Scholarly Works, Center for Injury Biomechanics
Permanent URI for this collection
Browse
Recent Submissions
- Methodology for assessing the biomechanical performance of helmets(United States Patent and Trademark Office, 2017-10-24)The present invention provides a method for testing a helmet that uses a risk function that incorporates both linear and rotational acceleration to predict the helmet's ability to prevent a concussion. In certain embodiments, the testing matrix includes 3 impact energy levels and 4 impact locations, for a total of 12 testing conditions per helmet.
- Brain Injury Prediction: Assessing the Combined Probability of Concussion Using Linear and Rotational Head AccelerationRowson, Steven; Duma, Stefan M. (BMES, 2013-05)Recent research has suggested possible long term effects due to repetitive concussions, highlighting the importance of developing methods to accurately quantify concussion risk. This study introduces a new injury metric, the combined probability of concussion, which computes the overall risk of concussion based on the peak linear and rotational accelerations experienced by the head during impact. The combined probability of concussion is unique in that it determines the likelihood of sustaining a concussion for a given impact, regardless of whether the injury would be reported or not. The risk curve was derived from data collected from instrumented football players (63,011 impacts including 37 concussions), which was adjusted to account for the underreporting of concussion. The predictive capability of this new metric is compared to that of single biomechanical parameters. The capabilities of these parameters to accurately predict concussion incidence were evaluated using two separate datasets: the Head Impact Telemetry System (HITS) data and National Football League (NFL) data collected from impact reconstructions using dummies (58 impacts including 25 concussions). Receiver operating characteristic curves were generated, and all parameters were significantly better at predicting injury than random guessing. The combined probability of concussion had the greatest area under the curve for all datasets. In the HITS dataset, the combined probability of concussion and linear acceleration were significantly better predictors of concussion than rotational acceleration alone, but not different from each other. In the NFL dataset, there were no significant differences between parameters. The combined probability of concussion is a valuable method to assess concussion risk in a laboratory setting for evaluating product safety.
- The Influence of the Specimen Shape and Loading Conditions on the Parameter Identification of a Viscoelastic Brain ModelUntaroiu, Costin D. (Hindawi Publishing Corporation, 2013)The mechanical properties of brain under various loadings have been reported in the literature over the past 50 years. Step-and-hold tests have often been employed to characterize viscoelastic and nonlinear behavior of brain under high-rate shear deformation; however, the identification of brain material parameters is typically performed by neglecting the initial strain ramp and/or by assuming a uniform strain distribution in the brain samples. Using finite element (FE) simulations of shear tests, this study shows that these simplifications have a significant effect on the identified material properties in the case of cylindrical human brain specimens. Material models optimized using only the stress relaxation curve under predict the shear force during the strain ramp, mainly due to lower values of their instantaneous shear moduli. Similarly, material models optimized using an analytical approach, which assumes a uniform strain distribution, under predict peak shear forces in FE simulations. Reducing the specimen height showed to improve the model prediction, but no improvements were observed for cubic samples with heights similar to cylindrical samples. Models optimized using FE simulations show the closest response to the test data, so a FE-based optimization approach is recommended in future parameter identification studies of brain.
- Piecewise-Constant-Model-Based Interior Tomography Applied to Dentin TubulesHe, Peng; Wei, Biao; Wang, Steve; Stock, Stuart R.; Yu, Hengyong; Wang, Ge (Hindawi Publishing Corporation, 2013)Dentin is a hierarchically structured biomineralized composite material, and dentin's tubules are difficult to study in situ. Nano-CT provides the requisite resolution, but the field of view typically contains only a few tubules. Using a plate-like specimen allows reconstruction of a volume containing specific tubules from a number of truncated projections typically collected over an angular range of about 140 degrees, which is practically accessible. Classical computed tomography (CT) theory cannot exactly reconstruct an object only from truncated projections, needless to say a limited angular range. Recently, interior tomography was developed to reconstruct a region-of-interest (ROI) from truncated data in a theoretically exact fashion via the total variation (TV) minimization under the condition that the ROI is piecewise constant. In this paper, we employ a TV minimization interior tomography algorithm to reconstruct interior microstructures in dentin from truncated projections over a limited angular range. Compared to the filtered backprojection (FBP) reconstruction, our reconstruction method reduces noise and suppresses artifacts. Volume rendering confirms the merits of our method in terms of preserving the interior microstructure of the dentin specimen.
- Comparison of Organ Location, Morphology, and Rib Coverage of a Midsized Male in the Supine and Seated PositionsHayes, Ashley R.; Gayzik, F. Scott; Moreno, Daniel P.; Martin, R. Shayn; Stitzel, Joel D. (Hindawi Publishing Corporation, 2013)The location and morphology of abdominal organs due to postural changes have implications in the prediction of trauma via computational models. The purpose of this study is to use data from a multimodality image set to devise a method for examining changes in organ location, morphology, and rib coverage from the supine to seated postures. Medical images of a male volunteer (78.6 +/- 0.77 kg, 175 cm) in three modalities (Computed Tomography, Magnetic Resonance Imaging (MRI), and Upright MRI) were used. Through image segmentation and registration, an analysis between organs in each posture was conducted. For the organs analyzed (liver, spleen, and kidneys), location was found to vary between postures. Increases in rib coverage from the supine to seated posture were observed for the liver, with a 9.6% increase in a lateral projection and a 4.6% increase in a frontal projection. Rib coverage area was found to increase 11.7% for the spleen. Morphological changes in the organs were also observed. The liver expanded 7.8% cranially and compressed 3.4% and 5.2% in the anterior-posterior and medial-lateral directions, respectively. Similar trends were observed in the spleen and kidneys. These findings indicate that the posture of the subject has implications in computational human body model development.
- Virginia Tech-Wake Forest University Center for Injury Biomechanics 10 Year HistoryDuma, Stefan M. (Brain Injuries and Biomechanics Symposium, 2013-09-19)The Virginia Tech-Wake Forest University Center for Injury Biomechanics (CIB) has completed 10 years of research in the fields of automobile safety, military restraints, and sports biomechanics. The CIB has grown to include 74 researchers lead by 10 faculty and 48 staff and student researchers. These researchers examine human tolerance across a range of dynamic loading environments for all body regions. The CIB is the largest university based injury biomechanics research group in the world. It includes five separate laboratory facilities with over 40,000 sq. ft. of dedicated research space. The faculty and staff have published nearly 300 journal and refereed conference papers in 10 general research areas. The objective of this paper is to summarize briefly the CIB research capabilities and accomplishments.
- Blasted Flies and Nanoparticles for TBIHockey, Kevin S.; Sholar, Christopher A.; Sajja, Venkata Siva Sai Sujith; Hubbard, W. Brad; Thorpe, Chevon; VandeVord, Pamela J.; Rzigalinski, Beverly A. (Brain Injuries and Biomechanics Symposium, 2013-09-19)This presentation briefly summaries two major areas of work in our lab, development of a Drosophila model of blast injury and treatment of traumatic brain injury (TBI) with cerium oxide nanoparticles. First, we discuss the design, methodology, and results for the Drosophila blast model, and its relevance to human head injury. Briefly, we found that the Drosophila model was able to reproduce the decreased lifespan and early death seen in military personnel exposed to repetitive mild blast and NFL players exposed to repeated mild head injury. Next we discuss our in vitro and in vivo work with cerium oxide nanoparticles as neuroprotective and regenerative agents for treatment of TBI. Using a tissue culture model for TBI, we found that cerium oxide nanoparticles, delivered up to 6 hrs. post-injury, improved neuronal survival and maintained near-normal glutamate signaling in neurons of mixed organotypic brain cell cultures. In vivo, we found that delivery of cerium oxide nanoparticles prior to lateral fluid percussion brain injury in the rat, improved motor performance, learning and memory.
- Literature Review of Eye Injuries and Eye Injury Risk from Blunt ObjectsAlphonse, Vanessa D.; Kemper, Andrew R. (Brain Injuries and Biomechanics Symposium, 2013-09-19)Eye injuries affect approximately two million people annually. Various studies that have evaluated the injury tolerance of animal and human eyes from blunt impacts are summarized herein. These studies date from the late 60s to present and illustrate various methods for testing animal and human cadaver eyes exposed to various blunt projectiles including metal rods, BBs, baseballs, and foam pieces. Experimental data from these studies have been used to develop injury risk curves to predict eye injuries based on projectile parameters such as kinetic energy and normalized energy. Recently, intraocular pressure (IOP) has been correlated to injury risk which allows eye injuries to be predicted when projectile characteristics are unknown. These experimental data have also been used to validate numerous computational and physical models of the eye used to assess injury risk from blunt loading. One such physical model is the the Facial and Ocular CountermeasUre Safety (FOCUS) headform, which is an advanced anthropomorphic device designed specifically to study facial and ocular injury. The FOCUS headform eyes have a biofidelic response to blunt impact and eye load cell data can be used to assess injury risk for eye injuries.
- Measuring Head Impact Exposure and Mild Traumatic Brain Injury in HumansCobb, Bryan (Brain Injuries and Biomechanics Symposium, 2013-09-19)Helmeted sports such as football offer a unique opportunity to study head injury biomechanics in live human subjects. Impact reconstruction using game videos and real-time measurements of head kinematics in football provide a method of quantifying the head impact exposure athletes experience. A total of 58 impacts from NFL games have been reconstructed using Hybrid III crash test dummies, including 25 concussive impacts. Roughly 2 million impacts have been recorded using helmet-mounted accelerometer devices, with 105 concussive impacts. Similar values have been found for peak linear acceleration, one of the best predictors of concussion, using the two methods. From the NFL impact reconstructions, researchers found a peak linear acceleration value of 98 ± 28 g which is not substantially different from the value of 105 ± 27 g from the helmet-mounted sensor data. Both methods provide valuable head impact biomechanics data which are used to quantify impact exposure in football and assess injury risk due to head impact. Helmet mounted accelerometers have the added benefit of collecting every impact a player sustains while wearing the sensors, giving more detailed impact frequency data and many more data points. Future research will focus on expanding the head impact data set, especially at the youth level. The expanded data set will lead to improved injury risk curves which will guide future safety standards in sports as well as other areas, including the automotive industry and military, where head injury is a concern.
- Surrogate Head Forms for the Evaluation of Head Injury RiskMacAlister, Anna (Brain Injuries and Biomechanics Symposium, 2013-09-19)This paper summarizes the use of surrogate head forms in biomechanical research pertaining to head injury and, more specifically, mild traumatic brain injury. Because cadavers are limited and controlled studies of brain injury using live human subjects would be unethical, surrogate head forms are used to study the response of the human head to impact. Different head forms have been developed and optimized for different purposes. The Hybrid III 50th percentile male crash test dummy was developed for use in vehicle crash testing and instrumented in such a way as to provide HIC values in frontal crash tests. The NOCSAE head form is used by the National Operating Committee on Standards for Athletic Equipment to be used in the certification of commercially produced athletic helmets. The Facial and Ocular Countermeasure Safety (FOCUS) head form was developed jointly by the Virgina Tech-Wake Forest Center for Injury Biomechanics, Robert A. Denton, Inc., and the United States Army Aeromedical Research Laboratory as a tool to aid in the development and evaluation of safety devices designed to prevent face and eye injuries. The vast majority of biomechanical research of head injury conducted using surrogate anthropomorphic test devices (ATDs) utilized one of these three head forms.
- Predicting Mild Traumatic Brain Injury with Injury Risk FunctionsYoung, Tyler James (Brain Injuries and Biomechanics Symposium, 2013-09-19)To assess the safety of various products, equipment, and vehicles during traumatic events injury risk curves have been developed correlate measurable parameters with risk of injury. The first risk curves to predict head injuries focused on severe head injuries such as skull fractures. These curves were generated by impacting cadaver heads. To understand the biomechanics of mild traumatic brain injuries, cadaver heads have also been used to monitor pressure and strain in the brain during impacts. Live animal models have been used to understand the physiological response of the brain to impact to create thresholds for mild traumatic brain injuries such as concussions. These results have been scaled to humans. To generate injury risk curves from live human models, impacts from games in the NFL have been reconstructed in the laboratory. Helmets of NCAA football players have also be instrumented with accelerometers to collect all impacts during a season resulting in the development of injury risk curves that predict concussion as a function of both linear and rotational acceleration. These risk curves provide researchers with a better understanding of the efficacy of various safety systems and give insight as to how safety systems can be improved.
- Evaluation of Eye Injury Risk from Consumer FireworksAlphonse, Vanessa D.; Kemper, Andrew R. (Brain Injuries and Biomechanics Symposium, 2013-09-19)Eye injuries affect approximately two million people annually. Various experimental studies have been performed to evaluate potentially injurious conditions from blunt objects using animal and human cadaver eyes. Experimental data from these studies have been used to develop injury risk curves to predict eye injuries based on projectile parameters such as kinetic energy and normalized energy. Recently, intraocular pressure (IOP) has been correlated to injury risk, which allows eye injuries to be predicted if projectile characteristics are unknown. Additionally, the measurement of IOP and the association of IOP to injury risk in experimental tests has opened up the field to studying eye injury mechanisms from overpressure. The current manuscript presents recent experimental tests that evaluated the response of human cadaver eyes exposed to firework overpressure. Consumer fireworks serve as a model of low level blast, and provides a foundation to studying higher blast overpressures (i.e., that would be observed in military combat). Although some studies state that eye injury can result solely from primary blast (overpressure), there is no empirical evidence in the literature to support this. Future experimental studies should be conducted to assess this statement.