Publications
64 results found
Grigoriadis G, Carpanen D, Webster C, et al., 2018, The posture of the lower limb alters the mechanism of injury in under-body blast, International Research Council on the Biomechanics of Injury, IRCOBI, Pages: 758-759, ISSN: 2235-3151
Draper D, Newell N, Wernicke P, et al., 2018, A comparison of the compressive behaviour of lumbar intervertebral discs in five human body finite element models, International Research Council on the Biomechanics of Injury, IRCOBI, Pages: 242-244, ISSN: 2235-3151
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
Pandelani T, Newell N, Pearce AP, et al., 2018, The use of hybrid III ATD to assess the effect of body armour upon under-body blast injuries, Pages: 764-765, 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, Grant CA, Keenan BE, et al., 2017, A comparison of four techniques to measure anterior and posterior vertebral body heights and sagittal plane wedge angles in adolescent idiopathic scoliosis., Med Biol Eng Comput, Vol: 55, Pages: 561-572
Adolescent idiopathic scoliosis (AIS) is a three-dimensional (3D) spinal deformity of unknown aetiology. Increased growth of the anterior part of the vertebrae known as anterior overgrowth has been proposed as a potential driver for AIS initiation and progression. To date, there has been no objective evaluation of the 3D measurement techniques used to identify this phenomenon and the majority of previous studies use 2D planar assessments which contain inherent projection errors due to the vertebral rotation which is part of the AIS deformity. In this study, vertebral body (VB) heights and wedge angles were measured in a test group of AIS patients and healthy controls using four different image analysis and measurement techniques. Significant differences were seen between the techniques in terms of VB heights and VB wedge angles. The low variability, and the fact that the rotation and tilt of the deformed VBs are taken into account, suggests that the proposed technique using the full 3D orientation of the vertebrae is the most reliable method to measure anterior and posterior VB heights and sagittal plane wedge angles in 3D image data sets. These results have relevance for future investigations that aim to quantify anterior overgrowth in AIS patients for comparison with healthy controls.
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.
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.
Ranger TA, Newell N, Grant CA, et al., 2016, The role of the middle lumbar fascia on spinal mechanics: A human biomechanical assessment, Spine, ISSN: 1528-1159
Grant CA, Newell N, Izatt MT, et al., 2016, A comparison of vertebral venous networks in adolescent idiopathic scoliosis patients and healthy controls, Surgical and Radiologic Anatomy, Vol: 39, Pages: 281-291, ISSN: 0930-1038
Newell N, Grant CA, Keenan BE, et al., 2016, Quantifying Progressive Anterior Overgrowth in the Thoracic Vertebrae of Adolescent Idiopathic Scoliosis Patients A Sequential Magnetic Resonance Imaging Study, SPINE, Vol: 41, Pages: E382-E387, ISSN: 0362-2436
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.
Newell N, Neal W, Pandelani T, et al., 2016, The Dynamic Behaviour of the Floor of a Surrogate Vehicle Under Explosive Blast Loading, Journal of Materials Science Research, Vol: 5, Pages: 59-59, ISSN: 1927-0585
<jats:p><p class="1Body">Improvised Explosive Devices have been the signature weapon in the recent conflicts in Iraq and Afghanistan. High-rate axial forces exerted by the vehicle floor to the lower limbs of occupants have been the cause of severe injuries. In order to gain a greater understanding of the mechanisms of these injuries so that countermeasures can be developed, one is required to know how the vehicle floor behaves; therefore, the purpose of this study was to characterise the behaviour of a vehicle floor surrogate to a range of explosive loads. Explosive loads between 1 and 6 kg TNT were detonated beneath a vehicle floor surrogate resulting in peak floor velocities between 5.8 and 80.5 m/s reached in a time between 0.10 and 3.13 ms. The data can now be used to (a) test numerical models of blast and its interaction with structures for validity, and (b) ensure that the velocity profiles replicated in a laboratory environment to understand human tolerance to injury are relevant to the blast process. These will ensure that preventive measures are developed based on realistic physical and numerical models of injury.</p></jats:p>
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
Newell N, Grant CA, Izatt MT, et al., 2015, A semiautomatic method to identify vertebral end plate lesions (Schmorl's nodes), SPINE JOURNAL, Vol: 15, Pages: 1665-1673, ISSN: 1529-9430
- Author Web Link
- Cite
- Citations: 2
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, 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
- Author Web Link
- Cite
- Citations: 11
Newell N, Masouros SD, Bull AMJ, 2013, A comparison of MiL-Lx and hybrid-III responses in seated and standing postures with blast mats in simulated under-vehicle explosions, 2013 IRCOBI Conference Proceedings - International Research Council on the Biomechanics of Injury, Pages: 135-144
Blast mats that can be retrofitted to the floor of military vehicles are considered to reduce the risk of injury from under-vehicle explosions. Anthropometric test devices (ATDs) are validated for use only in the seated position. The aim of this study was to use a traumatic injury simulator fitted with 3 different blast mats in order to assess the ability of 2 ATD designs to evaluate the protective capacity of the mats in 2 occupant postures under 2 severities. Tests were performed for each combination of mat design, ATD, severity and posture using an antivehicle under-belly injury simulator. The differences between mitigation systems were larger under the H-III compared to the MiL-Lx. There was little difference in how the 2 ATDs and how posture ranked the mitigation systems. Results from this study suggest that conclusions obtained by testing in the seated position can be extrapolated to the standing. However, the different percentage reductions observed in the 2 ATDs suggests different levels of protection. It is therefore unclear which ATD should be used to assess such mitigation systems. A correlation between cadavers and ATDs on the protection offered by blast mats is required in order to elucidate this issue.
Newell N, Masouros SD, Ramasamy A, et al., 2012, Use of cadavers and anthropometric test devices (ATDs) for assessing lower limb injury outcome from under-vehicle explosions, 2012 IRCOBI Conference Proceedings - International Research Council on the Biomechanics of Injury, Pages: 296-303
Lower extremities are particularly susceptible to injury in an under-vehicle explosion. Operational fitness of military vehicles is assessed through anthropometric test devices (ATDs) in full-scale blast tests. The aim of this study was to compare the response between the Hybrid-III ATD, the MiL-Lx ATD and cadavers in our traumatic injury simulator, which is able to replicate the response of the vehicle floor in an under-vehicle explosion. All specimens were fitted with a combat boot and tested on our traumatic injury simulator in a seated position. The load recorded in the ATDs was above the tolerance levels recommended by NATO in all tests; no injuries were observed in any of the 3 cadaveric specimens. The Hybrid-III produced higher peak forces than the MiL-Lx. The time to peak strain in the calcaneus of the cadavers was similar to the time to peak force in the ATDs. Maximum compression of the sole of the combat boot was similar for cadavers and MiL-Lx, but significantly greater for the Hybrid-III. These results suggest that the MiL-Lx has a more biofidelic response to under-vehicle explosive events compared to the Hybrid-III. Therefore, it is recommended that mitigation strategies are assessed using the MiL-Lx surrogate and not the Hybrid-III.
Masouros SD, Newell N, Bonner TJ, et al., 2012, A standing vehicle occupant is likely to sustain a more severe injury than one who has flexed knees in an under-vehicle explosion: A cadaveric study, 2012 IRCOBI Conference Proceedings - International Research Council on the Biomechanics of Injury, Pages: 289-295
The lower limb of military vehicle occupants has been the most injured body part due to undervehicle explosions in recent conflicts. Understanding the injury mechanism and causality of injury severity could aid in developing better protection. Therefore, we tested 4 different occupant postures (seated, brace, standing, standing with knee locked in hyper-extension) in a simulated under-vehicle explosion (solid blast) using our traumatic injury simulator in the laboratory; we hypothesised that occupant posture would affect injury severity. No skeletal injury was observed in the specimens in seated and braced postures. Severe, impairing injuries were observed in the foot of standing and hyper-extended specimens. These results demonstrate that a vehicle occupant whose posture at the time of the attack incorporates knee flexion is more likely to be protected against severe skeletal injury to the lower leg.
Newell N, Masouros SD, Pullen AD, et al., 2012, The comparative behaviour of two combat boots under impact, Injury Prevention, Vol: 18, Pages: 109-112, ISSN: 1353-8047
Background Improvised explosive devices have become the characteristic weapon of conflicts in Iraq and Afghanistan. While little can be done to mitigate against the effects of blast in free-field explosions, scaled blast simulations have shown that the combat boot can attenuate the effects on the vehicle occupants of anti-vehicular mine blasts. Although the combat boot offers some protection to the lower limb, its behaviour at the energies seen in anti-vehicular mine blast has not been documented previously.Methods The sole of eight same-size combat boots from two brands currently used by UK troops deployed to Iraq and Afghanistan were impacted at energies of up to 518 J, using a spring-assisted drop rig.Results The results showed that the Meindl Desert Fox combat boot consistently experienced a lower peak force at lower impact energies and a longer time-to-peak force at higher impact energies when compared with the Lowa Desert Fox combat boot.Discussion This reduction in the peak force and extended rise time, resulting in a lower energy transfer rate, is a potentially positive mitigating effect in terms of the trauma experienced by the lower limb.Conclusion Currently, combat boots are tested under impact at the energies seen during heel strike in running. Through the identification of significantly different behaviours at high loading, this study has shown that there is rationale in adding the performance of combat boots under impact at energies above those set out in international standards to the list of criteria for the selection of a combat boot.
Bonner TJ, Eardley WGP, Newell N, et al., 2011, Accurate placement of a pelvic binder improves reduction of unstable fractures of the pelvic ring, JOURNAL OF BONE AND JOINT SURGERY-BRITISH VOLUME, Vol: 93B, Pages: 1524-1528, ISSN: 0301-620X
- Author Web Link
- Cite
- Citations: 52
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.