Preliminary observations of the sequence of damage in excised human juvenile cranial bone at speeds equivalent to falls from 1.6 m

Abstract

There is much debate within the forensic community around the indications that suggest a head injury sustained by a child resulted from abusive head trauma, rather than from accidental causes, especially when a fall from low height is the explanation given by a caregiver. To better understand this problem, finite element models of the paediatric head have been and continue to be developed. These models require material models that fit the behaviour of paediatric head tissues under dynamic loading conditions. Currently, the highest loading rate for which skull data exists is 2.81 ms -1 . This study improves on this by providing preliminary experimental data for a loading rate of 5.65 ± 0.14 ms -1 , equivalent to a fall of 1.6 m. Eleven specimens of paediatric cranial bone (frontal, occipital, parietal and temporal) from seven donors (age range 3 weeks -18 years) were tested in three-point bending with an impactor of radius 2 mm. It was found that prompt brittle fracture with virtually no bending occurring in all specimens but those aged 3 weeks old, where bending preceded brittle fracture. The maximum impact force increased with age (or thickness) and was higher in occipital bone. Energy absorbed to failure followed a similar trend, with values 0.11 and 0.35 mJ/mm 3 for age three-weeks, agreeing with previously published static tests, increasing with age up to 9 mJ/mm 3 for 18-year-old occipital bone. The preliminary data provided here can help analysts improve pediatric head finite element models that can be used to provide better predictions of the nature of head injuries from both a biomechanical and forensic point of view.

Systematic review and meta-analysis of the biomechanical properties of the human dura mater applicable in computational human head models

“…Given that predominantly quasi-static testing velocities were used to determine the biomechanical properties of the human cranial dura mater, current values may not be representative of the forces applied to the dura during head impacts, such as sustained in falls, gunshots, or contacts sports, which are likely of a dynamic nature (Brooks et al 2021 ). Therefore, there is an urgent need to explore the dynamic biomechanical properties of the human cranial dura mater in future studies.…”

The dynamic impact behavior of the human neurocranium

“…Generally, the availability of cadaveric material for mechanical testing purposes is limited, restricting the concurrent investigation of demographic influences such as age (at death) and sex (of the deceased) on the mechanical parameters. Previous studies on the dynamic mechanical properties of the human neurocranium predominantly described either infants 17 , 19 , 25 or the elderly 20 . This, in consequence, does not allow for general conclusions on the age-related mechanical properties of neurocranial bones over the entire human lifespan.…”

Experimental characterisation of porcine subcutaneous adipose tissue under blunt impact up to irreversible deformation

“…A promising tool for the evaluation of this influence is the finite element (FE) method, which has already been applied for the investigation of different impact scenarios in the field of forensic science [5,[12][13][14][15][16]. But for the application of these models, experimental data on the behaviour of the involved tissues is needed for the intended loading scenarios to develop and validate appropriate material descriptions, which can be quite challenging for soft tissues such as subcutaneous adipose tissue [16][17][18][19].…”