Publications

2024

1. Biofidelity and Limitations of Instrumented Mouthguard Systems for Assessment of Rigid Body Head Kinematics

   Mitchell Z. Abrams, Jay Venkatraman, Donald Sherman, Maria Ortiz-Paparoni, Jefferson R. Bercaw, Robert E. MacDonald, Jason Kait, Elizabeth D. Dimbath, Derek Y. Pang, Alexandra Gray, Jason F. Luck, Cynthia A. Bir, and Cameron R. Bass

   Annals of Biomedical Engineering, 2024

   Abs DOI

   Instrumented mouthguard systems (iMGs) are commonly used to study rigid body head kinematics across a variety of athletic environments. Previous work has found good fidelity for iMGs rigidly fixed to anthropomorphic test device (ATD) headforms when compared to reference systems, but few validation studies have focused on iMG performance in human cadaver heads. Here, we examine the performance of two boil-and-bite style iMGs in helmeted cadaver heads. Three unembalmed human cadaver heads were fitted with two instrumented boil-and-bite mouthguards [Prevent Biometrics and Diversified Technical Systems (DTS)] per manufacturer instructions. Reference sensors were rigidly fixed to each specimen. Specimens were fitted with a Riddell SpeedFlex American football helmet and impacted with a rigid impactor at three velocities and locations. All impact kinematics were compared at the head center of gravity. The Prevent iMG performed comparably to the reference system up to   60 g in linear acceleration, but overall had poor correlation (CCC = 0.39). Prevent iMG angular velocity and BrIC generally well correlated with the reference, while underestimating HIC and overestimating HIC duration. The DTS iMG consistently overestimated the reference across all measures, with linear acceleration error ranging from 10 to 66%, and angular acceleration errors greater than 300%. Neither iMG demonstrated consistent agreement with the reference system. While iMG validation efforts have utilized ATD testing, this study highlights the need for cadaver testing and validation of devices intended for use in-vivo, particularly when considering realistic (non-idealized) sensor-skull coupling, when accounting for interactions with the mandible and when subject-specific anatomy may affect device performance.

2. Female vs. Male Relative Fatality Risk in Fatal Motor Vehicle Crashes in the US, 1975–2020

   Mitchell Z. Abrams, and Cameron R. Bass

   PLOS ONE, Feb 2024

   Abs DOI

   Motor vehicle accidents are the leading cause of death for young adults 18–29 years old worldwide, resulting in nearly 1 million years of life lost annually in the United States. Despite improvements in vehicle safety technologies, young women are at higher risk of dying in car crashes compared with men in matched scenarios. Vehicle crash testing primarily revolves around test dummies representative of the 50th percentile adult male, potentially resulting in these differences in fatality risk for female occupants compared to males. Vehicle occupants involved in fatal car crashes were matched using seating location, vehicle type, airbag deployment, seatbelt usage, and age. The relative risk for fatality (R) between males and females was calculated using a Double Pair Comparison. Young women (20s-40s) are at approximately 20% higher risk of dying in car crashes compared with men of the same age in matched scenarios. In passenger cars, 25-year-old female occupants in passenger car crashes from 1975–2020 exhibit R = 1.201 (95% CI 1.160–1.250) compared to 25-year-old males, and R-1.117 (95% CI 1.040–1.207) for passenger car crashes from 2010–2020. This trend persists across vehicle type, airbag deployment, seatbelt use, and number of vehicles involved in a crash. Known sex-based differences do not explain this large risk differential, suggesting a need for expanded test methodologies and research strategies to address as-yet unexplored sex differences in crash fatalities. These differences should be further investigated to ensure equitable crash protection.

2023

1. Low-Level Validation of an In-Ear Sensor for Measuring Head Impact Exposure in American Football

   Jefferson Bercaw, Jay Venkatraman, Maria Ortiz-Paparoni, Donald Sherman, Robert MacDonald, Jason Kait, Elizabeth Dimbath, Jason Luck, Cynthia Bir, C.R. Bass, and Mitchell Abrams

   May 2023

   Poster presented at 2023 Ohio State Injury Biomechanics Research Symposium

   PDF Poster DOI
2. Biofidelity and Limitations of Instrumented Mouthguard Systems for Assessment of Rigid Body Head Kinematics

   Mitchell Z. Abrams, Jay Venkatraman, Donald Sherman, Maria Ortiz-Paparoni, Jefferson R. Bercaw, Robert E. MacDonald, Jason Kait, Elizabeth Dimbath, Derek Pang, Alexandra Gray, Jason F. Luck, Cynthia A. Bir, and C.R. Bass

   In Proceedings of the International Research Council on the Biomechanics of Injury , Sep 2023

   Abs PDF

   Instrumented mouthguard systems are used to study rigid body head kinematics in vivo in a variety of athletic environments. Previous work has assessed these systems when rigidly attached to anthropomorphic test device (ATD) heads and found good fidelity compared with reference sensors. Here, we examine the fidelity of two instrumented boil-and-bite mouthguards (iMGs) in helmeted, human cadaver impact tests at three velocities and three impact locations. The Prevent Biometrics iMG correlates with reference linear acceleration up to approximately 60 g, underestimating impacts at higher magnitudes. The Prevent iMG correlates well with angular velocity, while underestimating angular acceleration past approximately 3,000 rad/s^2. The DTS iMG consistently overestimates angular acceleration and velocity, and transformed linear kinematics are not well-correlated to reference kinematics at the head centre of gravity (HCG) for these impact conditions. Future work should examine the influence of the mandible and subject-specific mouthguard fit on fidelity of impact kinematics. This study highlights the need for cadaver validation studies of wearable head impact instrumentation systems, particularly when considering realistic (non-idealised) sensor-skull coupling and accounting for interactions with the mandible.

2022

1. fars_cleaner: A Python package for downloading and pre-processing vehicle fatality data in the US

   Mitchell Z. Abrams, and Cameron R. Bass

   Journal of Open Source Software, Sep 2022

   PDF Code DOI
2. Expanded Combined Lumbar Injury Criterion Due to Underbody Blast

   Concetta Morino, Maria Ortiz-Paparoni, Joost Op’t Eynde, Jason Kait, Mitchell Abrams, Frank Pintar, Narayan Yoganandan, Jason Moore, Kathryn Loftis, David Barnes, and Cameron R. Bass

   Sep 2022

   Poster presented at 2022 Ohio State Injury Biomechanics Research Symposium

   PDF Poster
3. Female vs. Male Relative Fatality Risk in Fatal Crashes – United States and United Kingdom

   Mitchell Z Abrams, and C.R. Bass

   Jul 2022

   Abstract presented at 9th World Congress of Biomechanics 2022, Taipei, Taiwan
4. Female vs. Male Relative Risk of Body System Injuries in Fatal and Non-Fatal Crashes

   Mitchell Z. Abrams, and C.R. Bass

   In Proceedings of the International Research Council on the Biomechanics of Injury , Sep 2022

   Abs PDF

   Motor vehicle crashes are a leading cause of death both in the United States and around the world. While research has showed younger females are at increased risk of fatality in fatal crashes, the underlying cause of this disparity is unclear. Data from the Fatality Analysis Reporting System (FARS), Mortality Multiple Cause of Death (MCOD), and National Automotive Sampling System Crashworthiness Data System (NASS-CDS) were used with the double-pair comparison method to identify relative risk of head injury and injury to other major body systems in motor vehicle crashes. FARS cases were linked to detailed cause of death records in MCOD. Young female occupants are at increased risk of fatal and severe head and abdominal injuries in motor vehicle crashes. This increased risk is pronounced for young females in both fatal crashes and non-fatal crashes with severe injuries. Along with previous research pointing to an increased overall fatality risk for young females in fatal crashes, these findings suggest a need to more carefully study biomechanical sex differences in car crashes.

2021

1. Using Wavelet Analysis to Distinguish Cavitation Acoustic Emissions From Blunt Impact Noise

   Christopher Eckersley, Joost Eynde, Mitchell Abrams, and Cameron R. Bass

   Journal of Biomechanical Engineering, Jul 2021

   Abs HTML DOI

   Cavitation has been shown to have implications for head injury, but currently there is no solution for detecting the formation of cavitation through the skull during blunt impact. The goal of this communication is to confirm the wideband acoustic wavelet signature of cavitation collapse, and determine that this signature can be differentiated from the noise of a blunt impact. A controlled, laser induced cavitation study was conducted in an isolated water tank to confirm the wide band acoustic signature of cavitation collapse in the absence of a blunt impact. A clear acrylic surrogate head was impacted to induce blunt impact cavitation. The bubble formation was imaged using a high speed camera, and the collapse was synched up with the wavelet transform of the acoustic emission. Wideband acoustic response is seen in wavelet transform of positive laser induced cavitation tests, but absent in laser induced negative controls. Clear acrylic surrogate tests showed the wideband acoustic wavelet signature of collapse can be differentiated from acoustic noise generated by a blunt impact. Broadband acoustic signal can be used as a biomarker to detect the incidence of cavitation through the skull as it consists of frequencies that are low enough to potentially pass through the skull but high enough to differentiate from blunt impact noise. This lays the foundation for a vital tool to conduct CSF cavitation research in-vivo.

2020

1. Female vs. Male Relative Fatality Risk in Fatal Crashes

   Mitchell Z. Abrams, and C.R. Bass

   In Proceedings of the International Research Council on Biomechanics of Injury , Sep 2020

   Abs PDF

   Since 1975, the US has seen a decrease in vehicle crash fatalities, noticeably among recent model vehicles. However, a lack of requirement to test motor vehicles using anthropomorphic test devices representative of both the average male and the average female occupant may be driving a disparity in the risk of fatality in severe crash scenarios. The double pair comparison method, first developed by Evans, was applied to many different cross-sections of the US Fatality Analysis Reporting System to investigate sex-dependent differences in relative fatality risk in crashes. Despite a dramatic decline in fatalities over the reporting period, female vehicle occupants aged 20–30 years are 20–25% more likely to die as a result of a fatal crash than males in the same age range. The risk to females and males becomes similar as age increases to 60. These trends hold when looking at subsets of crashes in either rural or urban areas, when looking at vehicles manufactured since 2010, and when isolating by single, two- or multiple-vehicle crashes. The consistency of this age-dependent relative risk emphasises a need to further investigate sex differences in crash-related outcomes.

2. Acoustic Detection of Blunt Induced Cavitation in the Head

   Christopher P Eckersley, Joost Eynde, Mitchell Abrams, Allen W Yu, Mucong Li, Junjie Yao, and C.R. Bass

   In Proceedings of the International Research Council on Biomechanics of Injury , Sep 2020

   Abs PDF

   The occurrence of cavitation in the brain from blunt impact is difficult to investigate and remains controversial. The objective of this study was to investigate cavitation formation from blunt impact, without compromising the cranial cavity, using novel acoustic biomarkers. These biomarkers were developed using a laser-induced cavitation study, acrylic surrogate impact tests, and fresh non-frozen pig cadaver impact tests. Laser-induced cavitation displayed a  125 and 250 kHz response on high frequency sensors, and a  13–20 kHz,  50–70 kHz and  100–140 kHz frequency response on hydrophones. For surrogate tests, a harmonic response ( 50–70, 100–140 and 250 kHz) was recorded 0–5 ms following confirmed cavitation impacts. In cadaver tests, largest impacts elicited a coupled low frequency ( 50–70 kHz) and high frequency ( 100–140 kHz) acoustic response 0–5 ms following impact. Negative control pig cadaver head tests provided low frequency response but were not associated with high frequency content for any impact. Using a series of validation tests and negative controls, this study developed an acoustic biomarker, a low frequency response coupled with a high frequency harmonic, which is sensitive and specific to CSF cavitation without compromising the cranial cavity. This provided evidence of cavitation within a fresh pig cadaver skull upon blunt impact.

3. Female vs. Male Relative Fatality Risk In Fatal Crashes: 1975-2018

   Mitchell Abrams, and C.R. Bass

   May 2020

   Oral presentation at 2020 Ohio State Injury Biomechanics Research Symposium

   Abs PDF

   Known sex-based physiological and biomechanical differences do not explain the much larger fatality risk to young women in car crashes compared with men under matched conditions, suggesting a need for expanded test methodologies and research strategies to address as-yet unexplored sex contributing to crash outcomes. Vehicle occupants who died in crashes with at least two occupants between 1975 and 2018 were examined. National Highway Traffic Safety Administration (NHTSA) Fatality Analysis Reporting System (FARS) data was used to calculate relative risk using a modified Double Pair Comparison method, with a bootstrap estimation for determining confidence intervals. This method matches subject occupants exhibiting one of two characteristics based on the characteristics of a common control occupant in the same vehicle. Participants were matched using vehicle seating location, vehicle type, airbag deployment, seatbelt usage, age and a control occupant. Male (n=205,325) and female (n=126,075) vehicle occupants sustaining fatal injury in passenger car or light truck crashes between 1975 and 2018 were examined. This population was binned by crash year (1975-2018, n=331,400; 1999-2018, n=112,032; 2010-2018, n=36,481; 2015-2018, n=14,796). Across all conditions, 25-year-old female vehicle occupants in crashes from 2010-2018 exhibit a relative fatality risk of 1.107 (95% CI 1.097 – 1.116) compared to 25-year-old male occupants. There is an age-dependent risk to females in vehicle crashes, with younger females at higher risk of death than younger males. This difference is robust across many variables, and is not attributable to vehicle weight, belt usage, or airbag deployment. Female vehicle occupants aged 20–30 years are 20–25% more likely to die as a result of a fatal crash than males in the same age range. Known sex-based differences do not explain this large risk differential, and should be further examined to ensure all occupants are well-protected.

2019

1. Measuring High School Football Head Impact Exposure With An Instrumented Earpiece (DASHR): A Pilot Study

   Mitchell Abrams, Jason F Luck, Patrick Liu, Kyle Matthews, Adam Mehlenbacher, Jason Kait, and C.R. Bass

   May 2019

   Poster presented at 2019 Ohio State Injury Biomechanics Research Symposium

   PDF Poster

2018

1. Improvements In Baseline Drift Removal From EOG Signal And Headset Design

   Mitchell Abrams, Austin Murray, Drew Levy, Jason F Luck, Divya Chowbey, Joost Eynde, and C.R. Bass

   Mar 2018

   Poster presented at 2018 Human Movement Science and Biomechanics Research Symposium, Chapel Hill

2017

1. Baseline drift removal with an electrooculography headset.

   John T. D’Angelo, Austin Murray, Joost Eynde, Jason F Luck, Mitchell Abrams, and C.R. Bass

   Mar 2017

   Chapel Hill
2. Baseline drift removal with an electrooculography headset.

   John T. D’Angelo, Austin Murray, Joost Eynde, Jason F Luck, Mitchell Abrams, and C.R. Bass

   Apr 2017

   Durham