the mechanical properties of the spinal cord tissue is very important. In this study, we have systematically characterised the spatiotemporal changes in elastic stiffness (elastic modulus, Pa) and viscosity (drop in peak force, %) of injured rat thoracic spinal cord tissues at distinct time points after crush injury using the indentation technique. Our results demonstrate that in comparison with uninjured spinal cord tissue, the injured tissues exhibited lower stiffness (median 3281 Pa versus 9632 Pa; P < 0.001) but demonstrated elevated viscosity (median 80% versus 57%; P < 0.001) at 3 days postinjury. Between 4 and 6 weeks after SCI, the overall viscoelastic properties of injured tissues returned to baseline values. At 12 weeks after SCI, in comparison with uninjured tissue, the injured spinal cord tissues displayed a significant increase in both elasticity (median 13698 Pa versus 9920 Pa; P < 0.001) and viscosity (median 64% versus 58%; P < 0.001). This work constitutes the first quantitative mapping of spatiotemporal changes in spinal cord tissue elasticity and viscosity in injured rats, providing a mechanical basis of the tissue for future studies on the development of biomaterials for SCI repair. STATEMENT OF SIGNIFICANCE: Spinal cord injury (SCI) is a devastating disease often leading to permanent paralysis. While enormous progress in understanding the molecular pathomechanisms of SCI has been made, the mechanical properties of injured spinal cord tissue have received considerably less attention. This study provides systematic characterization of the biomechanical evolution of rat spinal cord tissue after SCI using a microindentation test method. We find spinal cord tissue behaves significantly softer but more viscous immediately postinjury. As time passes, the lesion site gradually returns to baseline values and then displays pronounced increased viscoelastic properties. As host tissue mechanical properties are a crucial consideration for any biomaterial implanted into central nervous system, our results may have important implications for further studies of SCI repair.
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Gadomski BC, Hindman BJ, Poland MJ, Page MI, Dexter F, Puttlitz CM. Intubation biomechanics: Computational modeling to identify methods to minimize cervical spine motion and spinal cord strain during laryngoscopy and tracheal intubation in an intact cervical spine. J Clin Anesth 2022; 81:110909. [PMID: 35738028 DOI: 10.1016/j.jclinane.2022.110909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 06/08/2022] [Accepted: 06/13/2022] [Indexed: 11/15/2022]
Abstract
STUDY OBJECTIVE To minimize the risk of cervical spinal cord injury in patients who have cervical spine pathology, minimizing cervical spine motion during laryngoscopy and tracheal intubation is commonly recommended. However, clinicians may better aim to reduce cervical spinal cord strain during airway management of their patients. The aim of this study was to predict laryngoscope force characteristics (location, magnitude, and direction) that would minimize cervical spine motions and cord strains. DESIGN We utilized a computational model of the adult human cervical spine and spinal cord to predict intervertebral motions (rotation [flexion/extension] and translation [subluxation]) and cord strains (stretch and compression) during laryngoscopy. INTERVENTIONS Routine direct (Macintosh) laryngoscopy conditions were defined by a specific force application location (mid-C3 vertebral body), magnitude (48.8 N), and direction (70 degrees). Sixty laryngoscope force conditions were simulated using 4 force locations (cephalad and caudad of routine), 5 magnitudes (25-200% of routine), and 3 directions (50, 70, 90 degrees). MAIN RESULTS Under all conditions, extension at Oc-C1 and C1-C2 were greater than in all other cervical segments. Decreasing force magnitude to values reported for indirect laryngoscopes (8-17 N) decreased cervical extension to ~50% of routine values. The cervical cord was most likely to experience potentially injurious compressive strain at C3, but force magnitudes ≤50% of routine (≤24.4 N) decreased strain in C3 and all other cord regions to non-injurious values. Changing laryngoscope force locations and directions had minor effects on motion and strain. CONCLUSIONS The model predicts clinicians can most effectively minimize cervical spine motion and cord strain during laryngoscopy by decreasing laryngoscope force magnitude. Very low force magnitudes (<5 N, ~10% of routine) are necessary to decrease overall cervical extension to <50% of routine values. Force magnitudes ≤24.4 N (≤50% of routine) are predicted to help prevent potentially injurious compressive cord strain.
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Affiliation(s)
- Benjamin C Gadomski
- Department of Mechanical Engineering, School of Biomedical Engineering, Orthopaedic Bioengineering Research Laboratory, 300 West Drake Street, Colorado State University, Fort Collins, CO 80523, United States.
| | - Bradley J Hindman
- Department of Anesthesia, University of Iowa Roy J. and Lucille A. Carver College of Medicine, 451 Newton Road, 200 Medicine Administration Building, Iowa City, IA 52242, United States.
| | - Michael J Poland
- Department of Mechanical Engineering, School of Biomedical Engineering, Orthopaedic Bioengineering Research Laboratory, 300 West Drake Street, Colorado State University, Fort Collins, CO 80523, United States.
| | - Mitchell I Page
- Department of Mechanical Engineering, School of Biomedical Engineering, Orthopaedic Bioengineering Research Laboratory, 300 West Drake Street, Colorado State University, Fort Collins, CO 80523, United States.
| | - Franklin Dexter
- Department of Anesthesia, University of Iowa Roy J. and Lucille A. Carver College of Medicine, 451 Newton Road, 200 Medicine Administration Building, Iowa City, IA 52242, United States.
| | - Christian M Puttlitz
- Department of Mechanical Engineering, School of Biomedical Engineering, Orthopaedic Bioengineering Research Laboratory, 300 West Drake Street, Colorado State University, Fort Collins, CO 80523, United States.
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Intubation Biomechanics: Clinical Implications of Computational Modeling of Intervertebral Motion and Spinal Cord Strain during Tracheal Intubation in an Intact Cervical Spine. Anesthesiology 2021; 135:1055-1065. [PMID: 34731240 DOI: 10.1097/aln.0000000000004024] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND In a closed claims study, most patients experiencing cervical spinal cord injury had stable cervical spines. This raises two questions. First, in the presence of an intact (stable) cervical spine, are there tracheal intubation conditions in which cervical intervertebral motions exceed physiologically normal maximum values? Second, with an intact spine, are there tracheal intubation conditions in which potentially injurious cervical cord strains can occur? METHODS This study utilized a computational model of the cervical spine and cord to predict intervertebral motions (rotation, translation) and cord strains (stretch, compression). Routine (Macintosh) intubation force conditions were defined by a specific application location (mid-C3 vertebral body), magnitude (48.8 N), and direction (70 degrees). A total of 48 intubation conditions were modeled: all combinations of 4 force locations (cephalad and caudad of routine), 4 magnitudes (50 to 200% of routine), and 3 directions (50, 70, and 90 degrees). Modeled maximum intervertebral motions were compared to motions reported in previous clinical studies of the range of voluntary cervical motion. Modeled peak cord strains were compared to potential strain injury thresholds. RESULTS Modeled maximum intervertebral motions occurred with maximum force magnitude (97.6 N) and did not differ from physiologically normal maximum motion values. Peak tensile cord strains (stretch) did not exceed the potential injury threshold (0.14) in any of the 48 force conditions. Peak compressive strains exceeded the potential injury threshold (-0.20) in 3 of 48 conditions, all with maximum force magnitude applied in a nonroutine location. CONCLUSIONS With an intact cervical spine, even with application of twice the routine value of force magnitude, intervertebral motions during intubation did not exceed physiologically normal maximum values. However, under nonroutine high-force conditions, compressive strains exceeded potentially injurious values. In patients whose cords have less than normal tolerance to acute strain, compressive strains occurring with routine intubation forces may reach potentially injurious values. EDITOR’S PERSPECTIVE
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Mattucci S, Speidel J, Liu J, Tetzlaff W, Oxland TR. Temporal Progression of Acute Spinal Cord Injury Mechanisms in a Rat Model: Contusion, Dislocation, and Distraction. J Neurotrauma 2021; 38:2103-2121. [PMID: 33820470 DOI: 10.1089/neu.2020.7255] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Traumatic spinal cord injuries (SCIs) occur due to different spinal column injury patterns, including burst fracture, dislocation, and flexion-distraction. Pre-clinical studies modeling different SCI mechanisms have shown distinct histological differences between these injuries both acutely (3 h and less) and chronically (8 weeks), but there remains a temporal gap. Different rates of injury progression at specific regions of the spinal cord may provide insight into the pathologies that are initiated by specific SCI mechanisms. Therefore, the objective of this study was to evaluate the temporal progression of injury at specific tracts within the white matter, for time-points of 3 h, 24 h, and 7 days, for three distinct SCI mechanisms. In this study, 96 male Sprague Dawley rats underwent one of three SCI mechanisms: contusion, dislocation, or distraction. Animals were sacrificed at one of three times post-injury: 3 h, 24 h, or 7 days. Histological analysis using eriochrome cyanide and immunostaining for MBP, SMI-312, neurofilament-H (NF-H), and β-III tubulin were used to characterize white matter sparing and axon and myelinated axon counts. The regions analyzed were the gracile fasciculus, cuneate fasciculus, dorsal corticospinal tract, and ventrolateral white matter. Contusion, dislocation, and distraction SCIs demonstrated distinct damage patterns that progressed differently over time. Myelinated axon counts were significantly reduced after dislocation and contusion injuries in most locations and time-points analyzed (compared with sham). This indicates early myelin damage often within 3 h. Myelinated axon counts after distraction dropped early and did not demonstrate any significant progression over the next 7 days. Important differences in white matter degeneration were identified between injury types, with distraction injuries showing the least variability across time-points These findings and the observation that white matter injury occurs early, and in many cases, without much dynamic change, highlight the importance of injury type in SCI research-both clinically and pre-clinically.
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Affiliation(s)
- Stephen Mattucci
- Department of Orthopedics, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Mechanical Engineering, University of British Columbia, Vancouver, British Columbia, Canada
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jason Speidel
- Department of Orthopedics, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Mechanical Engineering, University of British Columbia, Vancouver, British Columbia, Canada
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jie Liu
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
| | - Wolfram Tetzlaff
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
| | - Thomas R Oxland
- Department of Orthopedics, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Mechanical Engineering, University of British Columbia, Vancouver, British Columbia, Canada
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
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Fournely M, Petit Y, Wagnac E, Evin M, Arnoux PJ. Effect of experimental, morphological and mechanical factors on the murine spinal cord subjected to transverse contusion: A finite element study. PLoS One 2020; 15:e0232975. [PMID: 32392241 PMCID: PMC7213721 DOI: 10.1371/journal.pone.0232975] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 04/24/2020] [Indexed: 12/22/2022] Open
Abstract
Finite element models combined with animal experimental models of spinal cord injury provides the opportunity for investigating the effects of the injury mechanism on the neural tissue deformation and the resulting tissue damage. Thus, we developed a finite element model of the mouse cervical spinal cord in order to investigate the effect of morphological, experimental and mechanical factors on the spinal cord mechanical behavior subjected to transverse contusion. The overall mechanical behavior of the model was validated with experimental data of unilateral cervical contusion in mice. The effects of the spinal cord material properties, diameter and curvature, and of the impactor position and inclination on the strain distribution were investigated in 8 spinal cord anatomical regions of interest for 98 configurations of the model. Pareto analysis revealed that the material properties had a significant effect (p<0.01) for all regions of interest of the spinal cord and was the most influential factor for 7 out of 8 regions. This highlighted the need for comprehensive mechanical characterization of the gray and white matter in order to develop effective models capable of predicting tissue deformation during spinal cord injuries.
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Affiliation(s)
- Marion Fournely
- Laboratoire de Biomécanique Appliquée (LBA), UMR T24, Aix-Marseille Université, IFSTTAR, Marseille, France
- International Laboratory on Spine Imaging and Biomechanics (iLab-Spine), Marseille, France
| | - Yvan Petit
- International Laboratory on Spine Imaging and Biomechanics (iLab-Spine), Marseille, France
- Mechanical Engineering Department, École de technologie supérieure, Montréal, Canada
- Research Center, Hôpital du Sacré-Cœur, Montréal, Canada
| | - Eric Wagnac
- International Laboratory on Spine Imaging and Biomechanics (iLab-Spine), Marseille, France
- Mechanical Engineering Department, École de technologie supérieure, Montréal, Canada
- Research Center, Hôpital du Sacré-Cœur, Montréal, Canada
| | - Morgane Evin
- Laboratoire de Biomécanique Appliquée (LBA), UMR T24, Aix-Marseille Université, IFSTTAR, Marseille, France
- International Laboratory on Spine Imaging and Biomechanics (iLab-Spine), Marseille, France
| | - Pierre-Jean Arnoux
- Laboratoire de Biomécanique Appliquée (LBA), UMR T24, Aix-Marseille Université, IFSTTAR, Marseille, France
- International Laboratory on Spine Imaging and Biomechanics (iLab-Spine), Marseille, France
- * E-mail:
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Differences in Morphometric Measures of the Uninjured Porcine Spinal Cord and Dural Sac Predict Histological and Behavioral Outcomes after Traumatic Spinal Cord Injury. J Neurotrauma 2019; 36:3005-3017. [DOI: 10.1089/neu.2018.5930] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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Verma R, Virdi JK, Singh N, Jaggi AS. Animals models of spinal cord contusion injury. Korean J Pain 2019; 32:12-21. [PMID: 30671199 PMCID: PMC6333579 DOI: 10.3344/kjp.2019.32.1.12] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 11/30/2018] [Accepted: 12/01/2018] [Indexed: 12/03/2022] Open
Abstract
Spinal cord contusion injury is one of the most serious nervous system disorders, characterized by high morbidity and disability. To mimic spinal cord contusion in humans, various animal models of spinal contusion injury have been developed. These models have been developed in rats, mice, and monkeys. However, most of these models are developed using rats. Two types of animal models, i.e. bilateral contusion injury and unilateral contusion injury models, are developed using either a weight drop method or impactor method. In the weight drop method, a specific weight or a rod, having a specific weight and diameter, is dropped from a specific height on to the exposed spinal cord. Low intensity injury is produced by dropping a 5 g weight from a height of 8 cm, moderate injury by dropping 10 g weight from a height of 12.5–25 mm, and high intensity injury by dropping a 25 g weight from a height of 50 mm. In the impactor method, injury is produced through an impactor by delivering a specific force to the exposed spinal cord area. Mild injury is produced by delivering 100 ± 5 kdyn of force, moderate injury by delivering 200 ± 10 kdyn of force, and severe injury by delivering 300 ± 10 kdyn of force. The contusion injury produces a significant development of locomotor dysfunction, which is generally evident from the 0–14th day of surgery and is at its peak after the 28–56th day. The present review discusses different animal models of spinal contusion injury.
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Affiliation(s)
- Renuka Verma
- Department of Pharmaceutical Sciences and Drug Research, Punjabi University Patiala, Patiala, India
| | - Jasleen Kaur Virdi
- Department of Pharmaceutical Sciences and Drug Research, Punjabi University Patiala, Patiala, India
| | - Nirmal Singh
- Department of Pharmaceutical Sciences and Drug Research, Punjabi University Patiala, Patiala, India
| | - Amteshwar Singh Jaggi
- Department of Pharmaceutical Sciences and Drug Research, Punjabi University Patiala, Patiala, India
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Lucas E, Whyte T, Liu J, Russell C, Tetzlaff W, Cripton PA. High-Speed Fluoroscopy to Measure Dynamic Spinal Cord Deformation in an In Vivo Rat Model. J Neurotrauma 2018; 35:2572-2580. [PMID: 29786472 DOI: 10.1089/neu.2017.5478] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Although spinal cord deformation is thought to be a predictor of injury severity, few researchers have investigated dynamic cord deformation, in vivo, during impact. This is needed to establish correlations among impact parameters, internal cord deformation, and histological and functional outcomes. Relying on surface deformations alone may not sufficiently represent spinal cord deformation. The objective of this study was to develop a high-speed fluoroscopic method of tracking the surface and internal cord deformations of rat spinal cord during experimental cord injury. Two radio-opaque beads were injected into the cord at C5/6 in the dorsal and ventral white matter. Four additional beads were glued to the surface of the cord. Dynamic bead displacement was tracked during a dorsal impact (130 mm/sec, 1 mm depth) by high-speed radiographic imaging at 3000 FPS, laterally. The internal spinal cord beads displaced significantly more than the surface beads in the ventral direction (1.1-1.9 times) and more than most surface beads in the cranial direction (1.2-1.5 times). The dorsal beads (internal and surface) displaced more than the ventral beads during all impacts. The bead displacement pattern implies that the spinal cord undergoes complex internal and surface deformations during impact. Residual displacement of the internal beads was significantly greater than that of the surface beads in the cranial-caudal direction but not the dorsoventral direction. Finite element simulation confirmed that the additional bead mass likely had little effect on the internal cord deformations. These results support the merit of this technique for measuring in vivo spinal cord deformation.
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Affiliation(s)
- Erin Lucas
- 1 Orthopaedic Injury Biomechanics Group, Departments of Mechanical Engineering and Orthopaedics and the School of Biomedical Engineering, The University of British Columbia , Vancouver, British Columbia, Canada .,2 International Collaboration on Repair Discoveries (ICORD), The University of British Columbia , Vancouver, British Columbia, Canada
| | - Thomas Whyte
- 1 Orthopaedic Injury Biomechanics Group, Departments of Mechanical Engineering and Orthopaedics and the School of Biomedical Engineering, The University of British Columbia , Vancouver, British Columbia, Canada .,2 International Collaboration on Repair Discoveries (ICORD), The University of British Columbia , Vancouver, British Columbia, Canada
| | - Jie Liu
- 2 International Collaboration on Repair Discoveries (ICORD), The University of British Columbia , Vancouver, British Columbia, Canada
| | - Colin Russell
- 1 Orthopaedic Injury Biomechanics Group, Departments of Mechanical Engineering and Orthopaedics and the School of Biomedical Engineering, The University of British Columbia , Vancouver, British Columbia, Canada .,2 International Collaboration on Repair Discoveries (ICORD), The University of British Columbia , Vancouver, British Columbia, Canada
| | - Wolfram Tetzlaff
- 2 International Collaboration on Repair Discoveries (ICORD), The University of British Columbia , Vancouver, British Columbia, Canada
| | - Peter Alec Cripton
- 1 Orthopaedic Injury Biomechanics Group, Departments of Mechanical Engineering and Orthopaedics and the School of Biomedical Engineering, The University of British Columbia , Vancouver, British Columbia, Canada .,2 International Collaboration on Repair Discoveries (ICORD), The University of British Columbia , Vancouver, British Columbia, Canada
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Gadomski BC, Shetye SS, Hindman BJ, Dexter F, Santoni BG, Todd MM, Traynelis VC, From RP, Fontes RB, Puttlitz CM. Intubation biomechanics: validation of a finite element model of cervical spine motion during endotracheal intubation in intact and injured conditions. J Neurosurg Spine 2018; 28:10-22. [DOI: 10.3171/2017.5.spine17189] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVEBecause of limitations inherent to cadaver models of endotracheal intubation, the authors’ group developed a finite element (FE) model of the human cervical spine and spinal cord. Their aims were to 1) compare FE model predictions of intervertebral motion during intubation with intervertebral motion measured in patients with intact cervical spines and in cadavers with spine injuries at C-2 and C3–4 and 2) estimate spinal cord strains during intubation under these conditions.METHODSThe FE model was designed to replicate the properties of an intact (stable) spine in patients, C-2 injury (Type II odontoid fracture), and a severe C3–4 distractive-flexion injury from prior cadaver studies. The authors recorded the laryngoscope force values from 2 different laryngoscopes (Macintosh, high intubation force; Airtraq, low intubation force) used during the patient and cadaver intubation studies. FE-modeled motion was compared with experimentally measured motion, and corresponding cord strain values were calculated.RESULTSFE model predictions of intact intervertebral motions were comparable to motions measured in patients and in cadavers at occiput–C2. In intact subaxial segments, the FE model more closely predicted patient intervertebral motions than did cadavers. With C-2 injury, FE-predicted motions did not differ from cadaver measurements. With C3–4 injury, however, the FE model predicted greater motions than were measured in cadavers. FE model cord strains during intubation were greater for the Macintosh laryngoscope than the Airtraq laryngoscope but were comparable among the 3 conditions (intact, C-2 injury, and C3–4 injury).CONCLUSIONSThe FE model is comparable to patients and cadaver models in estimating occiput–C2 motion during intubation in both intact and injured conditions. The FE model may be superior to cadavers in predicting motions of subaxial segments in intact and injured conditions.
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Affiliation(s)
- Benjamin C. Gadomski
- 1Department of Mechanical Engineering, School of Biomedical Engineering, Orthopaedic Bioengineering Research Laboratory, Colorado State University, Fort Collins, Colorado
| | - Snehal S. Shetye
- 1Department of Mechanical Engineering, School of Biomedical Engineering, Orthopaedic Bioengineering Research Laboratory, Colorado State University, Fort Collins, Colorado
| | - Bradley J. Hindman
- 2Department of Anesthesia, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, Iowa
| | - Franklin Dexter
- 2Department of Anesthesia, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, Iowa
| | | | - Michael M. Todd
- 4Department of Anesthesia, University of Minnesota, Minneapolis, Minnesota; and
| | | | - Robert P. From
- 2Department of Anesthesia, University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, Iowa
| | - Ricardo B. Fontes
- 5Department of Neurosurgery, Rush University Medical Center, Chicago, Illinois
| | - Christian M. Puttlitz
- 1Department of Mechanical Engineering, School of Biomedical Engineering, Orthopaedic Bioengineering Research Laboratory, Colorado State University, Fort Collins, Colorado
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