Human Occupant Kinematic Response to Low Speed Rear-End Impacts

Szabo, Thomas J.; Welcher, Judson; Anderson, R. D.; Rice, Michelle M.; Ward, Jennifer A.; Paulo, Lori R.; Carpenter, Nicholas

doi:10.4271/940532

Cited by 85 publications

(39 citation statements)

References 16 publications

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“…In the setting of controlled collision events, and in combination with other objective measurements, surface EMG studies have helped to model the mechanism of acute muscle injury in low-velocity collisions. Studies suggest a central role may be played by the cervical muscles in injury causation during low-velocity collisions [16,17].…”

Section: Discussionmentioning

confidence: 99%

Cervical muscle response to whiplash-type right anterolateral impacts

2004

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Frontal impacts are a common cause of whiplash injury. Yet, volunteer studies of the cervical muscular response and head-neck kinematics to frontal impacts are uncommon, and specifically, the effect of an offset (anterolateral) frontal impact on the resultant muscle responses is unknown. The purpose of this study was to determine the response of the cervical muscles to increasing low-velocity frontal impacts offset by 45°to the right, and to compare the quantitative effects of expected and unexpected impact. Ten healthy volunteers were subjected to frontal impacts, offset by 45°to the subject's right, of 5.1-, 8.7-, 12-, and 13.7-m/s 2 peak acceleration at two levels of expectation: expected and unexpected. Bilateral electromyograms of the sternocleidomastoids, trapezii, and splenii capitis were recorded. Triaxial accelerometers recorded the acceleration of the chair, torso at the shoulder level, and head of the participant. At a peak acceleration of 13.7 m/s 2 , with an unexpected impact, the contralateral trapezius (i.e., left trapezius in a right anterolateral impact) generated 83% of its maximal voluntary contraction electromyogram, whereas all other muscles generated 50% or less of this variable. Although it generated less EMG, the splenius capitis muscle also tended to show an asymmetric EMG response, with the left (contralateral) splenius capitis generating a higher percentage (46%) of its maximal voluntary contraction electromyogram than the ipsilateral (right) splenius capitis. In comparison, the sternocleidomastoid muscles behaved symmetrically and generated 25% or less of this variable under all impact conditions. Similarly, the times to onset and times to peak electromyogram for the contralateral (left) splenius capitis and (left) trapezius progressively decreased with increasing levels of acceleration (p<0.01). Subjects exhibited lower levels of their maximal voluntary contraction electromyogram when the impact was expected (p<0.01). The kinetic variables and the electromyographic variables regressed significantly on the acceleration (p<0.01). In response to right anterolateral impacts, muscle responses were greater with higher levels of acceleration, and more specifically, when a frontal impact is offset to the subject's right, it results in not only increased EMG generation in the contralateral trapezius, but the splenius capitis contralateral to the direction of impact also bears part of the force of the neck pertubation. Expecting or being aware of imminent impact plays a role in reducing muscle responses in low-velocity anterolateral impacts.

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Section: Discussionmentioning

confidence: 99%

Cervical muscle response to whiplash-type right anterolateral impacts

2004

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“…[7][8][9][10][11] These conclusions, however, are not necessarily those of the original researchers conducting the crash tests and do not take into account the practical limitations of human volunteer crash tests, as such testing does not consist of sufficient variation in either crash circumstances or individual occupant injury risk to enable researchers to establish accurate risk thresholds. It has been hypothesized that the number of meaningful permutations of crash circumstance, vehicle factors, and occupant susceptibility variables numbers in the tens of thousands and thus cannot be representatively sampled by the small population of subjects willing to subject themselves to crash testing or the vehicles available for such tests.…”

Section: Discussionmentioning

confidence: 99%

“…6 Many authors have endeavored to define a minimum crash speed change (or delta V) threshold for neck injury in rear impact collision, relying primarily on the results of human volunteer crash tests as a basis for the hypothesized threshold. [7][8][9][10][11] The concept of an absolute injury threshold for whiplash has been dismissed as methodologically unsound, 12 as the variation in experimental crash tests and among the volunteers for such tests is not representative of the crash circumstances and injury risk seen in the real world. Human volunteer crash tests, although lacking in generalizability for highly individual characteristics such as injury threshold, can generate useful information on occupant kinematics and aid in the design of vehicle interior and seat/head restraint safety innovations.…”

Section: Introductionmentioning

confidence: 99%

Human subject rear passenger symptom response to frontal car-to-car low-speed crash tests

Croft

Eldridge²

2011

Journal of Chiropractic Medicine

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Objective: The purpose of this study was to determine whether healthy adult volunteers report symptoms following exposure to low-speed frontal crashes at low velocities. Methods: Nineteen medically screened, healthy, informed, and willing volunteers (17 men, 2 women; mean age, 37 years) were exposed to low-speed frontal crashes. All volunteers were seated in the rear seat position of the bullet vehicle. Closing velocities ranged from 4.1 to 8.3 mph (mean, 6.7 mph). For the bullet vehicle, the delta V ranged from 1.4 to 3.9 mph with a mean of 2.8 mph.Results: Eighty-eight percent of volunteers attributed symptoms of discomfort to their crash exposure. All reported symptoms were transient, and none required medical treatment. The mean duration was 1 day. Conclusions: Even at relatively low speeds, there is no lower threshold below which it can be reasonably assumed that healthy and prepared volunteer rear seat passengers will not sustain some level of minor injury in a frontal collision. Although the reported mean delta V for injured persons in real-world frontal crashes has been reported to be as high as 8.1 mph, this does not offer any insight into the minimum threshold for such injuries among all at-risk vehicle occupants.

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“…The disadvantage of almost all of these studies is the insufficient stress (low A V) and/or the lack or insufficiency of clinical and diagnostic imaging studies of the test subjects. Only Szabo and coworkers [17] conducted six two-car rear-end collisions with volunteers between the ages of 27 and 88 who underwent MRI and CT examinations before and after the tests. A V in these tests was approximately 8 km/h.…”

Section: Discussionmentioning

confidence: 99%

European Spine Society —The AcroMed prize for spinal research 1997

Castro

Schilgen

Meyer³

et al. 1997

Eur Spine J

160

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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 socalled "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 perforemd 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 367 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 wa...

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Human Occupant Kinematic Response to Low Speed Rear-End Impacts

Cited by 85 publications

References 16 publications

Cervical muscle response to whiplash-type right anterolateral impacts

Cervical muscle response to whiplash-type right anterolateral impacts

Human subject rear passenger symptom response to frontal car-to-car low-speed crash tests

European Spine Society —The AcroMed prize for spinal research 1997

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