Publications
125 results found
Newell N, Pearce AP, Spurrier E, et al., 2018, Analysis of isolated transverse process fractures sustained during blast related events, Journal of Trauma and Acute Care Surgery, Vol: 85, Pages: S129-S133, ISSN: 2163-0763
BACKGROUND: A range of devastating blast injuries have been sustained by personnel during recent conflicts. Previous studies have focused on severe injuries, including to the spine, however, no study has specifically focused on the most common spinal injury; transverse process (TP) fractures. Although their treatment usually requires limited intervention, analysis of TP fractures may help determine injury mechanisms. METHODS: Data was collected from victims with spinal fractures injured in Improvised Explosive Device (IED) attacks, from the UK's Joint Theatre Trauma Registry. The level and side of each TP fracture was recorded, as well as associated injuries, whether they were mounted or dismounted, and outcome (survivor or fatality). RESULTS: The majority of TP fractures were lumbar (80%). More bilateral (both left and right fractures at the same level), and L5 TP fractures, were seen in fatalities than survivors. In the mounted group, lumbar TP fractures were statistically significantly associated with fatality, head injury, non-compressible torso haemorrhage, pelvic injury, and other spinal injuries. In the dismounted group, thoracic TP fractures were associated with head, chest wall, and other spinal injuries, and lumbar TP fractures were associated with pelvic, and other spinal injuries. CONCLUSIONS: Different injury mechanisms of the TP in the mounted and dismounted groups are likely. Inertial forces acting within the torso due to rapid loading being transferred through the seat, or high intra-abdominal pressures causing the tensile forces acting through the lumbar fascia to avulse the TPs are likely mechanisms in the mounted group. Blunt trauma, violent lateral flexion-extension forces, or rapid flail of the lower extremities causing tension of the psoas muscle, avulsing the TP are likely causes in the dismounted group. Isolated lumbar TP fractures can be used as markers for more severe injuries, and fatality, in mounted blast casualties. LEVEL OF EVIDENCE: P
Webster CE, Clasper J, Stinner DJ, et al., 2018, Characterization of Lower Extremity Blast Injury, MILITARY MEDICINE, Vol: 183, Pages: E448-E453, ISSN: 0026-4075
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- Citations: 9
Rebelo E, Grigoriadis G, Carpanen D, et al., 2018, Protection of the foot and ankle in under-body blast, Pages: 756-757, ISSN: 2235-3151
Christou A, Grigoriadis G, Carpanen D, et al., 2017, Biomechanics of a lumbar functional unit using the finite element method, 2017 IRCOBI Conference, Pages: 668-669, ISSN: 2235-3151
Grigoriadis G, Carpanen D, Webster C, et al., 2017, The effect of the posture of the lower limb in anti-vehicular explosions, 2017 IRCOBI Conference, Pages: 709-710, ISSN: 2235-3151
Newell N, Carpanen D, Christou A, et al., 2017, Strain rate dependence of internal pressure and external bulge in human intervertebral discs during axial compression, 2017 IRCOBI Conference, Pages: 670-671, ISSN: 2235-3151
Newell N, Little JP, Chirstou A, et al., 2017, Biomechanics of the human intervertebral disc: a review of testing techniques and results, Journal of the Mechanical Behavior of Biomedical Materials, Vol: 69, Pages: 420-434, ISSN: 1751-6161
Many experimental testing techniques have been adopted in order to provide an understanding of the biomechanics of the human intervertebral disc (IVD). The aim of this review article is to amalgamate results from these studies to provide readers with an overview of the studies conducted and their contribution to our current understanding of the biomechanics and function of the IVD. The overview is presented in a way that should prove useful to experimentalists and computational modellers. Mechanical properties of whole IVDs can be assessed conveniently by testing ‘motion segments’ comprising two vertebrae and the intervening IVD and ligaments. Neural arches should be removed if load-sharing between them and the disc is of no interest, and specimens containing more than two vertebrae are required to study ‘adjacent level’ effects. Mechanisms of injury (including endplate fracture and disc herniation) have been studied by applying complex loading at physiologically-relevant loading rates, whereas mechanical evaluations of surgical prostheses require slower application of standardised loading protocols. Results can be strongly influenced by the testing environment, preconditioning, loading rate, specimen age and degeneration, and spinal level. Component tissues of the disc (anulus fibrosus, nucleus pulposus, and cartilage endplates) have been studied to determine their material properties, but only the anulus has been thoroughly evaluated. Animal discs can be used as a model of human discs where uniform non-degenerate specimens are required, although differences in scale, age, and anatomy can lead to problems in interpretation.
Newell N, Grigoriadis G, Christou A, et al., 2017, Material properties of bovine intervertebral discs across strain rates, Journal of The Mechanical Behavior of Biomedical Materials, Vol: 65, Pages: 824-830, ISSN: 1751-6161
The intervertebral disc (IVD) is a complex structure responsible for distributing compressive loading to adjacent vertebrae and allowing the vertebral column to bend and twist. To study the mechanical behaviour of individual components of the IVD, it is common for specimens to be dissected away from their surrounding tissues for mechanical testing. However, disrupting the continuity of the IVD to obtain material properties of each component separately may result in erroneous values. In this study, an inverse finite element (FE) modelling optimisation algorithm has been used to obtain material properties of the IVD across strain rates, therefore bypassing the need to harvest individual samples of each component. Uniaxial compression was applied to ten fresh-frozen bovine intervertebral discs at strain rates of 10-3–1/s. The experimental data were fed into the inverse FE optimisation algorithm and each experiment was simulated using the subject specific FE model of the respective specimen. A sensitivity analysis revealed that the IVD's response was most dependent upon the Young's modulus (YM) of the fibre bundles and therefore this was chosen to be the parameter to optimise. Based on the obtained YM values for each test corresponding to a different strain rate (View the MathML source), the following relationship was derived:View the MathML source. These properties can be used in finite element models of the IVD that aim to simulate spinal biomechanics across loading rates.
Ramasamy A, masouros S, grigoriadis, 2017, The lower extremities: Computational Modelling Attempts to Predict Injury, Military Injury Biomechanics The Cause and Prevention of Impact Injuries, Publisher: CRC Press, ISBN: 9781498742825
An international team of experts have been brought together to examine and review the topics. The book is intended for researchers, postgraduate students and others working or studying defence and impact injuries.
Carpanen D, Kedgley AE, Plant D, et al., 2016, The risk of injury of the metacarpophalangeal and interphalangeal joints of the hand, International Research Council on the Biomechanics of Injury, Pages: 902-903
Grigoriadis G, Carpanen D, Bull AMJ, et al., 2016, A finite element model of the foot and ankle for prediction of injury in under-body blast, International Research Council on the Biomechanics of Injury, Publisher: IRCOBI, Pages: 457-458, ISSN: 2235-3151
Grigoriadis G, Newell N, Carpanen D, et al., 2016, Material properties of the heel fat pad across strain rates, Journal of the Mechanical Behavior of Biomedical Materials, Vol: 65, Pages: 398-407, ISSN: 1751-6161
The complex structural and material behaviour of the human heel fat pad determines the transmission of plantar loading to the lower limb across a wide range of loading scenarios; from locomotion to injurious incidents. The aim of this study was to quantify the hyper-viscoelastic material properties of the human heel fat pad across strains and strain rates. An inverse finite element (FE) optimisation algorithm was developed and used, in conjunction with quasi-static and dynamic tests performed to five cadaveric heel specimens, to derive specimen-specific and mean hyper-viscoelastic material models able to predict accurately the response of the tissue at compressive loading of strain rates up to 150 s−1. The mean behaviour was expressed by the quasi-linear viscoelastic (QLV) material formulation, combining the Yeoh material model (C10=0.1MPa, C30=7MPa, K=2GPa) and Prony׳s terms (A1=0.06, A2=0.77, A3=0.02 for τ1=1ms, τ2=10ms, τ3=10s). These new data help to understand better the functional anatomy and pathophysiology of the foot and ankle, develop biomimetic materials for tissue reconstruction, design of shoe, insole, and foot and ankle orthoses, and improve the predictive ability of computational models of the foot and ankle used to simulate daily activities or predict injuries at high rate injurious incidents such as road traffic accidents and underbody blast.
Webster C, Clasper J, Masouros S, 2016, Pelvic Fracture and Posture at the time of injury: The potential for mitigation strategies and improving survivability, BRITISH JOURNAL OF SURGERY, Vol: 103, Pages: 91-91, ISSN: 0007-1323
Newell N, Masouros SD, 2016, Testing and development of mitigation systems for tertiary blast, Blast Injury Science and Engineering A Guide for Clinicians and Researchers, Editors: Bull, Clasper, Mahoney, Publisher: Springer, Pages: 249-255, ISBN: 9783319218670
Biomechanics in blast is a key discipline in blast injury science and engineering that addresses the consequences of high forces, large deformations and extreme failure and thus relates closely to knowledge of materials science (Chap. 3) and ...
Newell N, Salzar R, Bull AMJ, et al., 2016, A validated numerical model of a lower limb surrogate to investigate injuries caused by under-vehicle explosions, Journal of Biomechanics, Vol: 49, Pages: 710-717, ISSN: 0021-9290
Under-vehicle explosions often result in injury of occupants׳ lower extremities. The majority of these injuries are associated with poor outcomes. The protective ability of vehicles against explosions is assessed with Anthropometric Test Devices (ATDs) such as the MIL-Lx, which is designed to behave in a similar way to the human lower extremity when subjected to axial loading. It incorporates tibia load cells, the response of which can provide an indication of the risk of injury to the lower extremity through the use of injury risk curves developed from cadaveric experiments. In this study an axisymmetric finite element model of the MIL-Lx with a combat boot was developed and validated. Model geometry was obtained from measurements taken using digital callipers and rulers from the MIL-Lx, and using CT images for the combat boot. Appropriate experimental methods were used to obtain material properties. These included dynamic, uniaxial compression tests, quasi-static stress-relaxation tests and 3 point bending tests. The model was validated by comparing force-time response measured at the tibia load cells and the amount of compliant element compression obtained experimentally and computationally using two blast-injury experimental rigs. Good correlations between the numerical and experimental results were obtained with both. This model can now be used as a virtual test-bed of mitigation designs and in surrogate device development.
Carpanen D, Masouros SD, Newell N, 2016, Surrogates of human injury, Blast injury science and engineering, Editors: Bull, Clasper, Mahoney, Publisher: Springer, Pages: 189-199
In this chapter we will explore surrogates that are being used to help in our understanding of the pathophysiology of human injury and of predicting injury risk when exposed to a set loading environment. We will mainly focus on anthropomorphic test devices (ATDs), usually known as dummies. Dummies are physical human surrogates that have been designed to evaluate occupant protection in response to collision. Even though ATDs are classified according to size, age, sex and impact direction, injury assessment in automotive and blast applications is mostly conducted using the adult midsize dummy.
Spurrier E, Gibb I, Masouros S, et al., 2016, Identifying spinal injury patterns in underbody blast to develop mechanistic hypotheses, Spine, Vol: 41, Pages: E268-E275, ISSN: 1528-1159
Study Design. A retrospective case series of UK victims of blast injury.Objective. To identify the injury patterns in the spine caused by under-vehicle blast, and attempt to derive the mechanism of those injuries.Summary of Background Data. The Improvised Explosive Device has been a feature of recent conflicts with frequent attacks on vehicles, leading to devastating injuries. Vehicle design has evolved to reduce the risk of injury to occupants in underbody blast, where the device detonates beneath the vehicle. The mechanism of spinal injury in such attacks is not well understood; understanding the injury mechanism is necessary to produce evidence-based mitigation strategies.Methods. A Joint Theatre Trauma Registry search identified UK victims of blast between 2008 and 2013. Each victim had their initial scan reviewed to classify spinal fractures.Results. Seventy-eight victims were identified, of whom 53 were survivors. There were a total of 284 fractures, including 101 thoracolumbar vertebral body fractures and 39 cervical spine fractures. Most thoracolumbar fractures were wedge compression injuries. Most cervical spine fractures were compression-extension injuries.The most common thoracic and lumbar body fractures in this group suggest a flexed posture at the time of injury. Most cervical spine fractures were in extension, which might be compatible with the head having struck another object.Conclusion. Modifying the seated posture might reduce the risk of thoracolumbar injury, or allow the resulting injury patterns to be controlled. Cervical spine injuries might be mitigated by changing vehicle design to protect the head.
Newell N, Grigoriadis G, Christou A, et al., 2016, Mechanical characterisation of bovine intervertebral discs at a range of strain rates, Ircobi, Pages: 158-159
Masouros S, Halewood C, Bull A, et al., 2015, Biomechanics, Expertise orthopadie und unfallchirurgie: Knie, Editors: Kohn, ISBN: 978-3-1317500-1-3
Proud WG, Nguyen T-TN, Bo C, et al., 2015, The High-Strain Rate Loading of Structural Biological Materials, METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, Vol: 46A, Pages: 4559-4566, ISSN: 1073-5623
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- Citations: 4
Spurrier E, Singleton JAG, Gibb I, et al., 2015, Blast Injury in the Spine: Dynamic Response Index Is Not an Appropriate Model for Predicting Injury, CLINICAL ORTHOPAEDICS AND RELATED RESEARCH, Vol: 473, Pages: 2929-2935, ISSN: 0009-921X
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- Citations: 11
Halewood C, Masouros S, Amis AA, 2015, Structure and function of the menisci, Meniscal Allograft Transplantation. A comprehensive review., Editors: Getgood, Spalding, Cole, Gersoff, Verdonk, ISBN: 978-0-9558873-5-2
Christou AK, Spurrier E, Grigoriadis G, et al., 2015, Human cadaveric bi-segment impact experiments at different postures, Pages: 742-743
Newell N, Bull AMJ, Masouros SD, 2015, A computational model for prediction of lower-limb injury in under-vehicle explosions, Pages: 748-749
Bonner TJ, Newell N, Karunaratne A, et al., 2015, Strain-rate sensitivity of the lateral collateral ligament of the knee, Journal of The Mechanical Behavior of Biomedical Materials, Vol: 41, Pages: 261-270, ISSN: 1751-6161
The material properties of ligaments are not well characterized at rates of deformation that occur during high-speed injuries. The aim of this study was to measure the material properties of lateral collateral ligament of the porcine stifle joint in a uniaxial tension model through strain rates in the range from 0.01 to 100/s. Failure strain, tensile modulus and failure stress were calculated. Across the range of strain rates, tensile modulus increased from 288 to 905 MPa and failure stress increased from 39.9 to 77.3 MPa. The strain-rate sensitivity of the material properties decreased as deformation rates increased, and reached a limit at approximately 1/s, beyond which there was no further significant change. In addition, time resolved microfocus small angle X-ray scattering was used to measure the effective fibril modulus (stress/fibril strain) and fibril to tissue strain ratio. The nanoscale data suggest that the contribution of the collagen fibrils towards the observed tissue-level deformation of ligaments diminishes as the loading rate increases. These findings help to predict the patterns of limb injuries that occur at different speeds and improve computational models used to assess and develop mitigation technology.
Ramasamy A, Newell N, Masouros S, 2014, From the battlefield to the laboratory: the use of clinical data analysis in developing models of lower limb blast injury, JOURNAL OF THE ROYAL ARMY MEDICAL CORPS, Vol: 160, Pages: 117-120, ISSN: 0035-8665
Grigoriadis G, Newell N, Masouros SD, et al., 2014, The material properties of the human heel fat pad across strain-rates: An inverse finite element approach, Pages: 478-479
Masouros SD, Brown KA, Clasper J, et al., 2013, Briefing: Blast effects on biological systems, Proceedings of the Institution of Civil Engineers: Engineering and Computational Mechanics, Vol: 166, Pages: 113-118, ISSN: 1755-0777
A signature of current conflicts is the use of buried improvised explosive devices to cause injury to military personnel and damage to their vehicles. Explosive devices also cause injuries to non-military populations in current and former conflict zones. The nature and placement of the explosive charge has a marked effect on the loading experienced. In all situations, damage to tissues occurs when the energy and loading rate exceeds that which the human body can support. Currently, it is difficult to predict the various time-dependent effects of blast injury because of the complexities of the rapid initial accelerations, the loading geometries and the heterogeneous nature of the tissues that can be damaged. An outline of the ways in which one may study how explosive energy interacts with biological systems is presented along with a discussion of how the data generated can be used to develop improved, costeffective strategies for studying blast injury processes.
Masouros SD, Newell N, Ramasamy A, et al., 2013, Design of a Traumatic Injury Simulator for Assessing Lower Limb Response to High Loading Rates, ANNALS OF BIOMEDICAL ENGINEERING, Vol: 41, Pages: 1957-1967, ISSN: 0090-6964
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- Citations: 11
Ramasamy A, Hill AM, Masouros S, et al., 2013, Outcomes of IED foot and ankle blast injuries., J Bone Joint Surg Am, Vol: 95
BACKGROUND: Improvements in protection and medical treatments have resulted in increasing numbers of modern-warfare casualties surviving with complex lower-extremity injuries. To our knowledge, there has been no prior analysis of foot and ankle blast injuries as a result of improvised explosive devices (IEDs). The aims of this study were to report the pattern of injury and determine which factors are associated with a poor clinical outcome. METHODS: U.K. service personnel who had sustained lower leg injuries following an under-vehicle explosion from January 2006 to December 2008 were identified with the use of a prospective trauma registry. Patient demographics, injury severity, the nature of the lower leg injury, and the type of clinical management were recorded. Clinical end points were determined by (1) the need for amputation and (2) ongoing clinical symptoms. RESULTS: Sixty-three U.K. service personnel (eighty-nine injured limbs) with lower leg injuries from an explosion were identified. Fifty-one percent of the casualties sustained multisegmental injuries to the foot and ankle. Twenty-six legs (29%) required amputation, with six of them amputated because of chronic pain eighteen months following injury. Regression analysis revealed that hindfoot injuries, open fractures, and vascular injuries were independent predictors of amputation. At the time of final follow-up, sixty-six (74%) of the injured limbs had persisting symptoms related to the injury, and only nine (14%) of the service members were fit to return to their preinjury duties. CONCLUSIONS: This study demonstrates that foot and ankle injuries from IEDs are associated with a high amputation rate and frequently with a poor clinical outcome. Although not life-threatening, they remain a source of long-term morbidity in an active population.
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