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Source publication
Objective:
The objectives of this study are to propose a new instrumentation technique for measuring cervical spine kinematics, validate it, and apply the instrumentation technique to postmortem human subjects (PMHS) in rear impact sled tests so that cervical motions can be investigated.
Methods:
First, a new instrumentation and dissection techn...
Contexts in source publication
Context 1
... is important not to damage the muscles in the neck during the dissection so that the passive resistance of the musculature is maintained during the neck extension that occurs in rear impact scenarios. Due to the extensive musculature in the anterior portion of the neck, this was accomplished by entering the retropharyngeal space from the lateral aspect of the neck, thus providing access to the anterior aspect of the cervical vertebral bodies (Figure 1). Specifically, an incision was made on the anterior border of the sternocleidomastoid muscle to access the lateral retropharyngeal space, and then the retropharyngeal space was expanded to make room for instrumentation by moving the trachea and esophagus ante- riorly, separating them from the cervical vertebrae. ...
Context 2
... to Sled) In order to visualize the PMHS cervical spine motions and assess them qualitatively, subject-specific cervical spine mod- els for each PMHS were created using CT image data and are shown in Figure B1 (see online supplement). Sequential im- ages of the cervical spine kinematics and the overall kinematics for an exemplar PMHS are shown for both 17 and 24 km/h tests in Figures B2 and B3 (see online supplement). ...
Citations
... 6 In this experimental model, surrogates were subjected to different accelerative load vectors that included horizontal force along the anteriorto-posterior direction (G -x ), posterior-to-anterior direction (G +x ), and vertical force along the superior-to-inferior direction (G +z load). [7][8][9][10][11] Because of the experimental nature of the study, segmental biomechanical parameters (range of motion) and biomedical injury metrics (such as load) could not be measured. Furthermore, there is limited literature on load-ing injury models conducted via clinical investigations and epidemiological studies. ...
Introduction
The evolution of military helmet devices has increased the amount of head-supported mass (HSM) worn by warfighters. HSM has important implications for spine biomechanics, and yet, there is a paucity of studies that investigated the effects of differing HSM and accelerative profiles on spine biomechanics. The aim of this study is to investigate the segmental motions in the subaxial cervical spine with different sizes of HSM under Gx accelerative loading.
Methods
A three-dimensional finite element model of the male head-neck spinal column was used. Three different size military helmets were modeled and incorporated into head–neck model. The models were exercised under Gx accelerative loading by inputting low and high pulses to the cervical vertebra used in the experimental studies. Segmental motions were obtained and normalized with respect to the non-HSM case to quantify the effect of HSM.
Results
Segmental motions increased with an increase in velocity at all segments of the spine. Increasing helmet size resulted in larger motion increases. Angulations ranged from 0.9° to 9.3° at 1.8 m/s and from 1.3° to 10.3° at 2.6 m/s without a helmet. Helmet increased motion between 5% to 74% at 1.8 m/s. At 2.6 m/s, the helmet increased segmental motion anywhere from 10% to 105% in the subaxial cervical spine. The greatest motion was seen at the C5-C6 level, followed by the C6-C7 level.
Conclusions
The subaxial cervical spine experiences motion increases at all levels at both velocity profiles with increasing HSM. Larger helmet and greater impact velocity increased motion at all levels, with C5-C6 demonstrating the largest range of motion. HSM should be minimized to reduce the risk of cervical spine injury to the warfighter.
... Le cas des autres tissus est plus complexe et fait l'objet d'une ample littérature (Clark et al. 1997, Hau et al. 2014. Des approches alternatives (comparaison avec des tissus repressurisés, des données d'accident, des résultats sur modèle animal, etc.) sont utilisées en complément pour vérifier la pertinence des résultats (Pattimore et al. 1958, Tamura et al. 2002 (Kang et al. 2013), ou encore obliques (Humm et al. 2018(Humm et al. , 2020. ...
Des efforts de recherche et développement considérables portent actuellement sur des véhicules automatisés qui pourraient libérer les conducteurs des tâches de conduite. Le siège et l’intérieur de l’habitacle pourraient être modifiés pour mieux accommoder les activités autres que la conduite, telle que dormir, lire et travailler etc. Cependant, même si un grand niveau de sécurité est attendu pour ces futurs véhicules, des accidents continueront à survenir. Les dispositifs de protection actuels sont conçus pour une position de conduite. Ils pourraient nécessiter des modifications afin de conserver le niveau de protection actuel pour de nouvelles positions d’occupant. Cette thèse vise à identifier les risques et les opportunités en termes de protection de l’occupant associés à de nouvelles positions pouvant être introduites avec les véhicules automatisés. Sur le plan méthodologique, elle s’est largement appuyée sur les modèles humains numériques pour le choc qui se sont révélés comme un outil pertinent d'évaluation du risque. Une attention particulière a été portée à l'évaluation de la validité des modèles après repositionnement. Les travaux ont permis de mieux comprendre les mécanismes de retenue dans des positions semi-allongées en choc frontal. Ces positions apparaissent critiques avec une retenue délicate du bassin ou un chargement de la colonne lombaire selon l’angle d’assise. Une sensibilité importante à la position initiale du bassin a également été observée. Ces résultats pourront être utilisés afin d’aider à concevoir et à évaluer des nouveaux dispositifs de retenue. Afin de mieux connaître la posture de confort dans ces positions inclinées, une étude expérimentale a été réalisée à l’aide d’un siège multi-réglable. Ces expérimentations ont permis d’une part d‘identifier des configurations de siège de confort, et d’autre part d’établir les relations entre ces configurations de siège et la position du squelette interne, et en particulier celle du bassin. Ces résultats pourront notamment aider au positionnement des occupants lors d’essais physiques ou numériques. Dans l’ensemble, ces travaux montrent l’interaction forte entre le confort et la sécurité pour la conception de nouveaux habitacles automobiles.
... In 2012 and 2013, biomechanical data from moderate-speed rear impacts (17 km/h and 24 km/h pulses) were generated using eight PMHS that were seated in an experimental seat with a yielding seat back and padding/cushion from a production seat [16][17]. The biomechanical targets generated were acceleration, rotation, force, and moment from various body regions to evaluate biofidelity of the rear impact ATDs [16] [20]. ...
... Biomechanical responses created from this study were acceleration and rotation from the head and T1. While several studies have been published using this combined data set of 21 tests of 15 PMHS in moderate-speed rear impact to generate biomechanical responses used for evaluating biofidelity of rear impact ATDs [16][17][18][19][20], none have included head trajectories. Therefore, the objective of this study is to investigate head trajectories of PMHS in moderate-speed rear impacts. ...
... Three different types of seats (Exp: experimental seat, Prod A: 2012 Chevrolet Cruze, Prod B: 2011 Toyota Camry) were used in moderate-speed rear impact conditions (Table I). Since 2012-2013 studies [16,17] focused on evaluating biofidelity of rear impact dummies, an experimental seat that was capable of measuring external forces (e.g., reaction forces from the seat pan, seat back and head restraint) was built and used. The detailed information for the experimental seat can be found in Appendix B. Since 2014-2015 studies [18,19] focused on cervical spine injury in moderate-speed rear impacts, the production seats were selected based on IIHS head restraint rating (Prod A was good, while Prod B was marginal). ...
One potential non-standard seating configuration for vehicles with automated driving systems is to have seating that faces the centre of the vehicle. This would result in the rear-facing seats experiencing rear-impact crash dynamics when the vehicle is in a frontal collision. Because rear crashes often occur at low speeds, there are limited biomechanical data in this seating configuration in moderate speed rear impacts. The objective of this study was to investigate head trajectories of post-mortem human surrogates (PMHS) with respect to seats that have different seat back rotations, so that human body models and anthropomorphic test devices can be evaluated and potentially modified to better reflect head trajectories. Twenty-one rear impact sled tests using fifteen PMHS were conducted with ∆Vs ranging from 17 to 24 km/h. The PMHS were placed in both experimental and production seats that exhibited seat back rotations ranging from 5 to 35 degrees. The head average downward displacements were 48.7 mm (17 km/h) and 140.3 mm (24 km/h) in the experimental seats, while the average upward displacements were 47.9 mm (17 km/h) and 83.6 mm (24 km/h) in the production seats. This directional difference in the z direction is likely due to the higher rotation of the seat back in the experimental seat than in the production seat and different subject interaction with the seat back from different seat back properties.
... Anderson, et al., measured the accelerations of the head and lumbar spine in volunteers during lowspeed frontal impacts [7], and rear-end sled tests performed by Welch, et [12,13]. Kang et al., has reported head and neck kinematics for post-mortem human specimens (PMHS) in experimental seats "similar" to a 1999 Toyota Camry seat [14,15] as well as for PMHS and BioRID ATDs in production seats from 2010 and 2011 model year vehicles [16] subjected to sled accelerations with delta-Vs of 17 and 24 kph. Kang, et al. (2012) also reported loads calculated at the occipital condyle for PMHS, but these calculations were limited to loads occurring prior to head contact with the experimental seat's head restraint. ...
... These depictions are not consistent with observations from this test series and other contemporary studies with modern seats and head restraints [21,24]. A recent study by Kang et al. [15] reflects this trend toward limited kinematics in modern FMVSS 202a compliant seats. The authors contrasted limited neck rotation in that study to greater neck rotation in a prior study by the same group in an experimental seat similar to a 1999 production model [14,15]. ...
... A recent study by Kang et al. [15] reflects this trend toward limited kinematics in modern FMVSS 202a compliant seats. The authors contrasted limited neck rotation in that study to greater neck rotation in a prior study by the same group in an experimental seat similar to a 1999 production model [14,15]. ...
... Cervical spine injuries occur commonly in different impact modes, and societal costs due to the injuries are high in motor vehicle crashes (MVC) [1][2][3][4][5][6][7]. Upper cervical injuries tend to be the most serious type of neck injury so the neck injury criterion, Nij, calculated at the upper cervical vertebrae was developed and has been used for frontal crashes [16]. ...
... In order to investigate neck injury tolerance and criteria, many studies have been conducted using human volunteers or post mortem human surrogates (PMHSs) in different impact directions [3][4][5] [7][8][9][10][11][12][13]. Upper neck criteria exist in Federal Motor Vehicle Safety Standard (FMVSS) No. 208, partly because upper neck injuries tend to be the most serious type of neck injury in frontal crashes, but also because upper neck loads, i.e., forces and moments at occipital condyle, in PMHS testing are relatively easy to calculate using the inertial properties and kinematics of the head alone. Due to the difficulty of accurately measuring lower neck loads, many studies have focused primarily on upper neck loads of human volunteers and PMHSs by using inverse dynamics approaches [5] [17][18][19][20][21][22][23][24][25][26][27]. ...
... Due to the difficulty of accurately measuring lower neck loads, many studies have focused primarily on upper neck loads of human volunteers and PMHSs by using inverse dynamics approaches [5] [17][18][19][20][21][22][23][24][25][26][27]. However, lower neck injuries are also important in that they have been commonly observed in both epidemiological [14] and experimental studies using PMHSs in frontal, side, and rear impacts [3][4][5] [7][8] [15]. If lower neck (cervicothoracic junction) biomechanical data could be obtained along with an injury risk function for the lower neck, it could be used in conjunction with the work that has been conducted on upper neck loads to evaluate the biofidelity of anthropomorphic test devices (ATDs) and to validate and improve finite element human body models (HBMs). ...
Head and neck responses of anthropomorphic test devices and computational human body models should be validated in different impact modes, e.g., frontal, oblique, side, and twist. The main objective of this study is to create biomechanical response targets of the head and neck of post mortem human surrogates using a controlled mini-sled system in various impact scenarios. A mini-sled was designed to dynamically test a post mortem human subject head-neck complex. A six axis load cell was attached at the T3 level of the spine to measure the reaction loads at the upper thoracic spine for the frontal, oblique and side impacts, while T1 was attached to the load cell for the twist test. The post mortem human subject head, C3, and C5 were instrumented using accelerometers and angular rate sensors to capture head and cervical kinematics. Five post mortem human subjects were tested in frontal (5), oblique (2), side (2), and twist (1) scenarios at a nominal mini-sled velocity of 14 km/h for frontal, side, and oblique impacts and 1,800 deg/s for the twist scenario. Biomechanical responses of the head and lower neck were measured in various impact conditions. Biomechanical targets were created for future biofidelity evaluation for anthropomorphic test devices and computational human body models.
... Cervical spine injuries are common, and often costly, in motor vehicle crashes (MVC) [1][2][3][4][5][6][7]. Survivors with neck injuries in frontal and rear MVC often sustain injuries in the lower portion of the cervical spine [7]. ...
... With the exception of very young occupants (8 years or less), where the majority of neck injuries are in the OC/C1/C2 region [39], children and adults are more likely to sustain lower cervical spine and cervicothoracic junction injuries than upper cervical injuries [6]. In order to investigate neck injury tolerance and criteria, many studies have been conducted using human volunteers or post-mortem human surrogates (PMHS) in different impact directions [3][4][5] [7][8][9][10][11][12][13]. Lower neck injuries have been commonly observed in experiments using PMHS in frontal, side and rear impacts [3][4][5] [7][8] [15]. The need exists to obtain accurate lower neck (cervicothoracic junction) biomechanical data, in order to develop an injury risk function for the lower neck in anthropomorphic test devices (ATDs). ...
... With the exception of very young occupants (8 years or less), where the majority of neck injuries are in the OC/C1/C2 region [39], children and adults are more likely to sustain lower cervical spine and cervicothoracic junction injuries than upper cervical injuries [6]. In order to investigate neck injury tolerance and criteria, many studies have been conducted using human volunteers or post-mortem human surrogates (PMHS) in different impact directions [3][4][5] [7][8][9][10][11][12][13]. Lower neck injuries have been commonly observed in experiments using PMHS in frontal, side and rear impacts [3][4][5] [7][8] [15]. The need exists to obtain accurate lower neck (cervicothoracic junction) biomechanical data, in order to develop an injury risk function for the lower neck in anthropomorphic test devices (ATDs). ...
Most anthropomorphic test devices possess both an upper neck and a lower neck load cell to measure the risk of neck injury in crash simulations. For post‐mortem human subject (PMHS) testing, the neck is frequently assumed to be a “massless link”. It is unknown how much error is generated by this assumption. The objective of this study is to investigate lower neck loads using inverse dynamics techniques in frontal impacts. A mini‐sled was designed to dynamically test a PMHS head‐neck complex. A custom‐sized elliptical ring was used for attaching upper thoracic structures in an anatomic configuration, to account for the contribution of these structures to the overall kinematics. A six‐axis load cell was attached at the T3 level of the spine to measure the reaction loads at the upper thoracic spine. The PMHS head, C3, and C6 kinematics were measured to calculate lower neck loads using inverse dynamics techniques (IDT). A total of five PMHS tests were conducted to simulate a frontal impact. Lower neck loads were calculated using IDT, while considering either a massless link assumption (IDT‐MLA) or the actual mass moment of inertia (MMI) and center of gravity (CG) of the neck, along with measured cervical kinematics (IDT‐MMICG). The IDT‐MMICG method resulted in less error from the measured forces and moments than the IDT‐MLA method. It is recommended that instrumentation of at least one cervical level between C3 and C6 along with head/neck mass properties should be used for improved estimation of lower neck loads.
... However, rotation of the cervical spine is regarded as an important factor for determining the mechanisms underlying cervical spine injuries, such as that reported for fractural dislocation of the vertebral facet in a traffic crash [4,5]. Although rotation of the cervical vertebrae upon impact has been reported in human subjects postmortem and in a dummy model [6], we are not aware of any published reports on experiments with human subjects. ...
... An experiment of the finite element method in frontal collision at high energy showed a strong rotational force in the cervical spine [26]. Moreover, rotation of the cervical vertebrae during frontal collision has been reported in human subjects postmortem and in a dummy model [6]. Cervical spine injury from a frontal impact with the air bag has also been reported [28]. ...
Study design:
Prospective experimental study on humans.
Purpose:
To determine whether postural differences during a low-speed impact are observed in the sagittal and axial views, particularly in a relaxed state.
Overview of literature:
Three-dimensional motion capture systems have been used to analyze posture and head-neck-torso kinematics in humans during a simulated low-speed impact, yet little research has focused on the axial view. Since a seatbelt asymmetrically stabilizes a drivers right shoulder and left lower waist into the seat, it potentially creates movement in the axial view.
Methods:
Three healthy adult men participated in the experimental series, which used a low-speed sled system. The acceleration pulse created a full sine shape with a maximum acceleration of 8.0 m/s(2) at 500 ms, during which the kinematics were evaluated in relaxed and tensed states. The three-dimensional motion capture system used eight markers to record and analyze body movement and head-neck-torso kinematics in the sagittal and axial views during the low-speed impact. Head and trunk rotation angles were also calculated.
Results:
Larger movements were observed in the relaxed than in the tensed state in the sagittal view. The cervical and thoracic spine flexed and extended, respectively, in the relaxed state. In the axial view, larger movements were also observed in the relaxed state than in the tensed state, and the left shoulder rotated.
Conclusions:
During simulated frontal impact, the rotation angle between the head and trunk was significantly larger in the relaxed state. Therefore, we recommend also observing movement in the axial view during impact tests.
... In 2012, eight unembalmed PMHS and rear impact ATDs were tested under an identical test condition in two moderate speeds (8.5 g and 17 km/h; 10.5 g and 24 km/h) using an experimental seat [19]. Additionally, an instrumentation technique for measuring the kinematics of each vertebra in the PMHS cervical spine was developed, validated and used to assess the cervical kinematics of the PMHS in that test series [21]. An angular rate sensor was installed on each of the cervical vertebrae of the BioRID II so that rotations of the cervical spine of the BioRID II could be compared to those measured from the PMHS [21]. ...
... Additionally, an instrumentation technique for measuring the kinematics of each vertebra in the PMHS cervical spine was developed, validated and used to assess the cervical kinematics of the PMHS in that test series [21]. An angular rate sensor was installed on each of the cervical vertebrae of the BioRID II so that rotations of the cervical spine of the BioRID II could be compared to those measured from the PMHS [21]. They found that the BioRID II exhibited comparable results to the PMHS in the 17 km/h test. ...
... They found that the BioRID II exhibited comparable results to the PMHS in the 17 km/h test. For the 24 km/h test, the cervical spine of the BioRID II exhibited less extension than the PMHS at all levels (C2-C7) [21]. It is also reported that the intervertebral rotations for both the PMHS and the BioRID II were primarily relative flexion rotations, even though the cervical vertebrae rotated rearward with respect to the global coordinate system [21]. ...
In a previous study, a comparison of cervical spine kinematics between a current rear impact
dummy, BioRID II, and post mortem human subjects (PMHS) was made by subjecting them to moderate speed rear impacts while positioned in an experimental seat. The objective of this study is to make a similar comparison of head and cervical spine kinematics in more realistic production seat conditions. A total of seven
sled tests using seven PMHS (males 181.9 ± 3.9 cm of stature and 79.0 ± 4.7 kg of weight) were conducted in several moderate speed rear impact test conditions. The BioRID II was also tested under the same conditions, with each cervical vertebra instrumented with one angular rate sensor so that rotational kinematics of the cervical spine of BioRID II could be compared to those measured from the PMHS. Results show that the BioRID II exhibited generally comparable results to the PMHS, although the biofidelity of the BioRID spine in flexion could
be improved. As seen previously in the experimental seat, the intervertebral rotations for both PMHS and the BioRID II in the production seats were primarily relative forward rotations (i.e. intervertebral flexion) even though the cervical vertebrae rotated rearward with respect to the global coordinate system. Contrary to the experimental seat, a transition to relative rearward rotation (i.e. intervertebral extension) occurs in the lower spine of the BioRID in the two production seats in this study.
... kinematics of each vertebra in the PMHS cervical spine was developed, validated and used to assess the cervical kinematics of the PMHS in that test series [21]. For the PMHS cervical kinematics in this experimental seat it was found that although the head and each vertebra rotated rearward in the global coordinate system, the head rotated forward with respect to T1 (i.e. ...
... Rear impact HYGE sled tests were conducted using three different pulses (FMVSS 202a [1], JNCAP [26] and 10.5g, 24 km/h [21]). A total of seven rear impact sled tests were conducted with seven different PMHS using two different types of production seats (seat A and seat B) in the three speeds. ...
... Anthropometric data of subjects' head and neck are provided in Fig. 1. IRC- [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] IRCOBI Conference 2014 Subject Instrumentation and sled set up A PMHS instrumentation scheme was devised based on the instrumentation of the BioRID II ATD [27][28][29] so that a direct comparison of the ATD to the PMHS could be made as part of a separate biofidelity study. Instrumentation was attached at the head, cervical spine (C2-C7), T1, T8, T12 and S1, but the focus of this study is only on the head, cervical spine and T1 kinematics. ...
The objective of this study was to obtain head and cervical spine responses of post mortem human
subjects (PMHS) in moderate speed rear impacts while positioned in production seats. Instrumentation used to
measure biomechanical responses of the PMHS included both accelerometers and angular rate sensors (ARS). A
total of seven sled tests using seven PMHS (males 181.9 ± 3.9 cm of stature and 79.0 ± 4.7 kg of weight) were
conducted in several moderate speed rear impact test conditions (FMVSS 202a, JNCAP and 10.5g, 24 km/h).
Results show that the intervertebral rotations of the cervical vertebrae were relative flexion rotations although
all cervical vertebrae rotated rearward in the global coordinate system. This relative flexion rotation occurred in
all three moderate speed conditions and at all intervertebral levels: 4.2 ± 2.8 degrees for C2/C3, 4.0 ± 2.3
degrees for C3/C4, 6.3 ± 3.8 degrees for C4/C5, 6.1 ± 3.5 degrees for C5/C6, and 5.8 ± 3.2 degrees for C6/C7.
Although the cervical flexion kinematics observed in this study in production seats are not representative of the
traditional neck extension kinematics attributed to whiplash‐type cervical spine injuries, results indicated that
intervertebral flexion kinematics might also be regarded as an additional potential injury mechanism of the
cervical spine in moderate speed rear impacts.
