Human Subject Kinematics and Electromyographic Activity During Low Speed Rear Impacts

Szabo, Thomas J.; Welcher, Judson

doi:10.4271/962432

Cited by 107 publications

(46 citation statements)

References 13 publications

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“…In our study, we did not find a difference in the expected impacts and the unexpected ones (i.e., excluding the vestibular and visual systems) and believe the trigger in this methodology of impact application was of a somato-sensory feature, when the backrest hit the back. Szabo and Welcher reported latency times of neck flexors and extensors as low as 20-30 ms from head acceleration, and inferred that the stimulus occurred before the onset of head acceleration, triggered by the lumbar spine acceleration that occurred 90-120 ms before the onset of muscle activity [23]. This is in excellent agreement with our results of 20 ms (13 ms in the expected case) from head acceleration and 73 ms from sled acceleration.…”

Section: Discussionsupporting

confidence: 91%

“…Later, Szabo and Welcher presented a study that supported the idea of a central response, and concluded that muscle activities in different parts of the body occurred at approximately the same time and were not dependent on acceleration or movement of that area of the body [23]. It was suggested that the trigger mechanism for the centrally generated response could come from three sources: the somato-sensory system, the vestibular system, and the vision [5].…”

Section: Discussionmentioning

confidence: 99%

“…The role of the muscles has not until recently been studied or been incorporated in models of the mechanics of injury [23]. The basic assumption behind this is that muscles do not play a significant role during the injurycausing phase, as muscle reaction times necessary to develop sufficient muscle forces to brace the spine (100-200 ms) are much longer than the rise times of the loads causing injury [24].…”

mentioning

confidence: 99%

“…The basic assumption behind this is that muscles do not play a significant role during the injurycausing phase, as muscle reaction times necessary to develop sufficient muscle forces to brace the spine (100-200 ms) are much longer than the rise times of the loads causing injury [24]. Szabo and Welcher studied the muscle activity of cervical flexors and extensors and the lumbar paraspinal musculature, using surface electromyograph (EMG) electrodes, and found that the muscle reaction time was 100-125 ms after the moment of bumper contact [23]. In our previous studies we found that the reaction time of the lumbar muscles to sudden load was about 100 ms, and when the load was unexpected the response was significantly delayed.…”

mentioning

confidence: 99%

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Cervical electromyographic activity during low-speed rear impact

Magnusson

Pope

Hasselquist

et al. 1999

European Spine Journal

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IntroductionRear-end collisions typically occur in dense traffic at very low speeds. The vehicle is subjected to a forward acceleration during which the occupants are pushed forward by the seatbacks. The head lags behind forcing the neck into extension. This head motion continues until the neck hits the headrest or reaches its maximum range of motion, or is counteracted by the muscles. The head then reacts by moving forward into a flexed neck posture. This is the typically described injurious extension-flexion motion of the neck called "whiplash motion" [12]. Hypertranslation of the head was suggested by Penning as being the primary mechanism of whiplash injury [16]. The translatory motion takes place in the upper cervical spine followed by an angular extension in the lower part, forming as S-shape of the cervical spine. This means that the upper cervical spine is undergoing a flexion motion while the lower cervical spine is undergoing an extension motion. When the upper cervical spine reaches its limit for maximum flexion, the lower cervical spine reaches its limit for full extension. The cervical spine then goes into full extension and stops before the motion is reversed [22].The hyperextension of the cervical spine results in compressive forces on the posterior structures, such as the Abstract Whiplash motion of the neck is characterized by having an extension-flexion motion of the neck. It has been previously assumed that muscles do not play a role in the injury. Eight healthy males were seated in a car seat mounted on a sled. The sled was accelerated by a spring mechanism. Muscle electromyographic (EMG) activity was measured by wire electrodes in semispinalis capitis, splenius capitis, and levator scapulae. Surface EMG activity was measured over trapezius and sternocleidomastoideus. Wavelet analysis was used to establish the onset of muscle activity with respect to sled movement. Shorter reaction times were found to be as low as 13.2 ms from head acceleration and 65.6 ms from sled acceleration. Thus the muscles could influence the injury pattern. It is of interest that clinical symptoms are often attributed to muscle tendon injuries.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Cervical electromyographic activity during low-speed rear impact

Magnusson

Pope

Hasselquist

et al. 1999

European Spine Journal

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“…AV values of up to 15 km/h were measured. In a review of the literature (a total of 242 experimental rear-end collisions with test persons), Szabo and Welcher [18] found a value similar to the one described by Meyer at el. [8,9], namely 9 km/h.…”

Section: Introductionmentioning

confidence: 56%

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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Do Low-Speed Vehicle Collisions Cause Intervertebral Disc Degeneration or Herniation?

Wood¹,

Greenston²,

Bain

et al. 2018

AMA Guides® Newsletter

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Complaints of spinal pain are common after motor vehicle collisions (MVCs), and evaluators may be asked whether the collision caused permanent injury to the spine, including aggravating intervertebral disc degeneration (IDD) and/or causing a disc herniation. To determine causality, evaluators can use the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) to understand if a low-speed collision caused IDD. Injury causation analysis (ICA) is the scientific method used to analyze the mechanism and magnitude of injury for people who experience an MVC. ICA involves comparing the mechanical forces involved in the incident with the body's injury tolerance. Low back pain (LBP) is a common complaint following MVCs, but the literature regarding automobile collision testing has been compared to the body of evidence regarding real-world collision data and shows that, for low-speed impacts, any injuries are minor and self-limiting. Further, disability due to LBP was predicted by an abnormal baseline psychological test profile or a previously disputed compensation claim. The motions, forces, and accelerations generated in low-speed collisions are less than those encountered in activities of everyday living. ICA suggests that disc degeneration and disc herniations are pre-existing and are not caused by low-speed MVCs. Although the pain caused by a muscle sprain associated with a low-speed collision may prompt imaging studies that show disc pathology, these are coincidental and are not causally related.

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Human Subject Kinematics and Electromyographic Activity During Low Speed Rear Impacts

Cited by 107 publications

References 13 publications

Cervical electromyographic activity during low-speed rear impact

Cervical electromyographic activity during low-speed rear impact

European Spine Society —The AcroMed prize for spinal research 1997

Do Low-Speed Vehicle Collisions Cause Intervertebral Disc Degeneration or Herniation?

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