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Mixed martial arts (MMA) is a sport where the fighters are at high risk of brain trauma, with characteristics, such as the frequency, magnitude, and interval of head impacts influencing the risk of developing short- and long-term negative brain health outcomes. These characteristics may be influenced by weight class as they may have unique fighting styles. The purpose of this research was to compare frequency, magnitude, and interval of head impacts between lightweight and heavyweight fighters in professional MMA. Frequency, interval, event type, velocity, and location of head impacts were documented for 60 fighters from 15 Lightweight and 15 Heavyweight professional MMA fights. Head impact reconstructions of these events were performed using physical and finite element modelling methods to determine the strain in the brain tissues. The results found that LW and HW fighters sustained similar head impact frequencies and intervals. The LW fighters sustained a significantly higher frequency of very low and high magnitude impacts to the head from punches; HW a larger frequency of high category strains from elbow strikes. These brain trauma profiles reflect different fight strategies and may inform methods to manage and mitigate the long-term effects of repetitive impacts to the head.

Rugby league has been identified as a contact sport with a high incidence of concussion. Research has been conducted to describe incidence and mechanisms of concussion in rugby league, however the risks associated with injury events (shoulder, hip, head to head) are unknown. The purpose of this study was to describe the common injury events leading to concussion in the National Rugby League and compare these events through analysis of dynamic response and brain tissue deformation. Twenty-seven impact videos of concussive injuries were physically reconstructed to obtain linear and rotational accelerations of the head. Dynamic response data were input into the University College Dublin Brain Trauma Model (UCDBTM) to calculate maximum principal strain (MPS). Head-to-head events produced a short duration event with an average peak linear and peak rotational acceleration of 205 g and 15,890 rad/s2, respectively, which were significantly greater than the longer duration hip-to-head (24.7 g and 2650 rad/s2) and shoulder-to-head (24.2 g and 3280 rad/s2) impacts. There were no differences in MPS between events. These results suggest that risk of strain to the brain may be produced by short and long duration acceleration events. Thus, both of these accelerations need to be accounted for in the development of improved head and body protection in rugby. In addition, this data demonstrates that these events cause a risk of concussion requiring efforts to limit or modify how energy is transferred to the head.

Compared to adults, it has been documented that children are at elevated risk for concussion, repeated concussions, and experience longer recovery times. What is unknown, is whether the developing brain may be injured at differing strain levels. This study examined peak and cumulative brain strain from 20 cases of concussion in both young children and adults using physical reconstructions and finite element modelling of the brain response to impacts. The child group showed lower impact kinematics as well as strain metrics. Results suggest children may suffer concussive injuries with lower brain strains compared to adults.

The purpose of this study was to test the effectiveness of a helmet to reduce maximum principal strain by decoupling the head–helmet interface in reconstructions of head-to-head concussive impacts in American football. The primary goal of the American football helmet has been protection of players against skull fractures and other traumatic brain injuries. The modern-day helmet has evolved and been designed to mitigate traumatic brain injury, but it does not offer optimized protection against concussive injury. Studies to determine the influence of decoupling strategies on changes to brain motion and the resulting influence on maximum principal strain, a metric associated with concussive injury, have not yet been examined under concussive impact conditions. In this study, 19 helmet-to-helmet concussive events from professional American football were reconstructed using a pneumatically driven linear impactor to determine the components (resultant and dominant) of linear and rotational acceleration. The University of College Dublin Brain Trauma Model was used to determine maximum principal strain values. A prototype helmet with a decoupling liner strategy was shown to significantly reduce maximum principal strain in seven of the head-to-head concussive impact reconstructions. In each case, the prototype helmet significantly reduced the dominant coordinate component of rotational acceleration. The results of this study indicate the potential of a helmet liner decoupling system in reducing maximum principal strain for reconstructions of concussive events in American football.

In cycling, oblique head impacts from a fall cause rotational motion of a cyclist’s head and it is rotational kinematics that are most commonly associated with mild and severe brain injuries. This ...

Objective Impacts to the head are the primary cause of concussive injuries in sport and can occur in a multitude of different environments. Each event is composed of combinations of impact characteristics (striking velocity, impact mass, and surface compliance) that present unique loading conditions on the head and brain. The purpose of this study was to compare falls, collisions, and punches from accident reconstructions of sports-related head impacts using linear, rotational accelerations and maximal principal strain of brain tissue from finite element simulation. Methods This study compared four types of head impact events through reconstruction. Seventy-two head impacts were taken from medical reports of accidental falls and game video of ice hockey, American football, and mixed-martial arts. These were reconstructed using physical impact systems to represent helmeted and unhelmeted falls, player-to-player collisions, and punches to the head. Head accelerations were collected using a Hybrid III headform and were input into a finite element brain model used to approximate strain in the cerebrum associated with the external loading conditions. Results Significant differences ( p 2) and pulse durations between all impact event types characterized by unique impact parameters. The only exception was found where punch impacts and helmeted falls had similar rotational durations. Regression analysis demonstrated that increases to strain from unhelmeted falls were significantly influenced by both linear and rotational accelerations, meanwhile helmeted falls, punches, and collisions were influenced by rotational accelerations alone. Conclusion This report illustrates that the four distinct impact events created unique peak head kinematics and brain tissue strain values. These distinct patterns of head acceleration characteristics suggest that it is important to keep in mind that head injury can occur from a range of low to high acceleration magnitudes and that impact parameters (surface compliance, striking velocity, and impact mass) play an important role on the duration-dependent tolerance to impact loading.

Despite young children being a high-risk population for sustaining concussive injuries in sport, few studies have investigated head impact biomechanics from sporting impacts using physical models and finite element models of the brain. Physical reconstructions are often used in concussive research, using the recorded kinematics to load finite element models of the brain to obtain better information of real-life head injuries. For children, scaling adult models is a common method used to study the youth population. However, this method does not capture age-dependent material properties or the unique geometry of the developing brain. To address these deficiencies, a novel three-dimensional finite element model of a 6-year-old child was developed and compared to a scaled adult model, for use with physical reconstructions. With the lack of intracranial validation data for the youth population, adult cadaveric data for brain motion was used for comparison. The new brain model showed unique responses in motion and strain compared to the scaled adult model. Using the normalized integral square error method, the new model was classified to have ‘fair’ to ‘excellent’ biofidelity. The new model is proposed as more appropriate for conducting concussion and brain injury research in young children near 6 years of age.

The use of anthropomorphic test devices in head impact biomechanics research is common; however, each device has unique properties based on its construction. When conducting reconstructions, choice of head form is at the discretion of the researcher. In addition, different data collection methods are often used. The influence of different test devices can affect comparisons between studies, as each device elicits different impact responses due to different physical properties. This study describes a method of comparison for anthropomorphic test devices based on finite element response of brain motion. Occipital impacts were conducted on a monorail drop rig, following impact parameters similar to a cadaveric impact that has been used for validation of finite element models of the brain. Two commonly used anthropomorphic test devices, the Hodgson-WSU and Hybrid III, were impacted. These head forms were evaluated by dynamic responses, brain motion via neutral density target traces, and maximum principal strain for two impact velocities. The Hybrid III head form showed lower magnitude results compared to the Hodgson-WSU for peak linear and rotational accelerations, rotational velocity, maximum principal strain, and neutral density target excursions. The smallest differences in response were 11% for peak linear acceleration with differences in neutral density target excursions reaching 60%. Maximum principal strain is suggested as the most comparable metric between anthropomorphic test devices after peak linear acceleration, with expectation of lower responses from the Hybrid III as compared to those of the Hodgson-WSU.

American football helmets used by youth players are currently designed and tested to the same standards as professionals. The National Operating Committee on Standard and Safety requested research aiming at understanding the differences in brain trauma in youth American football for players aged five to nine and nine to fourteen years old to inform a youth specific American football standard. Video analysis and laboratory reconstructions of head impacts were undertaken to measure differences in head impact frequency, event types, and magnitudes of maximum principal strain (MPS) for the two age groups. Overall frequencies and frequencies for five categories of MPS representing different magnitudes of risk were tabulated. The MPS categories were very low (0.08), low (0.08-0.169), medium (0.17-0.259), high (0.26-0.349) and very high (0.35). Both cohorts experienced a majority of head impacts (56%) at very low magnitude of MPS. Youth American football players aged 9-14 yrs. sustained a greater frequency of head impacts at MPS between 0.08 and 0.169 % associated with changes in brain structure and function. There were no differences in overall frequency, or in frequency of head impacts in other categories of MPS. The proportion of impacts considered injurious (MPS 0.08) was greater in the 5-9 group (44%), than the 9-14 group (39%), and impacts above 0.35 % were only reported for the younger age group. The larger helmet-to-shoulder ratio in the younger age groups may have contributed to this finding suggesting that youth American football players under the age of nine would benefit from a child-specific football helmet.

American football players are frequently exposed to head impacts, which can cause concussions and may lead to neurodegenerative diseases such as chronic traumatic encephalopathy (CTE). Player position appears to influence the risk of concussion but there is limited work on its effect on the risk of CTE. Computational modelling has shown that large brain deformations during head impacts co-localise with CTE pathology in sulci. Here we test whether player position has an effect on brain deformation within the sulci, a possible biomechanical trigger for CTE. We physically reconstructed 148 head impact events from video footage of American Football games. Players were separated into 3 different position profiles based on the magnitude and frequency of impacts. A detailed finite element model of TBI was then used to predict Green-Lagrange strain and strain rate across the brain and in sulci. Using a one-way ANOVA, we found that in positions where players were exposed to large magnitude and low frequency impacts (e.g. defensive back and wide receiver), strain and strain rate across the brain and in sulci were highest. We also found that rotational head motion is a key determinant in producing large strains and strain rates in the sulci. Our results suggest that player position has a significant effect on impact kinematics, influencing the magnitude of deformations within sulci, which spatially corresponds to where CTE pathology is observed. This work can inform future studies investigating different player-position risks for concussion and CTE and guide design of prevention systems.

Brain injuries are prevalent in the sport of American football. Helmets have been used which effectively have reduced the incidence of traumatic brain injury, but have had a limited effect on concussion rates. In an effort to improve the protective capacity of American football helmets, a standard has been proposed by National Operating Committee on Standards for Athletic Equipment that may better represent helmet-to-helmet impacts common to football concussions. The purpose of this research was to examine the National Operating Committee on Standards for Athletic Equipment standard and a new impact method similar to the proposed National Operating Committee on Standards for Athletic Equipment standard to examine the information these methods provide on helmet performance. Five National Operating Committee on Standards for Athletic Equipment–certified American football helmets were impacted according to the National Operating Committee on Standards for Athletic Equipment standard test and a new method based on the proposed standard test. The results demonstrated that the National Operating Committee on Standards for Athletic Equipment test produced larger linear accelerations than the new method, which were a reflection of the stiffer compliance of the standard meant to replicate traumatic brain injury mechanisms of injury. When the helmets were impacted using a new helmet-to-helmet method, the results reflected significant risk of concussive injury but showed differences in rotational acceleration responses between different helmet models. This suggests that the new system is sensitive enough to detect the effect of different design changes on rotational acceleration, a metric more closely associated with risk of concussion. As only one helmet produced magnitudes of response lower than the National Operating Committee on Standards for Athletic Equipment pass/fail using the new system, and all helmets passed the National Operating Committee on Standards for Athletic Equipment standard, these results suggest that further development of helmet technologies must be undertaken to reduce this risk in the future. Finally, these results show that it would be prudent to use both standards together to address risk of injury from traumatic brain injury and concussion.

Students, faculty, administration, and community members of three Iowa rural school districts were interviewed to identify educational issues in their communities The results of the Iowa investigation are compared with the results of the Claremont Graduate School investigation published in Voices from the inside: A report on schooling from inside the classroom (1992). The Claremont study investigated large urban schools. The Iowa study provides insight into small, rural school districts. Although similar issues emerged from the two studies, other issues demonstrated the different realities of education in rural Iowa and education in a large culturally diverse urban setting.

Objective Like many sports involving high speeds and body contact, head injuries are a concern for short track speed skating athletes and coaches. While the mandatory use of helmets has managed to nearly eliminate catastrophic head injuries such as skull fractures and cerebral haemorrhages, they may not be as effective at reducing the risk of a concussion. The purpose of this study was to evaluate the performance characteristics of speed skating helmets with respect to managing peak linear and peak rotational acceleration, and to compare their performance against other types of helmets commonly worn within the speed skating sport. Materials and methods Commercially available speed skating, bicycle and ice hockey helmets were evaluated using a three-impact condition test protocol at an impact velocity of 4 m/s. Results and discussion Two speed skating helmet models yielded mean peak linear accelerations at a low-estimated probability range for sustaining a concussion for all three impact conditions. Conversely, the resulting mean peak rotational acceleration values were all found close to the high end of a probability range for sustaining a concussion. A similar tendency was observed for the bicycle and ice hockey helmets under the same impact conditions. Conclusion Speed skating helmets may not be as effective at managing rotational acceleration and therefore may not successfully protect the user against risks associated with concussion injuries.

Transparent conductive oxide layers (TCO) are used as electrodes for thin film applications. The optical performance of TCOs can be improved by implementing textured surfaces that will increase the overall transmission of light through the TCO layer. In this paper, a model is developed using Synopsys TCAD to accurately predict the behavior of a thin film of fluorine doped tin oxide (FTO) on a glass substrate. Its accuracy is assessed using experimental data and was further validated by using the simulated transmission curve to estimate the thickness. It is then used to assess the effect of two types of texturization patterns: rectangular and pyramidal. Inductively coupled plasma- reactive ion etching (ICP-RIE) was used to implement rectangular type patterns on FTO samples. The results show that the rectangular patterns result in minor total transmission gains of 1 – 2 percentage points. This is due to a reduced absorption caused by the removal of material. The best pyramidal patterns increased total transmission by over 5 percentage points. These increases are attributed to reduced reflection.

A linear impactor system was used to apply a condensed version of the University of Ottawa Test Protocol, employing five centric and non-centric impact conditions, to a Hybrid III headform fitted with six certified ice hockey helmets. None of the helmeted conditions exceeded linear acceleration thresholds for traumatic or mild traumatic brain injury; however, five of the six helmets had angular acceleration results that were above the 80% risk of mild traumatic brain injury threshold proposed by Zhang et al. High risk of mild traumatic brain injury was associated with non-centric impact conditions and peak angular accelerations, supporting the need for improved three-dimensional helmet certification standards.

To properly assess sports helmet performance, it is important to select impact conditions that yield high peak linear or angular accelerations. This was done by measuring the kinematic response of a Hybrid III headform when impacted with a modified Wayne State University linear impactor with special consideration for impact locations and angles. The 20 impact conditions (five locations and four angles) were then compared to published thresholds to identify the conditions, which were linked to an increased risk of head injury. These conditions were the following: 1A (linear 121.3g; angular 3.84 krad s−2), 2A (linear 102.1g; angular 9.28 krad s−2), 2C (linear 94.4g; angular 8.67 krad s−2), 3A (linear 132.8g; angular 9.38 krad s−2), 4A (linear 92.8g; angular 11.49 krad s−2), 4D (linear 113.3g; angular 12.86 krad s−2), 5A (linear 116.9g; angular 9.01 krad s−2) and 5D (linear 87.5g; angular 8.81 krad s−2). The results presented in this study were specific to the test rig used as well as the tested conditions; however, it is believed that a test protocol using the above impact conditions could identify the ability of sports helmets to reduce risk of head injuries.

In American football repetitive brain trauma is associated with high risk of neurologic disorders. Head contact is integral to the game, resulting in high frequency of head contacts during a game/season. Low energy impacts that do not manifest signs recognized as injury still present metabolic and/or physiologic changes within the brain. The purpose was to estimate player position specific brain trauma profiles based on strain magnitude and impact frequency. Head impacts from 32 game films of professional football were documented and categorized based on event type, head location, and velocity for 8 positions. Inbound velocity was calculated using Kinovea 0.8.20 software. Events were reconstructed using 50th percentile Hybrid III headform, unbiased neckform, linear impactor (collisions) and monorail drop tower (falls). Maximum principal strain (MPS) within the cerebrum was calculated using UCDBTM. Frequency [p < 0.0005] and magnitude [p < 0.0005] were significantly different between the 8 positions. No significant differences in frequencies between the following; quarterback, wide receiver, and defensive back; running back, tight end, and linebacker; and between offensive and defensive linemen. Approximately 60% of documented impacts were received by linemen and tight end. The magnitudes of impacts experienced by quarterbacks were significantly different to all positions excluding wide receiver and defensive back. Wide receiver experienced significantly different magnitudes than both linemen; and differences were found between offensive linemen and defensive back. Approximately 95% of impacts experienced by linemen were below 17% MPS. Conversely, over 90% of impacts documented for quarterback were above moderate strain magnitudes (>17%). Results show risks of repetitive trauma and injury vary with position; some experience high frequency impacts of low magnitude while others receive lower hit counts of higher magnitudes. Findings showed that tight end and running back are particularly risky with relatively high brain strain magnitudes coupled with high frequency making them susceptible to high trauma loads.

IntroductionLoss of consciousness (LOC) occurs with approximately 8 percent of concussions in professional American football and has been associated with severity of injury (1, 2). However it is unknown how LOC relates to severity of head impact responses. The purpose of this study was to compare the head accelerations and brain tissue deformation between cases of concussions with and without LOC in elite American football to inform prevention strategies.MethodsConcussive injuries with and without LOC from helmet-to-helmet and shoulder collisions as well as falls in elite American football were reconstructed in laboratory using hybrid III headform to obtain peak linear and rotational acceleration and maximum principal strain, cumulative strain damage at 10%, and strain rate metrics in 5 brain regions associated with loss of consciousness.ResultsImpact velocity, peak linear and rotational acceleration were greater in the LOC group than the no LOC group. The brain tissue deformation metrics were greater in the LOC group than the no LOC group. Linear acceleration was most predictive for cases of helmet-to-helmet collisions whereas shoulder collisions were best predicted by rotational acceleration. The best overall predictor was impact velocity.Discussion/conclusionThe presence of a loss of consciousness in concussive impacts is a result of greater magnitude of brain tissue trauma. This was primarily caused by greater impact velocities in head impacts leading to LOC. Rules aiming at mitigating this aspect of the game would decrease the risk of a loss of consciousness in this sport. Each type of events resulted in different values of kinematic data and brain tissue deformation, which suggests that studies evaluating risk of concussions based 1 type of event cannot be generalized.

IntroductionTrauma related neuropathologies including recent reports involving chronic traumatic encephalopathy (CTE) in 8 soccer players have been concerning. Purposeful sub-concussive head impacts, known as headers, are an integral part of the game. The purpose of this study was to describe dynamic head response and brain tissue strains for front ball-to-head impacts in elite soccer.MethodsVideo analysis thirteen (13) Champion's League soccer footage was completed to establish reconstruction parameters of head impact events. Analysis of 5 (5) front ball-to-head events were reconstructed using a Hybrid III 50th percentile headform and a pneumatic linear impactor. The University College Dublin Brain Trauma Model was used to calculate maximum principal strain (MPS).Results and discussionRecorded head impact velocities during elite soccer game play were 3.5–23.0 m/s. Most purposeful head-to-ball impacts occurred on the front-temporal region of the head (66.4%) at 0–15 degrees of cervical flexion. There was an average of 1.5 unintentional head impacts and 62.2 headers per game; 49.6% of headers occurred at an inbound velocity below 10 m/s. The lowest velocity reconstructed was 4.7 m/s, yielding 12.8 g and 604 rad/s2 for peak resultant linear and rotational accelerations, respectively; the MPS for this impact was 0.09. Neurophysiologic changes and functional impairment have been reported in past research on sub-concussive impacts with 5%–15% strain. The mean 0.11 MPS yielded in this study reflects a potential for these changes in elite soccer athletes.ConclusionThe main objective of this analysis was to identify impact characteristics and quantify dynamic cerebral response and brain tissue deformation in elite soccer game play. Further research must include cervical muscle activation, the level of play and player position, inbound ball-to-head velocities during different game play events and appropriate impact characteristics to appropriately characterize risk of injury in the attempts of mitigating risk of head injury during soccer game play.

The objective of this study was to compare the capacity of vinyl nitrile and expanded polypropylene, two materials commonly used in ice hockey helmets, to reduce the peak linear acceleration, peak angular acceleration, and head injury criterion values during a direct impact to a hybrid III headform. Six different ice hockey helmets were tested using a pneumatic linear impactor at velocities similar to those in hockey. The results showed that helmets using expanded polypropylene foam liners are significantly better at reducing linear acceleration; however, helmets using vinyl nitrile foam liners are significantly better at reducing angular acceleration. Furthermore, the impact location influenced the performance of the liner.

Many helmet safety standards require children's helmets to be tested using adult-weighted headforms of approximately 5 kg and impact velocities representative of adult anatomy. The purpose of this study was to test the individual and combined effect of variable headform mass and inbound headform velocity on helmet test results. Testing was conducted on sample sections of helmet liner materials commonly used in multi- and single-impact helmets. Three densities of expanded polystyrene and expanded polypropylene were moulded into 2.54-cm thick foam blocks and cut into circular samples with a 5-cm diameter. Each sample was impacted once using an EN 960 magnesium K1A headform of variable mass on a monorail apparatus in the crown position. A total of 25 impact conditions were used: 5 headform masses and 5 inbound velocities. A PCB 203B force sensor collected force data at 20 kHz in the y-axis of the impact and a 1000-Hz low-pass Butterworth filter was applied during analysis. A three-way analysis of va...

Traumatic brain injury (TBI) is a common injury and is a leading cause of morbidity and mortality throughout the world. Research has been undertaken in order to better understand the characteristics of the injury event and measure the risk of injury to develop more effective environmental, technological, and clinical management strategies. This research used methods that have limited applications to predicting human responses. This limits the current understanding of the mechanisms of TBI in humans. As a result, the purpose of this research was to examine the characteristics of impact and dynamic response that leads to a high risk of incurring a TBI in a human population. Twenty TBI events collected from hospital reports and eyewitness accounts were reconstructed in the laboratory using a combination of computational mechanics models and Hybrid III anthropometric dummy systems. All cases were falls, with an average impact velocity of approximately 4.0 m/s onto hard impact surfaces. The results of the methodology were consistent with current TBI research, describing TBI to occur in the range of 335 to 445 g linear accelerations and 23.7 to 51.2 krad/s2 53 angular accelerations. More significantly, this research demonstrated that lower responses in the antero-posterior direction can cause TBI, with lateral impact responses requiring larger magnitudes for the same types of brain lesions. This suggests an increased likelihood of incurring TBI for impacts to the front or back of the head, a result that has implications affecting current understanding of themechanisms of TBI and associated threshold parameters. Canadian Institutes of Health Research (CIHR)

Reconstruction of real-life events can be used to investigate the relationship between the mechanical parameters of the impact and concussion risk. Striking mass has typically been approximated as being the mass of the body part coming into contact with the head without accounting for the force applied by the striking athlete. Thus, the purpose of this study was to measure the effective impact mass of three common striking techniques in ice hockey. Fifteen participants were instructed to strike a suspended 50th percentile Hybrid III headform at least three times with their elbow or shoulder. Effective impact mass was calculated by measuring the change in velocity of the player and the headform. Mean effective impact mass for the extended elbow, tucked-in elbow, and shoulder check conditions were 4.8, 3.0, and 12.9 kg, respectively. Peak linear accelerations were lower than the values associated with concussion in American football which could be a reflection of the methodology used in this study as well as inherent differences between both sports.

BACKGROUND:: Head impact direction has been identified as an influential risk factor in the risk of traumatic brain injury (TBI) from animal and anatomic research; however, to date, there has been little investigation into this relationship in human subjects. If a susceptibility to certain types of TBI based on impact direction was found to exist in humans, it would aid in clinical diagnoses as well as prevention methods for these types of injuries. OBJECTIVE:: To examine the influence of impact direction on the presence of TBI lesions, specifically, subdural hematomas, subarachnoid hemorrhage, and parenchymal contusions. METHODS:: Twenty reconstructions of falls that resulted in a TBI were conducted in a laboratory based on eyewitness, interview, and medical reports. The reconstructions involved impacts to a Hybrid III anthropometric dummy and finite element modeling of the human head to evaluate the brain stresses and strains for each TBI event. RESULTS:: The results showed that it is likely that increased risk of incurring a subdural hematoma exists from impacts to the frontal or occipital regions, and parenchymal contusions from impacts to the side of the head. There was no definitive link between impact direction and subarachnoid hemorrhage. In addition, the results indicate that there is a continuum of stresses and strain magnitudes between lesion types when impact location is isolated, with subdural hematoma occurring at lower magnitudes for frontal and occipital region impacts, and contusions lower for impacts to the side. CONCLUSION:: This hospital data set suggests that there is an effect that impact direction has on TBI depending on the anatomy involved for each particular lesion. ABBREVIATIONS:: MPS, maximum principal strainSAH, subarachnoid hemorrhageSDH, subdural hematomaTBI, traumatic brain injuryUCDBTM, University College Dublin Brain Trauma ModelVMS, von Mises stress. Language: en

Many studies have assessed the ability of hockey helmets to protect against falls and collisions, yet none have addressed the injury risk associated with puck impacts. Thus, the purpose of this study was to document the capacity of a typical vinyl nitrile ice hockey helmet to reduce head accelerations and brain deformation caused by a puck impact. A bare and a helmeted Hybrid III male 50th percentile headform was struck with a puck three times to the forehead at 17, 23, 29, 35, and 41 m/s using a pneumatic puck launcher. Linear and rotational accelerations were captured using accelerometers fitted in the headform and used as input in the University College Dublin Brain Trauma Model to obtain brain deformation. The helmet reduced peak resultant linear acceleration, peak resultant rotational acceleration, and maximum principal strain, but a comparison with published brain injury risk curves shows that it did not reduce the concussion risk below 50 % for impacts at or above 23 m/s. Thus, a vinyl nitrile ice hockey helmet can protect players from direct puck impacts in amateur and youth leagues but may not be adequate in competitive elite leagues, where the puck can be shot at velocities well above 23 m/s. Furthermore, competitive adult male ice hockey players struck to the helmet by a puck may need to consider changing their helmet, as it was shown that direct impacts at or above 35 m/s decreased the helmet’s ability to reduce head peak linear acceleration in subsequent impacts. Deposited by bulk import

Head injuries, and concussion in particular, have become a source of interest in the sport of ice hockey. This study proposes a monorail test methodology combined with a finite element method to evaluate ice hockey helmets in a centric/non-centric protocol with performance metrics more closely associated with risk of concussion. Two conditions were tested using the protocol: (a) helmeted versus no helmet, and (b) vinyl nitrile lined hockey helmet versus expanded polypropylene lined hockey helmet. The results indicate that the impact velocities and locations produced distinct responses. Also, the protocol distinguished important design characteristics of the two helmet liner types, with the vinyl nitrile lined helmet producing lower strain responses in the cerebrum. Furthermore, it was discovered that low risk of injury peak linear and rotational acceleration values can combine to produce much higher risks of injury when using brain deformation metrics. In conclusion, the use of finite element modeling of the human brain along with a centric/non-centric protocol provides an opportunity for researchers and helmet developers to observe how the dynamic response produced by these impacts influences brain tissue deformation and injury risk. This type of centric/non-centric physical to finite element modeling methodology could be used to guide innovation for new methods to prevent concussion. Deposited by bulk import

When determining head injury risks through event reconstruction, it is important to understand how individual impact characteristics influence the dynamic response of the head and its internal structures. The effect of impactor mass has not yet been analyzed in the literature. The purpose of this study was to determine the effects of impactor mass on the dynamic impact response and brain tissue deformation. A 50th-percentile Hybrid III adult male head form was impacted using a simple pendulum system. Impacts to a centric and a non-centric impact location were performed with six varied impactor masses at a velocity of 4.0 m/s. The peak linear and peak angular accelerations were measured. A finite element model (University College Dublin Brain Trauma Model) was used to determine brain deformation, namely, peak maximum principal strain and peak von Mises stress. Impactor mass produced significant differences for peak linear acceleration for centric (F5,24 = 217.55, p = 0.0005) and non-centric (F5,24 = 161.98, p = 0.0005) impact locations, and for peak angular acceleration for centric (F5,24 = 52.51, p = 0.0005) and non-centric (F5,24 = 4.18, p = 0.007) impact locations. A change in impactor mass also had a significant effect on the peak maximum principal strain for centric (F5,24 = 11.04, p = 0.0005) and non-centric (F5,24 = 5.87, p = 0.001) impact locations, and for peak von Mises stress for centric (F5,24 = 24.01, p = 0.0005) and non-centric (F5,24 = 4.62, p = 0.004) impact locations. These results confirm that the impactor mass of an impact should be considered when determining risks and prevention of head and brain injury. Deposited by bulk import

The objective of this study was to investigate the influence of impact angle on the dynamic response of a Hybrid III headform and brain tissue deformation by impacting the front and side of the headform with four angle conditions (0° at the impact site and 5°, 10° and 15° counter-clockwise rotations from 0°) as well as three additional angles of -5°, -10° and -15° (clockwise rotations from 0°) at the side location to examine the effect of direction. The acceleration-time curves were used as input into a finite element model of the brain where maximum principal strain was calculated. The results from this study show that impact angle has an asymmetrical influence on headform dynamic responses and strain. An increase in impact angle tends to result in a growth of headform linear and rotational acceleration and maximum principal strain for the front location as well as the negative angles (0 to -15°) at the side, however varying trends were observed for the positive angles (from 0° to 15°) at the side. When developing sophisticated impact protocols and undertaking head injury reconstruction research, it is important to be aware of impact angle. Deposited by bulk import

This research was undertaken to examine a new method for assessing the performance of ice hockey helmets. It has been proposed that the current centric impact standards for ice hockey helmets, measuring peak linear acceleration, have effectively eliminated traumatic head injuries in the sport, but that angular acceleration and brain tissue deformation metrics are more sensitive to the conditions associated with concussive injuries, which continue to be a common injury. Ice hockey helmets were impacted using both centric and non-centric impact protocols at 7.5 m/s using a linear impactor. Dynamic impact responses and brain tissue deformations from the helmeted centric and non-centric head form impacts were assessed with respect to proposed concussive injury thresholds from the literature. The results of the helmet impacts showed that the method used was sensitive enough to distinguish differences in performance between helmet models. The results have shown that peak linear acceleration yielded low magnitudes of response to an impact, but peak angular acceleration and brain deformation metrics consistently reported higher magnitudes, reflecting a high risk for incurring a mild traumatic brain injury. Deposited by bulk import 02/10/13 RB