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Voo L, Ott K, Metzger T, Merkle A, Drewry D. Severe Calcaneus Injury Probability Curves Due to Under-Body Blast. Ann Biomed Eng 2021; 49:3118-3127. [PMID: 34117584 DOI: 10.1007/s10439-021-02768-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 03/18/2021] [Indexed: 11/29/2022]
Abstract
The lower extremity is the most frequently injured body region to mounted soldiers during underbody blast (UBB) events. UBB events often produce large deformations of the floor and subsequent acceleration of the lower limb that are not sufficiently mitigated by the combat boot, leaving the calcaneus bone vulnerable to injury. Biomechanical experiments simulating UBB loading scenarios were conducted in a laboratory environment using isolated postmortem human subject (PMHS) leg components. Each leg component was tested twice: one sub-injurious test followed by a injury-targeted test. This enabled the use of interval censoring for each specimen in the survival statistical analysis to generate the human injury probability curves (HIPCs). Foot contact forces were measured in both the hindfoot and forefoot. Strains and acoustic emission signals at the calcaneus and distal tibia were utilized to determine injury timing. The footplate velocities of the injury tests ranged 8-13 m/s with time-to-peak velocity of 1.8-2.5 ms while the velocities of non-injury tests ranged from 4 to 6 m/s with the same time-to-peak. The majority of the injuries were severe calcaneus fractures (Sanders III-IV). Secondary injuries included fractures to the distal tibia, talus, cuboid and cuneiform. These injury outcomes were found to be consistent with those reported in UBB injury literature. The HIPCs for the severe calcaneus fracture were developed using the vertical heel contact force as the injury correlation measure through survival analysis statistical method in the form of lognormal function. This work represents the first set of HIPCs dedicated to the severe calcaneus fracture using the biomechanical force measurement closest to the injury location. This injury probability curve will enable biomechanical response validation of computational models, development of ATD injury assessment reference curve, and injury prediction capability for computational models or ATDs in the UBB environment.
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Affiliation(s)
- Liming Voo
- Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD, 20723, USA.
| | - Kyle Ott
- Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD, 20723, USA
| | - Thomas Metzger
- Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD, 20723, USA
| | - Andrew Merkle
- Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD, 20723, USA
| | - David Drewry
- Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD, 20723, USA
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Yoganandan N, Rooks TF, Chancey VC, Pintar FA, Banerjee A. Pelvic Injury Risk Curves for the Military Populations From Lateral Impact. Mil Med 2021; 186:424-429. [PMID: 33499484 DOI: 10.1093/milmed/usaa303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 08/05/2020] [Accepted: 08/24/2020] [Indexed: 11/13/2022] Open
Abstract
INTRODUCTION Current methods for transporting military troops include nonstandard seating orientations, which may result in novel injuries because of different types/directions of loading impact. The objective of this study is to develop pelvic injury risk curves (IRCs) under lateral impacts from human cadaver tests using survival analysis for application to military populations. METHODS Published data from lateral impacts applied to whole-body cadaver specimens were analyzed. Forces were treated as response variables. Demographics and body mass index (BMI) were covariates. Injury risk curves were developed for forces without covariates, for males, females, 83 kg body mass, and 25 kg/m2 BMI. Mean and ± 95% confidence interval IRCs, normalized confidence interval sizes at discrete risk levels, and quality indices were obtained for each metric-covariate combination curve. RESULTS Mean age, stature, total body mass, and BMI were 70.1 ± 8.6 years, 1.67 ± 0.1 m, 67.0 ± 14.4 kg, and 23.9 ± 3.97 kg/m2, respectively. For a total body mass of 83 kg, peak forces at 10%, 25%, and 50% probability levels were 5.7 kN, 7.4 kN, and 9.6 kN, respectively. For males, peak forces at the 10%, 25%, and 50% probability levels were 4.8 kN, 6.4 kN, and 8.4 kN, respectively. For females, peak forces at the 10%, 25%, and 50% probability levels were 3.0 kN, 4.0 kN, and 5.2 kN, respectively. Other data and risk curves are given. CONCLUSIONS The IRCs developed in this study can be used as injury criteria for the crashworthiness of future generation military vehicles. The introduction of BMI, sex, and total body mass as covariates quantified their contributions. These IRCs can be used with finite element models to assess and predict injury in impact environments to advance Soldier safety. Manikins specific to relevant military anthropometry may be designed and/or evaluated with the present IRCs to assess and mitigate musculoskeletal injuries associated with this posture and impact direction.
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Affiliation(s)
- Narayan Yoganandan
- Center for NeuroTrauma Research, Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Tyler F Rooks
- Injury Biomechanics and Protection Group, U.S. Army Aeromedical Research Laboratory, Fort Rucker, AL, 36362, USA
| | - Valeta Carol Chancey
- Injury Biomechanics and Protection Group, U.S. Army Aeromedical Research Laboratory, Fort Rucker, AL, 36362, USA
| | - Frank A Pintar
- Center for NeuroTrauma Research, Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Anjishnu Banerjee
- Division of Biostatistics, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
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Somasundaram K, Sherman D, Begeman P, Ciarelli T, McCarty SA, Kochkodan JJ, Demetropoulos CK, Cavanaugh JM. Mechanisms and timing of injury to the thoracic, lumbar and sacral spine in simulated underbody blast PMHS impact tests. J Mech Behav Biomed Mater 2020; 116:104271. [PMID: 33517100 DOI: 10.1016/j.jmbbm.2020.104271] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 11/11/2020] [Accepted: 12/12/2020] [Indexed: 11/29/2022]
Abstract
During an underbody blast (UBB) event, mounted occupants are exposed to high rate loading of the spine via the pelvis. The objective of this study was to simulate UBB loading conditions and examine mechanisms of injury in the thoracic, lumbar and sacral spine. Fourteen instrumented, whole-body, postmortem human subject (PMHS) experiments were performed using the WSU-decelerative horizontal sled system. The specimens were positioned supine on a decelerative sled, which then impacted an energy absorbing system mounted to a concrete barrier. Variables included the peak velocity and time-to-peak velocity for seat and floor, and the presence or absence of personal protective equipment (PPE) and seat padding. Post-test CT scans and autopsies were performed to identify the presence and severity of injuries. Acceleration and angular rate data collected at vertebra T1, T5, T8, T12, and S1 were used to assess injury timing and mechanisms. Additionally, joint time-frequency analysis (JTFA) of the spinal Z acceleration of the sacrum and vertebrae was developed with the aim of verifying spinal fracture timing. Injuries observed in the spine were attributed to axial compression applied through the pelvis, together with flexion moment due to the offset in the center of gravity of the torso, and are consistent with UBB-induced combat injuries reported in the literature. The injury timing estimation techniques discussed in this study provide a time interval when the fractures are predicted to have occurred. Furthermore, this approach serves as an alternative to the estimation methods using acoustic sensors, force and acceleration traces, and strain gauges.
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Affiliation(s)
| | - Donald Sherman
- Department of Biomedical Engineering, Wayne State University, Detroit, MI, USA
| | - Paul Begeman
- Department of Biomedical Engineering, Wayne State University, Detroit, MI, USA
| | - Traci Ciarelli
- Department of Biomedical Engineering, Wayne State University, Detroit, MI, USA
| | - Scott A McCarty
- Department of Orthopedic Surgery, Detroit Medical Center, Detroit, MI, USA
| | - James J Kochkodan
- Department of Orthopedic Surgery, Wayne State University School of Medicine, MI, USA
| | | | - John M Cavanaugh
- Department of Biomedical Engineering, Wayne State University, Detroit, MI, USA.
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Brazda IJ, Reeves J, Langohr GDG, Crookshank MC, Schemitsch EH, Zdero R. Biomechanical properties and thermal characteristics of frozen versus thawed whole bone. Proc Inst Mech Eng H 2020; 234:874-883. [PMID: 32515277 DOI: 10.1177/0954411920929455] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Biomechanics research often requires cadaveric whole bones to be stored in a freezer and then thawed prior to use; however, the literature shows a variety of practices for thawing. Consequently, this is the first study to report the mechanical properties of fully frozen versus fully thawed whole bone as 'proof of principle'. Two groups of 10 porcine ribs each were statistically equivalent at baseline in length, cross-sectional area, and bone mineral density. The two groups were stored in a freezer for at least 24 h, thawed in air at 23 °C for 4 h while temperature readings were taken to establish the time needed for thawing, and once again returned to the freezer for at least 24 h. Mechanical tests to failure using three-point bending were then done on the 'frozen' group immediately after removal from the freezer and the 'thawed' group when steady-state ambient air temperature was reached. Temperature readings over the entire thawing period were described by the line-of-best-fit formula T = (28.34t - 6.69)/(t + 0.38), where T = temperature in degree Celsius and t = time in hours, such that frozen specimens at t = 0 h had a temperature of -17 °C and thawed specimens at t = 1.75 h reached a steady-state temperature of 20 °C-23 °C. Mechanical tests showed that frozen versus thawed specimens had an average of 32% higher stiffness k, 34% higher ultimate force Fu, 28% lower ultimate displacement δu, 40% lower ultimate work Wu, 43% higher elastic modulus E, 37% higher ultimate normal stress σu, and 33% higher ultimate shear stress τu. Whole ribs failed at midspan primarily by transverse cracking (16 of 20 cases), oblique cracking (three of 20 cases), or surface denting (one of 20 cases), each having unique shapes for force versus displacement graphs differentiated mainly by ultimate force location.
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Affiliation(s)
- Ignace J Brazda
- Orthopaedic Biomechanics Lab, Victoria Hospital, London, ON, Canada
| | - Jacob Reeves
- Department of Mechanical and Materials Engineering, Western University, London, ON, Canada
| | - G Daniel G Langohr
- Department of Mechanical and Materials Engineering, Western University, London, ON, Canada
| | | | - Emil H Schemitsch
- Orthopaedic Biomechanics Lab, Victoria Hospital, London, ON, Canada.,Division of Orthopaedic Surgery, Western University, London, ON, Canada
| | - Radovan Zdero
- Orthopaedic Biomechanics Lab, Victoria Hospital, London, ON, Canada.,Department of Mechanical and Materials Engineering, Western University, London, ON, Canada.,Division of Orthopaedic Surgery, Western University, London, ON, Canada.,Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, ON, Canada
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Yoganandan N, Humm JR, DeVogel N, Banerjee A, Pintar FA, Somers JT. Pelvis injury risk curves in side impacts from human cadaver experiments using survival analysis and Brier score metrics. TRAFFIC INJURY PREVENTION 2019; 20:S137-S142. [PMID: 31762331 PMCID: PMC8325432 DOI: 10.1080/15389588.2019.1682565] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 09/18/2019] [Accepted: 10/14/2019] [Indexed: 06/10/2023]
Abstract
Objectives: Post Mortem Human Surrogate (PMHS) experiments are used for describing tolerance and improve safety. For nearside impacts, the United States Standard Federal Motor Vehicle Safety Standards (FMVSS-214) used PMHS tests and binary regression methods to achieve these goals. Since this promulgation, Parametric Statistical Survival Modeling (PSSM) has become a de facto standard for developing injury risk curves (IRCs). This study is focused on pelvic injuries from side impacts. The objectives are as follows. Analyze impactor-based intact PMHS tests and develop IRCs at different AIS levels using the force metric and examine the effectiveness of other force-related variables on IRCs.Methods: Impactor-driven pelvic tests conducted using whole body PMHS were selected from published studies. The dataset had 63 tests. Peak force, 3-ms clip force, and impulse were used to develop IRCs for Abbreviated Injury Scores (AIS) AIS2+ and AIS3+, i.e., groups A and B. Brier Score Metric (BSM) was used for ranking metrics. 95% confidence intervals were computed, Normalized Confidence Interval Sizes (NCIS) were determined, and quality of the IRCs were obtained.Results: Impulse best described the underlying response of the pelvis. BSMs were the lowest for the impulse for both groups. At 10% and 50% probabilities, impulses were 71 Ns and 125 Ns for group A and 79 Ns and 160 Ns for group B; peak forces were 3.8 kN and 7.1 kN and 4 kN and 10 kN for groups A and B; and clip forces were 2.7 kN and 6.5 kN and 3.6 kN and 8.6 kN, for groups A and B. NCIS at discrete probability levels, qualities of risk curves, and individual IRCs are given.Conclusion: This study underscores the importance of using impulse to describe pelvis injury criteria in lateral impacts. These findings are applicable to anthropomorphic test devices, as matched pair tests are done to determine dummy-based injury criteria/injury assessment risk curves (IARCs). Although IRCs have been developed for WorldSID, it may be appropriate to use impulse-based IARCs. Because THOR is a potential device for automated vehicle environments, it may be appropriate to develop THOR-based IARCS. The present IRCs act as fundamental human-based injury criteria. These responses can also be used in human body and subsystem computational models.
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Affiliation(s)
| | - John R. Humm
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI
| | - Nicholas DeVogel
- Division of Biostatistics, Medical College of Wisconsin, Milwaukee, WI
| | - Anjishnu Banerjee
- Division of Biostatistics, Medical College of Wisconsin, Milwaukee, WI
| | - Frank A. Pintar
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI
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Robinson DL, Tse KM, Franklyn M, Zhang J, Ackland D, Lee PVS. Cortical and Trabecular Bone Fracture Characterisation in the Vertebral Body Using Acoustic Emission. Ann Biomed Eng 2019; 47:2384-2401. [DOI: 10.1007/s10439-019-02316-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 06/28/2019] [Indexed: 12/20/2022]
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DeVogel N, Banerjee A, Yoganandan N. Application of resampling techniques to improve the quality of survival analysis risk curves for human frontal bone fracture. Clin Biomech (Bristol, Avon) 2019; 64:28-34. [PMID: 29753560 DOI: 10.1016/j.clinbiomech.2018.04.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 04/12/2018] [Accepted: 04/17/2018] [Indexed: 02/07/2023]
Abstract
BACKGROUND In automotive events, head injuries (skull fractures and/or brain injuries) are associated with head contact loading. While the widely-used head injury criterion is based on frontal bone fracture and linear accelerations, injury risk curves were not developed from original datasets. OBJECTIVES Develop skull fracture-based risk curves for using previously published data and apply resampling techniques to assess their qualities. METHODS Force, deflection, energy, and stiffness data from thirteen human cadaver head impact tests were used to develop risk curves using parametric survival analysis. Injuries occurred to all specimens. Data points were treated as uncensored. Variables were ranked, and the variable best explaining the underlying fracture response was determined using the Brier Score Metric (BSM). The qualities of the risk curves were determined using normalized confidence interval sizes. Statistical resampling methods were used to assess the quality of the risk curves and the impact of the sample size by conducting 2000 simulations. Sample sizes ranged from 13 to 26. FINDINGS The Weibull distribution was optimal for all the response variables, except deflection (log-logistic). The quality of the risk curves was the highest for deflection. This variable best explained the underlying head injury response, based on BSM. Improvements in the quality of the risk curves were achieved with additional samples of force and deflection (<13), while energy and stiffness variables required more size. Individual risk curves are given. INTERPRETATION These probability curves from head contact loading add to the understanding skull fractures and can be used to improve safety in injury producing environments.
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Affiliation(s)
- Nicholas DeVogel
- Division of Biostatistics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States
| | - Anjishnu Banerjee
- Division of Biostatistics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, United States
| | - Narayan Yoganandan
- Department of Neurosurgery, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, United States.
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