Pilot Collection and Evaluation of Head Kinematics in Stock Car Racing.

The goal of this work was to collect on-track driver head kinematics using instrumented mouthpieces and characterize environmental exposure to accelerations and vibrations. Six NASCAR drivers were instrumented with custom-fit mouthpieces to collect head kinematic data. Devices were deployed at four tracks during practice and testing environments and configured to collect approximately 11 min of linear acceleration and rotational velocity data at 200 Hz. This continuous data collection, combined with film review, allowed extraction of complete laps of data. In addition to typical data processing methods, a moving-point average was calculated and subtracted from the overall signal for both linear acceleration and rotational velocity to determine the environmental component of head motion. The current analysis focuses on 42 full laps of data collected at four data collection events. The number of laps per track ranged from 2 to 23. Linear acceleration magnitudes for all 42 laps ranged from 2.46 to 7.48 g and rotational velocity ranged from 1.25 to 3.35 rad/s. After subtracting the moving average, linear acceleration ranged from 0.92 to 5.45 g and rotational velocity ranged from 0.57 to 2.05 rad/s. This study has established the feasibility of using an instrumented mouthpiece to measure head kinematics in NASCAR and presented a technique for isolating head motion due to cornering acceleration from those due to short-term perturbations experienced by the driver.

Head Impact Exposure in Female Collegiate Soccer by Activity Type.

Soccer, one of the most popular sports in the world, has one of the highest rates of sports-related concussions. Additionally, soccer players are frequently exposed to nonconcussive impacts from intentionally heading the ball, a fundamental component of the sport. There have been many studies on head impact exposure in soccer, but few focus on soccer practices or practice activities. This study aimed to characterize the frequency and magnitude of head impacts in National Collegiate Athletic Association Division I female soccer practice activities using a custom-fit instrumented mouthpiece. Sixteen players were instrumented over the course of 54 practice sessions. Video analysis was performed to verify all mouthpiece-recorded events and classify practice activities. Category groupings of practice activities include technical training, team interaction, set pieces, position-specific, and other. Differences in head impact rates and peak resultant kinematics were observed across activity types and category groupings. Technical training had the highest impact rate compared to other category groupings. Impacts occurring during set piece activities had the highest mean kinematic values. Understanding drill exposure can help inform coaches on training plans aimed to reduce head impact exposure for their athletes.

Characterization of Head Acceleration Exposure During Youth Football Practice Drills.

Many head acceleration events (HAEs) observed in youth football emanate from a practice environment. This study aimed to evaluate HAEs in youth football practice drills using a mouthpiece-based sensor, differentiating between inertial and direct HAEs. Head acceleration data were collected from athletes participating on 2 youth football teams (ages 11-13 y) using an instrumented mouthpiece-based sensor during all practice sessions in a single season. Video was recorded and analyzed to verify and assign HAEs to specific practice drill characteristics, including drill intensity, drill classification, and drill type. HAEs were quantified in terms of HAEs per athlete per minute and peak linear and rotational acceleration and rotational velocity. Mixed-effects models were used to evaluate the differences in kinematics, and generalized linear models were used to assess differences in HAE frequency between drill categories. A total of 3237 HAEs were verified and evaluated from 29 football athletes enrolled in this study. Head kinematics varied significantly between drill categorizations. HAEs collected at higher intensities resulted in significantly greater kinematics than lower-intensity drills. The results of this study add to the growing body of evidence informing evidence-based strategies to reduce head impact exposure and concussion risk in youth football practices.

Characterization of head impact exposure in boys' youth ice hockey.

Ice hockey has one of the highest concussion rates among youth sports. Sensor technology has been implemented in contact and collision sports to inform the frequency and severity of head impacts experienced on-ice. However, existing studies have utilized helmet-mounted sensors with limited accuracy. The objective of this study was to characterize head kinematics of contact events in a sample of youth boys' hockey players using a validated instrumented mouthpiece with improved accuracy. Head kinematics from 892 video-verified events were recorded from 18 athletes across 127 sessions. Median peak resultant linear acceleration, rotational velocity, and rotational acceleration of video-verified events were 7.4 g, 7.7 rad/s, and 576 rad/s2, respectively. Contact events occurred at a higher rate in games (2.48 per game) than practices (1.30 per practice). Scenarios involving head contact had higher peak kinematics than those without head contact. This study improves our understanding of head kinematics in boys' youth hockey.

Head Impact Kinematics and Brain Deformation in Paired Opposing Youth Football Players.

Head impact exposure is often quantified using peak resultant kinematics. While kinematics describes the inertial response of the brain to impact, they do not fully capture the dynamic brain response. Strain, a measure of the tissue-level response of the brain, may be a better predictor of injury. In this study, kinematic and strain metrics were compared to contact characteristics in youth football. Players on 2 opposing teams were instrumented with head impact sensors to record impact kinematics. Video was collected to identify contact scenarios involving opposing instrumented players (ie, paired contact scenarios) and code contact characteristics (eg, player role, impact location). A previously validated, high-resolution brain finite element model, the atlas-based brain model, was used to simulate head impacts and calculate strain metrics. Fifty-two paired contact scenarios (n = 105 impacts) were evaluated. Lighter players tended to have greater biomechanical metrics compared to heavier players. Impacts to the top of the helmet were associated with lower strain metrics. Overall, strain was better correlated with rotational kinematics, suggesting these metrics may be better predictors of the tissue-level brain response than linear kinematics. Understanding the effect of contact characteristics on brain strain will inform future efforts to improve sport safety.

Head Kinematics in Youth Ice Hockey by Player Speed and Impact Direction.

Hockey is a fast-paced sport known for body checking, or intentional collisions used to separate opponents from the puck. Exposure to these impacts is concerning, as evidence suggests head impact exposure (HIE), even if noninjurious, can cause long-term brain changes. Currently, there is limited understanding of the effect of impact direction and collision speed on HIE. Video analysis was used to determine speed and direction for 162 collisions from 13 youth athletes. These data were paired with head kinematic data collected with an instrumented mouthpiece. Relationships between peak resultant head kinematics and speeds were evaluated with linear regression. Mean athlete speeds and relative velocity between athletes ranged from 2.05 to 2.76 m/s. Mean peak resultant linear acceleration, rotational velocity, and rotational acceleration were 13.1 g, 10.5 rad/s, and 1112 rad/s2, respectively. Significant relationships between speeds and head kinematics emerged when stratified by contact characteristics. HIE also varied by direction of collision; most collisions occurred in the forward-oblique (ie, offset from center) direction; frontal collisions had the greatest magnitude peak kinematics. These findings indicate that HIE in youth hockey is influenced by speed and direction of impact. This study may inform future strategies to reduce the severity of HIE in hockey.

Characterization of Head Impact Exposure in Women's Collegiate Soccer.

Soccer players are regularly exposed to head impacts by intentionally heading the ball. Evidence suggests repetitive subconcussive head impacts may affect the brain, and females may be more vulnerable to brain injury than males. This study aimed to characterize head impact exposure among National Collegiate Athletic Association women's soccer players using a previously validated mouthpiece-based sensor. Sixteen players were instrumented during 72 practices and 24 games. Head impact rate and rate of risk-weighted cumulative exposure were compared across session type and player position. Head kinematics were compared across session type, impact type, player position, impact location, and ball delivery method. Players experienced a mean (95% confidence interval) head impact rate of 0.468 (0.289 to 0.647) head impacts per hour, and exposure rates varied by session type and player position. Headers accounted for 89% of head impacts and were associated with higher linear accelerations and rotational accelerations than nonheader impacts. Headers in which the ball was delivered by a long kick had greater peak kinematics (all P < .001) than headers in which the ball was delivered by any other method. Results provide increased understanding of head impact frequency and magnitude in women's collegiate soccer and may help inform efforts to prevent brain injury.

MEGnet: Automatic ICA-based artifact removal for MEG using spatiotemporal convolutional neural networks.

Magnetoencephalography (MEG) is a functional neuroimaging tool that records the magnetic fields induced by neuronal activity; however, signal from non-neuronal sources can corrupt the data. Eye-blinks, saccades, and cardiac activity are three of the most common sources of non-neuronal artifacts. They can be measured by affixing eye proximal electrodes, as in electrooculography (EOG), and chest electrodes, as in electrocardiography (ECG), however this complicates imaging setup, decreases patient comfort, and can induce further artifacts from movement. This work proposes an EOG- and ECG-free approach to identify eye-blinks, saccades, and cardiac activity signals for automated artifact suppression. The contribution of this work is three-fold. First, using a data driven, multivariate decomposition approach based on Independent Component Analysis (ICA), a highly accurate artifact classifier is constructed as an amalgam of deep 1-D and 2-D Convolutional Neural Networks (CNNs) to automate the identification and removal of ubiquitous whole brain artifacts including eye-blink, saccade, and cardiac artifacts. The specific architecture of this network is optimized through an unbiased, computer-based hyperparameter random search. Second, visualization methods are applied to the learned abstraction to reveal what features the model uses and to bolster user confidence in the model's training and potential for generalization. Finally, the model is trained and tested on both resting-state and task MEG data from 217 subjects, and achieves a new state-of-the-art in artifact detection accuracy of 98.95% including 96.74% sensitivity and 99.34% specificity on the held out test-set. This work automates MEG processing for both clinical and research use, adapts to the acquired acquisition time, and can obviate the need for EOG or ECG electrodes for artifact detection.

Mapping default mode connectivity alterations following a single season of subconcussive impact exposure in youth football.

Repetitive head impact (RHI) exposure in collision sports may contribute to adverse neurological outcomes in former players. In contrast to a concussion, or mild traumatic brain injury, "subconcussive" RHIs represent a more frequent and asymptomatic form of exposure. The neural network-level signatures characterizing subconcussive RHIs in youth collision-sport cohorts such as American Football are not known. Here, we used resting-state functional MRI to examine default mode network (DMN) functional connectivity (FC) following a single football season in youth players (n = 50, ages 8-14) without concussion. Football players demonstrated reduced FC across widespread DMN regions compared with non-collision sport controls at postseason but not preseason. In a subsample from the original cohort (n = 17), players revealed a negative change in FC between preseason and postseason and a positive and compensatory change in FC during the offseason across the majority of DMN regions. Lastly, significant FC changes, including between preseason and postseason and between in- and off-season, were specific to players at the upper end of the head impact frequency distribution. These findings represent initial evidence of network-level FC abnormalities following repetitive, non-concussive RHIs in youth football. Furthermore, the number of subconcussive RHIs proved to be a key factor influencing DMN FC.

Characterization of On-Field Head Impact Exposure in Youth Soccer.

The objective of this research was to characterize head impacts with a validated mouthpiece sensor in competitive youth female soccer players during a single season with a validated mouthpiece sensor. Participants included 14 youth female soccer athletes across 2 club-level teams at different age levels (team 1, ages 12-13 y; team 2, ages 14-15 y). Head impact and time-synchronized video data were collected for 66 practices and games. Video data were reviewed to characterize the type and frequency of contact experienced by each athlete. A total of 2216 contact scenarios were observed; heading the ball (n = 681, 30.7%) was most common. Other observed contact scenarios included collisions, dives, falls, and unintentional ball contact. Team 1 experienced a higher rate of headers per player per hour of play than team 2, while team 2 experienced a higher rate of collisions and dives. A total of 935 video-verified contact scenarios were concurrent with recorded head kinematics. While headers resulted in a maximum linear acceleration of 56.1g, the less frequent head-to-head collisions (n = 6) resulted in a maximum of 113.5g. The results of this study improve the understanding of head impact exposure in youth female soccer players and inform head impact exposure reduction in youth soccer.

The Effect of Player Contact Characteristics on Head Impact Exposure in Youth Football Games.

To reduce head impact exposure (HIE) in youth football, further understanding of the context in which head impacts occur and the associated biomechanics is needed. The objective of this study was to evaluate the effect of contact characteristics on HIE during player versus player contact scenarios in youth football. Head impact data and time-synchronized video were collected from 4 youth football games over 2 seasons in which opposing teams were instrumented with the Head Impact Telemetry (HIT) System. Coded contact characteristics included the player's role in the contact, player speed and body position, contact height, type, and direction, and head contact surface. Head accelerations were compared among the contact characteristics using mixed-effects models. Among 72 instrumented athletes, 446 contact scenarios (n = 557 impacts) with visible opposing instrumented players were identified. When at least one player had a recorded impact, players who were struck tended to have higher rotational acceleration than players in striking positions. When both players had a recorded impact, lighter players and taller players experienced higher mean head accelerations compared with heavier players and shorter players. Understanding the factors influencing HIE during contact events in football may help inform methods to reduce head injury risk.

Lumbar Spine Response of Computational Finite Element Models in Multidirectional Spaceflight Landing Conditions.

The goals of this study are to compare the lumbar spine response variance between the hybrid III, test device for human occupant restraint (THOR), and global human body models consortium simplified 50th percentile (GHBMC M50-OS) finite element models and evaluate the sensitivity of lumbar spine injury metrics to multidirectional acceleration pulses for spaceflight landing conditions. The hybrid III, THOR, and GHBMC models were positioned in a baseline posture within a generic seat with side guards and a five-point restraint system. Thirteen boundary conditions, which were categorized as loading condition variables and environmental variables, were included in the parametric study using a Latin hypercube design of experiments. Each of the three models underwent 455 simulations for a total of 1365 simulations. The hybrid III and THOR models exhibited similar lumbar compression forces. The average lumbar compression force was 45% higher for hybrid III (2.2 ± 1.5 kN) and 51% higher for THOR (2.0 ± 1.6 kN) compared to GHBMC (1.3 ± 0.9 kN). Compared to hybrid III, THOR sustained an average 64% higher lumbar flexion moment and an average 436% higher lumbar extension moment. The GHBMC model sustained much lower bending moments compared to hybrid III and THOR. Regressions revealed that lumbar spine responses were more sensitive to loading condition variables than environmental variables across all models. This study quantified the intermodel lumbar spine response variations and sensitivity between hybrid III, THOR, and GHBMC. Results improve the understanding of lumbar spine response in spaceflight landings.

Characterizing head impact exposure in youth female soccer with a custom-instrumented mouthpiece.

While many research efforts have focused on head impact exposure in professional soccer, there have been few studies characterizing exposure at the youth level. The aim of this study is to evaluate a new instrumentation approach and collect some of the first head impact exposure data for youth female soccer players. Athletes were instrumented with custom-fit mouthpieces that measure head impacts. Detailed video analysis was conducted to identify characteristics describing impact source (e.g., kick, header, throw). A total of 763 verified head impacts were collected over 23 practices and 8 games from 7 athletes. The median peak linear accelerations, rotational velocities, and rotational accelerations of all impacts were 9.4 g, 4.1 rad/s, and 689 rad/s2, respectively. Pairwise comparisons resulted in statistically significant differences in kinematics by impact source. Headers following a kicked ball had the highest accelerations and velocity when compared to headers from thrown or another header.

Nationwide Procedural Trends for Renal Trauma Management.

OBJECTIVE: To characterize national trends in procedural management of renal trauma. BACKGROUND: Management of renal trauma has evolved to favor a more conservative approach. For patients requiring intervention, there is a paucity of information to characterize the nature of procedural therapy administered. METHODS: A retrospective cross-sectional analysis was performed using data contained within the National Trauma Data Bank. The National Trauma Data Bank is a voluntary data repository managed by the American College of Surgeons, containing data regarding trauma admissions at 747 level I to V trauma centers throughout the United States and Canada. Participants included any patient with renal trauma requiring intervention from 2002 to 2012. They were identified according to International Classification of Diseases, Ninth Revision (ICD-9) diagnosis codes, with codes 866.00 through 866.03 for blunt renal trauma, and codes 866.10 through 866.13 for penetrating trauma. Cases were separated into those requiring nephrectomy, renorrhaphy, or endovascular repair based on ICD-9 procedure code. The number of cases performed each year and yearly trends as measured by linear regression. RESULTS: A total of 4296 cases were reported during the study period. Of these cases, 2635 involved blunt trauma and 1661 involved penetrating injury. There was a significant increase in the percentage of cases managed by endovascular means for both blunt and penetrating trauma (R = 0.92, P < 0.01; and R = 0.86, P < 0.01, respectively). This was primarily at the expense of nephrectomy, with cases showing significant decline in both groups. CONCLUSIONS: National trends for procedural management of renal trauma are toward less invasive interventions. These trends suggest favorable change towards renal preservation and decreased morbidity, potentially facilitated, in part, by improved radiographic staging and endovascular techniques, and also increased provider awareness of the safety and value of conservative management.

Multidirection Validation of a Finite Element 50th Percentile Male Hybrid III Anthropomorphic Test Device for Spaceflight Applications.

The use of anthropomorphic test devices (ATDs) for calculating injury risk of occupants in spaceflight scenarios is crucial for ensuring the safety of crewmembers. Finite element (FE) modeling of ATDs reduces cost and time in the design process. The objective of this study was to validate a Hybrid III ATD FE model using a multidirection test matrix for future spaceflight configurations. Twenty-five Hybrid III physical tests were simulated using a 50th percentile male Hybrid III FE model. The sled acceleration pulses were approximately half-sine shaped, and can be described as a combination of peak acceleration and time to reach peak (rise time). The range of peak accelerations was 10-20 G, and the rise times were 30-110 ms. Test directions were frontal (-GX), rear (GX), vertical (GZ), and lateral (GY). Simulation responses were compared to physical tests using the correlation and analysis (CORA) method. Correlations were very good to excellent and the order of best average response by direction was -GX (0.916±0.054), GZ (0.841±0.117), GX (0.792±0.145), and finally GY (0.775±0.078). Qualitative and quantitative results demonstrated the model replicated the physical ATD well and can be used for future spaceflight configuration modeling and simulation.

Prediction of lumbar vertebral body compressive strength of overweight and obese older adults using morphed subject-specific finite-element models to evaluate the effects of weight loss.

BACKGROUND: Diet and exercise can promote weight loss in older adults; however, there is potential to increase fracture risk due to loss of bone mineral density (BMD) known to accompany weight loss. Weight loss effects on measures of bone quality and strength are currently unknown. AIMS: The purpose of this study is to develop subject-specific finite-element (FE) models of the lumbar spine and study the effect of intentional weight loss on bone strength in a pilot data set. METHODS: Computed tomography (CT) scans of the lumbar spine of 30 overweight and obese (mean BMI = 29.7 ± 3.9 kg/m2), older adults (mean age = 65.9 ± 4.6 years) undergoing an 18-month intentional weight loss intervention were obtained at baseline and post-intervention. Measures of volumetric BMD (vBMD) and variable cortical thickness were derived from each subject CT scan. Development of the subject-specific FE models of the lumbar spine involved model morphing techniques to accelerate the development of the models. vBMD-derived material properties and cortical thickness measures were directly mapped to baseline and post-intervention models. Bone strength was estimated through simulation of a quasi-static uniaxial compression test. RESULTS: From baseline to 18-month post-weight loss intervention, there were statistically significant decreases in estimated bone strength (6.5% decrease; p < 0.05). Adjusting for baseline bone measures and gender revealed no statistically significant correlations between weight change and change in vBMD, cortical thickness, or bone strength. CONCLUSION: Integration of CT-based measures and FE models with conventional areal BMD can improve the understanding of the effects of intentional weight loss on bone health.

Finite Element-Based Pelvic Injury Metric Creation and Validation in Lateral Impact for a Human Body Model.

Pelvic fractures are serious injuries resulting in high mortality and morbidity. The objective of this study is to develop and validate local pelvic anatomical, cross section-based injury risk metrics for a finite element (FE) model of the human body. Cross-sectional instrumentation was implemented in the pelvic region of the Global Human Body Models Consortium (GHBMC M50-O) 50th percentile detailed male FE model (v4.3). In total, 25 lateral impact FE simulations were performed using input data from cadaveric lateral impact tests performed by Bouquet et al. The experimental force-time data were scaled using five normalization techniques, which were evaluated using log rank, Wilcoxon rank sum, and correlation and analysis (CORA) testing. Survival analyses with Weibull distribution were performed on the experimental peak force (scaled and unscaled) and the simulation test data to generate injury risk curves (IRCs) for total pelvic injury. Additionally, IRCs were developed for regional injury using cross-sectional forces from the simulation results and injuries documented in the experimental autopsies. These regional IRCs were also evaluated using the receiver operator characteristic (ROC) curve analysis. Based on the results of all the evaluation methods, the equal stress equal velocity (ESEV) and ESEV using effective mass (ESEV-EM) scaling techniques performed best. The simulation IRC shows slight under prediction of injury in comparison to these scaled experimental data curves. However, this difference was determined not to be statistically significant. Additionally, the ROC curve analysis showed moderate predictive power for all regional IRCs.

Validation of a Custom Instrumented Retainer Form Factor for Measuring Linear and Angular Head Impact Kinematics.

Head impact exposure in popular contact sports is not well understood, especially in the youth population, despite recent advances in impact-sensing technology which has allowed widespread collection of real-time head impact data. Previous studies indicate that a custom-instrumented mouthpiece is a superior method for collecting accurate head acceleration data. The objective of this study was to evaluate the efficacy of mounting a sensor device inside an acrylic retainer form factor to measure six-degrees-of-freedom (6DOF) head kinematic response. This study compares 6DOF mouthpiece kinematics at the head center of gravity (CG) to kinematics measured by an anthropomorphic test device (ATD). This study found that when instrumentation is mounted in the rigid retainer form factor, there is good coupling with the upper dentition and highly accurate kinematic results compared to the ATD. Peak head kinematics were correlated with r2 > 0.98 for both rotational velocity and linear acceleration and r2 = 0.93 for rotational acceleration. These results indicate that a rigid retainer-based form factor is an accurate and promising method of collecting head impact data. This device can be used to study head impacts in helmeted contact sports such as football, hockey, and lacrosse as well as nonhelmeted sports such as soccer and basketball. Understanding the magnitude and frequency of impacts sustained in various sports using an accurate head impact sensor, such as the one presented in this study, will improve our understanding of head impact exposure and sports-related concussion.

Head Impact Exposure in Practices Correlates With Exposure in Games for Youth Football Players.

This study aimed to compare head impact exposures between practices and games in football players ages 9 to 14 years, who account for approximately 70% of all football players in the United States. Over a period of 2 seasons, 136 players were enrolled from 3 youth programs, and 49,847 head impacts were recorded from 345 practices and 137 games. During the study, individual players sustained a median of 211 impacts per season, with a maximum of 1226 impacts. Players sustained 50th (95th) percentile peak linear acceleration of 18.3 (46.9) g, peak rotational acceleration of 1305.4 (3316.6) rad·s-2, and Head Impact Technology Severity Profile of 13.7 (24.3), respectively. Overall, players with a higher frequency of head impacts at practices recorded a higher frequency of head impacts at games (P < .001, r2 = .52), and players who sustained a greater average magnitude of head impacts during practice also recorded a greater average magnitude of head impacts during games (P < .001). The youth football head impact data quantified in this study provide valuable insight into the player exposure profile, which should serve as a key baseline in efforts to reduce injury.

Biomechanical Evaluations of Ocular Injury Risk for Blast Loading.

Ocular trauma is one of the most common types of combat injuries resulting from the exposure of military personnel with improvised explosive devices. The injury mechanism associated with the primary blast wave is poorly understood. We employed a three-dimensional computational model, which included the main internal ocular structures of the eye, spatially varying thickness of the cornea-scleral shell, and nonlinear tissue properties, to calculate the intraocular pressure and stress state of the eye wall and internal ocular structure caused by the blast. The intraocular pressure and stress magnitudes were applied to estimate the injury risk using existing models for blunt impact and blast loading. The simulation results demonstrated that blast loading can induce significant stresses in the different components of the eyes that correlate with observed primary blast injuries in animal studies. Different injury models produced widely different injury risk predictions, which highlights the need for experimental studies evaluating mechanical and functional damage to the ocular structures caused by the blast loading.