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Controlled automobile rearend collisions, an investigation of related engineering and medical phenomena

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... Using equation 3, the velocity change data for the added-mass condition were corrected and replotted in the same figure. These corrected data show that the correction predicted by Equation 3 adequately accounts for the additional mass in the regions where the coefficient of restitution is relatively unaffected by the additional mass. In the case of the Volkswagen, the coefficient of restitution is altered by the additional mass and the corrected velocity changes fall along the edge of the unladen vehicle data. ...
... For the front bumper of the Malibu, the coefficient of restitution of the laden and unladen vehicles are similar up to about 1 mls and the velocity change correction of Equation 3 is adequate. Above 1 m/s, the coefficient of restitution of the laden vehicle drops below the unladen vehicle and the correction proposed in Equation 3 grows progressively worse. ...
... The coefficient of restitution appears to either remain the same or lessen with added mass. This suggests that any correction made using Equation 3 will either adequately estimate the actual velocity change if the coefficient of restitution remains the same, or slightly overestimate the velocity change if the coefficient of restitution decreases with added mass. ...
... An occupant in a stationary vehicle that is impacted from the rear remains at rest relative to the ground as the vehicle is accelerated beneath him. This motion is consistent with the laws of physics and has been well documented in the literature (Geigl et al., 1994;Matsushita et al., 1994;McConnell et al., 1993 andSevery et al., 1955;Szabo et al., 1994). The occupant essentially remains at rest relative to the ground until the seat back and head restraint interact with the occupant. ...
... For many occupants, the interaction between the seat back and head restraint and the occupant's upper torso and head occurs after the vehicle's acceleration is essentially complete. Occupant head and neck kinematics are thus largely a function of the final velocity change for the target vehicle as opposed to the shape of the acceleration pulse (King et al., 1993;McConnell et al., 1993; Siegmund et al 1996; Romilly et al., 1989;Severy et al., 1955;Siegmund et al, 1994;Szabo and Welcher, 1996). Occupant cervical injury tolerances for a given occupant-seat pairing are thus likely a function of the target vehicle change in velocity. ...
... Occupant tolerance to rear impacts is likely also influenced by the occupant's preparedness for impact. Occupants who brace and actively tense their muscles in response to an impending impact can typically withstand impacts with a greater severity than occupants who are unaware of the impending impact (Emori and Horiguchi,1990; Mertz and Patrick,1971;Severy et al.,1955;States,1969). The current study also compares head kinematics and subjective impressions of impact between an aware and unaware target vehicle occupant. ...
Article
Considerable research has been conducted over the past decade on the response of both vehicles and occupants to low speed rear impacts. This research has employed various conditions of target vehicle braking and target occupant awareness. Relatively little effort has been devoted to quantitatively comparing vehicle and occupant responses under different braking and awareness. Given the variety of potential braking and awareness conditions in actual rear impacts, it is desirable to better understand the influence of these reactions on both vehicle and occupant dynamics. Low speed vehicle-to-vehicle rear end collisions were conducted with instrumented vehicles and an instrumented human subject. Six conditions were evaluated: 1) unaware occupant without braking, 2) aware occupant without braking 3) unaware occupant braking "normally", 4) aware occupant full-braking, 5) unaware occupant with brakes mechanically fully applied, and 6) aware occupant with brakes mechanically fully applied. Three closing speeds were investigated (nominal 4, 8 and 13 km/h). The same occupant and vehicles were used for all impacts. Vehicle chassis velocity and acceleration were measured using 5th wheels and accelerometers, respectively. Occupant response was measured by accelerometers attached to the occupant's head and lumbar spine. Accelerations at the head static center of gravity were obtained via a 9-accelerometer headgear array. Little difference was found between vehicle kinematics for conditions in which the unaware occupant was not braking and the unaware occupant was braking "normally". Decreased target vehicle velocity changes and increased bullet vehicle velocity changes were observed with fully or mechanically applied braking. Full or mechanical braking decreased the collision duration for the target vehicle, while bullet vehicle collision durations were not affected. Awareness of the impending impact decreased occupant head kinematic parameters and the target vehicle occupant described those impacts for which he was prepared as feeling less severe than those for which he was unaware. No differences were found in target vehicle occupant head kinematics for the unbraked and fully braked tests.
... Malgré le manque d'explication clinique des symptômes rapportés par les victimes d'un coup du lapin, certains mécanismes de blessure ont été proposés. En premier lieu, il est connu que les forces impliquées dans un accident automobile sont considérables : lors d'un impact à 13.1 km/h (1.9 g enregistré au niveau de la voiture), la tête peut subir une accélération maximale de 5 g pendant la phase d'extension cervicale [8]. Cependant, Severy et al. (1955) [8] ont montré qu'un sujet pouvait répondre différemment (accélération céphalique maximale de 2.9 g) à un impact similaire présumément grâce à une pré-tension de la musculature cervicale. ...
... En premier lieu, il est connu que les forces impliquées dans un accident automobile sont considérables : lors d'un impact à 13.1 km/h (1.9 g enregistré au niveau de la voiture), la tête peut subir une accélération maximale de 5 g pendant la phase d'extension cervicale [8]. Cependant, Severy et al. (1955) [8] ont montré qu'un sujet pouvait répondre différemment (accélération céphalique maximale de 2.9 g) à un impact similaire présumément grâce à une pré-tension de la musculature cervicale. Szabo et al. (1994) [9] ont rapporté qu'un impact à 15-16 km/h causant un changement de vitesse de 8 km/h du véhicule accidenté entraînait une accélération maximale variant entre 5 à 6 g. ...
... En premier lieu, il est connu que les forces impliquées dans un accident automobile sont considérables : lors d'un impact à 13.1 km/h (1.9 g enregistré au niveau de la voiture), la tête peut subir une accélération maximale de 5 g pendant la phase d'extension cervicale [8]. Cependant, Severy et al. (1955) [8] ont montré qu'un sujet pouvait répondre différemment (accélération céphalique maximale de 2.9 g) à un impact similaire présumément grâce à une pré-tension de la musculature cervicale. Szabo et al. (1994) [9] ont rapporté qu'un impact à 15-16 km/h causant un changement de vitesse de 8 km/h du véhicule accidenté entraînait une accélération maximale variant entre 5 à 6 g. ...
Conference Paper
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En résumé, il n’existe pas de consensus concernant le ou les mécanismes entraînant les blessures suite à un coup du lapin. Certaines observations semblent suggérer un certain mécanisme de blessure alors que d’autres semblent infirmer ce même mécanisme. Cependant, les mécanismes de blessure cités précédemment suggèrent qu’une ou plusieurs structures puissent être lésées suite à un accident en véhicule motorisé. Lorsqu’une fracture vertébrale ou une lésion neurologique importante survient, il est possible de l’identifier à l’examen clinique ou lors d’examens spécialisés (radiologie, imagerie par résonance magnétique ou tomographie axiale). Dans ces cas particuliers, la relation entre la symptomatologie du patient et la blessure identifiée subie lors de l’accident est facile à déterminer. La difficulté survient lorsque les victimes d’un accident en véhicule motorisé se présentent avec plusieurs symptômes alors qu’aucune blessure n’est identifiable comme c’est le cas des blessures de tissus mous (muscles, ligaments, capsules zygapophysaires, disques intervertébraux). Ces personnes peuvent présenter une pléiade de symptômes difficilement liés à la blessure subie. De plus, les gens victimes d’un accident en véhicule motorisé peuvent développer un ou plusieurs symptômes de façon plus ou moins tardive; une partie de cette population demeurera même asymptomatique pendant plusieurs années avant de présenter une quelconque symptomatologie. Bien que toutes ces victimes d’accident de la route aient subi un traumatisme de la région cervicale, l’origine exacte de leur problème demeure obscure en plus de varier entre les individus.
... In passenger vehicular accidents, an 8-mile/hour rear-end collision produced a 2G acceleration of the vehicle and a 5G acceleration of the head with a span of 300ms or less [1]. Whiplash is the common occurrence during which the cervical spine is frequently injured. ...
... A 3-d FE model of the C0-C7 was developed based on the method previously reported [1] [3]. Briefly, the 3-d FE model of the head and cervical vertebrae were developed with geometrical data based on the actual geometry of a 68 year-old male cadaver specimen. ...
Article
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A detailed three-dimensional head-neck (C0-C7) finite element (FE) model was developed based on the actual geometry of a cadaveric specimen and used to characterize the whiplash phenomenon of the head-neck region during rear-end collision. A maximum rear impact pulse of 8.5G of acceleration, simulating about 20mile/hour rear-end collision, was applied to C7. The effects of headrest on the responses of head-neck complex were also discussed. The study demonstrates the effectiveness of the current C0-C7 FE model in characterizing the gross responses of human cervical spine under whiplash conditions. During whiplash, the lower cervical levels, especially the C6-C7, experience higher extension motion in the acceleration/decerleration syndrome of the neck, suggesting that the whole cervical spine is at risk of extension injuries than flexion injuries. Also the use of a proper headrest can effectively reduce the cervical spine from extension injury during the acceleration phase of cervical spine in whiplash.
... Severy further amplified this dilemma in his 1955 study, observing: "…unlike most injury-producing accidents, there is generally no visible sign of injury for the rear-end collision victim." (Severy, Mathewson & Bechtol, 1955). The apparent discrepancy between the severity of symptoms and the trauma causing them has remained the core of the controversy. ...
... At forces of 6G, a fighter pilot may begin to lose consciousness, and at 8G be unable to lift his extremities (U.S. Naval Flight Surgeon's Manual, 1978). A 15 miles-per-hour accident generates approximately 10G of force on the head (Severy, et al, 1955). These data suggest that low impacts may have substantial potential for soft tissue, and presumably brain injury. ...
... Cervical injuries are a major public health problem with a significant social cost [1,2]. In literature, we can find numerous biomechanical studies [3][4][5][6][7] focused on the assessment of cervical behaviour. Many of these studies were performed using animals [8][9][10][11][12][13][14][15][16], crash dummies [17][18][19][20][21][22][23], full-body cadavers [12,19,20,[24][25][26][27], isolated cervical [12,24,[28][29][30], head-neck complexes and computational models [31][32][33][34][35][36][37]. ...
Article
Full-text available
Nowadays, due to the advances and the increasing implementation of the autonomous braking systems in vehicles, the non-collision accident is expected to become more common than a crash when a sudden stop happens. The most common injury in this kind of accident is whiplash or cervical injury since the neck has high sensitivity to sharp deceleration. To date, biomechanical research has usually been developed inside laboratories and does not entirely represent real conditions (e.g., restraint systems or surroundings of the experiment). With the aim of knowing the possible neck effects and consequences of an automatic emergency braking inside an autonomous bus, a surface electromyography (sEMG) system built by low-cost elements and developed by us, in tandem with other devices, such as accelerometers or cameras, were used. Moreover, thanks to the collaboration of 18 participants, it was possible to study the non-collision effects in two different scenarios (braking test in which the passenger is seated and looking ahead while talking with somebody in front of him (BT1) and, a second braking test where the passenger used a smartphone (BT2) and nobody is seated in front of him talking to him). The aim was to assess the sEMG neck response in the most common situations when somebody uses some kind of transport in order to conclude which environments are riskier regarding a possible cervical injury.
... Numerous researchers have documented differences in the head and torso kinematics between human subjects and ATDs, like the Hybrid III, designed for high speed crash testing (Severy et al., 1955;Mertz and Patrick, 1967;Scott et al., 1993;Geigl et al., 1995;Davidsson et al., 1999aDavidsson et al., , 1999bGotou et al., 1999;Cappon et al., 2000). Specially designed rearimpact dummy (RID) necks were developed to address these differences (Svensson and Lövsund, 1992;Thunnissen et al., 1996), however, these solutions underestimated the contribution of the upper torso in generating a human-like head and neck response during whiplash loading. ...
... This research has shown that seat yielding (rotation) lowers forces on the occupant. Severy et al. (1955) reported that seat yielding was beneficial in mitigating whiplash injuries in rear crashes with 16.1-32.2 km/h (10-20 mph) rear delta V. Anderson (1961) carried out a broad-based study of seats in rear impacts that included crash tests, modeling, and anthropometric evaluations. ...
Article
Objective: This study compared biomechanical responses of a normally seated Hybrid III dummy on conventional and ABTS (all belts to seat) seats in 40.2 km/h (25 mph) rear sled tests. It determined the difference in performance with modern (≥2000 MY) seats compared to older (<2000 MY) seats and ABTS seats. Methods: The seats were fixed in a sled buck subjected to a 40.2 km/h (25 mph) rear sled test. The pulse was a 15 g double-peak acceleration with 150 ms duration. The 50th Hybrid III was lap-shoulder belted in the FMVSS 208 design position. The testing included 11 <2000 MY, 8 ≥2000 MY and 7 ABTS seats. The dummy was fully instrumented including head accelerations, upper and lower neck 6 axis load cells, chest acceleration, thoracic and lumbar spine load cells and pelvis accelerations. The peak responses were normalized by IARV to assess injury risks. Statistical analysis was conducted using the Student t-test. High-speed video documented occupant kinematics. Results: Biomechanical responses were lower with modern (≥2000 MY) seats than older (<2000 MY) designs. The lower-neck extension moment was 32.5% ± 9.7% of IARV in modern seats compared to 62.8% ± 31.6% in older seats (p = 0.01). Overall, there was a 34% reduction in the comparable biomechanical responses with the modern seats. Biomechanical responses were lower with modern seats than ABTS seats. The lower neck extension moment was 41.4% ± 7.8% with all MY ABTS seats compared to 32.5% ± 9.7% in modern seats (p = 0.07). Overall, the ABTS seats had 13% higher biomechanical responses than the modern seats. Conclusions: Modern (≥2000 MY) design seats have lower biomechanical responses in 40.2 km/h rear sled tests than older (<2000 MY) designs and ABTS designs. The improved performance is consistent with an increase in seat strength combined with improved occupant kinematics through pocketing of the occupant into the seatback, higher and more forward head restraint and other design changes. The methods and data presented here provide a basis for standardized testing of seats. However, a complete understanding of seat safety requires consideration of out of position occupants (OOP) in high-speed impacts and consideration of the much more common, low-speed rear impacts.
... The target car's driver seat and occupant's seating position are shown in Figure 4, which is taken from [8]. It should be noted that we reviewed a number of other papers [9][10][11][12][13] but found they did not provide as detailed vehicle acceleration output, or occupant and seatback input information to permit comparison with our analytical and numerical work. 1. Numbers in brackets refer to references with corresponding numbers at the end of this paper. ...
... An alerted condition, wherein subjects received a countdown to the perturbation, was used to represent sled tests in which subjects were moving initially rearward and could potentially predict when they would be abruptly halted 14,26 or staged vehicle-to-vehicle collisions in which instrumentation noise provided visual and auditory cues from which the time of impact could be predicted. 24,33 An unalerted condition was used to represent studies in which subjects knew an impact would occur, but could not predict its precise timing. ...
Article
Study Design. Human subjects were exposed experimentally to a single whiplash-like perturbation. Objective. To determine how awareness of the presence and timing of a whiplash-like perturbation affects the onset and amplitude of the neck muscle response and the peak magnitude of head and neck kinematics. Summary of Background Data. Although most whiplash injuries are sustained in rear-end collisions, which occur without warning, most studies of whiplash injury have used subjects aware of the imminent perturbation. Methods. Seated subjects ( 35 women and 31 men) underwent a single forward horizontal perturbation ( peak acceleration, 1.5 g). Surface electromyography measured the sternocleidomastoid and cervical paraspinal muscle activity. Three awareness conditions were tested: a countdown for subjects alerted to their perturbation, a perturbation without an alert for subjects who expected it within 60 seconds, and an unexpected perturbation for surprised subjects who were deceived. Results. The muscle and kinematic responses of aware ( alerted and unalerted) subjects were not significantly different. Sternocleidomastoid activation occurred 7 ms later in surprised subjects than in aware subjects (P < 0.0002). Cervical paraspinal amplitudes were 260% larger and angular head accelerations in flexion were 180% larger in surprised male subjects than in alerted male subjects. Surprised female subjects exhibited a 25% larger head retraction and a 30% lower forward acceleration of the mastoid process than aware female subjects. Conclusions. The larger retractions observed in surprised females likely produce larger tissue strains and may increase injury potential. Aware human subjects may not replicate the muscle response, kinematic response, or whiplash injury potential of unprepared occupants in real collisions.
... [1][2][3] Previous researches were focused on the volunteer tests. Severy et al. 4 firstly carried out the volunteer tests to study neck injury mechanism in rear impact. However, the behavior of neck muscle activation was not taken into account until Mertz and Patrick 5 conducted the volunteer tests. ...
Article
Full-text available
Muscle activation plays an important role in head–neck dynamic response in vehicle accidents, especially in low speed impacts. The aim of the present study was to analyze the mechanical characteristics and dynamic stability of the muscle using coupled non-linear finite element model, which could be further applied for biomechanical study of head–neck system in car crash accidents. A rabbit tibialis anterior (TA) geometry model was developed. Two finite element models of TA were developed with coupled constitutive models. One coupled model was developed combining quasi-linear viscoelastic (QLV) elements and Hill type elements, and the other was developed combining hyperelastic rubber elements and Hill type elements, representing the passive behavior and active behavior, respectively. The models were validated via eccentric contractions tests under different strain rates published by Myers et al. Isometric Contraction and axial compression were also simulated via both models to evaluate the computational stability. The results showed that the coupled constitutive muscle models had a good biofidelity for the simulation of muscle activation. Both muscle models can fulfill the requirement of neck muscle system modeling for biomechanical study.
... Dalian: Dalian University of Technology, 2006. (in Chinese) [2] Bowers E C. Harbour resonance due to set-down beneath wave groups [J]. Journal of Fluid Mechanical, 1976, 79(1): 71-92. ...
Article
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The second-order low-frequency oscillations inside a rectangular harbor induced by different wave groups with the same resonance frequency are simulated by the full nonlinear Boussinesq model. It is found that low-frequency oscillations could be evidently excited only when the ratio of the short wavelength to the harbor entrance is greater than 3.3. The second-order wave could be as large as the first-order wave inside the harbor. The paper interprets this phenomenoncan from the interactions beteen short waves and the harbor entrance. The wavelet-based bicoherence spectrum is employed to analyze the wave-wave interactions. It is shown that the second-order long wave not only participates in wave-wave interactions between the carrier short waves but also takes part in interactions between super-harmonic wave components.
... Hyperflexion, associated with "extensor recoil" of the neck, was then proposed to be the injury mechanism (40). In 1955, Severy et al. recorded whiplash loading to a human volunteer on film and recognised that hyperextension, followed by hyperflexion, was the correct sequence of events in rearend collisions (41). At that time, hyperextension of the head and neck was thought to be responsible for the possible injury mechanism (4244). ...
... Hyperflexion, associated with "extensor recoil" of the neck, was then proposed to be the injury mechanism (40). In 1955, Severy et al. recorded whiplash loading to a human volunteer on film and recognised that hyperextension, followed by hyperflexion, was the correct sequence of events in rearend collisions (41). At that time, hyperextension of the head and neck was thought to be responsible for the possible injury mechanism (4244). ...
Thesis
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The studies upon which this thesis is based were intended to identify measurable physical impairment in the stability system of the cervical spine in patients with chronic whiplash-associated disorders (WAD), grades I-II. Case-control and test-retest designs were used to identify and define the clinical characteristics investigated. Questionnaires were used to investigate self-reported characteristics and two radiographic studies explored the passive integrity of the cervical spine. The same subjects, all women, participated in the three above mentioned studies. Two studies into the muscular system investigated the deep pre- and paravertebral cervical muscles respectively. In three successive studies relocation and movement accuracy of the cervical spine were investigated. Different number of subjects participated in these five last mentioned studies. The results from the questionnaires indicated that women with chronic WAD have symptoms which are more disabling than women with chronic insidious onset neck pain (IONP). The first radiographic study revealed that, in the WAD group, the upper cervical lordosis was relatively increased and the lower cervical spine lordosis was relatively decreased. The C4 vertebra was also more kyphotic in the WAD group than in the asymptomatic group. The second radiographic study revealed increased segmental motion in the mid cervical segments of one third of the WAD group. These results point to mechanical instability in the lower cervical spine in a subgroup of patients with chronic WAD. A new test, the cranio-cervical flexion test, identified altered patterns of muscle co-ordination within the cervical flexor synergy in neck pain patients that could indicate inhibition of the deep ventral muscles. Ultrasound imaging revealed that the cervical multifidus muscle in WAD patients is smaller than in asymptomatic subjects. The diminished size of this muscle further reduces the weight bearing capacity of the cervical spine and contributes to deficient control of intersegmental motions. These findings indicate that the deep pre- and paravertebral muscles provide inadequate support in neck pain patients. Cervical spine proprioception was measured using a 3D measurement device (Fastrak) connected to specially designed software programmes. The measurements revealed relocation inaccuracy in neck pain patients, a deficit that tended to be greater in whiplash patients. A new clinical test, developed to measure movement inaccuracy of the cervical spine was able to discriminate between an asymptomatic group and a chronic WAD group. When the results from all these investigations are viewed as a whole, a definite pattern of musculoskeletal impairment emerges. Among patients with chronic WAD, there exists a subgroup which has an identifiable pattern of clinical characteristics indicating impaired stability of the cervical spine. This impairment pattern may be linked to the unphysilogic movements of the cervical spine which have been documented as occurring during the early phase of a rear-end collision. The between–group variance for the WAD groups, IONP groups and/or the asymptomatic groups overlapped to a different degree for each clinical characteristic investigated, suggesting that the variance in clinical characteristics in patients with chronic WAD is greater than earlier anticipated. It is therefore recommended, that patients with WAD be comprehensively evaluated to ensure that all clinical characteristics are investigated. In the future, the evaluation should include a detailed physical examination, the implementation of specially designed tests to detect subtle physical impairment and altered pain responses, and questionnaires to screen for diverse psychosocial factors. Key words: whiplash, cervical, instability, segmental, physical impairment, measurements
... The current rear impact dummy-neck designs (RID-neck and TRID-neck) have not been validated regarding head lag. Several studies indicate that head lag has significant influence on the head-neck kinematics in the rear-end collision situation (Severy et al. 1955;Clemens and Burow, 1972;Huelke et al, 1979;Geigl et al., 1995;McConnell et al., 1995). Figure 4 shows a schematic view of the neck in Figure 3 supplemented with anterior and posterior muscle substitutes in the form of straps between the head and the torso. ...
Conference Paper
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Neck injuries in car accidents are usually classified as AIS 1 but they often cause long term pain and disability. The number of these injuries is on the increase and the costs for the society and the insurance companies are significant. Rear-end impacts give the largest contribution to the number of neck injuries. Head-restraints offer little protection against neck injuries in rear-end collisions and there is no established method for performance testing. The injury symptoms are well documented but the actual injury, causing the symptoms, has not yet been established. Consequently the relationship between head-neck motion and injury risk is unknown. A research program to address these problems is ongoing at Chalmers University and one of the main activities is the development of new dummy components for improved rear-end impact testing. Several investigators have noted limitations of the commonest crash test dummy, the Hybrid III. It has a too stiff neck and torso response in rearward sagittal bending. As a first step, a new RID-neck (Rear Impact Dummy-neck) was designed and validated. This dummy neck has been used to investigate the head-neck motion in various standard car seats during rear-end impacts. TNO have now started producing a more durable and well defined version (TRID-neck). As more test data from volunteer tests have become available, further evaluation of the RID-neck has been undertaken and a need for a decreased resistance to retraction-protraction motion of the head-neck system has been revealed. It has also become evident that realistic stiffness and shape of the whole spine needed to attain . At the moment a new RID-neck with less resistance to retraction-protraction and a more realistic spinal shape is under development. In parallel, a mathematical model (MADYMO) of the new RID-neck is being developed. A first generation articulated thoracic and lumbar spine for rear-impact testing has been developed and with further refinement it is expected that a complete dummy spine from pelvis to head will result in a dummy with significantly improved biofidelity in the rear-end impact situation.
... Experimental studies (Severy et al. 1955;Clemens and Burow 1972) and computer models (McKenzie and Williams 1971;White and Panjabi 1978) have clearly defined the sequence of events following a rear-end collision (Barnsley et al. 1994): at the time of impact, the vehicle is accelerated forward, followed after 100 ms by a similar acceleration of the patient's trunk and shoulders induced by the car seat. The head with no force acting upon it remains static in space, resulting in forced extension of the neck as the shoulders travel anteriorly under the head. ...
... This observation is perhaps not surprising given that the cervical musculature represents the largest component of tissues in the human neck ( Figure 1). Since the Severy et al. (1955) study, numerous investigations have addressed this issue yet there remains no consensus in the literature on whether initially-relaxed muscles can (Reid et al., 1981;Pope et al, 1998;Brault et al., 2000) or cannot (Snyder et al., 1975;Ono et al., 1997;Panjabi et al., 1998;Yoganandan et al., 1999) affect whiplash injury biomechanics. The goal of this paper is to review the current literature to assess whether cervical muscles should be considered in the investigation of whiplash. ...
Article
Full-text available
There is a lack of consensus in the literature surrounding whether initially-relaxed cervical muscles can or cannot affect whiplash injury in a rear-end collision. For cervical muscles to play a role in whiplash injury biomechanics, both the timing and magnitude of the muscle response must be considered. This paper is a review of pertinent literature as well as past experiments in our laboratory to address whether initially-relaxed cervical muscles have the potential to alter the head and neck kinematics and kinetics resulting from a rear-end impact. Contrary to the common perception that cervical muscles activate too late and too slowly to affect whiplash injury, the literature indicates that the cervical muscles are active early in response to impact and are capable of generating forces sufficient to alter the head and neck kinematics. Assuming that induced head and neck kinematics and kinetics are related to whiplash injury, these findings indicate that initially-relaxed cervical muscles must be considered in the study of whiplash injury biomechanics.
... This observation is perhaps not surprising given that the cervical musculature represents the largest component of tissues in the human neck ( Figure 1). Since the Severy et al. (1955) study, numerous investigations have addressed this issue yet there remains no consensus in the literature on whether initially-relaxed muscles can (Reid et al., 1981;Pope et al, 1998;Brault et al., 2000) or cannot (Snyder et al., 1975;Ono et al., 1997;Panjabi et al., 1998;Yoganandan et al., 1999) affect whiplash injury biomechanics. The goal of this paper is to review the current literature to assess whether cervical muscles should be considered in the investigation of whiplash. ...
Article
Full-text available
There is a lack of consensus in the literature surrounding whether initially-relaxed cervical muscles can or cannot affect whiplash injury in a rear-end collision. For cervical muscles to play a role in whiplash injury biomechanics, both the timing and magnitude of the muscle response must be considered. This paper is a review of pertinent literature as well as past experiments in our laboratory to address whether initially-relaxed cer-vical muscles have the potential to alter the head and neck kinematics and kinetics resulting from a rear-end impact. Contrary to the common perception that cervical muscles activate too late and too slowly to affect whiplash injury, the literature indicates that the cervical muscles are active early in response to impact and are capable of generating forces sufficient to alter the head and neck kinematics. Assuming that induced head and neck kinemat-ics and kinetics are related to whiplash injury, these findings indicate that initially-relaxed cervical muscles must be considered in the study of whip-lash injury biomechanics.
Chapter
The impressionist/classicist composer Maurice Ravel (1875–1937) was—along with Claude Debussy (1862–1918)—one of the most famous musicians of his time. In the last five years of his life, however, Ravel never completed a new work: His last composition, the song cycle Don Quichotte à Dulcinée, was composed in 1932. He certainly had ideas, but he was no longer able to put them on paper. A rear-end collision may have been partly responsible: On the night of October 8–9, 1932, Ravel was a passenger in a Paris taxi that collided with another vehicle. Ravel suffered cuts to his face, lost a few teeth, and probably had a mild to severe concussion. Following this accident, Ravel had attention, concentration, and memory deficits in addition to his pre-existing word-finding problems (primary progressive aphasia) due to a frontotemporal dementia (Pick’s disease). At the time of the taxi accident, Ravel was 57 years old and at the peak of his international career.
Chapter
Diagnostics of the late whiplash syndrome has become a medicolegal problem. Up to now, functional neuroimaging was neglected in contrast to morphological imaging tools, the latter being inconspicuous in most cases, the first showing significant deficits in the posterior parietal occipital region, and decreases and increases in other brain regions, involved in pain processing or trying to compensate for the deactivation in adjacent brain areas.KeywordsFunctional neuroimagingMedicolegal problemFuture research
Article
Purpose: This study addressed the potential effect of higher seat stiffness with ABTS (All-Belt-to-Seat) compared to conventional seats in rear impacts. It analyzed field accidents and sled tests over a wide range in delta V and estimated the change in number of injured occupants if front-seats were replaced with stiffer ABTS. Methods: The rear-impact exposures and serious-to-fatal injury rates were determined for 15+ year old non-ejected drivers and right-front passengers in 1994+ model year vehicles using 1994-2015 NASS-CDS. More than 50 rear sled tests were analyzed using conventional and ABTS seats. An injury risk was calculated for selected ATD biomechanical responses. The results obtained with the ABTS and conventional seats were compared for matched tests based on head restraint position, ATD size and initial position and delta V. The change in risk was used to estimate the change in injury in the field by adjusting the injury rate by delta V. Results: On average, front seat occupants were 39 years old, weighed 78 kg and were 171 cm tall. About 29.3% of serious-to-fatally injured (MAIS 3 + F) front seat occupants were involved in delta Vs less than 24 km/h and about 28.4% in a delta V of 48 km/h or greater. The average biomechanical response and injury risk in sled tests were higher with an ABTS seat than with a conventional seat. The average maximum injury risk was assessed by delta V groups for conventional and ABTS seats. The relative risk of ABTS to conventional seats was 1.34 in less than 16 km/h, 1.69 in 16-24 km/h, 1.65 in 24-32 km/h, 1.33 in 32-40 km/h, 5.77 in 40-48 km/h and 48.24 in the 56-64 km/h delta V category. The estimated relative risk was 11.90 in 48-56 km/h and 34.11 in 64+ km/h. The number of serious-to-fatally injured occupants was estimated to increase by up to 6.88-times if stiffer ABTS seats replaced conventional seats. Conclusions: The field data indicate that the 50th percentile male Hybrid III size is representative of an average occupant involved in rear crashes. ABTS seats used in this study are stiffer than conventional seats and increase ATD responses and injury risks over a wide range of crash severities.
Article
Neck injuries caused by low-speed rear-end collisions are a worldwide problem. The reasonable design of car seat can effectively prevent or reduce the passenger neck injuries. In this paper, the finite element analysis (FEA) and whiplash test are combined to optimize the seat structure parameters to enhance the safety. The whiplash test results of the existing car seats according to C-NCAP (2015) were matched with FEA, and the optimization scheme was developed by computer simulation. For the improvement of seat safety, the optimizations are applied to determine backrest stiffness, backrest rotational stiffness, headrest rotational stiffness and headrest stiffness. The retest results of optimized seat show that its safety performance is greatly improved. Furthermore, it shows that the combination of finite element analysis and whiplash test can optimize seat structure to improve safety performance.
Chapter
Daß der Verkehr Opfer fordert, ist schlechthin unvermeidlich. Alle 15 sec ereignet sich irgendwo in der Welt ein Straßenverkehrsunfall. Die Gesamtzahl dieser Unfälle fordert Jahr um Jahr rd. 180000 Tote und weit mehr als 4 Mill. Verletzte.
Chapter
In high-speed rear crashes, the seatback needs to be sufficiently strong to manage energy transfer while maintaining the occupant on the seat. Integration of occupant load over seatback displacement or moment over angle change gives the energy transfer capability of a seat. Seatback rotation correlates with occupant kinetic energy transfer, which is determined by the rear crash delta V. The energy transfer is about 2000 J in a 32 kmph rear delta V crash. In low-to-high speed crashes, the head restraint and upper seatback need to reduce relative motion between the head and neck, thus controlling kinematics to prevent “whiplash”. A head restraint height above the head center of gravity and close to the back-of-head provides favorable neck responses. However, the trajectory of the head restraint is forward and downward in a rear crash. This promotes neck extension. A self-aligning head restraint gives a more horizontal direction of head restraint motion and a more upright head and neck orientation. The head restraint moves forward and upward by occupant load on the seatback. This closes the gap behind the head.
Conference Paper
The special experimental setup for a study of the head-neck system dynamics during impulse acceleration, which arises in the case of the ground and air vehicle crushes, was elaborated. Based on experimental results the authors proposed the simple mechanical model of the “head-neck” system with eight degrees of freedom, which are the rotation angles of the head and seven cervical vertebrae. For the search of the unknown model parameters the minimization of the discordance between experimental and theoretical results was used. In doing so the Nelder-Mead method was applied.
Chapter
Cases involving orthopaedic problems are many and varied. Whilst many will lead to argument, in nearly all, although there may be some divergence of opinion, agreement is usually probable. In some, however there is often more difficulty, probably due to lack of knowledge of the underlying pathology, which leads to diametrically opposed views. It may well be that in time, with further research, the causation will become clearer and as a result, agreement outside the court, rather than disagreement inside, will become the rule. The first two subjects I have chosen have been extensively investigated but the site of the pain still remains an enigma. All four conditions discussed are characterised by the subjective symptom of pain which is almost impossible to evaluate. Of necessity much of the opinion expressed is the result largely of research to be found in the literature, but coloured by the views of the author. The problems reviewed are: Repetitive stress injury Anterior knee pain Whiplash injuries of the neck Osteoarthritis and trauma
Conference Paper
The objective of this paper is to examine automobile bumper systems in aligned low-speed impacts and provide data which correlate compression of bumper systems with the vehicle impact severity. A significant number of automobile collisions involve bumper-to-bumper contact at speeds which produce little or no permanent vehicle damage. Contemporary bumper systems predominantly consist of a fascia and impact beam, which span the vehicle width, and some form of impact absorber. A common impact absorber is the shock-absorber-type isolator. Foam cores, deformable steel struts, rubber shear blocks and leaf springs also exist. Data from 58 vehicle-to-barrier and 136 vehicle-to-vehicle aligned impacts are presented. Impact duration, speed change, isolator compression, and coefficient of restitution results are presented and discussed. Static and dynamic compression tests on several isolators have been carried out. A number of isolators were sectioned to develop structure-property relationships. Speed change as a descriptor of impact severity in these collisions is proposed. Its relevance to injury potential is discussed and the data for estimating speed change based on the post-collision condition of the isolators are presented. It is concluded that bumper systems on passenger cars available in North America, though built to meet specific government standards, have impact characteristics that vary among vehicles. It is also shown that certain vehicles can sustain significant front or rear impacts without sustaining damage.
Article
Volunteer subject studies in low speed rear impacts have shown that significant lumbar spine injuries are unlikely in such collisions. Anthropomorphic test devices (ATD) used in low to medium speed rear impact simulations have similarly revealed an unlikely mechanism to cause lumbar spine injuries. However, low back complaints after rear impacts are common in clinical practice. We attempt here to determine the incidence of lumbar spine injuries from actual field data which may provide an insight into the apparent paradox between experimental data and clinical practice. We examined the incidence of all spine injuries in the NASSCDS (National Automotive Sampling System - Crashworthiness Data System) database from 1993 to 2009. We limited the data to only look at rear-end crashes involving two vehicles. We analyzed crash severity (delta-V), occupant injuries by AIS (Abbreviated Injury Scale) code, seat performance and restraint use in over 7,500 (with a weighted value of 2.5 million) passenger vehicle accidents. Of the 7,500 accidents, approximately 500 (weighted value of 225,000) passengers reported some type of lumbar spine injury. These injuries included strains or sprains to the spine (AIS 1 injuries), fractures and herniations (AIS 2). In particular, we stratify the incidence of lumbar spine injuries to low, medium and high speed rear impact crash severities, and correlate seatback deformation and restraint use to the lumbar injuries. The analysis indicated the small number of reported lumbar injuries associated with rear end collisions were mostly musculoskeletal strains/sprains and a few fractures and herniations. Furthermore, there was no correlation of higher incidence of lumbar injury with increasing delta-V. The results of the analysis agreed with those from low-speed human subject tests and low- to moderate-speed ATD rear end simulations that concluded the lumbar spine is well protected by the seat back for properly seat-belted passengers.
Article
Human subjects and the recently developed RID2 rear impact crash test dummy were exposed to a series of full scale, vehicle-to-vehicle crash tests to evaluate the biofidelity of the RID2 anthropometric test dummy on the basis of calculated neck injury criterion (NIC) values. Volunteer subjects, including a 50th percentile male, a 95th percentile male, and a 50th percentile female, were placed in the driver's seat of a vehicle and subjected to a series of three low speed rear impact crashes each. Both subjects and dummy were fully instrumented and acceleration-time histories were recorded. From this data, velocities of the heads and torsos were integrated and used to calculate the NIC values for both crash test subjects and the RID2. The RID2 dummy is designed to represent a 50th male. The overall performance and biofidelity of the RID2 compared most favorably to the human subject who was, himself, a 50th percentile male. Although the number of tests was small, the biofidelity of the RID2, in the context of the smaller female and larger male, was limited. The overall performance and biofidelity of the RID2 was reasonable when compared to the 50th percentile male volunteer. It is possible that under real world crash conditions, in which the occupant of the target vehicle is exposed to an unexpected impact, that their NIC values might be more comparable to those of the RID2, suggesting that its biofidelity could have been underestimated as a result of the alerted status of the crash test volunteers.
Conference Paper
Full-text available
A coordinated test and analysis program was conducted to determine whether a previously proposed, linear, analytical model could be adapted to simulate low speed impacts for vehicles with various combinations of energy absorbing bumpers (EAB). The types of bumper systems impacting one another in our program included, in various combinations; foam, piston and honeycomb systems. Impact speeds varied between 4.2 and 14.4 km/h (2.6 and 9.0 mph) and a total of 16 tests in 6 different combinations were conducted. The results of this study reveal that vehicle accelerations vary approximately linearly with impact velocity for a wide variety of bumper systems and that a linear mass-spring-damping model may be used to efficiently model each vehicle/bumper-system for low speed impacts.
Article
PurposeThis study collected and analyzed available testing of motor vehicle seat strength in rearward loading by a body block simulating the torso of an occupant. The data was grouped by single recliner, dual recliner and ABTS (all belts to seat) seats.Methods The strength of seats to rearward loading has been evaluated with body block testing from 1964–2008. The database of available tests includes 217 single recliner, 65 dual recliner and 18 ABTS seats. The trends in seat strength were determined by linear regression and differences between seat types were evaluated by the Student t-test. The average peak moment and force supported by the seat was determined by decade of vehicle model year (MY).ResultsSingle recliner seats were used in motor vehicles in the 1960s–70s. The average strength was 918 ± 224 Nm (n = 26) in 1960s and 1,069 ± 293 Nm (n = 65) in 1980s. There has been a gradual increase in strength over time. Dual recliner seats started to phase-into vehicles in the late 1980s. By 2000s, the average strength of single recliner seats increased to 1,501 ± 335 Nm (n = 14) and dual recliner seats to 2,302 ± 699 Nm (n = 26). Dual recliner seats are significantly stronger than single recliner seats for each decade of comparison (p<0.001). The average strength of ABTS seats was 4,395 ± 1,185 inlb for 1989–2004 MY seats (n = 18). ABTS seats are significantly stronger than single or dual recliner seats (p<0.001). The trend in ABTS strength is decreasing with time and converging toward that of dual recliner seats.Conclusions Body block testing is an quantitative means of evaluating the strength of seats for occupant loading in rear impacts. There has been an increase in conventional seat strength over the past 50 years. By the 2000s, most seats are 1,700–3,400 Nm moment strength. However, the safety of a seat is more complex than its strength and depends on many other factors.
Article
OBJECTIVE: To determine whether vehicle characteristics, measured using crash scene photography, are associated with anatomic patterns of injury and severity of injury sustained in motor vehicle crashes (MVCs) without air bag deployment. METHODS: A prospective observational study was conducted over 22 months, using 12 fire departments serving two hospitals. Two vehicle photographs (exterior and interior) were taken at each MVC. Vehicular variables were assigned by grading the photographs with a standardized scoring system, and outcome information on each patient was collected by chart review. RESULTS: Five hundred fifty-nine patients were entered into the study. Frontal crashes and increasing passenger space intrusion (PSI) were associated with head, facial, and lower-extremity injuries, while rear crashes were associated with spinal injuries. Restraint use had a protective effect in head, facial, and upper and lower extremity injuries, yet was associated with higher odds of spinal injury. Lack of restraint use, increasing PSI, and steering wheel deformity were associated with an increased hospital length of stay and hospital charges, yet only steering wheel deformity was associated with increasing injury severity when adjusting for other crash variables. CONCLUSIONS: Out-of-hospital variables, as obtained from crash vehicle photography, are associated with injury site, injury severity, hospital length of stay, and hospital charges in patients involved in MVCs without air bag deployment.
Article
Full-text available
Whiplash Injury and Head Injury Criterion during Deceleration Cervical spine injuries have become an urgent problem in modern society. Regardless of social status or background, the high rate of neck injuries is a serious healthcare issue worldwide. The cervical spine injury is mainly caused by external impact and is termed as whiplash injury. In addition, the head also performs a whiplash movement during rapid deceleration. The aim of this study is to monitor and describe physically the natural response of the head to rapid deceleration. The methodology of using an impact simulator was adopted for simulating a load which is applied to passengers wearing a seat belt in a head-on collision of a car at the speed of 30 km/h. Furthermore, a series of comparative tests of two versions (impact with and without a blindfold) were conducted to determine the influence of vision and consciousness on risk and the seriousness of trauma and the results were compared with measurements on a dummy.
Article
Crowe (1928) first used the word whiplash to describe cervical strains which had been caused by extension type injuries due to sudden acceleration. They were found to heal very slowly and hence the word whiplash soon became synonymous with irreparable damage, continuous pain and residual disability.
Article
Full-text available
Rear-impact collisions at low speed are the most frequent type of accident among all motor vehicle crashes. These collisions are also the subject of substantial investigation in the scientific literature neck injuries associated with them are commonly known as whiplash. The difficulty to identify an injury of this kind with an objective basis leads to litigation and high social costs. Costs in Europe have been estimated at between 5-10 billion euros each year, and this number increases annually. The aim of this paper is to establish clearly and rigorously the kinematic mechanism that the neck undergoes during a low-speed rear impact. The main criteria for injury accepted by the scientific community and used in the automotive industry will be analyzed. Finally, an analysis of the different aspects that could modify the nature of the collision will be conducted.
Article
A two-dimensional discrete-parameter ‘Whiplash’ model of the head, neck and torso, developed by McKenzie and Williams (1971) has been used to evaluate the effect of collision severity on the kinematic and kinetic behaviour of the cervical spine. The model yields acceptable results at low impact severities but the results at higher severities indicate the need for some revision of the neck stiffness and damping characteristics.
Article
This paper presents a brief discussion of some of the findings from forty-eight full-scale automobile collision experiments conducted at UCLA during the past ten years. These experiments have provided critically needed data on physical factors relating to vehicular collision dynamics and attending motorist injuries. Use of both human subjects and anthropometric dummies facilitate procurement of critically needed data on the relation of design to injury causation. Specific data derived from these experiments include deceleration patterns for different locations on the motorist and car structure, the relation of impact speed to car deformation and repair costs, the performance of motorist restraining devices and the interaction of human and dummy motorists with their cars' interior and external environment during collisions.
Article
A study was conducted to find out whether in a rear-impact motor vehicle accident, velocity changes in the impact vehicle of between 10 and 15 km/h can cause so-called “whiplash injuries”. An assessment of the actual injury mechanism of such whiplash injuries and comparison of vehicle rear-end collisions with amusement park bumper car collisions was also carried out. The study was based on experimental biochemical, kinematic, and clinical analysis with volunteers. In Europe between DM 10 and 20 billion each year is paid out by insurance companies alone for whiplash injuries, although various studies show that the biodynamic stresses arising in the case of slight to moderate vehicle damage may not be high enough to cause such injuries. Most of these experimental studies with cadavers, dummies, and some with volunteers were performed with velocity changes below 10 km/h. About 65% of the insurance claims, however, take place in cases with velocity changes of up to 15 km/h. Fourteen male volunteers (aged 28–47 years; average 33.2 years) and five female volunteers (aged 26–37 years; average 32.8 years) participated in 17 vehicle rear-end collisions and 3 bumper car collisions. All cars were fitted with normal European bumper systems. Before, 1 day after and 4–5 weeks after each vehicle crash test and in two of the three bumper car crash tests a clinical examination, a computerized motion analysis, and an MRI examination with Gd-DTPA of the cervical spine of the test persons were performed. During each crash test, in which the test persons were completely screened-off visually and acoustically, the muscle tension of various neck muscles was recorded by surface eletromyography (EMG). The kinematic responses of the test persons and the forces occurring were measured by accelerometers. The kinematic analyses were performed with movement markers and a screening frequency of 700 Hz. To record the acceleration effects of the target vehicle and the bullet vehicle, vehicle accident data recorders were installed in both. The contact phase of the vehicle structures and the kinematics of the test persons were also recorded using high-speed cameras. The results showed that the range of velocity change (vehicle collisions) was 8.7–14.2 km/h (average 11.4 km/h) and the range of mean acceleration of the target vehicle was 2.1–3.6 g (average 2.7 g). The range of velocity change (bumper car collisions) was 8.3–10.6 km/h (average 9.9 km/h) and the range of mean acceleration of the target bumper car was 1.8–2.6 g (average 2.2 g). No injury signs were found at the physical examinations, computerized motion analyses, or at the MRI examinations. Only one of the male volunteers suffered a reduction of rotation of the cervical spine to the left of 10° for 10 weeks. The kinematic analysis very clearly showed that the whiplash mechanism consists of translation/extension (high energy) of the cervical spine with consecutive flexion (low energy) of the cervical spine: hyperextension of the cervical spine during the vehicle crashes was not observed. All the tests showed that the EMG signal of the neck muscles starts before the head movement takes place. The stresses recorded in the vehicle collisions were in the same range as those recorded in the bumper car crashes. From the extent of the damage to the vehicles after a collision it is possible to determine the level of the velocity change. The study concluded that, the “limit of harmlessness” for stresses arising from rear-end impacts with regard to the velocity changes lies between 10 and 15 km/h. For everyday practice, photographs of the damage to cars involved in a rear-end impact are essential to determine this velocity change. The stress occurring in vehicle rear-end collisions can be compared to the stress in bumper car collisions.
Article
This paper deals with the development of a new (patented) headrest able to decrease whiplash injuries during a (rear) crash. The study has started with the definition of crash pulses that typically occur during a rear crash. In order to develop the new headrest system, a small sled (carrying only the headrest) was constructed and used. By means of the small sled, the accelerations that were registered at the top of the seat back during rear crashes were applied at the headrest under development. The braking action on the sled is developed by a pneumatic cylinder (100 mm diameter) with compensation chamber. A full virtual model of the small sled has been developed for design and tuning purposes. The actual crash pulses can be reproduced rather easily on the small sled. This has allowed the developing of a new headrest.
Article
Although head restraints became mandatory in several countries during the 1960s and 1970s, the number of neck injuries is still rising, which indicates that current head restraints are not giving sufficient protection. Despite numerous epidemiological and parameter studies, there are no methods to estimate in advance the potential neck injury risk reduction as a result of a better positioned head restraint. The purpose of this study is to assess the influence of the head restraints on the long-term AIS 1 neck injury risk for real-life crash conditions. Madymo simulations of rear-end crashes were performed. The BioRID II seated in three car models was exposed to 20 recorded crash pulses with the potential to cause neck injuries. For each crash pulse, 132 head restraint positions were analysed in terms of NICmax value and long-term AIS 1 neck injury risk. It was found that the optimal head restraint position for almost all crashes was that with zero backset and the top of the head restraint at the same level as the top of the head. In general, the NICmax and the injury risk were primarily influenced by the backset and only to a small extent by the head-to-head-restraint height; the neck injury risk was reduced by 0.1 for every 2.5 cm decrease of the backset. The results of this study show that it is possible during the development phase to estimate the potential protection for redesigned or active head restraints.
Article
This paper proposes a 2D dynamical model for evaluating parameters affecting whiplash. In fact a four segment dynamical model is developed in the sagittal plane for the analysis. The model response is validated using the existing experimental data and is shown to simulate the "S-Shape" and "initial upward ramping" kinematics of the cervical spine and the resulting dynamics observed in human and cadaver experiments. The model is then used to evaluate the effects of parameters such as velocity change between rear vehicle and the target vehicle ( ), head/head restraint separation (backset) and the awareness of occupant on the whiplash injuries. It is shown that the proposed model can simulate whiplash phenomena very well; therefore it is a suitable alternative for other existing models. v Δ
Article
It is common knowledge that whiplash-associated disorders are soft-tissue-related. Rear-end crashes account for a majority of trauma. Specific objective diagnoses have eluded clinicians because of the soft tissue nature of the disorder. Sophisticated tools such as magnetic resonance images are inconclusive. The disorder is recognized in the Western world with significant societal impact and staggering economic costs. An increased level of awareness towards safety from the vehicle user coupled with the above factors and an interest by the automotive community to improve vehicle component designs have accelerated research in the area of whiplash-associated disorders from various perspectives. One of the main emphases has been to clearly delineate the mechanisms of the disorder. Consequently, the objective of this article is to describe the postulated mechanisms of injury and biomechanical studies attempting to prove the hypotheses. Results indicate that structures such as the facet joint are involved in chronic pain, and the kinematics of this joint are such that it undergoes characteristic motions during the early stages of rear impact acceleration. The presence of the transient nonphysiologic reverse curve, i.e., upper head-neck flexion is attributed to headaches, and the concomitant existence of lower cervical extension (particularly the inferior facet joints) during the early stages of rear impact acceleration are attributed to the mechanism of neck pain in whiplash. These studies have provided a fundamental basis for understanding the mechanism of the two most common complaints in whiplash, headache and neck pain.
Article
Objectives: To analyze the relationship between somatic, radiological and neuropsychological findings and feautres of the accident mechanisms assessed early after trauma and long-term outcome after whiplash injury. Findings: Patients who remained symptomatic during two years of trauma were older, showed more rotated or inclined head position at the time of impact, had higher prevalence of pre-traumatic headache, scored higher on ratings of initial neck pain and headache, displayed a greater variety of symptoms, had a higher incidence of symptoms of radicular deficit and higher average scores on a multiple symptom analysis, and showed more osteoarthrosis on x-ray. These same patients, in addition, on testing showed impaired well-being and deficient attentional processing, and had more concern with regard to long-term suffering and disability. Conclusions: These findings essentially support the view that a poor outcome in the long-term after whiplash injury is primarily related to its initial severity.
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