249 results found
Bull AMJ, Eftaxiopoulou T, Persad L, Assessment of Performance Parameters of a Series of Five ‘Historical’ Cricket Bat Designs, Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology, ISSN: 1754-3371
Cheong VS, Karunaratne A, Amis AA, et al., 2017, Strain rate dependency of fractures of immature bone, JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS, Vol: 66, Pages: 68-76, ISSN: 1751-6161
Grigoriadis G, Newell N, Carpanen D, et al., 2017, 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
Junaid S, Sanghavi S, Anglin C, et al., 2017, Treatment of the Fixation Surface Improves Glenoid Prosthesis Longevity in vitro., J Biomech, Vol: 61, Pages: 81-87
Many commercial cemented glenoid components claim superior fixation designs and increased survivability. However, both research and clinical studies have shown conflicting results and it is unclear whether these design variations do improve loosening rates. Part of the difficulty in investigating fixation failure is the inability to directly observe the fixation interface, a problem addressed in this study by using a novel experimental set-up. Cyclic loading-displacement tests were carried out on 60 custom-made glenoid prostheses implanted into a bone substitute. Design parameters investigated included treatment of the fixation surface of the component resulting in different levels of back-surface roughness, flat-back versus curved-back, keel versus peg and more versus less conforming implants. Visually-observed failure and ASTM-recommended rim-displacements were recorded throughout testing to investigate fixation failure and if rim displacement is an appropriate measure of loosening. Roughening the implant back (Ra>3µm) improved resistance to failure (P<0.005) by an order of magnitude with the rough and smooth groups failing at 8712±5584 cycles (mean±SD) and 1080±1197 cycles, respectively. All other design parameters had no statistically significant effect on the number of cycles to failure. All implants failed inferiorly and 95% (57/60) at the implant/cement interface. Rim-displacement correlated with visually observed failure. The most important effect was that of roughening the implant, which strengthened the polyethylene-cement interface. Rim-displacement can be used as an indicator of fixation failure, but the sensitivity was insufficient to capture subtle effects. LEVEL OF EVIDENCE: Basic Science Study, Biomechanical Analysis.
Panagiotakis E, Mok K-M, Fong DT-P, et al., 2017, Biomechanical analysis of ankle ligamentous sprain injury cases from televised basketball games: Understanding when, how and why ligament failure occurs., J Sci Med Sport
OBJECTIVES: Ankle sprains due to landing on an opponent's foot are common in basketball. There is no analysis to date that provides a quantification of this injury mechanism. The aim of this study was to quantify the kinematics of this specific injury mechanism and relate this to lateral ankle ligament biomechanics. DESIGN: Case series. METHODS: The model-based image-matching technique was used to quantify calcaneo-fibular-talar kinematics during four ankle inversion sprain injury incidents in televised NBA basketball games. The four incidents follow the same injury pattern in which the players of interest step onto an opponent's foot with significant inversion and a diagnosed ankle injury. A geometric analysis was performed to calculate the in vivo ligament strains and strain rates for the anterior talofibular ligament (ATFL) and the calcaneofibular ligament (CFL). RESULTS: Despite the controlled selection of cases, the results show that there are two distinct injury mechanisms: sudden inversion and internal rotation with low levels of plantarflexion; and a similar mechanism without internal rotation. The first of these mechanisms results in high ATFL and CFL strains, whereas the second of these strains the CFL in isolation. CONCLUSIONS: The injury mechanism combined with measures of the ligament injury in terms of percentage of strain to failure correlate directly with the severity of the injury quantified by return-to-sport. The opportunity to control excessive internal rotation through proprioceptive training and/or prophylactic footwear or bracing could be utilised to reduce the severity of common ankle injuries in basketball.
Pandis P, Bull AM, 2017, A low-cost three-dimensional laser surface scanning approach for defining body segment parameters., Proc Inst Mech Eng H, Vol: 231, Pages: 1064-1068
Body segment parameters are used in many different applications in ergonomics as well as in dynamic modelling of the musculoskeletal system. Body segment parameters can be defined using different methods, including techniques that involve time-consuming manual measurements of the human body, used in conjunction with models or equations. In this study, a scanning technique for measuring subject-specific body segment parameters in an easy, fast, accurate and low-cost way was developed and validated. The scanner can obtain the body segment parameters in a single scanning operation, which takes between 8 and 10 s. The results obtained with the system show a standard deviation of 2.5% in volumetric measurements of the upper limb of a mannequin and 3.1% difference between scanning volume and actual volume. Finally, the maximum mean error for the moment of inertia by scanning a standard-sized homogeneous object was 2.2%. This study shows that a low-cost system can provide quick and accurate subject-specific body segment parameter estimates.
Pearce AP, Bull AMJ, Clasper JC, 2017, Mediastinal injury is the strongest predictor of mortality in mounted blast amongst UK deployed forces., Injury, Vol: 48, Pages: 1900-1905
BACKGROUND: Blast injury has been the most common cause of morbidity and mortality encountered by UK forces during recent conflicts. Injuries sustained by blast are categorised by the injuring component of the explosion and depend upon physical surroundings. Previous work has established that head injuries and intra cavity haemorrhage are the major causes of death following exposure to under body (mounted) blast but has yet to explore the precise nature of these torso injuries nor the effect of particular injuries upon survival. This study examines the patterns of torso injury within the mounted blast environment in order to understand the effect of these injuries upon survivability. METHODS: This retrospective study examined the UK Joint Theatre Trauma Registry to determine precise injury patterns of mounted blast casualties within a 13year period of UK military deployments. Survival rates of individual injuries were compared and a multivariable logistic regression model was developed in order to assess the effect that each injury had upon likelihood of death. RESULTS: 426 mounted casualties were reviewed of whom 129 did not survive. Median NISS and ISS for non-survivors was found to be 75. Torso injuries were significantly more common amongst non-survivors than survivors and high case fatality rates were associated with all haemorrhagic torso injuries. Multivariable analysis shows that mediastinal injuries have the largest odds ratio for mortality (20.4) followed by lung laceration and head injury. CONCLUSIONS: Non-compressible torso haemorrhage is associated with mortality amongst mounted blast. Of this group, mediastinal injury is the strongest predictor of death and could be considered as a surrogate marker of lethality. Future work to link blast loading characteristics with specific injury patterns will inform the design of mitigating strategies in order to improve survivability of underbody blast.
Pearce AP, Bull AMJ, Clasper JC, 2017, Re: Mediastinal injury is the strongest predictor of mortality in mounted blast amongst UK deployed forces: Methodological issues., Injury
Amabile C, Bull AMJ, Kedgley AE, 2016, The centre of rotation of the shoulder complex and the effect of normalisation, JOURNAL OF BIOMECHANICS, Vol: 49, Pages: 1938-1943, ISSN: 0021-9290
Barnett-Vanes A, Sharrock A, Eftaxiopoulou T, et al., 2016, CD43Lo classical monocytes participate in the cellular immune response to isolated primary blast lung injury, JOURNAL OF TRAUMA AND ACUTE CARE SURGERY, Vol: 81, Pages: 500-511, ISSN: 2163-0755
Buckeridge EM, Bull AMJ, McGregor AH, 2016, Incremental training intensities increases loads on the lower back of elite female rowers, JOURNAL OF SPORTS SCIENCES, Vol: 34, Pages: 369-378, ISSN: 0264-0414
Buckeridge EM, Weinert-Aplin RA, Bull AMJ, et al., 2016, Influence of foot-stretcher height on rowing technique and performance, SPORTS BIOMECHANICS, Vol: 15, Pages: 513-526, ISSN: 1476-3141
Campos-Pires R, Dickinson R, 2016, Modelling Blast Brain Injury, Blast Injury Science and Engineering A Guide for Clinicians and Researchers, Editors: Clasper, Bull, Mahoney, Publisher: Springer, Pages: 173-182, ISBN: 9783319218670
The consequences of blast traumatic brain injury (blast-TBI) in humans are largely determined by the characteristics of the trauma insult and, within certain limits, the individual responses to the lesions inflicted (1). In blast-TBI the mechanisms of brain vulnerability to the detonation of an explosive device are not entirely understood. They most likely result from a combination of the different physical aspects of the blast phenomenon, specifically extreme pressure oscillations (blast-overpressure wave), projectile penetrating fragments and acceleration-deceleration forces, creating a spectrum of brain injury that ranges from mild to severe blast-TBI (2). The pathophysiology of penetrating and inertially-driven blast-TBI has been extensively investigated for many years. However, the brain damage caused by blast-overpressure is much less understood and is unique to this type of TBI (3). Indeed, there continues to be debate about how the pressure wave is transmitted and reflected through the brain and how it causes cellular damage (4). No single model can mimic the clinical and mechanical complexity resulting from a real life blast-TBI (3). The different models, non-biological (in silico or surrogate physical) and biological (ex vivo, in vitro or in vivo), tend to complement each other.
Eftaxiopoulou T, Barnett-Vanes A, Arora H, et al., 2016, Prolonged but not short-duration blast waves elicit acute inflammation in a rodent model of primary blast limb trauma, INJURY-INTERNATIONAL JOURNAL OF THE CARE OF THE INJURED, Vol: 47, Pages: 625-632, ISSN: 0020-1383
Fratini A, Bonci T, Bull AMJ, 2016, Whole Body Vibration Treatments in Postmenopausal Women Can Improve Bone Mineral Density: Results of a Stimulus Focussed Meta-Analysis, PLOS ONE, Vol: 11, ISSN: 1932-6203
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, Pages: 457-458
McGregor AH, Buckeridge E, Murphy AJ, et al., 2016, Communicating and using biomechanical measures through visual cues to optimise safe and effective rowing, PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART P-JOURNAL OF SPORTS ENGINEERING AND TECHNOLOGY, Vol: 230, Pages: 246-252, ISSN: 1754-3371
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
Nolte D, Tsang CK, Zhang KY, et al., 2016, Non-linear scaling of a musculoskeletal model of the lower limb using statistical shape models, JOURNAL OF BIOMECHANICS, Vol: 49, Pages: 3576-3581, ISSN: 0021-9290
Rane L, Bull AMJ, 2016, Functional electrical stimulation of gluteus medius reduces the medial joint reaction force of the knee during level walking., Arthritis Res Ther, Vol: 18
BACKGROUND: By altering muscular activation patterns, internal forces acting on the human body during dynamic activity may be manipulated. The magnitude of one of these forces, the medial knee joint reaction force (JRF), is associated with disease progression in patients with early osteoarthritis (OA), suggesting utility in its targeted reduction. Increased activation of gluteus medius has been suggested as a means to achieve this. METHODS: Motion capture equipment and force plate transducers were used to obtain kinematic and kinetic data for 15 healthy subjects during level walking, with and without the application of functional electrical stimulation (FES) to gluteus medius. Musculoskeletal modelling was employed to determine the medial knee JRF during stance phase for each trial. A further computer simulation of increased gluteus medius activation was performed using data from normal walking trials by a manipulation of modelling parameters. Relationships between changes in the medial knee JRF, kinematics and ground reaction force were evaluated. RESULTS: In simulations of increased gluteus medius activity, the total impulse of the medial knee JRF was reduced by 4.2 % (p = 0.003) compared to control. With real-world application of FES to the muscle, the magnitude of this reduction increased to 12.5 % (p < 0.001), with significant inter-subject variation. Across subjects, the magnitude of reduction correlated strongly with kinematic (p < 0.001) and kinetic (p < 0.001) correlates of gluteus medius activity. CONCLUSIONS: The results support a major role for gluteus medius in the protection of the knee for patients with OA, establishing the muscle's central importance to effective therapeutic regimes. FES may be used to achieve increased activation in order to mitigate distal internal loads, and much of the benefit of this increase can be attributed to resulting changes in kinematic parameters and the gr
Southgate DFL, Childs PRN, Bull AMJ, 2016, Sports Innovation, Technology and Research, Publisher: World Scientific, ISBN: 9781786340412
Sports Innovation, Technology and Research gives an insight into recent research and design projects at Imperial College London. It presents the on-going development of a diverse range of areas from elite rowing performance to impact protection to sporting amenities in communities.Also included are descriptions of some of the latest innovations that have been developed as part of the Rio Tinto Sports Innovation Challenge, an initiative that tasked engineering students to design, build and implement Paralympic and other sporting equipment. It offers a glimpse at the breadth of creativity that can be achieved when human centred design is applied to an area such as disabled sport. It also shows the potential that design and engineering have to contribute to healthy lifestyles and the generation of whole new sporting domains.
Weinert-Aplin RA, Bull AMJ, McGregor AH, 2016, Orthotic Heel Wedges Do Not Alter Hindfoot Kinematics and Achilles Tendon Force During Level and Inclined Walking in Healthy Individuals, JOURNAL OF APPLIED BIOMECHANICS, Vol: 32, Pages: 160-170, ISSN: 1065-8483
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
Buckeridge EM, Bull AMJ, McGregor AH, 2015, Biomechanical determinants of elite rowing technique and performance, SCANDINAVIAN JOURNAL OF MEDICINE & SCIENCE IN SPORTS, Vol: 25, Pages: e176-e183, ISSN: 0905-7188
Cheong VS, Bull AMJ, 2015, A novel specimen-specific methodology to optimise the alignment of long bones for experimental testing., J Biomech, Vol: 48, Pages: 4317-4321
The choice of coordinate system and alignment of bone will affect the quantification of mechanical properties obtained during in-vitro biomechanical testing. Where these are used in predictive models, such as finite element analysis, the fidelic description of these properties is paramount. Currently in bending and torsional tests, bones are aligned on a pre-defined fixed span based on the reference system marked out. However, large inter-specimen differences have been reported. This suggests a need for the development of a specimen-specific alignment system for use in experimental work. Eleven ovine tibiae were used in this study and three-dimensional surface meshes were constructed from micro-Computed Tomography scan images. A novel, semi-automated algorithm was developed and applied to the surface meshes to align the whole bone based on its calculated principal directions. Thereafter, the code isolates the optimised location and length of each bone for experimental testing. This resulted in a lowering of the second moment of area about the chosen bending axis in the central region. More importantly, the optimisation method decreases the irregularity of the shape of the cross-sectional slices as the unbiased estimate of the population coefficient of variation of the second moment of area decreased from a range of (0.210-0.435) to (0.145-0.317) in the longitudinal direction, indicating a minimisation of the product moment, which causes eccentric loading. Thus, this methodology serves as an important pre-step to align the bone for mechanical tests or simulation work, is optimised for each specimen, ensures repeatability, and is general enough to be applied to any long bone.
Cleather DJ, Bull AMJ, 2015, The development of a segment-based musculoskeletal model of the lower limb: introducing FreeBody., R Soc Open Sci, Vol: 2, ISSN: 2054-5703
Traditional approaches to the biomechanical analysis of movement are joint-based; that is the mechanics of the body are described in terms of the forces and moments acting at the joints, and that muscular forces are considered to create moments about the joints. We have recently shown that segment-based approaches, where the mechanics of the body are described by considering the effect of the muscle, ligament and joint contact forces on the segments themselves, can also prove insightful. We have also previously described a simultaneous, optimization-based, musculoskeletal model of the lower limb. However, this prior model incorporates both joint- and segment-based assumptions. The purpose of this study was therefore to develop an entirely segment-based model of the lower limb and to compare its performance to our previous work. The segment-based model was used to estimate the muscle forces found during vertical jumping, which were in turn compared with the muscular activations that have been found in vertical jumping, by using a Geers' metric to quantify the magnitude and phase errors. The segment-based model was shown to have a similar ability to estimate muscle forces as a model based upon our previous work. In the future, we will evaluate the ability of the segment-based model to be used to provide results with clinical relevance, and compare its performance to joint-based approaches. The segment-based model described in this article is publicly available as a GUI-based Matlab® application and in the original source code (at www.msksoftware.org.uk).
Cleather DJ, Southgate DFL, Bull AM, 2015, The role of the biarticular hamstrings and gastrocnemius muscles in closed chain lower limb extension, JOURNAL OF THEORETICAL BIOLOGY, Vol: 365, Pages: 217-225, ISSN: 0022-5193
Ding Z, Nolte D, Tsang CK, et al., 2015, In Vivo Knee Contact Force Prediction Using Patient-Specific Musculoskeletal Geometry in a Segment-Based Computational Model., Journal of Biomechanical Engineering-Transactions of the ASME, Vol: 138, ISSN: 0148-0731
Segment-based musculoskeletal models allow the prediction of muscle, ligament and joint forces without making assumptions regarding joint degrees of freedom. The dataset published for the "Grand Challenge Competition to Predict In Vivo Knee Loads" provides directly-measured tibiofemoral contact forces for activities of daily living. For the "Sixth Grand Challenge Competition to Predict In Vivo Knee Loads", blinded results for "smooth" and "bouncy" gait trials were predicted using a customised patient-specific musculoskeletal model. For an unblinded comparison the following modifications were made to improve the predictions: • further customisations, including modifications to the knee centre of rotation; • reductions to the maximum allowable muscle forces to represent known loss of strength in knee arthroplasty patients; and • a kinematic constraint to the hip joint to address the sensitivity of the segment-based approach to motion tracking artefact. For validation, the improved model was applied to normal gait, squat and sit-to-stand for three subjects. Comparisons of the predictions with measured contact forces showed that segment-based musculoskeletal models using patient-specific input data can estimate tibiofemoral contact forces with root mean square errors (RMSEs) of 0.48-0.65 times body weight (BW) for normal gait trials. Tibiofemoral contact force patterns were estimated with an average coefficient of determination of 0.81 and with RMSEs of 0.46-1.01 times BW for squatting and 0.70-0.99 times BW for sit-to-stand tasks. This is comparable to the best validations in the literature using alternative models.
Edwards DS, Barbur SAR, Bull AMJ, et al., 2015, Posterior mini-incision total hip arthroplasty controls the extent of post-operative formation of heterotopic ossification., Eur J Orthop Surg Traumatol, Vol: 25, Pages: 1051-1055, ISSN: 1633-8065
Heterotopic ossification (HO) is the formation of bone at extra-skeletal sites. Reported rates of HO after hip arthroplasty range from 8 to 90 %; however, it is only severe cases that cause problems clinically, such as joint stiffness. The effects of surgical-related controllable intra-operative risk factors for the formation of HO were investigated. Data examined included gender, age of patient, fat depth, length of operation, incision length, prosthetic fixation method, the use of pulsed lavage and canal brush, and component size and material. All cases were performed by the same surgeon using the posterior approach. A total of 510 cases of hip arthroplasty were included, with an overall rate of HO of 10.2 %. Longer-lasting operations resulted in higher grades of HO (p = 0.047). Incisions >10 cm resulted in more widespread HO formation (p = 0.021). No further correlations were seen between HO formation and fat depth, blood loss, instrumentation, fixation methods or prosthesis material. The mini-incision approach is comparable to the standard approach in the aetiology of HO formation, and whilst the rate of HO may not be controllable, a posterior mini-incision approach can limit its extent.
Edwards DS, Phillip RD, Bosanquet N, et al., 2015, What Is the Magnitude and Long-term Economic Cost of Care of the British Military Afghanistan Amputee Cohort?, CLINICAL ORTHOPAEDICS AND RELATED RESEARCH, Vol: 473, Pages: 2848-2855, ISSN: 0009-921X
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