Tensile Failure Properties of the Perinatal, Neonatal, and Pediatric Cadaveric Cervical Spine

Luck, Jason F.; Nightingale, Roger W.; Song, Yin; Kait, Jason; Loyd, Andre Matthew; Myers, Barry S.; Bass, Cameron R.

doi:10.1097/brs.0b013e3182793873

Cited by 32 publications

(17 citation statements)

References 45 publications

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“…As a second evaluation, we simulated axial tension after decreasing the ligament stiffness to 10% of an adult and then compared our model results with published force-displacement predictions. 23,24 With a stiffness of 150 N/mm, our model's stiffness was well within the range of 7.1 to 199.0 N/mm measured by Luck et al, 23,24 and our model force-displacement response compared very well with the specimen highlighted in 25 This specimen population exhibited an even wider range of stiffness, ranging from 22 ± 7 N/mm for neonates to 504 N/mm for an 18-year-old individual, showing that greater ligamentous laxity occurred at younger ages.…”

Section: Discussionsupporting

confidence: 54%

“…Luck et al published the only experimental data appropriate for evaluating predictions from an FEM of pediatric CCJ. [23][24][25] The flexion-extension ROM data from this thesis were first used to evaluate our model. 23 The liga- ment stiffness values in our model were decreased until the model-predicted ROM was within a standard deviation of their experimental measurements.…”

Section: Discussionmentioning

confidence: 99%

“…[23][24][25] Luck et al reported both flexionextension range of motion (ROM) data and axial tension structural stiffness data for cadaveric pediatric cervical spine tissue. 23,24 These data were used previously to evaluate an FEM of the entire pediatric cervical spine, which consisted of a dynamic/explicit model created to simulate automobile-related crash scenarios.…”

mentioning

confidence: 99%

“…Our current biomechanical knowledge is based mostly on clinical experience 29,30 and a few cadaveric studies. [23][24][25]28 One way to overcome this deficiency is to create a finite element model (FEM) of the pediatric CCJ. Robust FEMs give an accurate representation of the complex geometrical structures that contain dissimilar material properties by discretizing the larger structure into numerous smaller pieces for evaluation.…”

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confidence: 99%

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Development and initial evaluation of a finite element model of the pediatric craniocervical junction

Phuntsok

Mazur

Ellis

et al. 2016

PED

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OBJECT There is a significant deficiency in understanding the biomechanics of the pediatric craniocervical junction (CCJ) (occiput–C2), primarily because of a lack of human pediatric cadaveric tissue and the relatively small number of treated patients. To overcome this deficiency, a finite element model (FEM) of the pediatric CCJ was created using pediatric geometry and parameterized adult material properties. The model was evaluated under the physiological range of motion (ROM) for flexion-extension, axial rotation, and lateral bending and under tensile loading. METHODS This research utilizes the FEM method, which is a numerical solution technique for discretizing and analyzing systems. The FEM method has been widely used in the field of biomechanics. A CT scan of a 13-month-old female patient was used to create the 3D geometry and surfaces of the FEM model, and an open-source FEM software suite was used to apply the material properties and boundary and loading conditions and analyze the model. The published adult ligament properties were reduced to 50%, 25%, and 10% of the original stiffness in various iterations of the model, and the resulting ROMs for flexion-extension, axial rotation, and lateral bending were compared. The flexion-extension ROMs and tensile stiffness that were predicted by the model were evaluated using previously published experimental measurements from pediatric cadaveric tissues. RESULTS The model predicted a ROM within 1 standard deviation of the published pediatric ROM data for flexion-extension at 10% of adult ligament stiffness. The model's response in terms of axial tension also coincided well with published experimental tension characterization data. The model behaved relatively stiffer in extension than in flexion. The axial rotation and lateral bending results showed symmetric ROM, but there are currently no published pediatric experimental data available for comparison. The model predicts a relatively stiffer ROM in both axial rotation and lateral bending in comparison with flexion-extension. As expected, the flexion-extension, axial rotation, and lateral bending ROMs increased with the decrease in ligament stiffness. CONCLUSIONS An FEM of the pediatric CCJ was created that accurately predicts flexion-extension ROM and axial force displacement of occiput–C2 when the ligament material properties are reduced to 10% of the published adult ligament properties. This model gives a reasonable prediction of pediatric cervical spine ligament stiffness, the relationship between flexion-extension ROM, and ligament stiffness at the CCJ. The creation of this model using open-source software means that other researchers will be able to use the model as a starting point for research.

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Section: Discussionsupporting

confidence: 54%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Development and initial evaluation of a finite element model of the pediatric craniocervical junction

Phuntsok

Mazur

Ellis

et al. 2016

PED

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“…In addition, the use of pediatric cadavers has been specifically limited by the rarity of pediatric cadavers. Only a handful of pediatric cadavers studies for the neck have been conducted (e.g., Dejeammes et al 1984;Duncan 1874;Kallieris et al 1976;Luck et al 2008Luck et al , 2013Ouyang 2005;Wismans et al 1979). These studies reported cervical stiffness and failure loads and are extremely valuable for understanding the pediatric neck.…”

Section: Introductionmentioning

confidence: 99%

Importance of Muscle Activations for Biofidelic Pediatric Neck Response in Computational Models

Dibb¹,

Cox²,

Nightingale³

et al. 2013

Traffic Injury Prevention

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Objective: During dynamic injury scenarios, such as motor vehicle crashes, neck biomechanics contribute to head excursion and acceleration, influencing head injuries. One important tool in understanding head and neck dynamics is computational modeling. However, realistic and stable muscle activations for major muscles are required to realize meaningful kinematic responses. The objective was to determine cervical muscle activation states for 6-year-old, 10-year-old, and adult 50th percentile male computational head and neck models. Currently, pediatric models including muscle activations are unable to maintain the head in an equilibrium position, forcing models to begin from nonphysiologic conditions. Recent work has realized a stationary initial geometry and cervical muscle activations by first optimizing responses against gravity. Accordingly, our goal was to apply these methods to Duke University's head-neck model validated using living muscle response and pediatric cadaveric data.Methods: Activation schemes maintaining an upright, stable head for 22 muscle pairs were found using LS-OPT. Two optimization problems were investigated: a relaxed state, which minimized muscle fatigue, and a tensed activation state, which maximized total muscle force. The model's biofidelity was evaluated by the kinematic response to gravitational and frontal impact loading conditions. Model sensitivity and uncertainty analyses were performed to assess important parameters for pediatric muscle response. Sensitivity analysis was conducted using multiple activation time histories. These included constant activations and an optimal muscle activation time history, which varied the activation level of flexor and extensor groups, and activation initiation and termination times.Results: Relaxed muscle activations decreased with increasing age, maintaining upright posture primarily through extensor activation. Tensed musculature maintained upright posture through coactivation of flexors and extensors, producing up to 32 times the force of the relaxed state. Without muscle activation, the models fell into flexion due to gravitational loading. Relaxed musculature produced 28.6-35.8 N of force to the head, whereas tensed musculature produced 450-1023 N. Pediatric model stiffnesses were most sensitive to muscle physiological cross-sectional area.Conclusions: Though muscular loads were not large enough to cause vertebral compressive failure, they would provide a prestressed state that could protect the vertebrae during tensile loading but might exacerbate risk during compressive loading. For example, in the 10-year-old, a load of 602 N was produced, though estimated compressive failure tolerance is only 2.8 kN. Including muscles and time-variant activation schemes is vital for producing biofidelic models because both vary by age. The pediatric activations developed represent physiologically appropriate sets of initial conditions and are based on validated adult cadaveric data.

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Pediatric Biomechanics

Arbogast¹,

Maltese²

2014

Accidental Injury

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During the human postnatal developmental process, extensive tissue and morphological changes occur. Many take place in the first few years of life but substantial development for several body regions continues well into young adulthood. Along with overall change in size, these material and structural changes influence the biomechanical response of child such that they respond differently to traumatic load than an adult. Understanding the unique biomechanical response of the child is challenging, as compared to the wealth of biomechanical data on the adult response to trauma, pediatric biomechanical data are relatively sparse. As a result, quantitative scaling relationships based on anatomical and material differences have been historically used to understand the biomechanics of the child. The last decade, however, has seen a tremendous increase in contributions to the biomechanics literature based upon pediatric subjects -volunteers, postmortem human subjects, and animal models -thus increasing our knowledge of how to design injury mitigation systems to protect the young.In this chapter, aspects of developmental anatomy and biomechanical knowledge are reviewed to provide context for pediatric human injury prediction. Emphasis is initially placed on the head and brain as this body region represents the most common seriously injured body region for children in virtually all unintentional injury modes. Specifically, head injuries are particularly relevant clinically as the developing brain is difficult to evaluate and treat, and even mild brain injuries in childhood can lead to deficits that remain long after the injury. Discussion follows on the cervical spine and thorax as these body regions are not only important from an injury mitigation standpoint but they govern the kinematics of the head during traumatic loading and therefore play a role in head injury protection. A brief description follows for the other body regions: the abdomen

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Tensile Failure Properties of the Perinatal, Neonatal, and Pediatric Cadaveric Cervical Spine

Cited by 32 publications

References 45 publications

Development and initial evaluation of a finite element model of the pediatric craniocervical junction

Development and initial evaluation of a finite element model of the pediatric craniocervical junction

Importance of Muscle Activations for Biofidelic Pediatric Neck Response in Computational Models

Pediatric Biomechanics

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