The response of the pediatric head to impacts onto a rigid surface

Loyd, Andre Matthew; Nightingale, Roger W.; Luck, Jason F.; Bass, Cameron Dale; Cutcliffe, Hattie C.; Myers, Barry S.

doi:10.1016/j.jbiomech.2019.06.027

Cited by 5 publications

(8 citation statements)

References 25 publications

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“…However, these forces vary with the surface area of the impactor and the impact velocity [20]. It should also be noted that skull fracture occurs at much lower loads for children [26]. Regardless, the measured loads in every test presented in this study fall within or exceed this range.…”

Section: Skull Fracturementioning

confidence: 59%

An Evidence Basis for Future Equestrian Helmet Lateral Crush Certification Tests

et al. 2020

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The aim of this study is to determine what loads are likely to be applied to the head in the event of a horse falling onto it and to determine by how much a typical equestrian helmet reduces these loads. An instrumented headform was designed and built to measure applied dynamic loads from a falling horse. Two differently weighted equine cadavers were then dropped repeatedly from a height of 1 m (theoretical impact velocity of 4.43 m/s) onto both the un-helmeted and helmeted instrumented headforms to collect primary force–time history data. The highest mean peak loads applied to the headform by the lighter horse were measured at the bony sacral impact location (15.57 kN ± 1.11 SD). The lowest mean peak loads were measured at the relatively fleshier right hind quarter (7.91 kN ± 1.84 SD). For the heavier horse, highest mean peak loads applied to the headform were measured at the same bony sacral impact location (16.02 kN ± 0.83 SD), whilst lowest mean peak loads were measured at the more compliant left hind quarter (10.47 kN ± 1.08 SD). When compared with the un-helmeted mean values, a reduction of 29.7% was recorded for the sacral impact location and a reduction of 43.3% for the lumbosacral junction location for helmeted tests. Notably, all measured loads were within or exceeded the range of published data for the fracture of the adult lateral skull bone. Current helmet certification tests are not biofidelic and inadequately represent the loading conditions of real-world “lateral crush” accidents sustained in equestrian sports. This work presents the first ever evidence basis upon which any future changes to a certification standards test method might be established, thereby ensuring that such a test would be both useful, biofidelic, and could ensure the desired safety outcome.

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Section: Skull Fracturementioning

confidence: 59%

An Evidence Basis for Future Equestrian Helmet Lateral Crush Certification Tests

et al. 2020

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“…For free-falling and unconstrained projectile methods, deformation was determined by double integration of an acceleration-time signal, which was recorded with an accelerometer fixed to the head or impactor, 4 , 6 , 37 , 41 or calculated by normalizing the force–time signal with the head mass. 20 , 22 …”

Section: Resultsmentioning

confidence: 99%

“…head injury criteria) and in clinical applications. 45 The remaining two studies 20 , 22 assessed the regional differences for non-destructive impact properties of adult and pediatric heads, and compared the impact response (stiffness, pulse duration, acceleration and HIC) against the response for age-matched surrogate heads. Overall, the head’s response was shown to be region- and rate-dependent.…”

Section: Resultsmentioning

confidence: 99%

“… 22 6 males 60 ± 5 years 1.71 4.8 4587 ± 368 3319 ± 551 b 3656 ± 605 – 3785 ± 309 – – – – – 3065 ± 483 1973 ± 589 b 2084 ± 541 – 2182 ± 441 2.42 9.6 6828 ± 797 4945 ± 870 b 5771 ± 930 – 5775 ± 835 – – – – 3699 ± 754 2162 ± 715 b 2918 ± 905 – 2959 ± 935 Loyd et al . 20 Same schematic as above N = 12 5 males 33 week gestation–16 years 1.71 2 816 ± 858 709 ± 878 b 762 ± 882 – 841 ± 1060 – – – – – 390 ± 665 273 ± 480 b 273 ± 428 – 343 ± 631 2.42 4 1219 ± 1448 <...…”

Section: Resultsmentioning

confidence: 99%

“…Three papers reported the mechanical response of adult 22 and pediatric 20 , 35 heads to repeated 15 and 30 cm free-falling impacts (1.71 and 2.42 m/s), at five regions (in order: forehead, occiput, vertex, right parietal, left parietal). In both studies, the following outcomes were supported by statistical significance: adult head stiffness was lower for parietal impacts than vertex impacts; adult and pediatric head stiffness increased with loading rate (Table 2 ); and pediatric head stiffness increased with age.…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

A Review of the Compressive Stiffness of the Human Head

2022

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Synthetic surrogate head models are used in biomechanical studies to investigate skull, brain, and cervical spine injury. To ensure appropriate biofidelity of these head models, the stiffness is often tuned so that the surrogate’s response approximates the cadaveric response corridor. Impact parameters such as energy, and loading direction and region, can influence injury prediction measures, such as impact force and head acceleration. An improved understanding of how impact parameters affect the head’s structural response is required for designing better surrogate head models. This study comprises a synthesis and review of all existing ex vivo head stiffness data, and the primary factors that influence the force–deformation response are discussed. Eighteen studies from 1972 to 2019 were identified. Head stiffness statistically varied with age (pediatric vs. adult), loading region, and rate. The contact area of the impactor likely affects stiffness, whereas the impactor mass likely does not. The head’s response to frontal impacts was widely reported, but few studies have evaluated the response to other impact locations and directions. The findings from this review indicate that further work is required to assess the effect of head constraints, loading region, and impactor geometry, across a range of relevant scenarios.

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Infant skull fractures align with the direction of bone mineralization

Chen,

Kleiven,

2024

Biomech Model Mechanobiol

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The geometry and mechanical properties of infant skull bones differ significantly from those of adults. Over the past decades, debates surrounding whether fractures in infants come from deliberate abuse or accidents have generated significant impacts in both legal and societal contexts. However, the etiology of infant skull fractures remains unclear, which motivates this study with two main components of work. Firstly, we present and implement a progressive unidirectional fabric composite damage model for infant cranial vaults to represent ductile and anisotropic properties—two typical mechanical characteristics of infant skulls. Secondly, we hypothesize that these intrinsic material properties cause injuries perpendicular to the fiber direction to dominate infant skull fractures, resulting in fracture lines that align with the direction of mineralization in the infant skull. The material model and the finite element (FE) model were verified hierarchically, and this hypothesis was verified by reconstructing two legal cases with known fall heights and implementing the above damage model into CT-based subject-specific infant FE head models. We discovered that the infant skull is more susceptible to injuries within planes perpendicular to the mineralization direction because of the anisotropic mechanical property caused by the direction of mineralization, leading to infant skull fractures aligning with the mineralization direction. Our findings corroborated the several previously reported observations of fractures on cranial vaults, demonstrating that these fractures were closely associated with sutures and oriented along the mineralization direction, and revealed the underlying mechanisms of infant skull fracture pattern. The modeling methods and results of this study will serve as an anchor point for more rigorous investigations of infant skull fractures, ultimately aiming to provide convincing biomechanical evidence to aid forensic diagnoses of abusive head trauma.

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The response of the pediatric head to impacts onto a rigid surface

Cited by 5 publications

References 25 publications

An Evidence Basis for Future Equestrian Helmet Lateral Crush Certification Tests

An Evidence Basis for Future Equestrian Helmet Lateral Crush Certification Tests

A Review of the Compressive Stiffness of the Human Head

Infant skull fractures align with the direction of bone mineralization

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