Impact test comparisons of 20th and 21st century American football helmets

Object Concussion is the signature American football injury of the 21st century. Modern varsity helmets, as compared with vintage leather helmets, or “leatherheads,” are widely believed to universally improve protection by reducing head impact doses and head injury risk for the 3 million young football players in the US. The object of this study was to compare the head impact doses and injury risks with 11 widely used 21st century varsity helmets and 2 early 20th century leatherheads and to hypothesize what the results might mean for children wearing similar varsity helmets. Methods In an injury biomechanics laboratory, the authors conducted front, oblique front, lateral, oblique rear, and rear head impact tests at 5.0 m/second using helmeted headforms, inducing near- and subconcussive head impact doses on par with approximately the 95th percentile of on-field collision severity. They also calculated impact dose injury risk parameters common to laboratory and on-field traumatic neuromechanics: linear acceleration, angular acceleration, angular velocity, Gadd Severity Index, diffuse axonal injury, acute subdural hematoma, and brain contusion. Results In many instances the head impact doses and head injury risks while wearing vintage leatherheads were comparable to or better than those while wearing several widely used 21st century varsity helmets. Conclusions The authors do not advocate reverting to leather headgear, but they do strongly recommend, especially for young players, instituting helmet safety designs and testing standards, which encourage the minimization of linear and angular impact doses and injury risks in near- and subconcussive head impacts.

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Risk assessment in different Judo techniques for children and adolescent athletes

Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine ◽

10.1177/0954411920915589 ◽

2020 ◽

Vol 234 (7) ◽

pp. 686-696

Author(s):

Luca Vacca ◽

Valeria Rosso ◽

Laura Gastaldi

Keyword(s):

Head Injury ◽

Injury Risk ◽

Inertial Sensors ◽

Angular Acceleration ◽

Linear Acceleration ◽

Severity Index ◽

Time Duration ◽

Neck Extension ◽

Children And Adolescent ◽

Experience Levels

Judo is a combat sport that involves throwing the opponent onto the back. When being thrown, head biomechanics may be related to head injury risk. This study aimed to assess head injury risks associated with four Judo techniques in children and adolescents with different experience levels. Twenty children (<12 years) and 20 adolescents (≥ 12 years) judoka were recruited. Each group was divided into non-expert and expert. Two inertial sensors were fixed on fallers’ head and torso. Two backward ( o-soto-gari and o-uchi-gari) and two forward ( ippon-seoi-nage and tai-otoshi) techniques were performed. Peak of linear and angular head acceleration magnitude, impact time duration, neck angle, and the Gadd Severity Index were assessed. Children did not show differences between techniques or experience levels. In contrast, adolescents showed greater linear acceleration peak in o-soto-gari than tai-otoshi (p = 0.03), greater angular acceleration peak in o-soto-gari and o-uchi-gari than ippon-seoi-nage (p < 0.05), and greater neck flexion in o-uchi-gari than ippon-seoi-nage (p = 0.004). Compared to expert adolescents, non-expert adolescents showed greater angular acceleration peak, impact duration, and the Gadd Severity Index in o-soto-gari (p < 0.05) and greater neck extension in o-uchi-gari (p = 0.02). Current results pointed out higher risks for adolescents judoka while being thrown with backward techniques, especially for non-expert participants. This study highlights the need of training athletes in controlling head and neck during back falls from a young age to become expert judoka in adulthood.

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Similar head impact acceleration measured using instrumented ear patches in a junior rugby union team during matches in comparison with other sports

Journal of Neurosurgery Pediatrics ◽

10.3171/2015.12.peds15605 ◽

2016 ◽

Vol 18 (1) ◽

pp. 65-72 ◽

Cited By ~ 15

Author(s):

Doug A. King ◽

Patria A. Hume ◽

Conor Gissane ◽

Trevor N. Clark

Keyword(s):

Injury Risk ◽

Linear Acceleration ◽

Rugby Union ◽

Head Impact ◽

American Football ◽

Football Players ◽

Head Impacts ◽

Impact Acceleration ◽

The Impact ◽

Rugby Players

OBJECTIVE Direct impact with the head and the inertial loading of the head have been postulated as major mechanisms of head-related injuries, such as concussion. METHODS This descriptive observational study was conducted to quantify the head impact acceleration characteristics in under-9-year-old junior rugby union players in New Zealand. The impact magnitude, frequency, and location were collected with a wireless head impact sensor that was worn by 14 junior rugby players who participated in 4 matches. RESULTS A total of 721 impacts > 10g were recorded. The median (interquartile range [IQR]) number of impacts per player was 46 (IQR 37–58), resulting in 10 (IQR 4–18) impacts to the head per player per match. The median impact magnitudes recorded were 15g (IQR 12g–21g) for linear acceleration and 2296 rad/sec2 (IQR 1352–4152 rad/sec2) for rotational acceleration. CONCLUSIONS There were 121 impacts (16.8%) above the rotational injury risk limit and 1 (0.1%) impact above the linear injury risk limit. The acceleration magnitude and number of head impacts in junior rugby union players were higher than those previously reported in similar age-group sports participants. The median linear acceleration for the under-9-year-old rugby players were similar to 7- to 8-year-old American football players, but lower than 9- to 12-year-old youth American football players. The median rotational accelerations measured were higher than the median and 95th percentiles in youth, high school, and collegiate American football players.

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Laboratory and field evaluation of a small form factor head impact sensor in un-helmeted play

Proceedings of the Institution of Mechanical Engineers Part P Journal of Sports Engineering and Technology ◽

10.1177/1754337117739458 ◽

2017 ◽

Vol 232 (3) ◽

pp. 242-254 ◽

Cited By ~ 3

Author(s):

Derek Nevins ◽

Kasee Hildenbrand ◽

Jeff Kensrud ◽

Anita Vasavada ◽

Lloyd Smith

Keyword(s):

Form Factor ◽

Center Of Mass ◽

False Negative ◽

Angular Acceleration ◽

Linear Acceleration ◽

Field Evaluation ◽

Head Impact ◽

Sensor Data ◽

Small Form ◽

Small Form Factor

Head impact sensors are increasingly used to quantify the frequency and magnitude of head impacts in sports. A dearth of information exists regarding head impact in un-helmeted sport, despite the substantial number of concussions experienced in these sports. This study evaluated the performance of one small form factor head impact sensor in both laboratory and field environments. In laboratory tests, sensor performance was assessed using a Hybrid III headform and neck. The headform assembly was mounted on a low-friction sled and impacted with three sports balls over a range of velocities (10–31 m/s) at two locations and from three directions. Measures of linear and angular acceleration obtained from the small form factor wireless sensor were compared to measures of linear and angular acceleration obtained by wired sensors mounted at the headform center of mass. Accuracy of the sensor varied inversely with impact magnitude, with relative differences across test conditions ranging from 0.1% to 266.0% for peak linear acceleration and 4.7% to 94.6% for peak angular acceleration when compared to a wired reference system. In the field evaluation, eight male high school soccer players were instrumented with the head impact sensor in seven games. Video of the games was synchronized with sensor data and reviewed to determine the number of false positive and false negative head acceleration event classifications. Of the 98 events classified as valid by the sensor, 20.5% (20 impacts) did not result from contact with the ball, another player, the ground or player motion and were therefore considered false positives. Video review of events classified as invalid or spurious by the sensor found 77.8% (14 of 18 impacts) to be due to contact with the ball, another player or player motion and were considered false negatives.

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Head Kinematics by Contact Scenarios in Youth Ice Hockey

Neurology ◽

10.1212/wnl.0000000000011045 ◽

2020 ◽

Vol 95 (20 Supplement 1) ◽

pp. S1.1-S1

Author(s):

Abigail Swenson ◽

Logan Miller ◽

Jillian Urban ◽

Joel Stitzel

Keyword(s):

Rotational Velocity ◽

Angular Acceleration ◽

Linear Acceleration ◽

Head Impact ◽

Ice Hockey ◽

Contact Sports ◽

Head Impacts ◽

Rigorous Study ◽

Improving Accuracy ◽

Impact Events

ObjectiveThe objective of this pilot study was to characterize head impact exposure in a sample of youth boys' ice hockey using a novel instrumented mouthpiece, improving accuracy.BackgroundFrom 2010 to 2018 youth ice hockey saw a 15% increase in participation, despite growing concerns for concussion risk in contact sports. While contact sports with similar rates of concussion have been subjected to rigorous study, head impact exposure in youth ice hockey has been largely underexplored. Existing youth studies have utilized helmet-mounted sensors, which are associated with error due to poor coupling with the skull.Design/MethodsCustom mouthpieces containing a tri-axial accelerometer and gyroscope were fit to seven enrolled athletes, and monitored during practices and games throughout the season. Linear acceleration and rotational velocity of the head were recorded for 60 ms when 5 g was exceeded on any axis for at least 3 ms. Time-synchronized film was reviewed to identify the contact scenario and head contact. Summary statistics of kinematics were calculated by scenario and presence of head contact.ResultsA total of 465 events were recorded over 25 weeks. Of these events 25% involved head contact; 92% of all contact scenarios were board checks, falls, or ice checks. Events involving head contact (i.e., head impacts) had median [95th percentile] peak linear acceleration, rotational velocity, and angular acceleration of 8.1 [30.9] g, 7.9 [20.2] rad/s, and 614 [2673] rad/s2, respectively. Events not involving head contact had median [95th percentile] peak linear acceleration, rotational velocity, and angular acceleration of 6.6 [43.8] g, 6.5 [17.5] rad/s, and 455 [4115] rad/s2, respectively.ConclusionsThe majority of the recorded events could be classified as board checks, falls, or ice checks. Median peak kinematics were higher for head impacts than non-head impact events. In contrast, 95th percentile linear and angular accelerations were greater for impacts not involving head contact.

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Development and Multi-Scale Validation of a Finite Element Football Helmet Model

Annals of Biomedical Engineering ◽

10.1007/s10439-019-02345-7 ◽

2019 ◽

Vol 48 (1) ◽

pp. 258-270 ◽

Cited By ~ 4

Author(s):

William Decker ◽

Alex Baker ◽

Xin Ye ◽

Philip Brown ◽

Joel Stitzel ◽

...

Keyword(s):

Finite Element ◽

Head Injury ◽

Scale Validation ◽

Linear Acceleration ◽

Football Player ◽

American Football ◽

Head Model ◽

Fe Model ◽

Contact Sports ◽

Football Helmet

Abstract Head injury is a growing concern within contact sports, including American football. Computational tools such as finite element (FE) models provide an avenue for researchers to study, and potentially optimize safety tools, such as helmets. The goal of this study was to develop an accurate representative helmet model that could be used in further study of head injury to mitigate the toll of concussions in contact sports. An FE model of a Schutt Air XP Pro football helmet was developed through three major steps: geometry development, material characterization, and model validation. The fully assembled helmet model was fit onto a Hybrid III dummy head–neck model and National Operating Committee on Standards for Athletic Equipment (NOCSAE) head model and validated through a series of 67 representative impacts similar to those experienced by a football player. The kinematic and kinetic response of the model was compared to the response of the physical experiments, which included force, head linear acceleration, head angular velocity, and carriage acceleration. The outputs between the model and the physical tests were quantitatively evaluated using CORelation and Analysis (CORA), amounting to an overall averaged score of 0.76. The model described in this study has been extensively validated and can function as a building block for innovation in player safety.

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Acute subdural hematoma and diffuse axonal injury after severe head trauma

Journal of Neurosurgery ◽

10.3171/jns.1988.68.6.0894 ◽

1988 ◽

Vol 68 (6) ◽

pp. 894-900 ◽

Cited By ~ 62

Author(s):

Juan Sahuquillo-Barris ◽

Jose Lamarca-Ciuro ◽

Jorge Vilalta-Castan ◽

Enrique Rubio-Garcia ◽

Manuel Rodriguez-Pazos

Keyword(s):

Head Injury ◽

Subdural Hematoma ◽

Traffic Accidents ◽

Road Traffic ◽

Axonal Injury ◽

Diffuse Axonal Injury ◽

Acute Subdural Hematoma ◽

Content Type ◽

Hypoxic Brain ◽

Clinicopathological Findings

✓ The association of acute subdural hematoma (SDH) and diffuse axonal injury has received little attention in the literature. The authors report the clinicopathological findings in six patients who died of severe head injury in whom computerized tomography revealed acute SDH as the predominant lesion. All patients were injured in road traffic accidents and lost consciousness on impact. The mean total contusion index was 17.4 and severe contusions were seen in only two cases. All patients presented histological criteria of intracranial hypertension (pressure necrosis focus in one or both parahippocampal gyri). Hypoxic brain damage was evident in the postmortem examination of three patients. In three cases, macroscopic hematic lesions were observed in the corpus callosum. All patients had widespread axonal retraction balls disseminated in the white brain matter. Three patients who survived for more than 11 days had microglial clusters. In some patients with a head injury, acute SDH may be only an epiphenomenon of a primary impact lesion of variable severity: that is, a diffuse axonal injury. In these cases, the final outcome is fundamentally dependent on the severity of the subjacent diffuse axonal injury.

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The influence of deflection and neck compliance on the impact dynamics of a Hybrid III headform

Proceedings of the Institution of Mechanical Engineers Part P Journal of Sports Engineering and Technology ◽

10.1243/17543371jset34 ◽

2009 ◽

Vol 223 (3) ◽

pp. 89-97 ◽

Cited By ~ 4

Author(s):

P Rousseau ◽

T B Hoshizaki

Keyword(s):

Angular Acceleration ◽

Linear Acceleration ◽

Severity Index ◽

Impact Dynamics ◽

Risk Of Injury ◽

Lateral Translation ◽

Hybrid Iii ◽

Front Impact ◽

The Impact

The objective of this study was to determine the influence of impact deflection and neck compliance on the Gadd severity index (GSI), peak linear acceleration, and peak angular acceleration during a front impact to a Hybrid III head using a pneumatic linear impactor. Impact deflection was performed by translating the headform laterally and was shown to be effective at reducing the linear and angular accelerations as well as the GSI. Neck compliance was altered using one Hybrid III 50th percentile neck and two modified Hybrid III necks. A less compliant neck increased linear acceleration but decreased angular acceleration and GSI. When compared with estimated injury thresholds, the results demonstrated that an increase in the lateral translation or a decrease in the neck compliance resulted in a significant decrease in the risk of injury as reflected by peak linear and angular accelerations and the GSI.

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Child ATD Reconstruction of a Fatal Pediatric Fall

Volume 2: Biomedical and Biotechnology Engineering ◽

10.1115/imece2009-12994 ◽

2009 ◽

Cited By ~ 2

Author(s):

Chris Van Ee ◽

David Raymond ◽

Kirk Thibault ◽

Warren Hardy ◽

John Plunkett

Keyword(s):

Head Injury ◽

Additional Data ◽

Skull Fracture ◽

Angular Acceleration ◽

Linear Acceleration ◽

Test Device ◽

Critical Data ◽

Animal Data ◽

Injury Assessment ◽

Accident Scenarios

The current head Injury Assessment Reference Values (IARVs) for the child dummies are based in part on scaling adult and animal data and on reconstructions of real world accident scenarios. Reconstruction of well-documented accident scenarios provides critical data in the evaluation of proposed IARV values, but relatively few accidents are sufficiently documented to allow for accurate reconstructions. This reconstruction of a well documented fatal-fall involving a 23-month old child supplies additional data for IARV assessment. The videotaped fatal-fall resulted in a frontal head impact onto a carpet-covered cement floor. The child suffered an acute right temporal parietal subdural hematoma without skull fracture. The fall dynamics were reconstructed in the laboratory and the head linear and angular accelerations were quantified using the CRABI-18 Anthropomorphic Test Device (ATD). Peak linear acceleration was 125 ± 7 g (range 114–139), HIC15 was 335 ± 115 (Range 257–616), peak angular velocity was 57± 16 (Range 26–74), and peak angular acceleration was 32 ± 12 krad/s2 (Range 15–56). The results of the CRABI-18 fatal fall reconstruction were consistent with the linear and rotational tolerances reported in the literature. This study investigates the usefulness of the CRABI-18 anthropomorphic testing device in forensic investigations of child head injury and aids in the evaluation of proposed IARVs for head injury.

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