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  • 1.
    Alvarez, Victor
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Fahlstedt, Madelen
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Halldin, Peter
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Importance of neck muscle tonus in head kinematics during pedestrian accidents2013In: 2013 IRCOBI Conference Proceedings - International Research Council on the Biomechanics of Injury, 2013, p. 747-761Conference paper (Refereed)
    Abstract [en]

    Unprotected pedestrians are an exposed group in the rural traffic and the most vulnerable human body region is the head which is the source of many fatal injuries. This study was performed to gain a better understanding of the influence that the neck muscle tonus has on head kinematics during pedestrian accidents. This was done using a detailed whole body FE model and a detailed FE vehicle model. To determine the influence of the muscle tonus a series of simulations were performed where the vehicle speed, pedestrian posture and muscle tonus were varied. Since the human reaction time for muscle activation is in the order of the collision time, the pedestrian was assumed to be prepared for the oncoming vehicle in order to augment the possible influence of muscle tonus. From the simulations performed, kinematic data such as head rotations, trajectory and velocities were extracted for the whole collision event, as well as velocity and accelerations at head impact. These results show that muscle tonus can influence the head rotation during a vehicle collision and therefore alter the head impact orientation. The level of influence on head rotation was in general lower than when altering the struck leg forward and backward, but in the same order of magnitude for some cases. The influence on head accelerations was higher due to muscle tonus than posture in all cases.

  • 2. Courteille, O.
    et al.
    Ho, Johnson
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Fahlstedt, Madelen
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Fors, U.
    Felländer-Tsai, L.
    Hedman, L.
    Möller, H.
    Face validity of VIS-Ed: A visualization program for teaching medical students and residents the biomechanics of cervical spine trauma2013In: Medicine Meets Virtual Reality 20, IOS Press, 2013, p. 96-102Conference paper (Refereed)
    Abstract [en]

    This RCT study aimed to investigate if VIS-Ed (Visualization through Imaging and Simulation - Education) had the potential to improve medical student education and specialist training in clinical diagnosis and treatment of trauma patients. The participants' general opinion was reported as high in both groups (lecture vs. virtual patient (VP)). Face validity of the VIS-Ed for cervical spine trauma was demonstrated and the VP group reported higher stimulation and engagement compared to the lecture group. No significant difference in the knowledge test between both groups could be observed, confirming our null hypothesis that VIS-Ed was on par with a lecture.

  • 3.
    Courteille, Olivier
    et al.
    Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
    Fahlstedt, Madelen
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Ho, Johnson
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Hedman, Leif
    Department of Psychology, Umeå University, Umeå, Sweden.
    Fors, Uno
    Department of Computer and Systems Sciences, Stockholm University, Stockholm, Sweden.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Felländer-Tsai, Li
    Department of Clinical Science, Intervention and Technology, Division of Orthopaedics and Biotechnology, Karolin-ska Institutet, Karolinska University Hospital, Huddinge, Stockholm, Sweden.
    Möller, Hans
    Department of Clinical Science, Intervention and Technology, Division of Orthopaedics and Biotechnology, Karolin-ska Institutet, Karolinska University Hospital, Huddinge, Stockholm, Sweden.
    Learning through a virtual patient vs. recorded lecture: a comparison of knowledge retention in a trauma case2018In: International Journal of Medical Education, E-ISSN 2042-6372, Vol. 9, p. 86-92Article in journal (Refereed)
    Abstract [en]

    Objectives: To compare medical students' and residents' knowledge retention of assessment, diagnosis and treatment procedures, as well as a learning experience, of patients with spinal trauma after training with either a Virtual Patient case or a video-recorded traditional lecture. Methods: A total of 170 volunteers (85 medical students and 85 residents in orthopedic surgery) were randomly allocated (stratified for student/resident and gender) to either a video-recorded standard lecture or a Virtual Patient-based training session where they interactively assessed a clinical case portraying a motorcycle accident. The knowledge retention was assessed by a test immediately following the educational intervention and repeated after a minimum of 2 months. Participants' learning experiences were evaluated with exit questionnaires. A repeated-measures analysis of variance was applied on knowledge scores. A total of 81% (n = 138) of the participants completed both tests. Results: There was a small but significant decline in first and second test results for both groups (F-(1,F-135) = 18.154, p = 0.00). However, no significant differences in short-term and long-term knowledge retention were observed between the two teaching methods. The Virtual Patient group reported higher learning experience levels in engagement, stimulation, general perception, and expectations. Conclusions: Participants' levels engagement were reported in favor of the VP format. Similar knowledge retention was achieved through either a Virtual Patient or a recorded lecture.

  • 4.
    Fahlstedt, Madelen
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Numerical Accident Reconstructions: A Biomechanical Tool to Understand and Prevent Head Injuries2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Traumatic brain injuries (TBIs) are a major health and socioeconomic problem throughout the world, with an estimated 10 million deaths and instances of hospitalization annually. Numerical methods such as finite element (FE) methods can be used to study head injuries and optimize the protection, which can lead to a decrease in the number of injuries. The FE head models were initially evaluated for biofidelity by comparing with donated corpses experiments. However, there are some limitations in experiments of corpses, including material degradation after death. One feasible alternative to evaluating head models with living human tissue is to use reconstruction of real accidents. However, the process of accident reconstruction entails some uncertainties since it is not a controlled experiment. Therefore, a deeper understanding of the accident reconstruction process is needed in order to be able to improve the FE human models. Thus, the aim of this thesis was to evaluate and further develop more advanced strategies for accident reconstructions involving head injuries.

    A FE head model was used to study head injuries in accidents. Existing bicycle accident data was used, as were hypothetical accident situations for cyclists and pedestrians. A FE bicycle helmet model having different designs was developed to study the protective effect.

    An objective method was developed based on the Overlap Index (OI) and Location Index (LI) to facilitate the comparison of FE model responses with injuries visible in medical images. Three bicycle accident reconstructions were performed and the proposed method evaluated. The method showed to have potential to be an objective method to compare FE model response with medical images and could be a step towards improving the evaluation of results from injury reconstructions.

    The simulations demonstrated the protective effect of a bicycle helmet. A decrease was seen in the injurious effect on both the brain tissue and the skull. However, the results also showed that the brain tissue strain could be further decreased by modifying the helmet design.

    Two different numerical pedestrian models were compared to evaluate whether the more time-efficient rigid body model could be used, instead of a FE pedestrian model, to roughly determine the initial conditions as an accident reconstruction involves some uncertainties. The difference, in terms of the head impact location, rotation and velocity, attributable to the two models was in the same range as differences due to uncertainties in some of the initial parameters, such as vehicle impact velocity.

    Download full text (pdf)
    Thesis
  • 5.
    Fahlstedt, Madelen
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Abayazid, F.
    Imperial College, Dyson School of Design Engineering.
    Panzer, M. B.
    University of Virginia, Department of Mechanical and Aerospace Engineering.
    Trotta, A.
    University Collge Dublin, School of Mechanical & Materials Engineering.
    Zhao, W.
    Worcester Polytechnic Institute, Department of Mechanical Engineering.
    Ghajari, M.
    Imperial College, Dyson School of Design Engineering.
    Gilchrist, M. D.
    University College Dublin, School of Mechanical & Materials Engineering.
    Ji, S.
    Worcester Polytechnic Institute, Department of Mechanical Engineering.
    Kleiven, Svein
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Li, Xiaogai
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Annaidh, A. N.
    University College Dublin, School of Mechanical & Materials Engineering.
    Halldin, Peter
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Ranking and Rating Bicycle Helmet Safety Performance in Oblique Impacts Using Eight Different Brain Injury Models2021In: Annals of Biomedical Engineering, ISSN 0090-6964, E-ISSN 1573-9686Article in journal (Refereed)
    Abstract [en]

    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.

  • 6.
    Fahlstedt, Madelen
    et al.
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Baeck, Katrien
    Mechanical Engineering Department, Biomechanics Section, Katholieke Universiteit Leuven, Belgium.
    Halldin, Peter
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Vander Sloten, Jos
    Mechanical Engineering Department, Biomechanics Section, Katholieke Universiteit Leuven, Belgium.
    Goffin, Jan
    Mechanical Engineering Department, Biomechanics Section, Katholieke Universiteit Leuven, Belgium.
    Depreitere, Bart
    Mechanical Engineering Department, Biomechanics Section, Katholieke Universiteit Leuven, Belgium.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Influence of impact velocity and angle in a detailed reconstruction of a bicycle accident2012In: 2012 IRCOBI Conference Proceedings - International Research Council on the Biomechanics of Injury, 2012, p. 787-799Conference paper (Refereed)
    Abstract [en]

    Bicycle accidents have become the most common cause of serious injury in the traffic during the last couple of years in Sweden. The objective of this study was to investigate the effect of the input variables, initial velocity and head orientation, of a bicycle accident reconstruction on the strain levels in the brain using a detailed FE head model. The accident involved a non-helmeted 68 year old male who sustained a linear skull fracture, contusions, acute subdural hematoma, and small bleeding at the swelling (subarachnoid blood). The orientation of the head just before impact was determined from the swelling appearing in the computer tomography (CT) scans. The head model used in this study was developed at the Royal Institute of Technology in Stockholm. The stress in the cranial bone, first principal strain in the brain tissue and acceleration were determined. The model was able to predict a strain pattern that correlated well with the medical images from the victim. The variation study showed that the tangential velocity had a large effect on the strain levels in the studied case. The strain pattern indicated larger areas of high strain with increased tangential velocity especially at the more superior sections.

  • 7.
    Fahlstedt, Madelen
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Depreitere, Bart
    Experimental Neurosurgery and Neuroanatomy, KU Leuven, Belgium.
    Halldin, Peter
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Vander Sloten, Jos
    Biomechanics, KU Leuven, Belgium.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Correlation between Injury Pattern and Finite Element Analysis in Biomechanical Reconstructions of Traumatic Brain Injuries2015In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 48, no 7Article in journal (Refereed)
    Abstract [en]

    At present, Finite Element (FE) analyses are often used as a tool to better understand the mechanisms of head injury. Previously, these models have been compared to cadaver experiments, with the next step under development being accident reconstructions. Thus far, the main focus has been on deriving an injury threshold and little effort has been put into correlating the documented injury location with the response displayed by the FE model. Therefore, the purpose of this study was to introduce a novel image correlation method that compares the response of the FE model with medical images.

    The injuries shown on the medical images were compared to the strain pattern in the FE model and evaluated by two indices; the Overlap Index (OI) and the Location Index (LI). As the name suggests, OI measures the area which indicates both injury in the medical images and high strain values in the FE images. LI evaluates the difference in center of mass in the medical and FE images. A perfect match would give an OI and LI equal to 1.

    This method was applied to three bicycle accident reconstructions. The reconstructions gave an average OI between 0.01 and 0.19 for the three cases and between 0.39 and 0.88 for LI. Performing injury reconstructions are a challenge as the information from the accidents often is uncertain. The suggested method evaluates the response in an objective way which can be used in future injury reconstruction studies.

  • 8.
    Fahlstedt, Madelen
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Halldin, Peter
    MIPS AB, Stockholm, Sweden.
    The difference in ranking of bike helmets when using different finite element head models2019In: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI, International Research Council on the Biomechanics of Injury , 2019, p. 660-661Conference paper (Refereed)
  • 9.
    Fahlstedt, Madelen
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Halldin, Peter
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Comparison of MADYMO and Finite Element Human Body Models in Pedestrian Accidents with the Focus on Head KinematicsManuscript (preprint) (Other academic)
  • 10.
    Fahlstedt, Madelen
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Halldin, Peter
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Comparison of multibody and finite element human body models in pedestrian accidents with the focus on head kinematics.2016In: Traffic Injury Prevention, ISSN 1538-9588, E-ISSN 1538-957X, Vol. 17, no 3Article in journal (Refereed)
    Abstract [en]

    OBJECTIVE: The objective of this study was to compare and evaluate the difference in head kinematics between the TNO and THUMS models in pedestrian accident situations.

    METHODS: The TNO pedestrian model (version 7.4.2) and the THUMS pedestrian model (version 1.4) were compared in one experiment setup and 14 different accident scenarios where the vehicle velocity, leg posture, pedestrian velocity, and pedestrian's initial orientation were altered. In all simulations, the pedestrian model was impacted by a sedan. The head trajectory, head rotation, and head impact velocity were compared, as was the trend when various different parameters were altered.

    RESULTS: The multibody model had a larger head wrap-around distance for all accident scenarios. The maximum differences of the head's center of gravity between the models in the global x-, y-, and z-directions at impact were 13.9, 5.8, and 5.6 cm, respectively. The maximum difference between the models in head rotation around the head's inferior-superior axis at head impact was 36°. The head impact velocity differed up to 2.4 m/s between the models. The 2 models showed similar trends for the head trajectory when the various parameters were altered.

    CONCLUSIONS: There are differences in kinematics between the THUMS and TNO pedestrian models. However, these model differences are of the same magnitude as those induced by other uncertainties in the accident reconstructions, such as initial leg posture and pedestrian velocity.

  • 11.
    Fahlstedt, Madelen
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Halldin, Peter
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Importance of the Bicycle Helmet Design and Material for the Outcome in Bicycle Accidents2014In: Proceedings, International Cycling Safety Conference 2014, Chalmers , 2014, p. 1-14Conference paper (Refereed)
    Abstract [en]

    In Sweden the most common traffic group that needs to be hospitalized due to injury is cyclists where head injuries are the most common severe injuries. According to current standards, the performance of a helmet is only tested against radial impact which is not commonly seen in real accidents. Some studies about helmet design have been published but those helmets have been tested for only a few loading conditions. Therefore, the purpose of this study was to use finite element models to evaluate the effect of the helmet’s design on the head in some more loading conditions.

    A detailed head model was used to evaluate three different helmet designs as well as non-helmet situations. The first helmet (Baseline Helmet) was an ordinary helmet available on the market. The two other helmet designs were a modification of the Baseline helmet with either a lower density of the EPS liner (Helmet 1) or a sliding layer between the scalp and the EPS liner (Helmet 2). Four different impact locations combined with four different impact directions were tested.

    The study showed that using a helmet can reduce the peak linear acceleration (85%), peak angular acceleration (87%), peak angular velocity (77%) and peak strain in the brain tissue (77%). The reduction of the strain level was dependent on the loading conditions. Moreover, in thirteen of the sixteen loading conditions Helmet 2 gave lowest peak strain.

    The alteration of the helmet design showed that more can be done to improve the protective effect of the helmet. This study highlighted the need of a modification of current helmet standard test which can lead to helmets with even better protective properties as well as some challenges in implementing new test standards.

    Download full text (pdf)
    fulltext
  • 12.
    Fahlstedt, Madelen
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Halldin, Peter
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    The protective effect of a helmet in three bicycle accidents: A finite element study2016In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 91, p. 135-143Article in journal (Refereed)
    Abstract [en]

    There is some controversy regarding the effectiveness of helmets in preventing head injuries among cyclists. Epidemiological, experimental and computer simulation studies have suggested that helmets do indeed have a protective effect, whereas other studies based on epidemiological data have argued that there is no evidence that the helmet protects the brain. The objective of this study was to evaluate the protective effect of a helmet in single bicycle accident reconstructions using detailed finite element simulations. Strain in the brain tissue, which is associated with brain injuries, was reduced by up to 43% for the accident cases studied when a helmet was included. This resulted in a reduction of the risk of concussion of up to 54%. The stress to the skull bone went from fracture level of 80 MPa down to 13-16 MPa when a helmet was included and the skull fracture risk was reduced by up to 98% based on linear acceleration. Even with a 10% increased riding velocity for the helmeted impacts, to take into account possible increased risk taking, the risk of concussion was still reduced by up to 46% when compared with the unhelmeted impacts with original velocity. The results of this study show that the brain injury risk and risk of skull fracture could have been reduced in these three cases if a helmet had been worn.

  • 13.
    Fahlstedt, Madelen
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Halldin, Peter
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    The Protective Effect of Bicycle HelmetsManuscript (preprint) (Other academic)
  • 14.
    Fahlstedt, Madelen
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Halldin, Peter
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    S. Alvarez, Victor
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Influence of the Body and Neck on Head Kinematics and Brain Injury Risk in Bicycle Accident Situations2016In: IRCOBI Conference Proceedings - International Research Council on the Biomechanics of Injury, International Research Council on the Biomechanics of Injury , 2016, p. 459-478Conference paper (Refereed)
    Abstract [en]

    Previous studies about the influence of the neck on head kinematics and brain injuries have shown different results. Today bicycle helmets are certified with only a headform in radial experiments but could be improved with oblique impacts. Then the question is how the helmet's performance will be affected by the neck and the rest of the body. Therefore, the objective of this study was to use finite element simulations to investigate the influence of the body on head kinematics and injury prediction in single bicycleaccident situations with and without a helmet. The THUMS-KTH model was used to study the difference between head only and full body. In total, a simulation matrix of 120 simulations was compared by altering initial impact posture, head protection, and muscle activation. The results show that the body in impacts against a hard surface can change the amplitudes and curve shapes of the kinematics and brain tissue strain. The study found an average ratio between head only and full body for peak brain tissue strain to be 1.04 (SD 0.11), for peak linear acceleration 1.06 (SD 0.04), for peak angular acceleration 1.08 (SD 0.09) and for peak angular velocity 1.05 (SD 0.13).

  • 15.
    Fahlstedt, Madelen
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Kleiven, Svein
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Li, Xiaogai
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Current Playground Surface Test Standards Underestimate Brain Injury Risk for Children2019In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380Article in journal (Refereed)
    Abstract [en]

    Playgrounds surface test standards have been introduced to reduce the number of fatal and severe injuries. However, these test standards have several simplifications to make it practical, robust and cost-effective, such as the head is represented with a hemisphere, only the linear kinematics is evaluated and the body is excluded. Little is known about how these simplifications may influence the test results. The objective of this study was to evaluate the effect of these simplifications on global head kinematics and head injury prediction for different age groups. The finite element human body model PIPER was used and scaled to seven different age groups from 1.5 up to 18 years old, and each model was impacted at three different playground surface stiffness and three head impact locations. All simulations were performed in pairs, including and excluding the body. Linear kinematics and skull bone stress showed small influence if excluding the body while head angular kinematics and brain tissue strain were underestimated by the same simplification. The predicted performance of the three different playground surface materials, in terms of head angular kinematics and brain tissue strain, was also altered when including the body. A body and biofidelic neck need to be included, together with suitable head angular kinematics based injury thresholds, in future physical or virtual playground surface test standards to better prevent brain injuries.

  • 16.
    Fahlstedt, Madelen
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Kleiven, Svein
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Li, Xiaogai
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    The Influence of the Body on Head Kinematics in Playground Falls for Different Age Groups2018In: Proceedings of International Research Council on Biomechanics of Injury (IRCOBI) Conference, 2018Conference paper (Refereed)
  • 17.
    Fahlstedt, Madelen
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Meng, Shiyang
    MIPS AB, Kemistvagen 1B, S-18379 Taby, Sweden..
    Kleiven, Svein
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Influence of Strain post-processing on Brain Injury Prediction2022In: Journal of Biomechanics, ISSN 0021-9290, E-ISSN 1873-2380, Vol. 132, article id 110940Article in journal (Refereed)
    Abstract [en]

    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.

  • 18.
    Halldin, Peter
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Fahlstedt, Madelen
    How sensitive are different headform design parameters in oblique helmeted impacts?2018In: Proceedings of International Research Council on Biomechanics of Injury (IRCOBI) Conference, 2018Conference paper (Refereed)
  • 19. Hedman, L.
    et al.
    Fahlstedt, Madelen
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Schlickum, M.
    Möller, H.
    Halldin, Peter
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Von Holst, Hans
    KTH, School of Technology and Health (STH), Neuronic Engineering.
    Felländer-Tsai, L.
    Training diagnosis and treatment of cervical spine trauma using a new educational program for visualization through imaging and simulation (VIS): A first evaluation by medical students2012In: Stud. Health Technol. Informatics, 2012, p. 171-174Conference paper (Refereed)
    Abstract [en]

    In this pilot study we investigated how medical students evaluated a VIS practice session. Immediately after training 43 students answered a questionnaire on the training session. They evaluated VIS as a good interactive scenario based educational tool.

  • 20. Hedman, Leif
    et al.
    Fahlstedt, Madelen
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Schlickum, Marcus
    Möller, Hans
    von Holst, Hans
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Felländer-Tsai, Li
    A pilot evaluation of an educational program that offers visualizations of cervical spine injuries: medical students' self-efficacy increases by training2014In: Informatics for Health and Social Care, ISSN 1753-8157, E-ISSN 1753-8165, Vol. 39, no 1, p. 33-46Article in journal (Refereed)
    Abstract [en]

    In this pilot study, a new method for visualization through imaging and simulation (VIS-Ed) for teaching diagnosis and treatment of cervical spine trauma was formatively evaluated. The aims were to examine if medical students' self-efficacy would change by training using VIS-Ed, and if so these changes were related to how they evaluated the session, and the user interface (UI) of this program. Using a one-group, pre-post course test design 43 Swedish medical students (4th year, 17 males, 26 females) practiced in groups of three participants. Overall the practice and the UI were considered as positive experiences. They judged VIS-Ed as a good interactive scenario-based educational tool. All students' self-efficacy increased significantly by training (p<0.001). Spearman's rank correlation tests revealed that increased self-efficacy was only associated with: how the session was compared to as expected (p<0.007). Students' self-efficacy increased significantly by training, but replication studies should determine if this training effect is gender-related.

  • 21.
    Lindgren, Natalia
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Halldin, Peter
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Fahlstedt, Madelen
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Influence of Headform on Assessments and Ratings of the Protective Performance of Bicycle Helmets2022In: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI, International Research Council on the Biomechanics of Injury , 2022, p. 892-911Conference paper (Refereed)
    Abstract [en]

    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. 

  • 22.
    Meng, Shiyang
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering. Helmet division, Dainese S.p.A., Italy..
    Fahlstedt, Madelen
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Halldin, Peter
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    The effect of impact velocity angle on helmeted head impact severity: A rationale for motorcycle helmet impact test design2018In: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI, International Research Council on the Biomechanics of Injury , 2018, p. 454-469Conference paper (Refereed)
    Abstract [en]

    The impact velocity angle determined by the normal and tangential velocity has been shown to be an important description of head impact conditions but can vary in real-world accidents. The objective of this paper was to investigate the effect of impact velocity angle on helmeted head impact severity indicated by the brain tissue strain. The human body model coupled with a validated motorcycle helmet model was propelled at a constant resultant velocity but varying angle relative to a rigid surface. Different body angles, impact directions and helmet designs have also been incorporated in the simulation matrix (n=300). The results show an influence of impact velocity angle on brain tissue strain response. By aggregating all simulation cases into different impact velocity angle groups, i.e., 15, 30, 45, 60 and 75 degrees, a 30- or 45-degree angle group give the highest median and inter-quartile range of the peak brain tissue strain. Comparisons of strain pattern and its peak value between individual cases give consistent results. The brain tissue strain is less sensitive to the body angle than to the velocity angle. The study suggests that UN/ECE 22.05 can be improved by increasing the current 'oblique' angle, i.e. 15 degrees inclined to vertical axis, to a level that can produce sufficient normal velocity component and hence angular head motion. This study also underline the importance of understanding post-impact head kinematics, and the need for further evaluation of human body models.

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  • 23. Möller, H.
    et al.
    Creutzfeldt, J.
    Valeskog, K.
    Rystedt, H.
    Edelbring, S.
    Fahlstedt, Madelen
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Felländer-Tsai, L.
    Abrandt Dahlgren, M.
    Technology-Enhanced Learning of Human Trauma Biomechanics in an Interprofessional Student Context2021In: Teaching and learning in medicine, ISSN 1040-1334, E-ISSN 1532-8015, p. 1-10Article in journal (Refereed)
    Abstract [en]

    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. 

  • 24.
    Panzer, Matthew B.
    et al.
    Univ Virginia, Ctr Appl Biomech, Charlottesville, VA USA..
    Giudice, J. Sebastian
    Univ Virginia, Ctr Appl Biomech, Charlottesville, VA USA..
    Caudillo, Adrian
    Univ Virginia, Ctr Appl Biomech, Charlottesville, VA USA..
    Mukherjee, Sayak
    Univ Virginia, Ctr Appl Biomech, Charlottesville, VA USA..
    Kong, Kevin
    Univ Virginia, Ctr Appl Biomech, Charlottesville, VA USA..
    Cronin, Duane S.
    Univ Waterloo, Waterloo, ON, Canada..
    Barker, Jeffrey
    Univ Waterloo, Waterloo, ON, Canada..
    Gierczycka, Donata
    Univ Waterloo, Waterloo, ON, Canada..
    Bustamante, Michael
    Univ Waterloo, Waterloo, ON, Canada..
    Bruneau, David
    Univ Waterloo, Waterloo, ON, Canada..
    Corrales, Miguel
    Univ Waterloo, Waterloo, ON, Canada..
    Halldin, Peter
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Fahlstedt, Madelen
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Arnesen, Marcus
    Jungstedt, Erik
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Gayzik, F. Scott
    Wake Forest Univ, Bowman Gray Sch Med, Winston Salem, NC USA..
    Stitzel, Joel D.
    Wake Forest Univ, Bowman Gray Sch Med, Winston Salem, NC USA..
    Decker, William
    Wake Forest Univ, Bowman Gray Sch Med, Winston Salem, NC USA..
    Baker, Alex M.
    Wake Forest Univ, Bowman Gray Sch Med, Winston Salem, NC USA..
    Ye, Xin
    Wake Forest Univ, Bowman Gray Sch Med, Winston Salem, NC USA..
    Brown, Philip
    Wake Forest Univ, Bowman Gray Sch Med, Winston Salem, NC USA..
    NUMERICAL CROWDSOURCING OF NFL FOOTBALL HELMETS2018In: Journal of Neurotrauma, ISSN 0897-7151, E-ISSN 1557-9042, Vol. 35, no 16, p. A148-A148Article in journal (Other academic)
  • 25.
    Pedersen, Kyrre
    et al.
    Department of Neurosurgery, Karolinska University Hopsital.
    Fahlstedt, Madelen
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Jacobsson, Anders
    Department of Epidemiology, National Board of Health and Welfare.
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering. Department of Neurosurgery, Karolinska University Hopsital.
    A National Survey of Traumatic Brain Injuries Admitted to Hospital in Sweden from 1987 to 20102015In: Neuroepidemiology, ISSN 0251-5350, E-ISSN 1423-0208Article in journal (Refereed)
  • 26. Pedersen, Kyrre
    et al.
    Fahlstedt, Madelen
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Jacobsson, Anders
    Kleiven, Svein
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    von Holst, Hans
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    A National Survey of Traumatic Brain Injuries Admitted to Hospitals in Sweden from 1987 to 20102015In: Neuroepidemiology, ISSN 0251-5350, E-ISSN 1423-0208, Vol. 45, no 1, p. 20-27Article in journal (Refereed)
    Abstract [en]

    Background: With an increasing and aging population, there is a global demand for improving the primary prevention strategies aimed at reducing traumatic brain injuries (TBIs). The objective of the present epidemiological study was to evaluate the pattern of TBI in Sweden over a 24 years period (1987-2010). Methods: The Swedish Hospital Discharge Register was used, where in-patient care with a main diagnosis of TBI according to ICD9/10 was included. External factors, age and gender distribution was evaluated. Results: A decreasing number of annual incidence was observed, that is, from 230 to 156 per 100,000 inhabitants. A steady decrease of concussion was observed while other intracranial injuries increased especially traumatic subdural hemorrhage and subarachnoid hemorrhage. The study identified 3 groups of patients young, adults and elderly. The highest incidence and the largest increase of incidence were seen in the oldest age group (85+ years) while the population under 65 years had a decreasing incidence of TBI. The most frequent etiology was fall accidents (57%) with a relative constant trend over the study period. Conclusions: More effort should be focused on different strategies for different age groups, especially the elderly group. A well-planned strategy for primary prevention guidelines for different age groups will have the chance to further reduce not only the health-care costs but also complications among elderly care. (C) 2015 S. Karger AG, Basel

  • 27.
    Pipkorn, Bengt
    et al.
    Chalmers University of Technology.
    Alvarez, Victor
    Lightness by Design.
    Fahlstedt, Madelen
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Lundin, Linus
    Autoliv.
    Head Injury Risks and Countermeasures for a Bicyclist Impacted by a Passenger Vehicle2020In: Proceedings of International Research Council on the Biomechanics of Injury (IRCOBI) 2020, 2020, article id IRC-20-41Conference paper (Refereed)
    Abstract [en]

    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.

  • 28.
    Robinson, Yohan
    et al.
    Uppsala University Hospital, Uppsala, Sweden.
    Lison Almkvist, Viktor
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Olerud, Claes
    Uppsala University Hospital, Uppsala, Sweden.
    Halldin, Peter
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Fahlstedt, Madelen
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Finite Element Analysis of Long Posterior Transpedicular Instrumentation for Cervicothoracic Fractures Related to Ankylosing Spondylitis2018In: Global Spine Journal, ISSN 2192-5682, E-ISSN 2192-5690Article in journal (Refereed)
  • 29.
    Sahandifar, Pooya
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Makoundou, Christina
    Department of Civil, Chemical, Environmental, and Materials Engineering, University of Bologna, Bologna, Italy.
    Fahlstedt, Madelen
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Sangiorgi, Cesare
    Department of Civil, Chemical, Environmental, and Materials Engineering, University of Bologna, Bologna, Italy.
    Johansson, Kenth
    Department of Material and Surface Design, RISE Research Institutes of Sweden,.
    Wallqvist, Viveca
    Department of Material and Surface Design, RISE Research Institutes of Sweden,.
    Kleiven, Svein
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    A rubberized impact absorbing pavement can reduce the head injury risk in vulnerable road users: a bicycle and a pedestrian accident case study2022In: Traffic Injury Prevention, ISSN 1538-9588, E-ISSN 1538-957XArticle in journal (Refereed)
    Abstract [en]

    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.

  • 30.
    Stigson, Helena
    et al.
    Folksam Research and Department of Applied Mechanics Vehicle Safety Division Chalmers University of Technology.
    Fahlstedt, Madelen
    KTH, School of Technology and Health (STH), Medical Engineering, Neuronic Engineering.
    Svensson, Mats Y.
    Department of Applied Mechanics Vehicle Safety Division Chalmers University of Technology.
    Preventing Shoulder Injuries in Bicycle Crashes2016Conference paper (Refereed)
  • 31.
    Zhou, Z.
    et al.
    Stanford University, Stanford, California, USA..
    Li, Xiaogai
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Liu, Y.
    Stanford University, Stanford, California, USA..
    Fahlstedt, Madelen
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Georgiadis, M.
    Stanford University, Stanford, California, USA..
    Zhan, X.
    Stanford University, Stanford, California, USA..
    Raymond, S. J.
    Stanford University, Stanford, California, USA.Stanford University, Stanford, California, USA..
    Grant, G.
    Stanford University, Stanford, California, USA..
    Kleiven, Svein
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Neuronic Engineering.
    Camarillo, D.
    Stanford University, Stanford, California, USA..
    Zeineh, M.
    Stanford University, Stanford, California, USA..
    Toward a Comprehensive Delineation of White Matter Tract-Related Deformation2021In: Journal of Neurotrauma, ISSN 0897-7151, E-ISSN 1557-9042, Vol. 38, no 23, p. 3260-3278Article in journal (Refereed)
    Abstract [en]

    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.

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