Publications
125 results found
Pandelani T, Carpanen D, Masouros SD, 2024, Evaluating Pelvis Response During Simulated Underbody Blast Loading., J Biomech Eng, Vol: 146
In recent conflicts, blast injury from landmines and improvised explosive devices (IEDs) has been the main mechanism of wounding and death. When a landmine or IED detonates under a vehicle (an under-body blast), the seat acceleration rapidly transmits a high load to the pelvis of the occupants, resulting in torso and pelvic injury. Pelvic fractures have high mortality rates, yet their injury mechanism has been poorly researched. Three (3) fresh-frozen male pelvic specimens were tested under axial impact loading. The pelvis was impacted mounted upside down by dropping a 12 kg mass at target impact velocities ranging from 1 to 8.6 m/s with time to peak velocity ranging from 3.8 to 5.8 ms. Resulting fractures were broadly categorized as involving a bilateral pubis rami fracture, a bilateral ischium fracture, and sacroiliac joint disruption. The study provides insights into the type and severity of pelvic injury that may occur over a range of under-body blast (UBB)-relevant loading profiles.
Howe TJ, Claireaux H, Fox H, et al., 2023, Mechanical assessment of proprietary and improvised pelvic binders for use in the prehospital environment, BMJ MILITARY HEALTH, ISSN: 2633-3767
Carpanen D, Masouros SD, Stinner DJ, 2023, Biomechanical evaluation of a tool-less external fixator, BMJ MILITARY HEALTH, Vol: 169, Pages: E55-E58, ISSN: 2633-3767
Tsukada H, Nguyen T-TN, Breeze J, et al., 2023, The risk of fragment penetrating injury to the heart, Journal of The Mechanical Behavior of Biomedical Materials, Vol: 141, Pages: 1-6, ISSN: 1751-6161
Injury due to the penetration of fragments into parts of the body has been the major cause of morbidity and mortality after an explosion. Penetrating injuries into the heart present very high mortality, yet the risk associated with such injuries has not been quantified. Quantifying this risk is key in the design of personal protection and the design of infrastructure.This study is the first quantitative assessment of cardiac penetrating injuries from energised fragments. Typical fragments (5-mm sphere, 0.78-g right-circular cylinder and 1.1-g chisel-nosed cylinder) were accelerated to a range of target striking velocities using a bespoke gas-gun system and impacted ventricular and atrial walls of lamb hearts. The severity of injury was shown to not depend on location (ventricular or atrial wall). The striking velocity with 50% probability of critical injury (Abbreviated Injury Scale (AIS) 5 score) ranged between 31 and 36 m/s across all 3 fragments used. These findings can help directly in reducing morbidity and mortality from explosive events as they can be implemented readily into models that aim to predict casualties in an explosive event, inform protocols for first responders, and improve design of infrastructure and personal protective equipment.
Rebelo EA, Grigoriadis G, Carpanen D, et al., 2023, Stature and mitigation systems affect the risk of leg injury in vehicles attacked under the body by explosive devices, Frontiers in Bioengineering and Biotechnology, Vol: 11, Pages: 1-5, ISSN: 2296-4185
A finite-element (FE) model, previously validated for underbody blast (UBB) loading, was used here to study the effect of stature and of mitigation systems on injury risk to the leg. A range of potential UBB loadings was simulated. The risk of injury to the leg was calculated when no protection was present, when a combat boot (Meindl Desert Fox) was worn, and when a floor mat (IMPAXXTM), which can be laid on the floor of a vehicle, was added. The risk of injury calculated indicates that the floor mat provided a statistically significant reduction in the risk of a major calcaneal injury for peak impact speeds below 17.5 m/s when compared with the scenarios in which the floor mat was not present. The risk of injury to the leg was also calculated for a shorter and a taller stature compared to that of the nominal, 50th percentile male anthropometry; shorter and taller statures were constructed by scaling the length of the tibia of the nominal stature. The results showed that there is a higher risk of leg injury associated with the short stature compared to the nominal and tall statures, whereas the leg-injury risk between nominal and tall statures was statistically similar. These findings provide evidence that the combat boot and the floor mat tested here have an attenuating effect, albeit limited to a range of possible UBB loads. The effect of stature on injury has implications on how vehicle design caters for all potential anthropometries and indeed gender, as women, on average, are shorter than men. The results from the computational simulations here complement laboratory and field experimental models of UBB, and so they contribute to the improvement of UBB safety technology and strategy.
Carpanen D, Newell N, Masouros SD, 2023, Surrogates: Anthropometric Test Devices, Blast Injury Science and Engineering A Guide for Clinicians and Researchers: Second Edition, Pages: 333-341, ISBN: 9783031103544
This chapter presents and discusses the use of physical surrogates for the assessment of human injury. The focus is on anthropomorphic test devices (ATDs), otherwise known as dummies. These have been developed in order to evaluate occupant protection in response to impact loading. They are used extensively in the automotive industry to quantify occupant safety and the defence industry for military vehicle assessment. Their main design objective is to be robust and repeatable. Most ATDs do not assess failure directly; instead, they are heavily instrumented with transducers which record data during testing; these data are then analysed to determine the injury risk in the human.
Nguyen TTN, Carpanen D, Sory DR, et al., 2023, Physical Experimental Apparatus for Modelling Blast, Blast Injury Science and Engineering A Guide for Clinicians and Researchers: Second Edition, Pages: 295-308, ISBN: 9783031103544
Blast injuries inflicted by an explosive event are complex and difficult to characterise. There is a range of injury mechanisms which includes the direct insult of the blast overpressure, penetration by fragments and debris, and blunt or crush trauma induced by displacement of the body. These injury mechanisms are a result of loading at rates often beyond those that conventional testing platforms are designed to deliver, thus bespoke and well-controlled experimental devices are essential to recreate in the laboratory environment these injury mechanisms and reproduce the injury outcomes. This chapter summarises a range of physical experimental devices that have been developed for studying various blast injuries. They are classified into separate time-dependent processes of a blast loading: the primary, secondary, and tertiary blast effects.
Masouros SD, Pope DJ, 2023, Behaviour of Materials, Blast Injury Science and Engineering A Guide for Clinicians and Researchers: Second Edition, Pages: 39-59, ISBN: 9783031103544
This chapter presents the fundamental principles surrounding materials and their behaviour under load as relevant to blast. It begins by describing engineering and biological materials. Basic principles of the analysis of material behaviour follow, introducing the reader to terms such as stress and strain and the types of behaviour that different types of material might exhibit. The mechanical response of materials under static and dynamic loading is presented and basic tools for their analysis are introduced, including for estimating failure.
Masouros SD, Rebelo E, Newell N, 2023, Tertiary Blast Injury and its Protection, Blast Injury Science and Engineering A Guide for Clinicians and Researchers: Second Edition, Pages: 353-355, ISBN: 9783031103544
Tertiary blast injury results from the interaction of the body with solid structures due to bodily or structural displacement caused by blast. This chapter presents briefly the types of tertiary blast, the epidemiology of tertiary blast injury and key advancements in protecting against it.
Anderson KM, McGregor AH, Masouros SD, et al., 2023, Orthotics, Blast Injury Science and Engineering A Guide for Clinicians and Researchers: Second Edition, Pages: 437-446, ISBN: 9783031103544
Continued advances are required to address mobility limitations caused by lower extremity blast injury. Individuals who experience persistent deficits following trauma may benefit from external support and/or offloading provided by ankle foot orthoses (AFOs). Currently available AFOs vary widely in their design and potential benefit. Carbon fibre custom dynamic ankle foot orthoses (CDOs) have been increasingly used to improve mobility after traumatic injury. CDOs are made predominantly from carbon fibre and are intended to restore function across a range of daily and high-energy activities. Patient-reported outcomes, physical performance measures, and biomechanics data from studies focusing on CDO use have demonstrated positive outcomes. CDOs consist of a proximal cuff, posterior carbon fibre strut, and footplate, which can be tuned to meet the needs of the patient. Available literature provides guidance related to key design considerations during the fitting process. Further, intensive training when combined with the CDO has been found to enhance clinical outcomes and facilitate successful return to high-energy activity. A majority of available data related to CDO use following limb trauma is focused on a subset of military personnel, and available civilian data is limited.
Pope DJ, Fryer R, Masouros SD, 2023, In Silico Models, Blast Injury Science and Engineering A Guide for Clinicians and Researchers: Second Edition, Pages: 279-284, ISBN: 9783031103544
This chapter presents examples of computational models used to simulate injury due to blast loading. Examples from primary, secondary and tertiary blast loading that are used within our organisations are included. These are the Axelsson model for primary blast loading of the chest wall; overview of calculating the probability of injury to crowds due to a person-borne improvised explosive device; prediction of fragment penetration into the neck; prediction of injury to the lower extremity due to underbody blast (mine detonating underneath a vehicle) and evaluation of design parameters of an energy-attenuating vehicle seat for improved protection in underbody blast.
Masouros SD, Bull AMJ, 2023, Section Overview, Blast Injury Science and Engineering A Guide for Clinicians and Researchers: Second Edition, ISBN: 9783031103544
This section presents the engineering tools that we currently have at our disposal when investigating blast injury science and engineering and notes the challenges that are yet to be addressed. This short overview describes the various areas that are addressed within the chapters of this section.
Masouros SD, Pope DJ, 2023, Fundamentals of Computational Modelling, Blast Injury Science and Engineering A Guide for Clinicians and Researchers: Second Edition, Pages: 61-79, ISBN: 9783031103544
This chapter presents an introduction to the main formulations used in computational modelling. It presents the commonly used ways of discretising the continuum of space and time, and then focusses mainly on describing the finite element method, which is the most commonly used computational tool to analyse the deformation of structures, including the human body. It concludes with introducing the important terms of sensitivity, verification and validation of computational models, which are used to quantify the integrity of a model and its range of utility to predict behaviour.
Masouros SD, 2023, Section Overview, Blast Injury Science and Engineering A Guide for Clinicians and Researchers: Second Edition, ISBN: 9783031103544
This section covers the science and engineering foundations required to follow the rest of the book. This short overview introduces the following chapters and their purpose within the book.
Low L, Masouros S, Newell N, 2023, Compressive and Flexion Stiffnesses of Human Cervical, Thoracic and Lumbar Intervertebral Discs Under High-rate Loading, Pages: 1075-1077, ISSN: 2235-3151
Pandelani T, Masouros SD, Calvo-Gallego JL, 2023, Application of quasi-linear viscoelasticity for the characterisation of human buttocks adipose tissue, Pages: 315-319
The mechanical properties of the human buttocks adipose tissue were investigated theoretically. The material properties obtained from the stress relaxation test were fitted to with a new algorithm using Fung’s quasilinear viscoelastic (QLV) model with Prony series in conjunction with a hyperelastic model. The model was applied to fit the stress-time data during both the ramp and relaxation phases. By using the material properties obtained from the stress relaxation test, a numerical model was developed and the data from the model was fitted to Polynomial, Ogden and Exponential hyperelastic strain energy density (SED) function. It was found that, the QVL with the Polynomial SED function could predict the peak stress better than the other SED functions.
Nguyen T-TN, Tsukada H, Breeze J, et al., 2022, The critical role of a backing material in assessing the performance of soft ballistic protection, Human Factors and Mechanical Engineering for Defense and Safety, Vol: 6, Pages: 1-11, ISSN: 2509-8004
Penetrating trauma by energised fragments is the most common injury from an explosive event. Fragment penetrations to the truncal region can result in lethal haemorrhage. Personal armour is used to mitigate ballistic threats; it comprises hard armour to protect from high-velocity bullets and soft armour to protect against energised fragments and other ballistic threats (such as from a hand gun) with low impact velocities. Current testing standards for soft armour do not focus on realistic boundary conditions, and a backing material is not always recommended. This study provides a comprehensive set of evidence to support the inclusion of a backing used in testing of soft body armour. Experiments were performed with a gas-gun system using fragment-simulating projectiles (FSPs) of different shapes and sizes to impact on a woven aramid and a knitted high-performance polyethylene ballistic fabric, with and without the ballistic gelatine soft tissue simulant as the backing material. The results showed statistically significant differences in the impact velocities at 50% risk (V50) of fabric perforation across all test configurations when the gelatine backing was used. Furthermore, the backing material enabled the collection of injury-related metrics such as V50 of tissue-simulant penetrations as well as depth of penetration against impact velocity. The normalised energy absorbed by the fabric could also be calculated when the backing material was present. This study confirms that a backing material is essential, particularly when assessing the performance of single layer fabrics against FSPs of low mass. It also demonstrates the additional benefits provided by the backing for predicting injury outcomes.
Rankin IA, Nguyen T-TN, McMenemy L, et al., 2022, Protective clothing reduces lower limb injury severity against propelled sand debris in a laboratory setting, Human Factors and Mechanical Engineering for Defense and Safety, Vol: 6, Pages: 1-7, ISSN: 2509-8004
The contribution of energised environmental debris to injury patterns of the blast casualty is not known. The extent to which personal protective equipment (PPE) limits the injuries sustained by energised environmental debris following an explosive event is also not known. In this study, a cadaveric model exposed to a gas-gun mediated sand blast was utilised which reproduced soft-tissue injuries representative of those seen clinically following blast. Mean sand velocity across experiments was 506 ± 80 ms−1. Cadaveric samples wearing standard-issue PPE were shown to have a reduced injury severity to sand blast compared to control: a statistically significant reduction was seen in the total surface area (143 mm2 vs. 658 mm2, p = 0.004) and depth of injuries (0 vs. 23 deep injuries, odds ratio = 0.0074, 95% confidence intervals 0.0004–0.1379). This study is the first to recreate wounds from propelled sand in a human cadaveric model. These findings implicate environmental debris, such as sand ejected from a blast event, as a critical mechanism of injury in the blast casualty. Tier 1 pelvic PPE was shown to reduce markedly the severity of injury. This injury mechanism should be a key focus of future research and mitigation strategies.
Rankin IA, Nguyen TT, Webster C, et al., 2022, The Injury Mechanism of Explosive Blast Trauma, with Protective Strategies for the Pelvis and Lower Limbs, Pages: 652-653
Tsukada H, Nguyen TTN, Breeze J, et al., 2022, Fragment penetration into the heart: initial findings, Pages: 789-790
Low L, Salzar R, Newell N, et al., 2022, The Role of Non-linear Stiffness in Modelling High-Rate Axial Loading of the Spine, Pages: 650-651
Breeze J, Fryer RN, Nguyen T-TN, et al., 2022, Injury modelling for strategic planning in protecting the national infrastructure from terrorist explosive events, BMJ MILITARY HEALTH, ISSN: 2633-3767
Nguyen TT, Breeze J, Masouros S, 2022, Penetration of Energised Metal Fragments to Porcine Thoracic Tissues, Journal of Biomechanical Engineering, ISSN: 0148-0731
Energised fragments from explosive devices have been the most common mechanism of injury to both military personnel and civilians in recent conflicts and terrorist attacks. Fragments that penetrate into the thoracic cavity are strongly associated with death due to the inherent vulnerability of the underlying structures. The aim of this study was to investigate the impact of fragment-simulating projectiles (FSPs) to tissues of the thorax in order to identify the thresholds of impact velocity for perforation through these tissues and the resultant residual velocity of the FSPs. A gas-gun system was used to launch 0.78-g cylindrical and 1.13-g spherical FSPs at intact porcine thoracic tissues from different impact locations. The sternum and rib bones were the most resistant to perforation, followed by the scapula and intercostal muscle. For both FSPs, residual velocity following perforation was linearly proportional to impact velocity. These findings can be used in the development of numerical tools for predicting the medical outcome of explosive events, which in turn can inform the design of public infrastructure, of personal protection, and of medical emergency response.
Low L, Newell N, Masouros S, 2022, A Multibody Model of the Spine for Injury Prediction in High-Rate Vertical Loading, Pages: 452-460, ISSN: 2235-3151
Underbody blast (UBB) results in lumbar spine injuries in 35% of military-vehicle casualties, resulting in disability and reduced quality of life. A multibody model of a lab-simulated UBB on a full-body cadaver was developed using geometric and inertial properties acquired from a CT scan of the same cadaver. The model comprises a skull, individual vertebral bodies, and a sacrum. Vertebral levels were connected by spring-dampers. Stiffness and damping values were taken from literature of the intervertebral disc and optimized to calibrate the model. The sacrum acceleration recorded in the experiment was input to the model sacrum, and the optimization algorithm worked to maximize the CORA (ISO18571) score of the head and T1 vertebra axial acceleration. The peak accelerations at T1 in the experiment and optimized model were 128 g and 111 g and the times-to-peak were 13.8 ms and 13.9 ms, respectively. The CORA score of both the head and T1 was 0.645 (fair). Stiffness in flexion increased by two orders of magnitude, while other degrees of freedom were scaled by values <100. This study developed a simple, fast-running, subject-specific model to predict injury across the spine. The vision is to assess the probability of injury of any seat configuration, in any vehicle.
Rebelo EA, Grigoriadis G, Carpanen D, et al., 2021, An experimentally validated finite element model of the lower limb to investigate the efficacy of blast mitigation systems, Frontiers in Bioengineering and Biotechnology, Vol: 9, ISSN: 2296-4185
Improvised explosive devices (IEDs) used in the battlefield cause damage to vehicles and their occupants. The injury burden to the casualties is significant. The biofidelity and practicality of current methods for assessing current protection to reduce the injury severity is limited. In this study, a finite-element (FE) model of the leg was developed and validated in relevant blast-loading conditions, and then used to quantify the level of protection offered by a combat boot. An FE model of the leg of a 35 years old male cadaver was developed. The cadaveric leg was tested physically in a seated posture using a traumatic injury simulator and the results used to calibrate the FE model. The calibrated model predicted hindfoot forces that were in good correlation (using the CORrelation and Analysis or CORA tool) with data from force sensors; the average correlation and analysis rating (according to ISO18571) was 0.842. The boundary conditions of the FE model were then changed to replicate pendulum tests conducted in previous studies which impacted the leg at velocities between 4 and 6.7 m/s. The FE model results of foot compression and peak force at the proximal tibia were within the experimental corridors reported in the studies. A combat boot was then incorporated into the validated computational model. Simulations were run across a range of blast-related loading conditions. The predicted proximal tibia forces and associated risk of injury indicated that the combat boot reduced the injury severity for low severity loading cases with higher times to peak velocity. The reduction in injury risk varied between 6 and 37% for calcaneal minor injuries, and 1 and 54% for calcaneal major injuries. No injury-risk reduction was found for high severity loading cases. The validated FE model of the leg developed here was able to quantify the protection offered by a combat boot to vehicle occupants across a range of blast-related loading conditions. It can now be used as a design an
Rankin I, Nguyen T, McMenemy L, et al., 2021, The injury mechanism of traumatic amputation, Frontiers in Bioengineering and Biotechnology, Vol: 9, ISSN: 2296-4185
Traumatic amputation has been one of the most defining injuries associated with explosive devices. An understanding of the mechanism of injury is essential in order to reduce its incidence and devastating consequences to the individual and their support network. In this study, traumatic amputation is reproduced using high-velocity environmental debris in an animal cadaveric model. The study findings are combined with previous work to describe fully the mechanism of injury as follows. The shock wave impacts with the casualty, followed by energised projectiles (environmental debris or fragmentation) carried by the blast. These cause skin and soft tissue injury, followed by skeletal trauma which compounds to produce segmental and multifragmental fractures. A critical injury point is reached, whereby the underlying integrity of both skeletal and soft tissues of the limb has been compromised. The blast wind that follows these energised projectiles completes the amputation at the level of the disruption, and traumatic amputation occurs. These findings produce a shift in the understanding of traumatic amputation due to blast from a mechanism predominately thought mediated by primary and tertiary blast, to now include secondary blast mechanisms, and inform change for mitigative strategies.
Draper D, Newell N, Masouros S, et al., 2021, Multiscale validation of multiple human body model functional spinal units, Journal of Biomechanical Engineering, Vol: 143, ISSN: 0148-0731
A validation comparing five human body model (HBM) lumbar spines is carried out across two load cases, with the objective to use and apply HBMs in high strain rate applications such as car occupant simulation. The first load case consists of an individual intervertebral disc (IVD) loaded in compression at a strain rate of 1/s by a material testing machine. The second load case is a lumbar functional spine unit (FSU) loaded in compression using a drop tower setup, producing strain rates of up to 48/s. The IVD simulations were found to have a better agreement with the experiments than the FSU simulations, and the ranking of which HBMs matched best to the experiment differed by load case. These observations suggest the need for more hierarchical validations of the lumbar spine for increasing the utility of HBMs in high strain rate loading scenarios.
Rankin IA, Thuy-Tien N, Carpanen D, et al., 2021, Pelvic Protection Limiting Lower Limb Flail Reduces Mortality, JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME, Vol: 143, ISSN: 0148-0731
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Tavana S, Masouros S, Baxan N, et al., 2021, The Effect of Degeneration on Internal Strains and the Mechanism of Failure in Human Intervertebral Discs Analyzed Using Digital Volume Correlation (DVC) and Ultra-High Field MRI, Frontiers in Bioengineering and Biotechnology, Vol: 8, ISSN: 2296-4185
The intervertebral disc (IVD) plays a main role in absorbing and transmitting loads within the spinal column. Degeneration alters the structural integrity of the IVDs and causes pain, especially in the lumbar region. The objective of this study was to investigate non-invasively the effect of degeneration on human 3D lumbar IVD strains (n = 8) and the mechanism of spinal failure (n = 10) under pure axial compression using digital volume correlation (DVC) and 9.4 Tesla magnetic resonance imaging (MRI). Degenerate IVDs had higher (p < 0.05) axial strains (58% higher), maximum 3D compressive strains (43% higher), and maximum 3D shear strains (41% higher), in comparison to the non-degenerate IVDs, particularly in the lateral and posterior annulus. In both degenerate and non-degenerate IVDs, peak tensile and shear strains were observed close to the endplates. Inward bulging of the inner annulus was observed in all degenerate IVDs causing an increase in the AF compressive, tensile, and shear strains at the site of inward bulge, which may predispose it to circumferential tears (delamination). The endplate is the spine's “weak link” in pure axial compression, and the mechanism of human vertebral fracture is associated with disc degeneration. In non-degenerate IVDs the locations of failure were close to the endplate centroid, whereas in degenerate IVDs they were in peripheral regions. These findings advance the state of knowledge on mechanical changes during degeneration of the IVD, which help reduce the risk of injury, optimize treatments, and improve spinal implant designs. Additionally, these new data can be used to validate computational models.
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