Now showing 1 - 10 of 21
  • Publication
    Determining the relationship between linear and rotational acceleration and MPS for different magnitudes of classified brain injury risk in ice hockey
    (International Research Council on the Biomechanics of Injury (IRCOBI), 2015-09-11) ; ; ;
    Helmets have successfully decreased the incidence of traumatic brain injuries (TBI) in ice hockey, yet the incidence of concussions has essentially remained unchanged. Current ice hockey helmet certification standards use peak linear acceleration as the principal measuring helmet performance, however peak linear acceleration may not be an appropriate variable to evaluate risk at all magnitudes of brain injury. The purpose of this study is to determine the relationship between linear acceleration, rotational acceleration and maximum principal strain (MPS) for different magnitudes of classified brain injury risk in ice hockey. A helmeted and unhelmeted Hybrid III headform were impacted to the side of the head at two sites and at three velocities under conditions representing three common mechanisms of injury. Resulting linear and rotational accelerations were used as input for the University College Dublin Brain Trauma Model (UCDBTM), to calculate MPS in the brain. The resulting MPS magnitudes were used to separate the data into three groups: low risk; concussion; and TBI. The results demonstrate that the relationship between injury metrics in ice hockey impacts is dependent on the magnitude of classified injury risk and the mechanism of injury.
  • Publication
    Finite element analysis of the effect of loading curve shape on brain injury predictors
    Prediction of traumatic and mild traumatic brain injury is an important factor in managing their prevention. Currently, the prediction of these injuries is limited to peak linear and angular acceleration loading curves derived from laboratory reconstructions. However it remains unclear as to what aspect of these loading curves contributes to brain tissue damage. This research will use the University College Dublin Brain Trauma Model (UCDBTM) to analyze three distinct loading curve shapes meant to represent different helmet loading scenarios. The loading curves were applied independently in each axis of linear and angular acceleration, and their effect on currently used predictors of TBI and mTBI. Loading curve shape A had a late time to peak, B an early time to peak and C had a consistent plateau. The areas for all three loading curve shapes were identical. The results indicate that loading curve A produced consistently higher maximum principal strains and Von Mises Stress than the other two loading curve types. Loading curve C consistently produced the lowest values, with loading curve B being lowest in only 2 cases. The areas of peak Von Mises Stress and Principal strain also varied depending on loading curve shape and acceleration input.
      1026Scopus© Citations 70
  • Publication
    Comparison of Ice Hockey Goaltender Helmets for Concussion Type Impacts
    Concussions are among the most common injuries sustained by ice hockey goaltenders and can result from collisions, falls and puck impacts. However, ice hockey goaltender helmet certification standards solely involve drop tests to a rigid surface. This study examined how the design characteristics of different ice hockey goaltender helmets affect head kinematics and brain strain for the three most common impact events associated with concussion for goaltenders. A NOCSAE headform was impacted under conditions representing falls, puck impacts and shoulder collisions while wearing three different types of ice hockey goaltender helmet models. Resulting linear and rotational acceleration as well as maximum principal strain were measured for each impact condition. The results indicate that a thick liner and stiff shell material are desirable design characteristics for falls and puck impacts to reduce head kinematic and brain tissue responses. However for collisions, the shoulder being more compliant than the materials of the helmet causes insufficient compression of the helmet materials and minimizing any potential performance differences. This suggests that current ice hockey goaltender helmets can be optimized for protection against falls and puck impacts. However, given collisions are the leading cause of concussion for ice hockey goaltenders and the tested helmets provided little to no protection, a clear opportunity exists to design new goaltender helmets which can better protect ice hockey goaltenders from collisions.
      700Scopus© Citations 13
  • Publication
    Comparison of MADYMO and physical models for brain injury reconstruction
    (Informa UK (Taylor & Francis), 2014-05-04) ; ;
    Brain injury is researched using physical, mathematical, anatomical, and computational models. However, there has been little research to quantify the expected differences between these methods of brain injury research. The purpose of this research was to compare the brain deformation responses of identical traumatic brain injury (TBI) reconstructions, which were conducted first with Mathematical Dynamic Models (MADYMO) and then again with a Hybrid III headform. The ensuing finite element modelling was done using the University College Dublin Brain Trauma Model. The brain deformation parameters were analysed in discrete regions of interest which matched the TBI lesion as identified on computed tomography scans of the subject. The results indicated that overall the Hybrid III provided responses which were of considerably larger magnitude than the MADYMO simulation for all metrics analysed. The larger magnitude responses are likely a product of the more rigid nature of the Hybrid III in comparison to the MADYMO simulations. Interestingly, when the results are compared to the literature, the Hybrid III results match well with mild traumatic brain injury (mTBI) and TBI research, while the MADYMO simulations produce what would be considered very low local brain deformation responses for TBI lesions.
      530Scopus© Citations 8
  • Publication
    The Association among Injury Metrics for Different Events in Ice Hockey Goaltender Impact
    (International Research Council on Biomechanics of Injury (IRCOBI), 2016-09-16) ; ; ;
    Current ice hockey goaltender helmet standards use a drop test and peak linear acceleration to evaluate performance. However, ice hockey goaltenders are exposed to impacts from collisions, falls and pucks which each create unique loading conditions. As a result, the use of peak linear acceleration as a predictor for brain trauma in current ice hockey standards may not be most appropriate. The purpose of this study was to determine how kinematic response measures correlate to maximum principal strain and von Mises stress for different impact events. A NOCSAE headform was fitted with three ice hockey goaltender helmet models and impacted under conditions representing these three different impact events (fall, puck, collision). Peak resultant linear acceleration, rotational acceleration and rotational velocity of the headform were measured. Resulting accelerations were input into the University College Dublin Brain Trauma Model, which calculated maximum principal strain and von Mises stress in the cerebrum. The results demonstrated that the relationship between injury metrics in ice hockey goaltender impacts is dependent on the impact event and velocity. As a result of these changing relationships, the inclusion of finite element analysis in test protocols may provide a more practical representation of brain loading in evaluating the performance of ice hockey goaltender helmets.
  • Publication
    Effect of impact surface in equestrian falls
    (International Society of Biomechanics in Sports (ISBS), 2016-07-22) ; ; ; ;
    This study examines the effect of impact surface on head kinematic response and maximum principal strain (MPS) for equestrian falls. A helmeted Hybrid III headform was dropped unrestrained onto three impact surfaces of different stiffness (steel, turf and sand) and three locations. Peak resultant linear acceleration, rotational acceleration and duration of the impact events were measured. A finite element brain model was used to calculate MPS. The results revealed that drops onto steel produced higher peak linear acceleration, rotational acceleration and MPS but lower impact durations than drops to turf and sand. However, despite lower MPS values, turf and sand impacts compared to steel impacts still represented a risk of concussion. This suggests that certification standards for equestrian helmets do not properly account for the loading conditions experienced in equestrian accidents.
  • Publication
    A Comparison of dynamic impact response and brain deformation metrics within the cerebrum of head impact reconstructions representing three mechanisms of head injury in ice hockey
    (International Research Council on the Biomechanics of Injury, 2012) ; ;
    Ice hockey has been identified as having one of the highest concussion rates. The three most likely causes of concussive injury are; falls to the ice, shoulder to head impacts and punches to the head. The purpose of this study was to examine how these three mechanisms of injury in the sport of ice hockey influence the dynamic response of the head form and the magnitude and distribution of maximum principal strain in the cerebrum. The three impact mechanisms were simulated using a Hybrid III head and neck form attached to a linear impactor, pendulum or monorail system. Three dimensional linear and rotational acceleration data from each impact condition were used to undertake finite element modeling to calculate maximum principal strain in regions of brain tissue. The results indicated that each mechanism incurred a unique peak resultant linear and rotational acceleration response. The maximum principal strain magnitudes were found to be largest in the fall to the ice. The regions of the brain incurring the largest deformation varied per mechanism of injury. This variation of peak magnitude per brain region might explain the differences in symptomology for concussion. Furthering the understanding of these mechanisms would aid in improving the safety of the game.
  • Publication
    A Comparison of the Head Dynamic Response and Brain Tissue Deformation from Impacts Resulting in Concussion, Concussion with Persistent Post-Concussive Symptoms, and Subdural Hematoma
    (American Association of Neurological Surgeons, 2015-08) ; ; ; ;
    Objective: Concussions typically resolve within a few days however in a few cases the symptoms last for a month or longer and are termed persistent post-concussive symptoms (PPCS) with more serious brain trauma resulting in bleeds, such as subdural hematoma (SDH). Dynamic response and brain tissue deformation characteristics may provide a means of distinguishing between these three types of injuries. Methods: Reconstruction cases were recruited from sports medicine clinics and hospitals along with medical reports, video footage, and medical imaging. All subjects received a direct blow to the head resulting in head trauma symptoms, those that resolved in 9 days were termed concussions, those with symptoms longer than 18 months were PPCS and those presenting with subdural hematoma (SDH). An anthropometric dummy headform was dropped onto various impact surfaces using a monorail drop rig. Headform dynamic response data was collected and used as input into the University College Dublin Brain Trauma Model to obtain maximum principal strain and von Mises stress. Results: Both linear and rotational acceleration of the head increased in magnitude with an increase in injury severity (from concussion, to PPCS, and SDH). The PPCS group had peak resultant rotational accelerations similar to SDH and significantly higher than concussions. There were no significant differences for peak resultant linear accelerations between the two concussion groups however they were both significantly lower than the SDH group. Brain tissue deformation measures however, did not follow the same trend as dynamic response and resulted with SDH having the lowest values of stress and strain. PPCS had significantly higher values of strain than the SDH group, where both the concussion and PPCS groups had significantly higher stress values than the SDH group. Conclusion: This study supports the notion that there is a positive relationship between an increase in the dynamic response and the risk for more serious brain injury. Peak resultant linear acceleration may be more related to SDH meanwhile rotational acceleration may be more relatedto severity of concussion. Despite SDH being the more severe brain injury, on average this group had the lowest values for stress and strain as compared to concussion and PPCS. Finite element analysis of the SDH injuries examined brain tissue values for the group of elements in the model than corresponded to the location of the bleed which may not be reflective of the highest values if the entire cerebrum was considered. More importantly, SDH injuries are vascular injuries and may not necessarily result in damage to the brain. In summary, this study found that the dynamic response of an impact is reflective of injury severity. Understanding the relationship between the dynamic response and the nature of the injury provides important information for developing strategies for injury prevention.
      352Scopus© Citations 43
  • Publication
    The influence of centric and non-centric impacts to American football helmets on the correlation between commonly metrics in brain injury research
    (International Research Council on the Biomechanics of Injury, 2012) ; ; ;
    Concussion has become recognized as an injury which can be a source of long term neurological damage. This has led to research into which metrics may be more appropriate to define risk of injury. Some researchers support the use of linear acceleration as a metric for concussion, while others suggest the use of linear and rotational acceleration as well as brain deformation metrics. The purpose of this study was to examine the relationships between these metrics using a centric and non‐centric impact protocol. A linear impactor was used to impact a Hybrid III headform fitted with different models of American football helmet using a centric and non‐centric protocol. The dynamic response was then used as input to the FE model for analysis of brain deformations. The results showed that linear acceleration was correlated to rotational acceleration and brain deformation for centric conditions, but under non‐centric conditions it was not. These results indicate that the type of methodology used will influence the relationship between the variables used to assign risk of concussion. These results also support the use of a centric/non‐centric protocol and measurement of rotational acceleration and brain deformation when it comes to the development of helmet technologies.
  • Publication
    The application of brain tissue deformation values in assessing the safety performance of ice hockey helmets
    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 f 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.
      333Scopus© Citations 8