Declan Alexander Patton

Purpose: Traumatic brain injury (TBI) affects 69 million people annually and is most frequently caused by rapid rotational acceleration of the head. Modeling rotational acceleration injuries in pigs can employ biomechanical parameters scaled from humans, allowing researchers to answer basic and translational questions about the influence of injury kinematics on outcomes. However, precisely describing head kinematics during rotational acceleration injuries is imperative to understand the relationships between biomechanical parameters, pathology, and neurological outcomes. Methods: Using an established model of rapid rotational acceleration, we examined kinematic transfer efficiency by assessing how closely the motion of the subject’s head matched the motion of the rotational device. Pigs were submitted to head rotation in the sagittal plane at either a moderate or a high target velocity. Kinematics were recorded with transducers and high frame rate videography, which was quantified manually and with the deep learning neural network, DeepLabCut. The rotational device was programmed to generate peak angular velocities ranging from 85.8-108.1 rad/s. Results: The kinematic coupling of the peak angular velocities between the head and transducer-mounted injury device was 95.30 ± 3.41% during moderate velocity TBIs and 93.09 ± 8.08% during high velocity TBI. Angular velocity exhibited strong matching between the head and injury device while angular acceleration exhibited fair-to-strong matching, depending on the kinematic term. These angular velocity and acceleration levels exceeded clinical injury thresholds from the literature based on appropriate mass scaling. Conclusions: The high degree of kinematic matching between injury device and head in both moderate and high velocity TBIs suggests a high kinematic transfer efficiency within the target range of angular velocities. This validation study provide critical insights into the fidelity of large animal rotational acceleration injury by enhancing our understanding of force transmission and head kinematics, leading to more accurate scaling and representation of human TBI events.

To investigate the strength of support legs from rearward-facing infant CRS models and the strength of an underfloor storage compartment, with and without a foam filler, when subjected to loading by a support leg simulating a frontal crash. A range of support leg normal reaction force time-histories from previous frontal sled tests were simulated using a drop test rig with an impact mass of 39.4 kg. An exemplar support leg from a rearward-facing infant CRS model was tested across a range of drop heights (135-360 mm) and the reaction force was measured. Support legs from three alternate rearward-facing infant CRS models were tested at a drop height of 310 mm and the reaction force was measured. The reaction forces measured from these tests were applied via the exemplar support leg to the lids of an underfloor storage compartment across a range of drop heights (135-310 mm) and residual deformation was measured. Lids were subsequently loaded using the exemplar support leg for a drop height of 310 mm with an expanded polystyrene (EPS) foam filler placed inside the underfloor storage compartment. The integrity of the exemplar support leg from the rearward-facing infant CRS model was maintained during all tests, including tests up to a peak reaction force of 7.9 kN. For a drop height of 310 mm, the support legs from two alternate CRS models performed similarly to the exemplar leg; however, the support leg from the third alternate CRS model was observed post-test to have compressed by 23 mm. The underfloor storage compartment lid deformed plastically when loaded with a support leg and residual deformation increased proportionally with drop height. The extent of cracking of the lid also increased with drop height. The foam filler reduced the average residual deformation of the lids by 67%. Although the underfloor storage compartment lids deformed plastically when loaded with a support leg, no lid completely collapsed in any of the tests. The foam filler effectively reduced deformation of the lid, the use of which is recommended when a rearward-facing CRS with a support leg is being used in a vehicle with an underfloor storage compartment. The results of the current study may have implications for electric vehicles, which have unique floor designs to accommodate battery packs and other components.

Purpose Large mammal head injury models allow the pathophysiological response associated with traumatic brain injury (TBI) to be studied in vivo with precise control of the physical parameters. However, only some studies have used skull-mounted sensors to measure the kinematics of the animal head rather than relying on measurements of the system delivering the impact. Therefore, the aim of the current study was to compare the kinematics between a rotational injury device (HYGE, Inc., Kittanning, PA) and the head in a swine model of TBI across a range of target peak angular velocities. Methods Sexually mature Yucatan swine were subjected to a rotational TBI via the HYGE device at one of three targeted peak angular velocities: 110 rad/s (n = 16), 145 rad/s (n = 12) or 170 rad/s (n = 11). Sensor packages were used to measure both the angular kinematics of the animal head and HYGE device swing arm. Results Peak angular velocity of the animal head was on average 18–33% lower compared to that of the HYGE device swing arm with greater relative differences for greater target peak angular velocities. Similarly, peak angular acceleration of the animal head was lower than that of the HYGE device sing arm by 11–34% on average with greater relative differences for greater target peak angular velocities. Conclusions This study highlights the importance of directly measuring the head kinematics of the animal in TBI models for the purpose of directional comparisons, finite element simulations, and/or scaling kinematics from human-to-animal to determine boundary conditions or animal-to-human to develop injury criteria.

To quantify the head and chest injury metrics associated with a pediatric anthropomorphic test device (ATD) in rearward-facing infant child restraint system (CRS) models positioned directly behind a center console during frontal impact sled tests. Sled tests using the Federal Motor Vehicle Safety Standard (FMVSS) 213 frontal crash pulse were performed. The test buck comprised a second row middle seat and center console from the same 2023 model mid-size SUV spaced as per the in-vehicle relative dimensions, a force plate covered with an automotive floor mat, a post-mounted shoulder belt simulating the in-vehicle roof-mounted seatbelt and an array of high-speed cameras. The 12-month-old Child Restraint/Air Bag Interaction (CRABI-12) ATD was seated in one of two rearward-facing infant CRS models (model A, rigid lower anchors; model B, flexible lower anchors), which was installed with either the base (support leg or no support leg; attached using lower anchors or the seatbelt) or without the base (attached using the European or US belt path). Conductive foil was attached to the rear surface of the center console and to the shell of the CRS and/or base to quantify contact. The vehicle seat was replaced every second test and the center console was replaced when damaged. For sled tests of the CRS models with a base attached using lower anchors, there was no contact of the CRS with the center console when the support leg was used, and all head and chest injury metrics were reduced compared to the tests of CRS with no support leg. However, there was contact between the CRS and the center console when the base of the CRS models was attached using the seatbelt, which typically increased head and chest injury metrics compared to the lower anchor attachment method. For CRS model B with the base attached using either the lower anchors or the seatbelt but no support leg, head acceleration 3 ms clip exceeded the injury assessment reference value (IARV) of 80 g. All tests resulted in HIC36 values below the IARV of 1000. The tests of the CRS models without a base using the European belt path did not result in contact and had the lowest head and chest injury metrics of all tests, which were all below IARVs. For the tests of the CRS models with the base attached using the seatbelt and tests using the US belt path, chest acceleration 3 ms clip values exceeded the IARV of 60 g. Peak normal support leg reaction forces in this study ranged from 3.6 to 4.3 kN. The rearward-facing CRS models with a base and a support leg attached using lower anchors, or without a base using the European belt path, resulted in the lowest head and chest injury metrics due to not contacting the center console.

To assess the interaction of multiple rearward-facing (RF) and forward-facing (FF) CRS restrained pediatric occupants on their kinetics in oblique impacts. A Q3s and a Q1.5 ATD were restrained in 2 CRSs of varying widths-standard (503mm) and slim-fit (425mm)-in the 2 rear outboard seats of a 2023 compact sedan rigidized rear seat bench. A surrogate door structure was mounted at the left outboard location. The Q1.5 was seated in an RF configuration, and the Q3s was seated in RF or FF configurations across tests. The ATDs were restrained as follows: (1) both ATDs in standard CRSs and (2) both ATDs in slim-fit CRSs, switching between the outboard seats for a total of 8 conditions. The condition with the highest head kinetic metrics from these tests was reproduced in a ninth test with the rear seat's center armrest lowered between CRSs. The entire environment was subjected to an oblique impact at 60° using the FMVSS 213 impact pulse. The Q3s' head contacted the nearby CRS shell when seated farside. When seated nearside, the Q3s' head contacted the surrogate door structure in 1 of 4 conditions. The Q1.5's head contacted the nearby CRS in 2 of 4 conditions when seated farside. The Q3s when seated RF had higher HIC15 and head 3ms clip acceleration (H_3ms), regardless of farside or nearside position. When seated farside, upper neck tensile force (F_z) for the Q3s in FF configuration (2,317.4 and 2,077.9 N) was higher than that in RF configuration (1,850.8 and 1,802.8 N). When seated nearside, the same in FF configuration (701.3 and 1,029.4 N) was lower than that in RF configuration (997.6 and 1,261.7 N). Repeating the condition with the highest head kinetic metrics (HIC15 = 1246; H_3ms = 114.4 g) but lowering the center armrest between the CRSs resulted in lower head kinetic metrics (HIC15 = 916, H_3ms = 93.5 g). In most cases, the farside seated ATD's head contacted the nearside CRS shell, resulting in elevated injury metric numbers and higher loading in both CRS types. The nearside ATD did not experience detrimental effects of the interaction with the farside occupant and CRS.

Male lacrosse and female lacrosse have differences in history, rules, and equipment. There is current debate regarding the need for enhanced protective headwear in female lacrosse like that worn by male lacrosse players. To inform this discussion, 17 high school lacrosse players (6 female and 11 male) wore the Stanford Instrumented Mouthguard during 26 competitive games over the 2021 season. Time-windowing and video review were used to remove false-positive recordings and verify head acceleration events (HAEs). The HAE rate in high school female lacrosse (0.21 per athlete exposure and 0.24 per player hour) was approximately 35% lower than the HAE rate in high school male lacrosse (0.33 per athlete exposure and 0.36 per player hour). Previously collected kinematics data from the 2019 high school male and female lacrosse season were combined with the newly collected 2021 kinematics data, which were used to drive a finite element head model and simulate 42 HAEs. Peak linear acceleration (PLA), peak angular velocity (PAV), and 95th percentile maximum principal strain (MPS95) of brain tissue were compared between HAEs in high school female and male lacrosse. Median values for peak kinematics and MPS95 of HAEs in high school female lacrosse (PLA, 22.3 g; PAV, 10.4 rad/s; MPS95, 0.05) were lower than for high school male lacrosse (PLA, 24.2 g; PAV, 15.4 rad/s; MPS95, 0.07), but the differences were not statistically significant. Quantifying a lower HAE rate in high school female lacrosse compared to high school male lacrosse, but similar HAE magnitudes, provides insight into the debate regarding helmets in female lacrosse. However, due to the small sample size, additional video-verified data from instrumented mouthguards are required.

Traumatic brain injury (TBI) and severe blood loss resulting in hemorrhagic shock (HS) are each leading causes of mortality and morbidity worldwide, and present additional treatment considerations when they are comorbid (TBI+HS) as a result of competing pathophysiological responses. The current study rigorously quantified injury biomechanics with high precision sensors and examined whether blood-based surrogate markers were altered in general trauma as well as post-neurotrauma. Eighty-nine sexually mature male and female Yucatan swine were subjected to a closed-head TBI+HS (40% of circulating blood volume; n = 68), HS only ( n = 9), or sham trauma ( n = 12). Markers of systemic (e.g., glucose, lactate) and neural functioning were obtained at baseline, and at 35 and 295 min post-trauma. Opposite and approximately twofold differences existed for both magnitude (device > head) and duration (head > device) of quantified injury biomechanics. Circulating levels of neurofilament light chain (NfL), glial fibrillary acidic protein (GFAP), and ubiquitin C-terminal hydrolase L1 (UCH-L1) demonstrated differential sensitivity for both general trauma (HS) and neurotrauma (TBI+HS) relative to shams in a temporally dynamic fashion. GFAP and NfL were both strongly associated with changes in systemic markers during general trauma and exhibited consistent time-dependent changes in individual sham animals. Finally, circulating GFAP was associated with histopathological markers of diffuse axonal injury and blood–brain barrier breach, as well as variations in device kinematics following TBI+HS. Current findings therefore highlight the need to directly quantify injury biomechanics with head mounted sensors and suggest that GFAP, NfL, and UCH-L1 are sensitive to multiple forms of trauma rather than having a single pathological indication (e.g., GFAP = astrogliosis).

Finite element (FE) modeling provides a means to examine how global kinematics of repetitive head loading in sports influences tissue level injury metrics. FE simulations of controlled soccer headers in two directions were completed using a human head FE model to estimate biomechanical loading on the brain by direction. Overall, headers were associated with 95th percentile peak maximum principal strains up to 0.07 and von Mises stresses up to 1450 Pa, and oblique headers trended toward higher values than frontal headers but below typical injury levels. These quantitative data provide insight into repetitive loading effects on the brain.

There is concern that repetitive head impact exposure (RHIE) may lead to neurophysiological deficits in adolescents. Twelve high school varsity soccer players (5 female) completed the King-Devick (K-D) and complex tandem gait (CTG) assessments pre- and post-season while wearing a functional near-infrared spectroscopy (fNIRS) sensor. The average head impact load (AHIL) for each athlete-season was determined via a standardised protocol of video-verification of headband-based head impact sensor data. Linear mixed effect models were used to determine the effects of AHIL and task condition (3 K-D cards or 4 CTG conditions) on the change in mean prefrontal cortical activation measured by fNIRS, and performance on K-D and CTG, from pre- to post-season. Although there was no difference in the pre- to post-season change in K-D or CTG performance, greater AHIL was associated with greater cortical activation at post-season in comparison to pre-season during the most challenging conditions of K-D (p = 0.003) and CTG (p = 0.02), suggesting that greater RHIE necessitates increased cortical activation to complete the more challenging aspects of these assessments at the same level of performance. These results describe the effect of RHIE on neurofunction and suggest the need for further study of the time course of these effects.