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Silvestros P, Quarrington RD, Preatoni E, Gill HS, Jones CF, Cazzola D. An Extended Neck Position is Likely to Produce Cervical Spine Injuries Through Buckling in Accidental Head-First Impacts During Rugby Tackling. Ann Biomed Eng 2024:10.1007/s10439-024-03576-z. [PMID: 39004695 DOI: 10.1007/s10439-024-03576-z] [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: 01/27/2024] [Accepted: 06/30/2024] [Indexed: 07/16/2024]
Abstract
Catastrophic cervical spine injuries in rugby often occur during tackling. The underlying mechanisms leading to these injuries remain unclear, with neck hyperflexion and buckling both proposed as the causative factor in the injury prevention literature. The aim of this study was to evaluate the effect of pre-impact head-neck posture on intervertebral neck loads and motions during a head-first rugby tackle. Using a validated, subject-specific musculoskeletal model of a rugby player, and computer simulations driven by in vivo and in vitro data, we examined the dynamic response of the cervical spine under such impact conditions. The simulations demonstrated that the initial head-neck sagittal-plane posture affected intervertebral loads and kinematics, with an extended neck resulting in buckling and supraphysiologic intervertebral shear and flexion loads and motions, typical of bilateral facet dislocation injuries. In contrast, an initially flexed neck increased axial compression forces and flexion angles without exceeding intervertebral physiological limits. These findings provide objective evidence that can inform injury prevention strategies or rugby law changes to improve the safety of the game of rugby.
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Affiliation(s)
- Pavlos Silvestros
- Department for Health, University of Bath, Claverton Down, Bath, BA2 7AY, UK
- Centre for Analysis of Motion and Entertainment Research and Application, University of Bath, Bath, UK
| | - Ryan D Quarrington
- Centre for Orthopaedic & Trauma Research, Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide, Australia
- School of Electrical and Mechanical Engineering, The University of Adelaide, Adelaide, Australia
| | - Ezio Preatoni
- Department for Health, University of Bath, Claverton Down, Bath, BA2 7AY, UK
- Centre for Health and Injury and Illness Prevention in Sport (CHi2PS), University of Bath, Bath, UK
| | - Harinderjit S Gill
- Department of Mechanical Engineering, University of Bath, Bath, UK
- Centre for Therapeutic Innovation, University of Bath, Bath, UK
| | - Claire F Jones
- Centre for Orthopaedic & Trauma Research, Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide, Australia
- School of Electrical and Mechanical Engineering, The University of Adelaide, Adelaide, Australia
| | - Dario Cazzola
- Department for Health, University of Bath, Claverton Down, Bath, BA2 7AY, UK.
- Centre for Analysis of Motion and Entertainment Research and Application, University of Bath, Bath, UK.
- Centre for Health and Injury and Illness Prevention in Sport (CHi2PS), University of Bath, Bath, UK.
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2
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Ortiz-Paparoni M, Morino C, Bercaw J, Eynde JO', Nightingale R, Bass C'D. Translating Cadaveric Injury Risk to Dummy Injury Risk at Iso-energy. Ann Biomed Eng 2024; 52:406-413. [PMID: 37891432 DOI: 10.1007/s10439-023-03388-7] [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: 03/27/2023] [Accepted: 10/12/2023] [Indexed: 10/29/2023]
Abstract
Injury risk assessment based on cadaver data is essential for informing safety standards. The common 'matched-pair' method matches energy-based inputs to translate human response to anthropometric test devices (ATDs). However, this method can result in less conservative human injury risk curves due to intrinsic differences between human and ATDs. Generally, dummies are stiffer than cadavers, so force and displacement cannot be matched simultaneously. Differences in fracture tolerance further influence the dummy risk curve to be less conservative under matched-pair. For example, translating a human lumbar injury risk curve to a dummy of equivalent stiffness using matched-pair resulted in a dummy injury risk over 80% greater than the cadaver at 50% fracture risk. This inevitable increase arises because the dummy continues loading without fracture to attenuate energy beyond the 'matched' cadaver input selected. Human injury response should be translated using an iso-energy approach, as strain energy is well associated with failure in biological tissues. Until cadaver failure, dummy force is related to cadaver force at iso-energy. Beyond cadaver failure, dummy force is related to cadaver force through failure energy. This method does not require perfect cadaver/dummy biofidelity and ensures that energy beyond cadaver failure does not influence the injury risk function.
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Affiliation(s)
| | - Concetta Morino
- Department of Mechanical Engineering and Material Science, Duke University, Durham, NC, 27708, USA
| | - Jefferson Bercaw
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA.
| | - Joost Op 't Eynde
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
| | - Roger Nightingale
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
| | - Cameron 'Dale' Bass
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
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3
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Lalwala M, Koya B, Devane K, Gayzik FS, Weaver AA. Modular incorporation of deformable spine and 3D neck musculature into a simplified human body finite element model. Comput Methods Biomech Biomed Engin 2024; 27:45-55. [PMID: 36657616 PMCID: PMC10354211 DOI: 10.1080/10255842.2023.2168537] [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: 08/08/2022] [Accepted: 01/10/2023] [Indexed: 01/21/2023]
Abstract
Spinal injuries are a concern for automotive applications, requiring large parametric studies to understand spinal injury mechanisms under complex loading conditions. Finite element computational human body models (e.g. Global Human Body Models Consortium (GHBMC) models) can be used to identify spinal injury mechanisms. However, the existing GHBMC detailed models (with high computational time) or GHBMC simplified models (lacking vertebral fracture prediction capabilities) are not ideal for studying spinal injury mechanisms in large parametric studies. To overcome these limitations, a modular 50th percentile male simplified occupant model combining advantages of both the simplified and detailed models, M50-OS + DeformSpine, was developed by incorporating the deformable spine and 3D neck musculature from the detailed GHBMC model M50-O (v6.0) into the simplified GHBMC model M50-OS (v2.3). This new modular model was validated against post-mortem human subject test data in four rigid hub impactor tests and two frontal impact sled tests. The M50-OS + DeformSpine model showed good agreement with experimental test data with an average CORrelation and Analysis (CORA) score of 0.82 for the hub impact tests and 0.75 for the sled impact tests. CORA scores were statistically similar overall between the M50-OS + DeformSpine (0.79 ± 0.11), M50-OS (0.79 ± 0.11), and M50-O (0.82 ± 0.11) models (p > 0.05). This new model is computationally 6 times faster than the detailed M50-O model, with added spinal injury prediction capabilities over the simplified M50-OS model.
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Affiliation(s)
- Mitesh Lalwala
- Department of Biomedical Engineering, Wake Forest University School of Medicine, NC, USA
- Virginia Tech-Wake Forest University Center for Injury Biomechanics, NC, USA
| | - Bharath Koya
- Department of Biomedical Engineering, Wake Forest University School of Medicine, NC, USA
- Virginia Tech-Wake Forest University Center for Injury Biomechanics, NC, USA
| | - Karan Devane
- Department of Biomedical Engineering, Wake Forest University School of Medicine, NC, USA
- Virginia Tech-Wake Forest University Center for Injury Biomechanics, NC, USA
| | - F. Scott Gayzik
- Department of Biomedical Engineering, Wake Forest University School of Medicine, NC, USA
- Virginia Tech-Wake Forest University Center for Injury Biomechanics, NC, USA
| | - Ashley A. Weaver
- Department of Biomedical Engineering, Wake Forest University School of Medicine, NC, USA
- Virginia Tech-Wake Forest University Center for Injury Biomechanics, NC, USA
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4
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Silvestros P, Pizzolato C, Lloyd DG, Preatoni E, Gill HS, Cazzola D. Electromyography-Assisted Neuromusculoskeletal Models Can Estimate Physiological Muscle Activations and Joint Moments Across the Neck Before Impacts. J Biomech Eng 2022; 144:1120603. [PMID: 34557891 DOI: 10.1115/1.4052555] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Indexed: 01/20/2023]
Abstract
Knowledge of neck muscle activation strategies before sporting impacts is crucial for investigating mechanisms of severe spinal injuries. However, measurement of muscle activations during impacts is experimentally challenging and computational estimations are not often guided by experimental measurements. We investigated neck muscle activations before impacts with the use of electromyography (EMG)-assisted neuromusculoskeletal models. Kinematics and EMG recordings from four major neck muscles of a rugby player were experimentally measured during rugby activities. A subject-specific musculoskeletal model was created with muscle parameters informed from MRI measurements. The model was used in the calibrated EMG-informed neuromusculoskeletal modeling toolbox and three neural solutions were compared: (i) static optimization (SO), (ii) EMG-assisted (EMGa), and (iii) MRI-informed EMG-assisted (EMGaMRI). EMGaMRI and EMGa significantly (p < 0.01) outperformed SO when tracking cervical spine net joint moments from inverse dynamics in flexion/extension (RMSE = 0.95, 1.14, and 2.32 N·m) but not in lateral bending (RMSE = 1.07, 2.07, and 0.84 N·m). EMG-assisted solutions generated physiological muscle activation patterns and maintained experimental cocontractions significantly (p < 0.01) outperforming SO, which was characterized by saturation and nonphysiological "on-off" patterns. This study showed for the first time that physiological neck muscle activations and cervical spine net joint moments can be estimated without assumed a priori objective criteria before impacts. Future studies could use this technique to provide detailed initial loading conditions for theoretical simulations of neck injury during impacts.
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Affiliation(s)
- Pavlos Silvestros
- Department for Health, Centre for Analysis of Motion and Entertainment Research and Application (CAMERA), University of Bath, Bath BA2 7AY, UK
| | - Claudio Pizzolato
- School of Allied Health Sciences, Griffith Centre of Biomedical and Rehabilitation Engineering (GCORE), Menzies Health Institute Griffith University, Gold Coast, Queensland 4222, Australia
| | - David G Lloyd
- School of Allied Health Sciences, Griffith Centre of Biomedical and Rehabilitation Engineering (GCORE), Menzies Health Institute Griffith University, Gold Coast, Queensland 4222, Australia
| | - Ezio Preatoni
- Department for Health, University of Bath, Bath BA2 7AY, UK
| | - Harinderjit S Gill
- Centre for Therapeutic Innovation, Department of Mechanical Engineering, University of Bath, Bath BA2 7AY, UK
| | - Dario Cazzola
- Department for Health, Centre for Analysis of Motion and Entertainment Research and Application (CAMERA), University of Bath, Bath BA2 7AY, UK
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Fice JB, Mang DWH, Ólafsdóttir JM, Brolin K, Cripton PA, Blouin JS, Siegmund GP. Neck Muscle and Head/Neck Kinematic Responses While Bracing Against the Steering Wheel During Front and Rear Impacts. Ann Biomed Eng 2020; 49:1069-1082. [PMID: 33215369 DOI: 10.1007/s10439-020-02687-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 11/04/2020] [Indexed: 10/22/2022]
Abstract
Drivers often react to an impending collision by bracing against the steering wheel. The goal of the present study was to quantify the effect of bracing on neck muscle activity and head/torso kinematics during low-speed front and rear impacts. Eleven seated subjects (3F, 8 M) experienced multiple sled impacts (Δv = 0.77 m/s; apeak = 19.9 m/s2, Δt = 65.5 ms) with their hands on the steering wheel in two conditions: relaxed and braced against the steering wheel. Electromyographic activity in eight neck muscles (sternohyoid, sternocleidomastoid, splenius capitis, semispinalis capitis, semispinalis cervicis, multifidus, levator scapulae, and trapezius) was recorded unilaterally with indwelling electrodes and normalized by maximum voluntary contraction (MVC) levels. Head and torso kinematics (linear acceleration, angular velocity, angular rotation, and retraction) were measured with sensors and motion tracking. Muscle and kinematic variables were compared between the relaxed and braced conditions using linear mixed models. We found that pre-impact bracing generated only small increases in the pre-impact muscle activity (< 5% MVC) when compared to the relaxed condition. Pre-impact bracing did not increase peak neck muscle responses during the impacts; instead it reduced peak trapezius and multifidus muscle activity by about half during front impacts. Bracing led to widespread changes in the peak amplitude and timing of the torso and head kinematics that were not consistent with a simple stiffening of the head/neck/torso system. Instead pre-impact bracing served to couple the torso more rigidly to the seat while not necessarily coupling the head more rigidly to the torso.
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Affiliation(s)
- Jason B Fice
- Department of Mechanics and Maritime Sciences, Chalmers University of Technology, Göteborg, Sweden
| | - Daniel W H Mang
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | | | - Karin Brolin
- Department of Mechanics and Maritime Sciences, Chalmers University of Technology, Göteborg, Sweden.,Lightness by Design, Stockholm, Sweden
| | - Peter A Cripton
- School of Biomedical Engineering, University of British Columbia, Vancouver, BC, Canada
| | - Jean-Sébastien Blouin
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada.,Djavad Mowafaghian Centre for Brain Health and Institute for Computing, Information and Cognitive Systems, Vancouver, BC, Canada
| | - Gunter P Siegmund
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada. .,MEA Forensic Engineers & Scientists, Richmond, BC, V7A 4S5, Canada.
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6
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Krašna S, Đorđević S. Estimating the Effects of Awareness on Neck-Muscle Loading in Frontal Impacts with EMG and MC Sensors. SENSORS (BASEL, SWITZERLAND) 2020; 20:s20143942. [PMID: 32679857 PMCID: PMC7411674 DOI: 10.3390/s20143942] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 07/12/2020] [Accepted: 07/13/2020] [Indexed: 06/11/2023]
Abstract
Critical traffic situations, such as vehicle collisions and emergency manoeuvres, can cause an occupant to respond with reflex and voluntary actions. These affect the occupant's position and dynamic loading during interactions with the vehicle's restraints, possibly compromising their protective function. Electromyography (EMG) is a commonly used method for measuring active muscle response and can also provide input parameters for computer simulations with models of the human body. The recently introduced muscle-contraction (MC) sensor is a wearable device with a piezo-resistive element for measuring the force of an indenting tip pressing against the surface of the body. The study aimed to compare how data collected simultaneously with EMG, video motion capture, and the novel MC sensor are related to neck-muscle loading. Sled tests with low-severity frontal impacts were conducted, assuming two different awareness conditions for seated volunteers. The activity of the upper trapezius muscle was measured using surface EMG and MC sensors. The neck-muscle load F was estimated from an inverse dynamics analysis of the head's motion captured in the sagittal plane. The volunteers' response to impact was predominantly reflexive, with significantly shorter onset latencies and more bracing observed when the volunteers were aware of the impact. Cross-correlations between the EMG and MC, EMG and F, and F and MC data were not changed significantly by the awareness conditions. The MC signal was strongly correlated (r = 0.89) with the neck-muscle loading F in the aware and unaware conditions, while the mean ΔF-MC delays were 21.0 ± 15.1 ms and 14.6 ± 12.4 ms, respectively. With the MC sensor enabling a consistent measurement-based estimation of the muscle loading, the simultaneous acquisition of EMG and MC signals improves the assessment of the reflex and voluntary responses of a vehicle's occupant subjected to low-severity loading.
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Affiliation(s)
- Simon Krašna
- Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva Cesta 6, 1000 Ljubljana, Slovenia
| | - Srđan Đorđević
- TMG-BMC, d.o.o., Štihova Ulica 24, 1000 Ljubljana, Slovenia;
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7
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Correia MA, McLachlin SD, Cronin DS. Optimization of muscle activation schemes in a finite element neck model simulating volunteer frontal impact scenarios. J Biomech 2020; 104:109754. [DOI: 10.1016/j.jbiomech.2020.109754] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 03/12/2020] [Accepted: 03/13/2020] [Indexed: 11/25/2022]
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Alizadeh M, Knapik GG, Mageswaran P, Mendel E, Bourekas E, Marras WS. Biomechanical musculoskeletal models of the cervical spine: A systematic literature review. Clin Biomech (Bristol, Avon) 2020; 71:115-124. [PMID: 31715453 DOI: 10.1016/j.clinbiomech.2019.10.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 09/27/2019] [Accepted: 10/29/2019] [Indexed: 02/07/2023]
Abstract
BACKGROUND As the work load has been shifting from heavy manufacturing to office work, neck disorders are increasing. However, most of the current cervical spine biomechanical models were created to simulate crash situations. Therefore, the biomechanics of cervical spine during daily living and occupational activities remain unknown. In this effort, cervical spine biomechanical models were systematically reviewed based upon different features including approach, biomechanical properties, and validation methods. METHODS The objective of this review was to systematically categorize cervical spine models and compare the underlying logic in order to identify voids in the literature. FINDINGS Twenty-two models met our selection criteria and revealed several trends: 1) The multi-body dynamics modeling approach, equipped for simulating impact situations were the most common technique; 2) Straight muscle lines of action, inverse dynamic/optimization muscle force calculation, Hill-type muscle model with only active component were typically used in the majority of neck models; and 3) Several models have attempted to validate their results by comparing their approach with previous studies, but mostly were unable to provide task-specific validation. INTERPRETATION EMG-driven dynamic model for simulating occupational activities, with accurate muscle geometry and force representation, and person- or task-specific validation of the model would be necessary to improve model fidelity.
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Affiliation(s)
- Mina Alizadeh
- Spine Research Institute, The Ohio State University, 520 Baker Systems, 1971 Neil Avenue, Columbus, OH 43210, USA
| | - Gregory G Knapik
- Spine Research Institute, The Ohio State University, 520 Baker Systems, 1971 Neil Avenue, Columbus, OH 43210, USA
| | - Prasath Mageswaran
- Spine Research Institute, The Ohio State University, 520 Baker Systems, 1971 Neil Avenue, Columbus, OH 43210, USA
| | - Ehud Mendel
- Department of Neurological Surgery, The Ohio State University, Columbus, OH 43210, USA
| | - Eric Bourekas
- Department of Radiology, The Ohio State University, Columbus, OH 43210, USA
| | - William S Marras
- Spine Research Institute, The Ohio State University, 520 Baker Systems, 1971 Neil Avenue, Columbus, OH 43210, USA.
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Mo F, Li J, Dan M, Liu T, Behr M. Implementation of controlling strategy in a biomechanical lower limb model with active muscles for coupling multibody dynamics and finite element analysis. J Biomech 2019; 91:51-60. [PMID: 31101432 DOI: 10.1016/j.jbiomech.2019.05.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 05/02/2019] [Accepted: 05/04/2019] [Indexed: 11/28/2022]
Abstract
Computational biomechanics for human body modeling has generally been categorized into two separated domains: finite element analysis and multibody dynamics. Combining the advantages of both domains is necessary when tissue stress and physical body motion are both of interest. However, the method for this topic is still in exploration. The aim of this study is to implement unique controlling strategies in finite element model for simultaneously simulating musculoskeletal body dynamics and in vivo stress inside human tissues. A finite element lower limb model with 3D active muscles was selected for the implementation of controlling strategies, which was further validated against in-vivo human motion experiments. A unique feedback control strategy that couples together a basic Proportion-Integration-Differentiation (PID) controller and generic active signals from Computed Muscle Control (CMC) method of the musculoskeletal model or normalized EMG singles was proposed and applied in the present model. The results show that the new proposed controlling strategy show a good correlation with experimental test data of the normal gait considering joint kinematics, while stress distribution of local lower limb tissue can be also detected in real-time with lower limb motion. In summary, the present work is the first step for the application of active controlling strategy in the finite element model for concurrent simulation of both body dynamics and tissue stress. In the future, the present method can be further developed to apply it in various fields for human biomechanical analysis to monitor local stress and strain distribution by simultaneously simulating human locomotion.
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Affiliation(s)
- Fuhao Mo
- State Key Laboratory of Advanced Design and Manufacture for Vehicle Body, Hunan University, Changsha, Hunan 410082, China; Aix-Marseille University, IFSTTAR, LBA UMRT24, Faculté de Médecine Nord, Boulevard Pierre Dramard, 13916 Marseille Cedex 20, France
| | - Junjie Li
- State Key Laboratory of Advanced Design and Manufacture for Vehicle Body, Hunan University, Changsha, Hunan 410082, China
| | - Minchao Dan
- State Key Laboratory of Advanced Design and Manufacture for Vehicle Body, Hunan University, Changsha, Hunan 410082, China
| | - Tang Liu
- Department of Orthopedics, The Second Xiangya Hospital of Central South University, 139 Renmin Road, Changsha, Hunan 410011, China.
| | - Michel Behr
- Aix-Marseille University, IFSTTAR, LBA UMRT24, Faculté de Médecine Nord, Boulevard Pierre Dramard, 13916 Marseille Cedex 20, France
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Silvestros P, Preatoni E, Gill HS, Gheduzzi S, Hernandez BA, Holsgrove TP, Cazzola D. Musculoskeletal modelling of the human cervical spine for the investigation of injury mechanisms during axial impacts. PLoS One 2019; 14:e0216663. [PMID: 31071162 PMCID: PMC6508870 DOI: 10.1371/journal.pone.0216663] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 04/25/2019] [Indexed: 12/26/2022] Open
Abstract
Head collisions in sport can result in catastrophic injuries to the cervical spine. Musculoskeletal modelling can help analyse the relationship between motion, external forces and internal loads that lead to injury. However, impact specific musculoskeletal models are lacking as current viscoelastic values used to describe cervical spine joint dynamics have been obtained from unrepresentative quasi-static or static experiments. The aim of this study was to develop and validate a cervical spine musculoskeletal model for use in axial impacts. Cervical spine specimens (C2-C6) were tested under measured sub-catastrophic loads and the resulting 3D motion of the vertebrae was measured. Specimen specific musculoskeletal models were then created and used to estimate the axial and shear viscoelastic (stiffness and damping) properties of the joints through an optimisation algorithm that minimised tracking errors between measured and simulated kinematics. A five-fold cross validation and a Monte Carlo sensitivity analysis were conducted to assess the performance of the newly estimated parameters. The impact-specific parameters were integrated in a population specific musculoskeletal model and used to assess cervical spine loads measured from Rugby union impacts compared to available models. Results of the optimisation showed a larger increase of axial joint stiffness compared to axial damping and shear viscoelastic parameters for all models. The sensitivity analysis revealed that lower values of axial stiffness and shear damping reduced the models performance considerably compared to other degrees of freedom. The impact-specific parameters integrated in the population specific model estimated more appropriate joint displacements for axial head impacts compared to available models and are therefore more suited for injury mechanism analysis.
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Affiliation(s)
| | - Ezio Preatoni
- Department for Health, University of Bath, Bath, United Kingdom
| | - Harinderjit S. Gill
- Centre for Orthopaedic Biomechanics, Department of Mechanical Engineering, University of Bath, Bath, United Kingdom
| | - Sabina Gheduzzi
- Centre for Orthopaedic Biomechanics, Department of Mechanical Engineering, University of Bath, Bath, United Kingdom
| | - Bruno Agostinho Hernandez
- Centre for Orthopaedic Biomechanics, Department of Mechanical Engineering, University of Bath, Bath, United Kingdom
| | - Timothy P. Holsgrove
- College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, United Kingdom
| | - Dario Cazzola
- Department for Health, University of Bath, Bath, United Kingdom
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11
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Nightingale RW, Bass CR, Myers BS. On the relative importance of bending and compression in cervical spine bilateral facet dislocation. Clin Biomech (Bristol, Avon) 2019; 64:90-97. [PMID: 29544678 DOI: 10.1016/j.clinbiomech.2018.02.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 12/16/2017] [Accepted: 02/26/2018] [Indexed: 02/07/2023]
Abstract
BACKGROUND Cervical bilateral facet dislocations are among the most devastating spine injuries in terms of likelihood of severe neurological sequelae. More than half of patients with tetraparesis had sustained some form of bilateral facet fracture dislocation. They can occur at any level of the sub-axial cervical spine, but predominate between C5 and C7. The mechanism of these injuries has long been thought to be forceful flexion of the chin towards the chest. This "hyperflexion" hypothesis comports well with intuition and it has become dogma in the clinical literature. However, biomechanical studies of the human cervical spine have had little success in producing this clinically common and devastating injury in a flexion mode of loading. METHODS The purpose of this manuscript is to review the clinical and engineering literature on the biomechanics of bilateral facet dislocations and to describe the mechanical reasons for the causal role of compression, and the limited role of head flexion, in producing bilateral facet dislocations. FINDINGS Bilateral facet dislocations have only been produced in experiments where compression is the primary loading mode. To date, no biomechanical study has produced bilateral facet dislocations in a whole spine by bending. Yet the notion that it is primarily a hyper-flexion injury persists in the clinical literature. INTERPRETATION Compression and compressive buckling are the primary causes of bilateral facet dislocations. It is important to stop using the hyper-flexion nomenclature to describe this class of cervical spines injuries because it may have a detrimental effect on designs for injury prevention.
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Affiliation(s)
- Roger W Nightingale
- Duke University, Department of Biomedical Engineering, United States; Duke University, Division of Orthopaedic Surgery, United States.
| | - Cameron R Bass
- Duke University, Department of Biomedical Engineering, United States
| | - Barry S Myers
- Duke University, Department of Biomedical Engineering, United States; Duke University, Division of Orthopaedic Surgery, United States
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12
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Eckersley CP, Nightingale RW, Luck JF, Bass CR. The role of cervical muscles in mitigating concussion. J Sci Med Sport 2019; 22:667-671. [PMID: 30745221 DOI: 10.1016/j.jsams.2019.01.009] [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] [Received: 10/10/2018] [Revised: 01/08/2019] [Accepted: 01/13/2019] [Indexed: 10/27/2022]
Abstract
OBJECTIVES Increased neck strength has been hypothesized to lower sports related concussion risk, but lacks experimental evidence. The goal is to investigate the role cervical muscle strength plays in blunt impact head kinematics and the biofidelity of common experimental neck conditions. We hypothesize head kinematics do not vary with neck activation due to low short term human head-to-neck coupling; because of the lack of coupling, free-head experimental conditions have higher biofidelity than Hybrid III necks. METHODS Impacts were modeled using the Duke University Head and Neck Model. Four impact types were simulated with six neck conditions at eight impact positions. Peak resultant linear acceleration, peak resultant angular acceleration, Head Injury Criterion, and Head Impact Power compared concussion risk. To determine significance, maximum metric difference between activation states were compared to critical effect sizes (literature derived differences between mild and severe impact metrics). RESULTS Maximum differences between activation conditions did not exceed critical effect sizes. Kinematic differences from impact location and strength can be ten times cervical muscle activation differences. Hybrid III and free-head linear acceleration metrics were 6±1.0% lower and 12±1.5% higher than relaxed condition respectively. Hybrid III and free-head angular acceleration metrics were 12±4.0% higher and 2±2.7% lower than relaxed condition respectively. CONCLUSIONS Results from a validated neck model suggest increased cervical muscle force does not influence short term (<50ms) head kinematics in four athletically relevant scenarios. Impact location and magnitude influence head kinematics more than cervical muscle state. Biofidelic limitations of both Hybrid III and free-head experimental conditions must be considered.
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Affiliation(s)
- Christopher P Eckersley
- Injury Biomechanics Laboratory, Department of Biomedical Engineering, Duke University, United States.
| | - Roger W Nightingale
- Injury Biomechanics Laboratory, Department of Biomedical Engineering, Duke University, United States
| | - Jason F Luck
- Injury Biomechanics Laboratory, Department of Biomedical Engineering, Duke University, United States
| | - Cameron R Bass
- Injury Biomechanics Laboratory, Department of Biomedical Engineering, Duke University, United States
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The neutral posture of the cervical spine is not unique in human subjects. J Biomech 2018; 80:53-62. [PMID: 30170839 DOI: 10.1016/j.jbiomech.2018.08.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 08/14/2018] [Accepted: 08/15/2018] [Indexed: 12/31/2022]
Abstract
Cervical spine injuries often happen in dynamic environments (e.g., sports and motor vehicle crashes) where individuals may be moving their head and neck immediately prior to impact. This motion may reposition the cervical vertebrae in a way that is dissimilar to the upright resting posture that is often used as the initial position in cadaveric studies of catastrophic neck injury. Therefore our aim was to compare the "neutral" cervical alignment measured using fluoroscopy of 11 human subjects while resting in a neutral posture and as their neck passed through neutral during the four combinations of active flexion and extension movements in both an upright and inverted posture. Muscle activation patterns were also measured unilaterally using surface and indwelling electromyography in 8 muscles and then compared between the different conditions. Overall, the head posture, cervical spine alignment and muscle activation levels were significantly different while moving compared to resting upright. Compared to the resting upright condition, average head postures were 6-13° more extended, average vertebral angles varied from 11° more extended to 10° more flexed, and average muscle activation levels varied from unchanged to 10% MVC more active, although the exact differences varied with both direction of motion and orientation. These findings are important for ex vivo testing where the head and neck are statically positioned prior to impact - often in an upright neutral posture with negligible muscle forces - and suggest that current cadaveric head-first impact tests may not reflect many dynamic injury environments.
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The inclusion of hyoid muscles improve moment generating capacity and dynamic simulations in musculoskeletal models of the head and neck. PLoS One 2018; 13:e0199912. [PMID: 29953539 PMCID: PMC6023174 DOI: 10.1371/journal.pone.0199912] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Accepted: 06/16/2018] [Indexed: 11/19/2022] Open
Abstract
OpenSim musculoskeletal models of the head and neck can provide information about muscle activity and the response of the head and neck to a variety of situations. Previous models report weak flexion strength, which is partially due to lacking moment generating capacity in the upper cervical spine. Previous models have also lacked realistic hyoid muscles, which have the capability to improve flexion strength and control in the upper cervical spine. Suprahyoid and infrahyoid muscles were incorporated in an OpenSim musculoskeletal model of the head and neck. This model was based on previous OpenSim models, and now includes hyoid muscles and passive elements. The moment generating capacity of the model was tested by simulating physical experiments in the OpenSim environment. The flexor and extensor muscle strengths were scaled to match static experimental results. Models with and without hyoid muscles were used to simulate experimentally captured motions, and the need for reserve actuators was evaluated. The addition of hyoid muscles greatly increased flexion strength, and the model is the first of its kind to have realistic strength values in all directions. Less reserve actuator moment was required to simulate real motions with the addition of hyoid muscles. Several additional ways of improving flexion strength were investigated. Hyoid muscles add control and strength to OpenSim musculoskeletal models of the head and neck and improve simulations of head and neck movements.
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Exploring novel objective functions for simulating muscle coactivation in the neck. J Biomech 2018; 71:127-134. [PMID: 29452757 DOI: 10.1016/j.jbiomech.2018.01.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 12/26/2017] [Accepted: 01/28/2018] [Indexed: 11/23/2022]
Abstract
Musculoskeletal modeling allows for analysis of individual muscles in various situations. However, current techniques to realistically simulate muscle response when significant amounts of intentional coactivation is required are inadequate. This would include stiffening the neck or spine through muscle coactivation in preparation for perturbations or impacts. Muscle coactivation has been modeled previously in the neck and spine using optimization techniques that seek to maximize the joint stiffness by maximizing total muscle activation or muscle force. These approaches have not sought to replicate human response, but rather to explore the possible effects of active muscle. Coactivation remains a challenging feature to include in musculoskeletal models, and may be improved by extracting optimization objective functions from experimental data. However, the components of such an objective function must be known before fitting to experimental data. This study explores the effect of components in several objective functions, in order to recommend components to be used for fitting to experimental data. Four novel approaches to modeling coactivation through optimization techniques are presented, two of which produce greater levels of stiffness than previous techniques. Simulations were performed using OpenSim and MATLAB cooperatively. Results show that maximizing the moment generated by a particular muscle appears analogous to maximizing joint stiffness. The approach of optimizing for maximum moment generated by individual muscles may be a good candidate for developing objective functions that accurately simulate muscle coactivation in complex joints. This new approach will be the focus of future studies with human subjects.
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Huang J, Xu Y, Peng X, Hu L, Yang J. Development of a human head and neck muscle activation control model based on BPNN. JOURNAL OF INTELLIGENT & FUZZY SYSTEMS 2018. [DOI: 10.3233/jifs-169410] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Jing Huang
- State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha, China
| | - Ying Xu
- State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha, China
| | - Xiaoyan Peng
- State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha, China
| | - Lin Hu
- Changsha University of Science and Technology, College of Automotive and Mechanical Engineering, Changsha, China
| | - Jikuang Yang
- Department of Applied Mechanics, Chalmers University of Technology, Gothenburg, Sweden
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Untaroiu CD, Pak W, Meng Y, Schap J, Koya B, Gayzik S. A Finite Element Model of a Midsize Male for Simulating Pedestrian Accidents. J Biomech Eng 2017; 140:2653833. [DOI: 10.1115/1.4037854] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Indexed: 11/08/2022]
Abstract
Pedestrians represent one of the most vulnerable road users and comprise nearly 22% the road crash-related fatalities in the world. Therefore, protection of pedestrians in car-to-pedestrian collisions (CPC) has recently generated increased attention with regulations involving three subsystem tests. The development of a finite element (FE) pedestrian model could provide a complementary component that characterizes the whole-body response of vehicle–pedestrian interactions and assesses the pedestrian injuries. The main goal of this study was to develop and to validate a simplified full body FE model corresponding to a 50th male pedestrian in standing posture (M50-PS). The FE model mesh and defined material properties are based on a 50th percentile male occupant model. The lower limb-pelvis and lumbar spine regions of the human model were validated against the postmortem human surrogate (PMHS) test data recorded in four-point lateral knee bending tests, pelvic\abdomen\shoulder\thoracic impact tests, and lumbar spine bending tests. Then, a pedestrian-to-vehicle impact simulation was performed using the whole pedestrian model, and the results were compared to corresponding PMHS tests. Overall, the simulation results showed that lower leg response is mostly within the boundaries of PMHS corridors. In addition, the model shows the capability to predict the most common lower extremity injuries observed in pedestrian accidents. Generally, the validated pedestrian model may be used by safety researchers in the design of front ends of new vehicles in order to increase pedestrian protection.
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Affiliation(s)
- Costin D. Untaroiu
- Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA 24060 e-mail:
| | - Wansoo Pak
- Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA 24060
| | - Yunzhu Meng
- Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, VA 24060
| | - Jeremy Schap
- Department of Biomedical Engineering, Wake Forest University School of Medicine, Winston-Salem, NC 27101
| | - Bharath Koya
- Department of Biomedical Engineering, Wake Forest University School of Medicine, Winston-Salem, NC 27101
| | - Scott Gayzik
- Department of Biomedical Engineering, Wake Forest University School of Medicine, Winston-Salem, NC 27101
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Krašna S, Đorđević S, Hribernik M, Trajkovski A. A Novel Approach to Measuring Muscle Mechanics in Vehicle Collision Conditions. SENSORS (BASEL, SWITZERLAND) 2017; 17:s17061389. [PMID: 28613265 PMCID: PMC5492481 DOI: 10.3390/s17061389] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 06/08/2017] [Accepted: 06/09/2017] [Indexed: 06/07/2023]
Abstract
The aim of the study was to evaluate a novel approach to measuring neck muscle load and activity in vehicle collision conditions. A series of sled tests were performed on 10 healthy volunteers at three severity levels to simulate low-severity frontal impacts. Electrical activity-electromyography (EMG)-and muscle mechanical tension was measured bilaterally on the upper trapezius. A novel mechanical contraction (MC) sensor was used to measure the tension on the muscle surface. The neck extensor loads were estimated based on the inverse dynamics approach. The results showed strong linear correlation (Pearson's coefficient = 0.821) between the estimated neck muscle load and the muscle tension measured with the MC sensor. The peak of the estimated neck muscle force delayed 0.2 ± 30.6 ms on average vs. the peak MC sensor signal compared to the average delay of 61.8 ± 37.4 ms vs. the peak EMG signal. The observed differences in EMG and MC sensor collected signals indicate that the MC sensor offers an additional insight into the analysis of the neck muscle load and activity in impact conditions. This approach enables a more detailed assessment of the muscle-tendon complex load of a vehicle occupant in pre-impact and impact conditions.
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Affiliation(s)
- Simon Krašna
- Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva cesta 6, 1000 Ljubljana, Slovenia.
| | - Srđan Đorđević
- TMG-BMC d.o.o., Štihova ulica 24, 1000 Ljubljana, Slovenia.
| | - Marija Hribernik
- Faculty of Medicine, University of Ljubljana, Korytkova ulica 2, 1000 Ljubljana, Slovenia.
| | - Ana Trajkovski
- Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva cesta 6, 1000 Ljubljana, Slovenia.
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Happee R, de Bruijn E, Forbes PA, van der Helm FCT. Dynamic head-neck stabilization and modulation with perturbation bandwidth investigated using a multisegment neuromuscular model. J Biomech 2017; 58:203-211. [PMID: 28577906 DOI: 10.1016/j.jbiomech.2017.05.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2016] [Revised: 05/08/2017] [Accepted: 05/08/2017] [Indexed: 11/17/2022]
Abstract
The human head-neck system requires continuous stabilization in the presence of gravity and trunk motion. We investigated contributions of the vestibulocollic reflex (VCR), the cervicocollic reflex (CCR), and neck muscle co-contraction to head-in-space and head-on-trunk stabilization, and investigated modulation of the stabilization strategy with the frequency content of trunk perturbations and the presence of visual feedback. We developed a multisegment cervical spine model where reflex gains (VCR and CCR) and neck muscle co-contraction were estimated by fitting the model to the response of young healthy subjects, seated and exposed to anterior-posterior trunk motion, with frequency content from 0.3 up to 1, 2, 4 and 8Hz, with and without visual feedback. The VCR contributed to head-in-space stabilization with a strong reduction of head rotation (<8Hz) and a moderate reduction of head translation (>1Hz). The CCR contributed to head-on-trunk stabilization with a reduction of head rotation and head translation relative to the trunk (<2Hz). The CCR also proved essential to stabilize the individual intervertebral joints and prevent neck buckling. Co-contraction was estimated to be of minor relevance. Control strategies employed during low bandwidth perturbations most effectively reduced head rotation and head relative displacement up to 3Hz while control strategies employed during high bandwidth perturbations reduced head global translation between 1 and 4Hz. This indicates a shift from minimizing head-on-trunk rotation and translation during low bandwidth perturbations to minimizing head-in-space translation during high bandwidth perturbations. Presence of visual feedback had limited effects suggesting increased usage of vestibular feedback.
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Affiliation(s)
- Riender Happee
- Department of Biomechanical Engineering, Delft University of Technology, Delft, The Netherlands.
| | - Edo de Bruijn
- Department of Biomechanical Engineering, Delft University of Technology, Delft, The Netherlands
| | - Patrick A Forbes
- Department of Biomechanical Engineering, Delft University of Technology, Delft, The Netherlands; Department of Neuroscience, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Frans C T van der Helm
- Department of Biomechanical Engineering, Delft University of Technology, Delft, The Netherlands; Laboratory of Biomechanical Engineering, University of Twente, Enschede, The Netherlands
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Nightingale RW, Sganga J, Cutcliffe H, Bass CR'D. Impact responses of the cervical spine: A computational study of the effects of muscle activity, torso constraint, and pre-flexion. J Biomech 2016; 49:558-64. [PMID: 26874970 DOI: 10.1016/j.jbiomech.2016.01.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 01/06/2016] [Accepted: 01/08/2016] [Indexed: 10/22/2022]
Abstract
Cervical spine injuries continue to be a costly societal problem. Future advancements in injury prevention depend on improved physical and computational models, which are predicated on a better understanding of the neck response during dynamic loading. Previous studies have shown that the tolerance of the neck is dependent on its initial position and its buckling behavior. This study uses a computational model to examine three important factors hypothesized to influence the loads experienced by vertebrae in the neck under compressive impact: muscle activation, torso constraints, and pre-flexion angle of the cervical spine. Since cadaver testing is not practical for large scale parametric analyses, these factors were studied using a previously validated computational model. On average, simulations with active muscles had 32% larger compressive forces and 25% larger shear forces-well in excess of what was expected from the muscle forces alone. In the short period of time required for neck injury, constraints on torso motion increased the average neck compression by less than 250N. The pre-flexion hypothesis was tested by examining pre-flexion angles from neutral (0°) to 64°. Increases in pre-flexion resulted in the largest increases in peak loads and the expression of higher-order buckling modes. Peak force and buckling modality were both very sensitive to pre-flexion angle. These results validate the relevance of prior cadaver models for neck injury and help explain the wide variety of cervical spine fractures that can result from ostensibly similar compressive loadings. They also give insight into the mechanistic differences between burst fractures and lower cervical spine dislocations.
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Affiliation(s)
- Roger W Nightingale
- Duke University, Department of Biomedical Engineering and Division of Orthopaedic Surgery, Box 90281 Durham, NC 27708-0281, United States.
| | - Jake Sganga
- Duke University, Department of Biomedical Engineering and Division of Orthopaedic Surgery, Box 90281 Durham, NC 27708-0281, United States
| | - Hattie Cutcliffe
- Duke University, Department of Biomedical Engineering and Division of Orthopaedic Surgery, Box 90281 Durham, NC 27708-0281, United States
| | - Cameron R 'Dale' Bass
- Duke University, Department of Biomedical Engineering and Division of Orthopaedic Surgery, Box 90281 Durham, NC 27708-0281, United States
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Iwamoto M, Nakahira Y. Development and Validation of the Total HUman Model for Safety (THUMS) Version 5 Containing Multiple 1D Muscles for Estimating Occupant Motions with Muscle Activation During Side Impacts. STAPP CAR CRASH JOURNAL 2015; 59:53-90. [PMID: 26660740 DOI: 10.4271/2015-22-0003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Accurate prediction of occupant head kinematics is critical for better understanding of head/face injury mechanisms in side impacts, especially far-side occupants. In light of the fact that researchers have demonstrated that muscle activations, especially in neck muscles, can affect occupant head kinematics, a human body finite element (FE) model that considers muscle activation is useful for predicting occupant head kinematics in real-world automotive accidents. In this study, we developed a human body FE model called the THUMS (Total HUman Model for Safety) Version 5 that contains 262 one-dimensional (1D) Hill-type muscle models over the entire body. The THUMS was validated against 36 series of PMHS (Post Mortem Human Surrogate) and volunteer test data in this study, and 16 series of PMHS and volunteer test data on side impacts are presented. Validation results with force-time curves were also evaluated quantitatively using the CORA (CORrelation and Analysis) method. The validation results suggest that the THUMS has good biofidelity in the responses of the regional or full body for side impacts, but relatively poor biofidelity in its local level of responses such as brain displacements. Occupant kinematics predicted by the THUMS with a muscle controller using 22 PID (Proportional-Integral- Derivative) controllers were compared with those of volunteer test data on low-speed lateral impacts. The THUMS with muscle controller reproduced the head kinematics of the volunteer data more accurately than that without muscle activation, although further studies on validation of torso kinematics are needed for more accurate predictions of occupant head kinematics.
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22
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Ólafsdóttir JM, Brolin K, Blouin JS, Siegmund GP. Dynamic spatial tuning of cervical muscle reflexes to multidirectional seated perturbations. Spine (Phila Pa 1976) 2015; 40:E211-9. [PMID: 25423306 DOI: 10.1097/brs.0000000000000721] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Human volunteers were exposed experimentally to multidirectional seated perturbations. OBJECTIVE To determine the activation patterns, spatial distribution and preferred directions of reflexively activated cervical muscles for human model development and validation. SUMMARY OF BACKGROUND DATA Models of the human head and neck are used to predict occupant kinematics and injuries in motor vehicle collisions. Because of a dearth of relevant experimental data, few models use activation schemes based on in vivo recordings of muscle activation and instead assume uniform activation levels for all muscles within presumed agonist or antagonist groups. Data recorded from individual cervical muscles are needed to validate or refute this assumption. METHODS Eight subjects (6 males, 2 females) were exposed to seated perturbations in 8 directions. Electromyography was measured with wire electrodes inserted into the sternocleidomastoid, trapezius, levator scapulae, splenius capitis, semispinalis capitis, semispinalis cervicis, and multifidus muscles. Surface electrodes were used to measure sternohyoid activity. Muscle activity evoked by the perturbations was normalized with recordings from maximum voluntary contractions. RESULTS The multidirectional perturbations produced activation patterns that varied with direction within and between muscles. Sternocleidomastoid and sternohyoid activated similarly in forward and forward oblique directions. The semispinalis capitis, semispinalis cervicis, and multifidus exhibited similar spatial patterns and preferred directions, but varied in activation levels. Levator scapulae and trapezius activity generally remained low, and splenius capitis activity varied widely between subjects. CONCLUSION All muscles showed muscle- and direction-specific contraction levels. Models should implement muscle- and direction-specific activation schemes during simulations of the head and neck responses to omnidirectional horizontal perturbations where muscle forces influence kinematics, such as during emergency maneuvers and low-severity crashes. LEVEL OF EVIDENCE N/A.
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Affiliation(s)
- Jóna Marín Ólafsdóttir
- *Department of Applied Mechanics, Chalmers University of Technology, Gothenburg, Sweden †School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada; and ‡MEA Forensic Engineers & Scientists, Richmond, British Columbia, Canada
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Schwartz D, Guleyupoglu B, Koya B, Stitzel JD, Gayzik FS. Development of a computationally efficient full human body finite element model. TRAFFIC INJURY PREVENTION 2015; 16 Suppl 1:S49-S56. [PMID: 26027975 DOI: 10.1080/15389588.2015.1021418] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
INTRODUCTION A simplified and computationally efficient human body finite element model is presented. The model complements the Global Human Body Models Consortium (GHBMC) detailed 50th percentile occupant (M50-O) by providing kinematic and kinetic data with a significantly reduced run time using the same body habitus. METHODS The simplified occupant model (M50-OS) was developed using the same source geometry as the M50-O. Though some meshed components were preserved, the total element count was reduced by remeshing, homogenizing, or in some cases omitting structures that are explicitly contained in the M50-O. Bones are included as rigid bodies, with the exception of the ribs, which are deformable but were remeshed to a coarser element density than the M50-O. Material models for all deformable components were drawn from the biomechanics literature. Kinematic joints were implemented at major articulations (shoulder, elbow, wrist, hip, knee, and ankle) with moment vs. angle relationships from the literature included for the knee and ankle. The brain of the detailed model was inserted within the skull of the simplified model, and kinematics and strain patterns are compared. RESULTS The M50-OS model has 11 contacts and 354,000 elements; in contrast, the M50-O model has 447 contacts and 2.2 million elements. The model can be repositioned without requiring simulation. Thirteen validation and robustness simulations were completed. This included denuded rib compression at 7 discrete sites, 5 rigid body impacts, and one sled simulation. Denuded tests showed a good match to the experimental data of force vs. deflection slopes. The frontal rigid chest impact simulation produced a peak force and deflection within the corridor of 4.63 kN and 31.2%, respectively. Similar results vs. experimental data (peak forces of 5.19 and 8.71 kN) were found for an abdominal bar impact and lateral sled test, respectively. A lateral plate impact at 12 m/s exhibited a peak of roughly 20 kN (due to stiff foam used around the shoulder) but a more biofidelic response immediately afterward, plateauing at 9 kN at 12 ms. Results from a frontal sled simulation showed that reaction forces and kinematic trends matched experimental results well. The robustness test demonstrated that peak femur loads were nearly identical to the M50-O model. Use of the detailed model brain within the simplified model demonstrated a paradigm for using the M50-OS to leverage aspects of the M50-O. Strain patterns for the 2 models showed consistent patterns but greater strains in the detailed model, with deviations thought to be the result of slightly different kinematics between models. The M50-OS with the deformable skull and brain exhibited a run time 4.75 faster than the M50-O on the same hardware. CONCLUSIONS The simplified GHBMC model is intended to complement rather than replace the detailed M50-O model. It exhibited, on average, a 35-fold reduction in run time for a set of rigid impacts. The model can be used in a modular fashion with the M50-O and more broadly can be used as a platform for parametric studies or studies focused on specific body regions.
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Affiliation(s)
- Doron Schwartz
- a Wake Forest University School of Medicine , Winston-Salem , North Carolina
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Iwamoto M, Nakahira Y, Kimpara H. Development and Validation of the Total HUman Model for Safety (THUMS) Toward Further Understanding of Occupant Injury Mechanisms in Precrash and During Crash. TRAFFIC INJURY PREVENTION 2015; 16 Suppl 1:S36-S48. [PMID: 26027974 DOI: 10.1080/15389588.2015.1015000] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
OBJECTIVE Active safety devices such as automatic emergency brake (AEB) and precrash seat belt have the potential to accomplish further reduction in the number of the fatalities due to automotive accidents. However, their effectiveness should be investigated by more accurate estimations of their interaction with human bodies. Computational human body models are suitable for investigation, especially considering muscular tone effects on occupant motions and injury outcomes. However, the conventional modeling approaches such as multibody models and detailed finite element (FE) models have advantages and disadvantages in computational costs and injury predictions considering muscular tone effects. The objective of this study is to develop and validate a human body FE model with whole body muscles, which can be used for the detailed investigation of interaction between human bodies and vehicular structures including some safety devices precrash and during a crash with relatively low computational costs. METHODS In this study, we developed a human body FE model called THUMS (Total HUman Model for Safety) with a body size of 50th percentile adult male (AM50) and a sitting posture. The model has anatomical structures of bones, ligaments, muscles, brain, and internal organs. The total number of elements is 281,260, which would realize relatively low computational costs. Deformable material models were assigned to all body parts. The muscle-tendon complexes were modeled by truss elements with Hill-type muscle material and seat belt elements with tension-only material. The THUMS was validated against 35 series of cadaver or volunteer test data on frontal, lateral, and rear impacts. Model validations for 15 series of cadaver test data associated with frontal impacts are presented in this article. The THUMS with a vehicle sled model was applied to investigate effects of muscle activations on occupant kinematics and injury outcomes in specific frontal impact situations with AEB. RESULTS AND CONCLUSIONS In the validations using 5 series of cadaver test data, force-time curves predicted by the THUMS were quantitatively evaluated using correlation and analysis (CORA), which showed good or acceptable agreement with cadaver test data in most cases. The investigation of muscular effects showed that muscle activation levels and timing had significant effects on occupant kinematics and injury outcomes. Although further studies on accident injury reconstruction are needed, the THUMS has the potential for predictions of occupant kinematics and injury outcomes considering muscular tone effects with relatively low computational costs.
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Dibb AT, Cutcliffe HC, Luck JF, Cox CA, Myers BS, Bass CR, Arbogast KB, Seacrist T, Nightingale RW. Pediatric head and neck dynamics in frontal impact: analysis of important mechanical factors and proposed neck performance corridors for 6- and 10-year-old ATDs. TRAFFIC INJURY PREVENTION 2014; 15:386-394. [PMID: 24471363 DOI: 10.1080/15389588.2013.824568] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
OBJECTIVE Traumatic injuries are the leading cause of death of children aged 1-19 in the United States and are principally caused by motor vehicle collisions, with the head being the primary region injured. The neck, though not commonly injured, governs head kinematics and thus influences head injury. Vehicle improvements necessary to reduce these injuries are evaluated using anthropomorphic testing devices (ATDs). Current pediatric ATD head and neck properties were established by scaling adult properties using the size differences between adults and children. Due to the limitations of pediatric biomechanical research, computational models are the only available methods that combine all existing data to produce injury-relevant biofidelity specifications for ATDs. The purpose of this study is to provide the first frontal impact biofidelity corridors for neck flexion response of 6- and 10-year-olds using validated computational models, which are compared to the Hybrid III (HIII) ATD neck responses and the Mertz flexion corridors. METHODS Our virtual 6- and 10-year-old head and neck multibody models incorporate pediatric biomechanical properties obtained from pediatric cadaveric and radiological studies, include the effect of passive and active musculature, and are validated with data including pediatric volunteer 3 g dynamic frontal impact responses. We simulate ATD pendulum tests-used to calibrate HIII neck bending stiffness-to compare the pediatric model and HIII ATD neck bending stiffness and to compare the model flexion bending responses with the Mertz scaled neck flexion corridors. Additionally, pediatric response corridors for pendulum calibration tests and high-speed (15 g) frontal impacts are estimated through uncertainty analyses on primary model variables, with response corridors calculated from the average ± SD response over 650 simulations. RESULTS AND CONCLUSIONS The models are less stiff in dynamic anterioposterior bending than the ATDs; the secant stiffness of the 6- and 10-year-old models is 53 and 67 percent less than that of the HIII ATDs. The ATDs exhibit nonlinear stiffening and the models demonstrate nonlinear softening. Consequently, the models do not remain within the Mertz scaled flexion bending corridors. The more compliant model necks suggest an increased potential for head impact via larger head excursions. The pediatric anterioposterior bending corridors developed in this study are extensible to any frontal loading condition through calculation and sensitivity analysis. The corridors presented in this study are the first based on pediatric cadaveric data and provide the basis for future, more biofidelic, designs of 6- and 10-year-old ATD necks.
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Affiliation(s)
- Alan T Dibb
- a Department of Biomedical Engineering , Duke University , Durham , North Carolina
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