Effect of Head-Neck Position on Cervical Facet Stretch of Post Mortem Human Subjects during Low Speed Rear End Impacts

Sundararajan, S.; Prasad, Priya; Tashman, Scott; Begeman, Paul C.; Yang, King H.; King, Albert I.

doi:10.4271/2004-22-0015

Cited by 32 publications

(42 citation statements)

References 9 publications

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“…Comparison of CL strains measured in the model and in a full cadaver sled test 53. predicted by the model agreed well with the cadaver study at the C4-C5 and C5-C6 spinal levels, but the model under predicted CL strain at the other spinal levels, with the difference attributed to the musculature It should be noted that both the cadaver study and the model showed the highest CL…”

supporting

confidence: 57%

“…Sundararajan et al 53 exposed four female cadavers to 12 rear impacts (10.7g-11.6g severity) and calculated CL distraction using cineradiography to capture the motion of implanted spheres. The distractions measured by this group were converted to strain by dividing by the neutral ligament lengths used in this work and then compared to CL strain measured in the model during a 12g rear impact ( Table 3).…”

Section: Discussionmentioning

confidence: 99%

“…59 Low-speed rear impact studies using whole PMHS and cadaveric cervical spines reported peak CL strains from 29 to 40%, which is within the range of reported sub-catastrophic failure. 9,36,43,53 Post-impact tensile testing of the CLs exposed to rear impact showed a decrease in ligament stiffness compared to the untested control group, indicating the possibility that some damage had occurred in the ligaments during the impact tests. 20 The finite element cervical spine model used in this study was previously validated at the segment level, whole spine level in tension, and in frontal impact for head kinematics and local tissue response 41 (Appendix C-Electronic Supplementary Material).…”

Section: Introductionmentioning

confidence: 92%

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Cervical Spine Model to Predict Capsular Ligament Response in Rear Impact

2011

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Predicting neck kinematics and tissue level response is essential to evaluate the potential for occupant injury in rear impact. A detailed 50th percentile male finite element model, previously validated for frontal impact, was validated for rear impact scenarios with material properties based on actual tissue properties from the literature. The model was validated for kinematic response using 4 g volunteer and 7 g cadaver rear impacts, and at the tissue level with 8 g isolated full spine rear impact data. The model was then used to predict capsular ligament (CL) strain for increasing rear impact severity, since CL strain has been implicated as a source of prolonged pain resulting from whiplash injury. The model predicted the onset of CL injury for a 14 g rear impact, in agreement with motor vehicle crash epidemiology. More extensive and severe injuries were predicted with increasing impact severity. The importance of muscle activation was demonstrated for a 7 g rear impact where the CL strain was reduced from 28 to 13% with active muscles. These aspects have not previously been demonstrated experimentally, since injurious load levels cannot be applied to live human subjects. This study bridges the gap between low intensity volunteer impacts and high intensity cadaver impacts, and predicts tissue level response to assess the potential for occupant injury.

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supporting

confidence: 57%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 92%

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Cervical Spine Model to Predict Capsular Ligament Response in Rear Impact

2011

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“…Accordingly, the C6 vertebra underwent 2.5 mm of retraction under displacement control in the posterior direction to simulate the magnitude of that joint's motion during the whiplash kinematic. 28,29 To evaluate whether the capsular ligament's mechanical response during activities of daily living is altered following whiplash-like retraction, cyclic tensile loading in the axial direction was applied before and after retraction to simulate the primary mode of loading for the ligament during normal sagittal bending of the cervical spine. 30,37 A customized testing interface was designed for an Instron 5385 (Instron; Norwood, MA) to enable both tensile and retraction loading of each specimen.…”

Section: General Specimen Loading Protocolmentioning

confidence: 99%

“…4,13 This combination of forces and moments primarily induces a retraction of each vertebra in the posterior direction relative to its adjacent inferior vertebra in the lower cervical spine prior to head-headrest contact. 4,28,29 By tracking bony motions, studies have estimated that facet capsular ligament strains do, for some scenarios, exceed those strains measured during the cervical spine's normal range of motion. 20,36 These strain measurements suggest that the facet capsular ligament may be at risk for excessive motion during vertebral retraction, but strain does not provide direct evidence of tissue damage that would indicate if and under what conditions facet capsule injury occurs during whiplashlike vertebral motions.…”

Section: Introductionmentioning

confidence: 99%

Detection of Altered Collagen Fiber Alignment in the Cervical Facet Capsule After Whiplash-Like Joint Retraction

Quinn

Winkelstein

2011

Ann Biomed Eng

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The cervical facet joint has been identified as the source of pain in patients with whiplash-associated disorders, but most clinical studies report no radiographic evidence of tissue injury in these disorders. The goal of this study was to utilize quantitative polarized light imaging to assess the potential for altered collagen fiber alignment in human cadaveric cervical facet capsule specimens (n = 8) during and after a joint retraction simulating whiplash exposure. Although no evidence of ligament damage was detected during whiplash-like retraction, mechanical and microstructural changes were identified after loading. Retraction produced significant decreases in ligament stiffness (p = 0.0186) and increases in laxity (p = 0.0065). In addition, image analysis indicated that 21.1 ± 17.1% of the capsule sustained principal strains that were unrecovered immediately after retraction. Altered collagen fiber alignment was detected in 32.7 ± 22.9% of the capsule after retraction. The capsule regions with unrecovered strain and altered fiber alignment after retraction were significantly co-localized with each other (p < 0.0001), suggesting the altered mechanical function may relate to a change in the tissue's fiber organization. The identification of altered fiber alignment in this ligament following retraction without any tears implicates the whiplash kinematic as a potential cause of microstructural damage that is not detectable using standard clinical imaging techniques.

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The relationship between lower neck shear force and facet joint kinematics during automotive rear impacts

Stemper¹,

Yoganandan²,

Pintar³

et al. 2011

Clinical Anatomy

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A primary goal of biomechanical safety research is the definition of localized injury thresholds in terms of quantities that are repeatable and easily measureable during experimentation. Recent biomechanical experimentation using human cadavers has highlighted the role of lower cervical facet joints in the injury mechanism resulting from low-speed automotive rear impacts. The present study was conducted to correlate lower neck forces and moments with facet joint motions during simulated rear impacts in an effort to define facet joint injury tolerance thresholds that can be used to assess automobile safety. Four male and four female intact head-neck complexes were obtained from cadaveric specimens and subjected to simulated automotive rear impacts using a pendulum-minisled device. Cervical spine segmental angulations and localized facet joint kinematics were correlated to shear and axial forces, and bending moments at the cervico-thoracic junction using linear regression. R(2) coefficients indicated that spinal kinematics correlated well with lower neck shear force and bending moment. Correlation slope was steeper in female specimens, indicating greater facet joint motions for a given loading magnitude. This study demonstrated that lower neck loads can be used to predict lower cervical facet joint kinematics during automotive rear impacts. Higher correlation slope in female specimens corresponds to higher injury susceptibility in that population. Although lower neck shear force and bending moment demonstrated adequate correlation with lower cervical facet joint motions, shear force is likely the better predictor due to similarity in the timing of peak magnitudes with regard to maximum facet joint motions.

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Effect of Head-Neck Position on Cervical Facet Stretch of Post Mortem Human Subjects during Low Speed Rear End Impacts

Cited by 32 publications

References 9 publications

Cervical Spine Model to Predict Capsular Ligament Response in Rear Impact

Cervical Spine Model to Predict Capsular Ligament Response in Rear Impact

Detection of Altered Collagen Fiber Alignment in the Cervical Facet Capsule After Whiplash-Like Joint Retraction

The relationship between lower neck shear force and facet joint kinematics during automotive rear impacts

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