The biomechanics of concussion in unhelmeted football players in Australia: A case-control study
- Authors: McIntosh, Andrew , Patton, Declan , Fréchède, Bertrand , Pierré, Paul-André , Ferry, Edouard , Barthels, Tobias
- Date: 2014
- Type: Text , Journal article
- Relation: BMJ Open Vol. 4, no. 5 (2014), p.
- Full Text: false
- Reviewed:
- Description: Objective: Concussion is a prevalent brain injury in sport and the wider community. Despite this, little research has been conducted investigating the dynamics of impacts to the unprotected human head and injury causation in vivo, in particular the roles of linear and angular head acceleration. Setting: Professional contact football in Australia. Participants: Adult male professional Australian rules football players participating in 30 games randomly selected from 103 games. Cases selected based on an observable head impact, no observable symptoms (eg, loss-of-consciousness and convulsions), no on-field medical management and no injury recorded at the time. Primary and secondary outcome measures: A data set for no-injury head impact cases comprising head impact locations and head impact dynamic parameters estimated through rigid body simulations using the MAthematical DYnamic MOdels (MADYMO) human facet model. This data set was compared to previously reported concussion case data. Results: Qualitative analysis showed that the head was more vulnerable to lateral impacts. Logistic regression analyses of head acceleration and velocity components revealed that angular acceleration of the head in the coronal plane had the strongest association with concussion; tentative tolerance levels of 1747 rad/s2 and 2296 rad/s2 were reported for a 50% and 75% likelihood of concussion, respectively. The mean maximum resultant angular accelerations for the concussion and no-injury cases were 7951 rad/s2 (SD 3562 rad/s2) and 4300 rad/s2 (SD 3657 rad/s2), respectively. Linear acceleration is currently used in the assessment of helmets and padded headgear. The 50% and 75% likelihood of concussion values for resultant linear head acceleration in this study were 65.1 and 88.5 g, respectively. Conclusions: As hypothesised by Holbourn over 70 years ago, angular acceleration plays an important role in the pathomechanics of concussion, which has major ramifications in terms of helmet design and other efforts to prevent and manage concussion.
A review of the anthropometric characteristics, grading and dispensation of junior and youth rugby union players in Australia
- Authors: Patton, Declan , McIntosh, Andrew , Denny, Greg
- Date: 2016
- Type: Text , Journal article , Review
- Relation: Sports Medicine Vol. 46, no. 8 (2016), p. 1067-1081
- Full Text: false
- Reviewed:
- Description: The grading of Australian junior and youth rugby union players has received substantial media attention in recent years. Media reports have focussed on size mismatches observed between players, especially players with Polynesian heritage, and the concerned parents who fear for the safety of their child owing to perceived mismatches. Although such concerns are well meaning, few media reports recognise the need for substantial evidence to determine the best grading system for junior and youth rugby union players. The current study reviewed relevant literature pertinent to the grading and dispensation of junior and youth rugby union players. Using primary and secondary search strategies, a total of 33 articles reporting the anthropometric characteristics of junior and youth rugby players were identified. Anthropometric data from the literature were compared with normative population data and currently used dispensation criteria. Junior and youth rugby players were found to be taller and heavier than normative population data. Current dispensation criteria, in terms of body mass, were found to vary and it is suggested that criteria be revised and standardised across rugby unions throughout Australia. Although it is acknowledged that other factors are important for grading players, anthropometric characteristics should be considered as potential dispensation criteria to supplement current age-based grading for junior and youth rugby union players. Measuring the body mass and stature of each junior player upon pre-season registration is suggested, which would provide data to establish valid dispensation criteria for the following season.
Boxing headguard performance in punch machine tests
- Authors: McIntosh, Andrew , Patton, Declan
- Date: 2015
- Type: Text , Journal article
- Relation: British Journal of Sports Medicine Vol. 49, no. 17 (2015), p. 1108-1112
- Full Text: false
- Reviewed:
- Description: Background: The paper presents a novel laboratory method for assessing boxing headguard impact performance. The method is applied to examine the effects of headguards on head impact dynamics and injury risk. Methods: A linear impactor was developed, and a range of impacts was delivered to an instrumented Hybrid III head and neck system both with and without an AIBA (Association Internationale de Boxe Amateur)- approved headguard. Impacts at selected speeds between 4.1 and 8.3 m/s were undertaken. The impactor mass was approximately 4 kg and an interface comprising a semirigid 'fist' with a glove was used. Results: The peak contact forces were in the range 1.9-5.9 kN. Differences in head impact responses between the Top Ten AIBA-approved headguard and bare headform in the lateral and forehead tests were large and/or significant. In the 8.3 m/s fist-glove impacts, the mean peak resultant headform accelerations for bare headform tests was approximately 130 g compared with approximately 85 g in the forehead impacts. In the 6.85 m/s bare headform impacts, mean peak resultant angular head accelerations were in the range of 5200-5600 rad/s
An assessment of the utility and functionality of wearable head impact sensors in Australian Football
- Authors: McIntosh, Andrew , Willmott, Catherine , Patton, Declan , Mitra, Biswadev , Brennan, James , Dimech-Betancourt, Bleydy , Howard, Teresa , Rosenfeld, Jeffrey
- Date: 2019
- Type: Text , Journal article
- Relation: Journal of Science and Medicine in Sport Vol. 22, no. 7 (2019), p. 784-789
- Full Text: false
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- Description: Objectives: To assess the utility and functionality of the X-Patch® as a measurement tool to study head impact exposure in Australian Football. Accuracy, precision, reliability and validity were examined. Designs: Laboratory tests and prospective observational study. Methods: Laboratory tests on X-Patch® were undertaken using an instrumented Hybrid III head and neck and linear impactor. Differences between X-Patch® and reference data were analysed. Australian Football players wore the X-Patch® devices and games were video-recorded. Video recordings were analysed qualitatively for head impact events and these were correlated with X-Patch® head acceleration events. Wearability of the X-Patch® was assessed using the Comfort Rating Scale for Wearable Computers. Results: Laboratory head impacts, performed at multiple impact sites and velocities, identified significant correlations between headform-measured and device-measured kinematic parameters (p < 0.05 for all). On average, the X-Patch®-recorded peak linear acceleration (PLA) was 17% greater than the reference PLA, 28% less for peak rotational acceleration (PRA) and 101% greater for the Head Injury Criterion (HIC). For video analysis, 118 head acceleration events (HAE) were included with PLA ≥30 g across 53 players. Video recordings of X-Patch®-measured HAEs (PLA ≥30 g) determined that 31.4% were direct head impacts, 9.3% were indirect impacts, 44.1% were unknown or unclear and 15.3% were neither direct nor indirect head impacts. The X-Patch® system was deemed wearable by 95–100% of respondents. Conclusions: This study reinforces evidence that use of the current X-Patch® devices should be limited to research only and in conjunction with video analysis.
Helmets : Technological innovations for safety
- Authors: McIntosh, Andrew , Patton, Declan
- Date: 2016
- Type: Text , Book chapter
- Relation: Extreme Sports Medicine Chapter 32 p. 407-415
- Full Text: false
- Reviewed:
- Description: Helmets have been developed to be effective in preventing and/or reducing the severity of head injury for a number of activities, e.g. bicycle and motorcycle helmets. As a result of safety policies, health concerns and economics, both in terms of health costs and the supply of helmets, there is an understanding of impact exposure and helmet performance requirements, as well as systems to supply standard compliant helmets. The performance demands placed on helmets for sporting activities further away from the mainstream may be substantially different, although the principles governing helmet design and performance are the same. Knowledge regarding impact exposure in extreme sports, the economics of helmet development and the absence of standards mean that the helmets in extreme sports may not be optimal or meet the athletes’ expectations. The chapter will focus on the topic of fit for purpose in the context of extreme sports. Fit for purpose means that the helmet is functional for the activities in which it is worn and protects the head within a sport’s injury risk management objectives. The chapter will explain how helmets function to prevent injury and where decisions are required for extreme sports. The challenge of designing helmets for extreme sports will be addressed, e.g. producing helmets that are lightweight, affordable, aero- or hydrodynamically suitable, climate suitable and aesthetically acceptable, which prevent injury in high-energy impacts. © Springer International Publishing Switzerland 2017.
The biomechanical determinants of concussion : Finite element simulations to investigate tissue-level predictors of injury during sporting impacts to the unprotected head
- Authors: Patton, Declan , McIntosh, Andrew , Kleiven, Svein
- Date: 2015
- Type: Text , Journal article
- Relation: Journal of Applied Biomechanics Vol. 31, no. 4 (2015), p. 264-268
- Full Text: false
- Reviewed:
- Description: Biomechanical studies of concussions have progressed from qualitative observations of head impacts to physical and numerical reconstructions, direct impact measurements, and finite element analyses. Supplementary to a previous study, which investigated maximum principal strain, the current study used a detailed finite element head model to simulate unhelmeted concussion and no-injury head impacts and evaluate the effectiveness of various tissue-level brain injury predictors: strain rate, product of strain and strain rate, cumulative strain damage measure, von Mises stress, and intracranial pressure. Von Mises stress was found to be the most effective predictor of concussion. It was also found that the thalamus and corpus callosum were brain regions with strong associations with concussion. Tentative tolerance limits for tissue-level predictors were proposed in an attempt to broaden the understanding of unhelmeted concussions. For the thalamus, tolerance limits were proposed for a 50% likelihood of concussion: 2.24 kPa, 24.0 s-1, and 2.49 s-1 for von Mises stress, strain rate, and the product of strain and strain rate, respectively. For the corpus callosum, tolerance limits were proposed for a 50% likelihood of concussion: 3.51 kPa, 25.1 s-1, and 2.76 s-1 for von Mises stress, strain rate, and the product of strain and strain rate, respectively. © 2015 Human Kinetics, Inc.
Considerations for the performance requirements and technical specifications of soft-shell padded headgear
- Authors: Patton, Declan , McIntosh, Andrew
- Date: 2016
- Type: Text , Journal article , Review
- Relation: Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology Vol. 230, no. 1 (2016), p. 29-42
- Full Text: false
- Reviewed:
- Description: Laboratory and epidemiological research in Australian football, rugby league and rugby union has demonstrated that commercially available soft-shell padded headgear is currently ineffective in reducing the risk of concussion. However, modified headgear studies have demonstrated that significant improvements in impact energy attenuation performance are possible with small design changes, such as increases in foam density and thickness. A literature review of the design, performance and use of headgear in Australian football, rugby league and rugby union was conducted. A total of 23 articles were identified using primary and secondary search strategies, which included epidemiological field studies, laboratory impact test studies and studies investigating the behaviours and attitudes of players. The results of the review were synthesised and used to identify injury reduction objectives and appropriate design criteria. The need for a headgear standard was identified and performance requirements were discussed, which drew upon human tolerance and sports-specific head impact exposure data. Usability and behavioural issues, which require consideration during the design process, were also assessed. © IMechE 2015.
The impact performance of headguards for combat sports
- Authors: McIntosh, Andrew , Patton, Declan
- Date: 2015
- Type: Text , Journal article
- Relation: British Journal of Sports Medicine Vol. 49, no. 17 (2015), p. 1113-1117
- Full Text: false
- Reviewed:
- Description: Background/aim: To assess the impact energy attenuation performance of a range of headguards for combat sports. Methods: Seven headguards worn during combat sport training or competition, including two Association Internationale de Boxe Amateur (AIBA)-approved boxing models, were tested using drop tests. An International Organization for Standardization (ISO) rigid headform was used with a 5.6 kg drop assembly mass. Tests were conducted against a flat rigid anvil both with and without a boxing glove section. The centre forehead and lateral headguard areas were tested. Peak headform acceleration was measured. Tests from a selection of drop heights and repeated tests on the same headguard were conducted. Results: Headguard performance varied by test condition. For the 0.4 m rigid anvil tests, the best model headguard was the thickest producing an average peak headform acceleration over 5 tests of 48 g compared with 456 g for the worst model. The mean peak acceleration for the 0.4, 0.5 and 0.6 frontal and lateral rigid anvil impact tests was between 32% and 40% lower for the Top Ten boxing model compared with the Adidas boxing model. The headguard performance deterioration observed with repeat impact against the flat anvil was reduced for impacts against the glove section. The overall reduction in acceleration for the combination of glove and headguard in comparison to the headguard condition was in the range of 72-93% for 0.6 and 0.8 m drop tests. Conclusions: The impact tests show the benefits of performance testing in identifying differences between headguard models.
Radial and oblique impact testing of alpine helmets onto snow surfaces
- Authors: Patton, Declan , Mohammadi, Reza , Halldin, Peter , Kleiven, Svein , McIntosh, Andrew
- Date: 2023
- Type: Text , Journal article
- Relation: Applied Sciences (Switzerland) Vol. 13, no. 6 (2023), p.
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- Description: Recent studies have found that alpine helmets reduce the risk of focal injuries associated with radial impacts, which is likely due to current alpine helmet standards requiring helmets to be drop-tested on flat anvils with only linear acceleration pass criteria. There is a need to evaluate the performance of alpine helmets in more realistic impacts. The current study developed a method to assess the performance of alpine helmets for radial and oblique impacts on snow surfaces in a laboratory setting. Snow samples were collected from a groomed area of a ski slope. Radial impacts were performed as drop tests onto a stationary snow sample. Oblique impacts were performed as drop tests onto a snow sample moving horizontally. For radial impacts, snow sample collection time was found to significantly (p = 0.005) influence mean peak linear headform acceleration with an increase in ambient temperature softening the snow samples. For oblique tests, the recreational alpine sports helmet with a rotation-damping system (RDS) significantly (p = 0.002) reduced mean peak angular acceleration compared to the same helmets with no RDS by approximately 44%. The ski racing helmet also significantly (p = 0.006) reduced mean peak angular acceleration compared to the recreational alpine sports helmet with no RDS by approximately 33%, which was attributed to the smooth outer shell of the ski racing helmet. The current study helps to bridge the knowledge gap between real helmet impacts on alpine snow slopes and laboratory helmet impacts on rigid surfaces. © 2023 by the authors.