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Grindle D, Balubaid A, Untaroiu C. Investigation of traffic accidents involving seated pedestrians using a finite element simulation-based approach. Comput Methods Biomech Biomed Engin 2023; 26:484-497. [PMID: 35507427 DOI: 10.1080/10255842.2022.2068349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Pedestrians who use wheelchairs (seated pedestrians) report 36% - 75% higher mortality rates than standing pedestrians in car-to-pedestrian collisions but the cause of this mortality is unknown. This is the first study to investigate the cause of seated pedestrian mortality in vehicle impacts using finite element simulations. In this study a manual wheelchair model was developed using geometry taken from publicly available CAD data, and was tested to meet ISO standards. The GHBMC 50th percentile male simplified occupant model was used as the seated pedestrian and the EuroNCAP family car and sports utility vehicle models were used as the impacting vehicles. The seated pedestrian was impacted by the two vehicles at three different locations on the vehicle and at 30 and 40 km/h. In 75% of the impacts the pedestrian was ejected from the wheelchair. In the rest of the impacts, the pedestrian and wheelchair were pinned to the vehicle and the pedestrian was not ejected. The underlying causes of seated pedestrian mortality in these impacts were head and brain injury. Life-threatening head injury risks (0.0% - 100%) were caused by the ground-pedestrian contact, and life-threatening brain injury risks (0.0 - 97.9%) were caused by the initial vehicle-wheelchair contact and ground-pedestrian contact. Thoracic and abdominal compression reported no risks of life-threatening injuries, but may do so in faster impacts or with different wheelchair designs. Protective equipment such as the wheelchair seatbelt or personal airbag may be useful in reducing injury risks but future research is required to investigate their efficacy.
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Affiliation(s)
- Daniel Grindle
- Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, Virginia, USA
| | - Ahmed Balubaid
- Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, Virginia, USA
| | - Costin Untaroiu
- Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, Virginia, USA
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Pandey A, Yuk J, Chang B, Fish FE, Jung S. Slamming dynamics of diving and its implications for diving-related injuries. SCIENCE ADVANCES 2022; 8:eabo5888. [PMID: 35895822 PMCID: PMC9328685 DOI: 10.1126/sciadv.abo5888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Accepted: 06/15/2022] [Indexed: 06/15/2023]
Abstract
In nature, many animals dive into water at high speeds, e.g., humans dive from cliffs, birds plunge, and aquatic animals porpoise and breach. Diving provides opportunities for animals to find prey and escape from predators and is a source of great excitement for humans. However, diving from high platforms can cause severe injuries to a diver. In this study, we demonstrate how similarity in the morphology of diving fronts unifies the slamming force across diving animals and humans. By measuring a time-averaged impulse that increases linearly with the impact height, we are able to estimate the unsteady hydrodynamic forces that an average human body experiences during the slamming phase of a feet-first, hand-first, or head-first dive. We evaluate whether the unsteady forces put the diver at risk of muscle or bone injuries for a particular diving height. Therefore, this study sheds light on a hydrodynamics-based protocol for safe high diving and an evolutionary driver for animal morphology.
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Affiliation(s)
- Anupam Pandey
- Biological & Environmental Engineering Department, Cornell University, Ithaca, NY 14853, USA
| | - Jisoo Yuk
- Biological & Environmental Engineering Department, Cornell University, Ithaca, NY 14853, USA
| | - Brian Chang
- Cambridge Design Partnership, Raleigh, NC 27603, USA
| | - Frank E. Fish
- Department of Biology, West Chester University, West Chester, PA 19383, USA
| | - Sunghwan Jung
- Biological & Environmental Engineering Department, Cornell University, Ithaca, NY 14853, USA
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Melnyk A, Whyte T, Van Toen C, Yamamoto S, Street J, Oxland TR, Cripton PA. The effect of end condition on spine segment biomechanics in compression with lateral eccentricity. J Biomech 2021; 128:110617. [PMID: 34628202 DOI: 10.1016/j.jbiomech.2021.110617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 06/02/2021] [Accepted: 07/05/2021] [Indexed: 11/29/2022]
Abstract
During axial impact compression of the cervical spine, injury outcome is highly dependent on initial posture of the spine and the orientation, frictional properties and stiffness of the impact surface. These properties influence the "end condition" the spine experiences in real-world impacts. The effect of end condition on compression and sagittal plane bending in laboratory experiments is well-documented. The spine is able to escape injury in an unconstrained flexion-inducing end condition (e.g. against an angled, low friction surface), but when the end condition is constrained (e.g. head pocketing into a deformable surface) the following torso can compress the aligned spine causing injury. The aim of this study was to determine whether this effect exists under combined axial compression and lateral bending. Over two experimental studies, twenty-four human three vertebra functional spinal units were subjected to controlled dynamic axial compression at two levels of laterally eccentric force and in two end conditions. One end condition allowed the superior spine to laterally rotate and translate (T-Free) and the other end condition allowed only lateral rotation (T-Fixed). Spine kinetics, kinematics, injuries and occlusion of the spinal canal were measured during impact and pre- and post-impact flexibility. In contrast to typical spine responses in flexion-compression loading, the cervical spine specimens in this study did not escape injury in lateral bending when allowed to translate laterally. The specimen group that allowed lateral translation during compression had more injuries at high laterally eccentric force, saw greater peak canal occlusions and post-impact flexibility than constrained specimens.
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Affiliation(s)
- Angela Melnyk
- Department of Orthopaedics, University of British Columbia, 2775 Laurel Street, Vancouver, BC V5Z 1M9, Canada; Department of Mechanical Engineering, University of British Columbia, 6250 Applied Science Ln #2054, Vancouver, BC V6T 1Z4, Canada; International Collaboration on Repair Discoveries (ICORD), 818 W 10(th) Ave, Vancouver, BC V5Z 1M9, Canada
| | - Tom Whyte
- Department of Mechanical Engineering, University of British Columbia, 6250 Applied Science Ln #2054, Vancouver, BC V6T 1Z4, Canada; International Collaboration on Repair Discoveries (ICORD), 818 W 10(th) Ave, Vancouver, BC V5Z 1M9, Canada.
| | - Carolyn Van Toen
- Department of Orthopaedics, University of British Columbia, 2775 Laurel Street, Vancouver, BC V5Z 1M9, Canada; Department of Mechanical Engineering, University of British Columbia, 6250 Applied Science Ln #2054, Vancouver, BC V6T 1Z4, Canada; International Collaboration on Repair Discoveries (ICORD), 818 W 10(th) Ave, Vancouver, BC V5Z 1M9, Canada
| | - Shun Yamamoto
- Department of Orthopaedics, University of British Columbia, 2775 Laurel Street, Vancouver, BC V5Z 1M9, Canada; International Collaboration on Repair Discoveries (ICORD), 818 W 10(th) Ave, Vancouver, BC V5Z 1M9, Canada
| | - John Street
- Department of Orthopaedics, University of British Columbia, 2775 Laurel Street, Vancouver, BC V5Z 1M9, Canada; International Collaboration on Repair Discoveries (ICORD), 818 W 10(th) Ave, Vancouver, BC V5Z 1M9, Canada
| | - Thomas R Oxland
- Department of Orthopaedics, University of British Columbia, 2775 Laurel Street, Vancouver, BC V5Z 1M9, Canada; Department of Mechanical Engineering, University of British Columbia, 6250 Applied Science Ln #2054, Vancouver, BC V6T 1Z4, Canada; International Collaboration on Repair Discoveries (ICORD), 818 W 10(th) Ave, Vancouver, BC V5Z 1M9, Canada
| | - Peter A Cripton
- Department of Orthopaedics, University of British Columbia, 2775 Laurel Street, Vancouver, BC V5Z 1M9, Canada; Department of Mechanical Engineering, University of British Columbia, 6250 Applied Science Ln #2054, Vancouver, BC V6T 1Z4, Canada; School of Biomedical Engineering, University of British Columbia, 2222 Health Sciences Mall, Biomedical Research Centre (BRC), Vancouver, BC V6T 1Z3, Canada; International Collaboration on Repair Discoveries (ICORD), 818 W 10(th) Ave, Vancouver, BC V5Z 1M9, Canada
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Pollock RD, Hodkinson PD, Smith TG. Oh G: The x, y and z of human physiological responses to acceleration. Exp Physiol 2021; 106:2367-2384. [PMID: 34730860 DOI: 10.1113/ep089712] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Accepted: 10/18/2021] [Indexed: 01/06/2023]
Abstract
NEW FINDINGS What is the topic of this review? This review focuses on the main physiological challenges associated with exposure to acceleration in the Gx, Gy and Gz directions and to microgravity. What advances does it highlight? Our current understanding of the physiology of these environments and latest strategies to protect against them are discussed in light of the limited knowledge we have in some of these areas. ABSTRACT The desire to go higher, faster and further has taken us to environments where the accelerations placed on our bodies far exceed or are much lower than that attributable to Earth's gravity. While on the ground, racing drivers of the fastest cars are exposed to high degrees of lateral acceleration (Gy) during cornering. In the air, while within the confines of the lower reaches of Earth's atmosphere, fast jet pilots are routinely exposed to high levels of acceleration in the head-foot direction (Gz). During launch and re-entry of suborbital and orbital spacecraft, astronauts and spaceflight participants are exposed to high levels of chest-back acceleration (Gx), whereas once in space the effects of gravity are all but removed (termed microgravity, μG). Each of these environments has profound effects on the homeostatic mechanisms within the body and can have a serious impact, not only for those with underlying pathology but also for healthy individuals. This review provides an overview of the main challenges associated with these environments and our current understanding of the physiological and pathophysiological adaptations to them. Where relevant, protection strategies are discussed, with the implications of our future exposure to these environments also being considered.
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Affiliation(s)
- Ross D Pollock
- Centre for Human and Applied Physiological Sciences, King's College London, London, UK
| | - Peter D Hodkinson
- Centre for Human and Applied Physiological Sciences, King's College London, London, UK
| | - Thomas G Smith
- Centre for Human and Applied Physiological Sciences, King's College London, London, UK.,Department of Anaesthesia, Guy's and St Thomas' NHS Foundation Trust, London, UK
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Maroon JC, Faramand A, Agarwal N, Harrington AL, Agarwal V, Norwig J, Okonkwo DO. Management of thoracic spinal cord injury in a professional American football athlete: illustrative case. JOURNAL OF NEUROSURGERY: CASE LESSONS 2021; 2:CASE21206. [PMID: 36131575 PMCID: PMC9589477 DOI: 10.3171/case21206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 06/09/2021] [Indexed: 11/06/2022]
Abstract
BACKGROUND
A case of catastrophic thoracic spinal cord injury (SCI) sustained by a professional American football player with severe scoliosis is presented.
OBSERVATIONS
A 25-year-old professional football player sustained an axial loading injury while tackling. Examination revealed a T8 American Spinal Injury Association Impairment Scale grade A complete SCI. Methylprednisolone and hypothermia protocols were initiated. Computed tomography scan of the thoracic spine demonstrated T8 and T9 facet fractures on the left at the apex of a 42° idiopathic scoliotic deformity. Magnetic resonance imaging (MRI) demonstrated T2 spinal cord hyperintensity at T9. He regained trace movement of his right lower extremity over 12 hours, which was absent on posttrauma day 2. Repeat MRI revealed interval cord compression and worsening of T2 signal change at T7-T8 secondary to hematoma. Urgent decompression and fusion from T8 to T10 were performed. Additional treatment included high-dose omega-3 fatty acids and hyperbaric oxygen therapy. A 2-month inpatient spinal cord rehabilitation program was followed by prolonged outpatient physical therapy. He currently can run and jump with minimal residual distal left lower limb spasticity.
LESSONS
This is the first known football-related thoracic SCI with idiopathic scoliosis. Aggressive medical and surgical intervention with intensive rehabilitation formed the treatment protocol, with a favorable outcome achieved.
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Affiliation(s)
| | | | | | | | - Vikas Agarwal
- Radiology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania; and
| | - John Norwig
- Pittsburgh Steelers, Pittsburgh, Pennsylvania
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Whyte T, Barker JB, Cronin DS, Dumas GA, Nolte LP, Cripton PA. Load-Sharing and Kinematics of the Human Cervical Spine Under Multi-Axial Transverse Shear Loading: Combined Experimental and Computational Investigation. J Biomech Eng 2021; 143:1097188. [PMID: 33537737 DOI: 10.1115/1.4050030] [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: 08/27/2020] [Indexed: 11/08/2022]
Abstract
The cervical spine experiences shear forces during everyday activities and injurious events yet there is a paucity of biomechanical data characterizing the cervical spine under shear loading. This study aimed to (1) characterize load transmission paths and kinematics of the subaxial cervical spine under shear loading, and (2) assess a contemporary finite element cervical spine model using this data. Subaxial functional spinal units (FSUs) were subjected to anterior, posterior, and lateral shear forces (200 N) applied with and without superimposed axial compression preload (200 N) while monitoring spine kinematics. Load transmission paths were identified using strain gauges on the anterior vertebral body and lateral masses and a disc pressure sensor. Experimental conditions were simulated with cervical spine finite element model FSUs (GHBMC M50 version 5.0). The mean kinematics, vertebral strains, and disc pressures were compared to experimental results. The shear force-displacement response typically demonstrated a toe region followed by a linear response, with higher stiffness in anterior shear relative to lateral and posterior shear. Compressive axial preload decreased posterior and lateral shear stiffness and increased initial anterior shear stiffness. Load transmission patterns and kinematics suggest the facet joints play a key role in limiting anterior shear while the disc governs motion in posterior shear. The main cervical spine shear responses and trends are faithfully predicted by the GHBMC cervical spine model. These basic cervical spine biomechanics and the computational model can provide insight into mechanisms for facet dislocation in high severity impacts, and tissue distraction in low severity impacts.
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Affiliation(s)
- T Whyte
- Orthopaedic and Injury Biomechanics Group, Departments of Mechanical Engineering and Orthopaedics, The School of Biomedical Engineering and International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC V6T 1Z4, Canada; Neuroscience Research Australia, Margarete Ainsworth Building, Barker Street, Randwick, NSW 2031, Australia
| | - J B Barker
- Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue W, Waterloo, ON N2 L 3G1, Canada
| | - D S Cronin
- Department of Mechanical and Mechatronics Engineering, 200 University Avenue W, Waterloo, ON N2 L 3G1, Canada
| | - G A Dumas
- Department of Mechanical and Materials Engineering, Queen's University, 130 Stuart Street, Kingston, ON K7 L 3N6, Canada
| | - L-P Nolte
- ARTORG Center for Biomedical Engineering Research, University of Bern, Freiburgstrasse 3, Bern 3010, Switzerland
| | - P A Cripton
- Orthopaedic and Injury Biomechanics Group, Departments of Mechanical Engineering and Orthopaedics, The School of Biomedical Engineering and International Collaboration on Repair Discoveries, University of British Columbia, 6250 Applied Science Lane, Vancouver, BC V6T 1Z4, Canada
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