The purpose of this study was to investigate if the impact attenuation properties of ice hockey helmets change after being used for one season in a professional ice hockey league. Eighteen helmets from a male team and 10 helmets from a female team were compared to 13 new helmets. Every helmet was impact tested three times for two impact locations, side and front. The median peak linear acceleration for all front impacts were significantly higher (p < 0.05) for the helmets from the female team compared to the helmets from the male team. Compared to the new helmets, both men’s and women’s helmets had significantly lower median peak angular acceleration (p < 0.01) and peak angular velocity (p< 0.001). For side impacts, the women’s helmets had significantly higher peak linear acceleration compared to the men’s and new helmets (p < 0.001). Both men’s and women’s helmets had significantly higher peak angular acceleration compared to the new helmets (p < 0.001), and women’s helmets also had significantly higher peak angular acceleration compared to men’s helmets. Compared to men’s and new helmets, the results show that women’s helmets have worse impact attenuation properties after one season. However, all used helmets satisfied the passing threshold for test standards and the differences in calculated injury risk were small. This information may assist in establishing recommendations for the expected lifetime usage for ice hockey helmets and support manufacturers to develop safer ice hockey helmets.

Background: Even though women's ice hockey does not permit deliberate checking between players, female players are at similar or even higher risk to sustain concussions, as male players. Several studies have investigated head impacts in ice hockey, however to the best of the authors' knowledge, no previous study has used impact monitoring mouthguards to investigate head impact exposure among professional female ice hockey players.

Methods: Impact monitoring mouthguards were used to collect head impact data during games in the Swedish Women's Hockey League and in the men's Swedish J20 SuperElite League in 2020.

Results: Female players had significantly higher median linear accelerations than male players (26 [19–35] g, vs. 7 [5–9] g, p ​< ​0.001, d ​= ​1.98). Female players had significant higher median rotational accelerations compared to male players (3076 [2314–4243] rad/s² vs. 430 [281–752] rad/s², p ​< ​0.001, d ​= ​2.398). There were no notable variances in impact distribution by location for linear or rotational accelerations among female players. Similarly, male players didn't exhibit significant differences in impact location for linear acceleration. However, impacts at the Top Front location demonstrated significantly higher rotational accelerations compared to those at Front Low and Front High positions.

Conclusion: Compared to male players, female players sustain fewer but harder impacts to the head, which may explain the high occurrence of concussion in women's ice hockey.

Objective: Vulnerable Road Users (VRU), including pedestrians and cyclists, are generally the leastprotected road users and are frequently missed in the planning process of preventive measures.Rubberized asphalt mixtures were originally developed as a possible environmentally friendly solutionto recycle the End-of-Life Tires while making the pavements more durable. The objective ofthe current study was to explore the effects of increasing the rubber content of the common rubberizedasphalt mixtures in reducing the head injuries risk for VRUs.Method: To achieve this purpose, four different sample series with 0, 14, 28, and 33 weight percentrubber in each were tested. A compressive test without permanent deformation and onewith failure were performed on each sample series. The mechanical behavior of each set wasmodeled using a MAT_SIMPLIFIED_RUBBER material model in LS-Dyna and validated against astandard Head Injury Criterion (HIC) drop test. Ultimately, previously low-speed accident reconstructedcases, a bicycle and a pedestrian one, were used to assess the effect of varying the rubbercontent on reducing the head injury risk.Results: In the bicycle accident case, the risk of skull fracture was reduced from 0.99 to 0.29 whencomparing the non-rubberized asphalt mixture with the 33% rubber mixture. In the same accidentcase, the risk of concussion, evaluated using the logistic regression method, was reduced from0.97 in the non-rubberized mixture to 0.81 in the 33% rubber mixture. The initial conditions, linearand rotational velocities, were lower for the pedestrian case compared to the bicycle case (thebicycle case was more severe compared to the pedestrian case), which led to lower strains in thepedestrian case. In the pedestrian accident case, the risk of skull fracture was reduced from 1.00in the non-rubberized mixture to 0.63 in the 33% rubber mixture, while the risk of concussion wasreduced from 0.64 to 0.07.Conclusion: The rubberized asphalt mixtures could reduce the head injury risk for the studiedcases when the rubber content in the asphalt mixture increases.

Numerous helmet rating methods have been proposed to assess the safety and effectiveness of bicycle helmets. The methods usually involve a series of experimental impact tests using an Anthropomorphic Test Device (ATD) headform. There are several headforms available for the purpose and this study sought to assess how the choice of headform influences the safety assessment and ratings of bicycle helmets by following four proposed rating programs using three commonly used headforms. 19 head impact cases were evaluated computationally using the National Operating Committee on Standards for Athletic Equipment (NOCSAE) headform, Hybrid III (HIII) headform, and standard EN960 headform. The results show that for most oblique impact cases, EN960 produced considerably lower Peak Angular Acceleration (PAA), Peak Angular Velocity (PAV) and head injury risk compared to HIII and NOCSAE. This implies that the safety performance of bicycle helmets could be rated higher when using uncoated metal headforms compared to rubber-coated ones. The different headforms' tendency to produce varying rotational motion in oblique impacts raises questions about which of the headforms are suitable for such impact tests. The results presented in this study emphasize the occasional contradictions in helmet ratings presented by helmet rating programs. 

Finite element head models are a tool to better understand brain injury mechanisms. Many of the models use strain as output but with different percentile values such as 100th, 95th, 90th, and 50th percentiles. Some use the element value, whereas other use the nodal average value for the element. Little is known how strain post-processing is affecting the injury predictions and evaluation of different prevention systems. The objective of this study was to evaluate the influence of strain output on injury prediction and ranking.& nbsp;Two models with different mesh densities were evaluated (KTH Royal Institute of Technology head model and the Total Human Models for Safety (THUMS)). Pulses from reconstructions of American football impacts with and without a diagnosis of mild traumatic brain injury were applied to the models. The value for 100th, 99th, 95th, 90th, and 50th percentile for element and nodal averaged element strain was evaluated based on peak values, injury risk functions, injury predictability, correlation in ranking, and linear correlation.& nbsp;The injury risk functions were affected by the post-processing of the strain, especially the 100th percentile element value stood out. Meanwhile, the area under the curve (AUC) value was less affected, as well as the correlation in ranking (Kendall's tau 0.71-1.00) and the linear correlation (Pearson's r2 0.72-1.00). With the results presented in this study, it is important to stress that the same post-processed strain should be used for injury predictions as the one used to develop the risk function.

Phenomenon: This study aimed to investigate how students can develop their understanding of trauma biomechanics by means of technology-enhanced learning—an interactive visualization tool developed to enhance understanding of the biomechanics underlying an injury via dynamic imaging sequences. Approach: Students were invited to explore the content as a learning resource during an interprofessional clinical placement on an orthopedic ward. Thirty volunteer medical, nursing, and physiotherapy/occupational therapy students participated in 10 interprofessional groups of three participants. They were video recorded while interacting with learning software that was divided into five sections: Work Up, General Information, Biomechanical Case Study, Biomechanical Risk Assessment, and Treatment. Investigators probed students’ learning experiences via four focus group discussions. A sociomaterial perspective was adopted, directing the analytical focus to how students’ made use of talk, gestures, bodies, and material objects to understand the visualized phenomena. Findings: When connecting the visualization to a patient case, certain features of the technology stood out as important for promoting engagement and understanding trauma mechanisms. Decreased tempo, showing the directions and dynamics of trauma biomechanics in slow-motion, and color coding of the strain on the affected structures were especially important for evoking the emotional responses. The visualization tool also supported students’ explorations of causal relationships between external forces and their biomedical effects. These features emphasize the sociomaterial relation between the design of the technology and the student activities. Insights: Dynamic visualization of biomechanical events has the potential to improve the understanding of injury mechanisms and specifically to identify anatomical structures at high risk of injury. Dynamic visualizations for educational purposes seem to promote possibilities for learners to contextualize visual representations relative to one’s own body. Educational methods and practice need explicit attention and development in order to use the full potential of the visualization technology for learning for the health care professions. 

Bicycle helmets are shown to offer protection against head injuries. Rating methods and test standards are used to evaluate different helmet designs and safety performance. Both strain-based injury criteria obtained from finite element brain injury models and metrics derived from global kinematic responses can be used to evaluate helmet safety performance. Little is known about how different injury models or injury metrics would rank and rate different helmets. The objective of this study was to determine how eight brain models and eight metrics based on global kinematics rank and rate a large number of bicycle helmets (n=17) subjected to oblique impacts. The results showed that the ranking and rating are influenced by the choice of model and metric. Kendall’s tau varied between 0.50 and 0.95 when the ranking was based on maximum principal strain from brain models. One specific helmet was rated as 2-star when using one brain model but as 4-star by another model. This could cause confusion for consumers rather than inform them of the relative safety performance of a helmet. Therefore, we suggest that the biomechanics community should create a norm or recommendation for future ranking and rating methods.

Finite element (FE) models of the human head are valuable instruments to explore the mechanobiological pathway from external loading, localized brain response, and resultant injury risks. The injury predictability of these models depends on the use of effective criteria as injury predictors. The FE-derived normal deformation along white matter (WM) fiber tracts (i.e., tract-oriented strain) recently has been suggested as an appropriate predictor for axonal injury. However, the tract-oriented strain only represents a partial depiction of the WM fiber tract deformation. A comprehensive delineation of tract-related deformation may improve the injury predictability of the FE head model by delivering new tract-related criteria as injury predictors. Thus, the present study performed a theoretical strain analysis to comprehensively characterize the WM fiber tract deformation by relating the strain tensor of the WM element to its embedded fiber tract. Three new tract-related strains with exact analytical solutions were proposed, measuring the normal deformation perpendicular to the fiber tracts (i.e., tract-perpendicular strain), and shear deformation along and perpendicular to the fiber tracts (i.e., axial-shear strain and lateral-shear strain, respectively). The injury predictability of these three newly proposed strain peaks along with the previously used tract-oriented strain peak and maximum principal strain (MPS) were evaluated by simulating 151 impacts with known outcome (concussion or non-concussion). The results preliminarily showed that four tract-related strain peaks exhibited superior performance than MPS in discriminating concussion and non-concussion cases. This study presents a comprehensive quantification of WM tract-related deformation and advocates the use of orientation-dependent strains as criteria for injury prediction, which may ultimately contribute to an advanced mechanobiological understanding and enhanced computational predictability of brain injury.

The potential injury reducing benefits by a bicyclist helmet and a vehicle mounted bicyclist protectionairbag (BPA) was evaluated by means of human body model simulations. The human body model SAFER HBM waspositioned on a bicycle and impacted by a passenger vehicle in 40 km/h. Three conditions were evaluated; withoutcountermeasure, with helmet and helmet together with bicyclist protection airbag (BPA). Head injury risk wasevaluated by means of predicted HIC15, BrIC and strain in the brain.The impact conditions caused different impact points on the vehicle, windscreen and A-pillar. Both the impactpoints showed highest HIC and peak brain tissue strain for the case with no countermeasures and lowest valueswhen including both the helmet and BPA. BrIC increased when including the BPA for the windshield impact wherethe head did not impact the BPA, but a reduction was observed when the impact location was at the A-pillar.Generally head injury risk was reduced for a bicyclist wearing a helmet when impacted by a passenger vehiclein 40km/h. Additional reductions was obtained for a vehicle with a BPA. Therefore, the conclusion from this studywas that helmet and BPA have the potential to protect the head in vehicle to bicyclist impacts.