116 results found
Verbruggen S, Kainz B, Shelmerdine SC, et al., 2018, Altered biomechanical stimulation of the developing hip joint in presence of hip dysplasia risk factors, Journal of Biomechanics, Vol: 78, Pages: 1-9, ISSN: 0021-9290
Fetal kicking and movements generate biomechanical stimulation in the fetal skeleton, which is important for prenatal musculoskeletal development, particularly joint shape. Developmental dysplasia of the hip (DDH) is the most common joint shape abnormality at birth, with many risk factors for the condition being associated with restricted fetal movement. In this study, we investigate the biomechanics of fetal movements in such situations, namely fetal breech position, oligohydramnios and primiparity (firstborn pregnancy). We also investigate twin pregnancies, which are not at greater risk of DDH incidence, despite the more restricted intra-uterine environment. We track fetal movements for each of these situations using cine-MRI technology, quantify the kick and muscle forces, and characterise the resulting stress and strain in the hip joint, testing the hypothesis that altered biomechanical stimuli may explain the link between certain intra-uterine conditions and risk of DDH. Kick force, stress and strain were found to be significantly lower in cases of breech position and oligohydramnios. Similarly, firstborn fetuses were found to generate significantly lower kick forces than non-firstborns. Interestingly, no significant difference was observed in twins compared to singletons. This research represents the first evidence of a link between the biomechanics of fetal movements and the risk of DDH, potentially informing the development of future preventative measures and enhanced diagnosis. Our results emphasise the importance of ultrasound screening for breech position and oligohydramnios, particularly later in pregnancy, and suggest that earlier intervention to correct breech position through external cephalic version could reduce the risk of hip dysplasia.
Villette CC, Phillips ATM, Rate and age-dependent damage elasticity formulation for efficient hip fracture simulations, Medical Engineering and Physics, ISSN: 1350-4533
Sperry MM, Phillips ATM, McGregor AH, 2018, Lower back pain and healthy subjects exhibit distinct lower limb perturbation response strategies: a preliminary study, Journal of Back and Musculoskeletal Rehabilitation, ISSN: 1053-8127
BACKGROUND: It is hypothesized that inherent differences in movement strategies exist between control subjects and those with a history of lower back pain (LBP). Previous motion analysis studies focus primarily on tracking spinal movements, neglecting the connection between the lower limbs and spinal function. Lack of knowledge surrounding the functional implications of LBP may explain the diversity in success from general treatments currently offered to LBP patients. OBJECTIVE: This pilot study evaluated the response of healthy controls and individuals with a history of LBP (hLBP) to a postural disturbance. METHODS: Volunteers (n= 26) were asked to maintain standing balance in response to repeated balance disturbances delivered via a perturbation platform while both kinematic and electromyographic data were recorded from the trunk, pelvis, and lower limb. RESULTS: The healthy cohort utilized an upper body-focused strategy for balance control, with substantial activation of the external oblique muscles. The hLBP cohort implemented a lower limb-focused strategy, relying on activation of the semitendinosus and soleus muscles. No significant differences in joint range of motion were identified. CONCLUSIONS: These findings suggest that particular reactive movement patterns may indicate muscular deficits in subjects with hLBP. Identification of these deficits may aid in developing specific rehabilitation programs to prevent future LBP recurrence.
Zaharie DZ, Phillips ATM, Pelvic construct prediction of trabecular and cortical bone structural architecture, Journal of Biomechanical Engineering, ISSN: 0148-0731
Bellamy L, Phillips A, Ward J, 2018, Optimisation of structural form based on multiple sustainability factors, IABSE Conference Bath 2017, Pages: 119-120
Structural design and analysis is dependent on optimisation approaches. However, such optimisation is mostly performed for the permanent structure and constructability is rarely considered at the design stages. The goal of the research presented here is to develop a digital design process that encompasses constructability and sustainability factors. The initial process uses common methods for cross-sectional, structural arrangement and structural form optimisation in an automated fashion and facilitates software packages to work together. Further development will enable the process to optimise the structure across construction stages.
Gillie M, Phillips A, 2018, Teaching creative structural design - Seminar, IABSE Conference Bath 2017 - Creativity and Collaboration, Pages: 33-34
This seminar will examine how teaching structural design to encourage creativity is best approached. It will consist of four short presentations from different perspectives, followed by a facilitated discussion aimed at provoking debate.
Verbruggen S, Kainz B, Shelmerdine S, et al., 2018, Stresses and strains on the human fetal skeleton during development, Journal of the Royal Society Interface, Vol: 15, ISSN: 1742-5662
Mechanical forces generated by fetal kicks and movements result in stimulation of the fetal skeleton in the form of stress and strain. This stimulation is known to be critical for prenatal musculoskeletal development; indeed, abnormal or absent movements have been implicated in multiple congenital disorders. However, the mechanical stress and strain experienced by the developing human skeleton in utero have never before been characterized. Here, we quantify the biomechanics of fetal movements during the second half of gestation by modelling fetal movements captured using novel cine-magnetic resonance imaging technology. By tracking these movements, quantifying fetal kick and muscle forces, and applying them to three-dimensional geometries of the fetal skeleton, we test the hypothesis that stress and strain change over ontogeny. We find that fetal kick force increases significantly from 20 to 30 weeks' gestation, before decreasing towards term. However, stress and strain in the fetal skeleton rises significantly over the latter half of gestation. This increasing trend with gestational age is important because changes in fetal movement patterns in late pregnancy have been linked to poor fetal outcomes and musculoskeletal malformations. This research represents the first quantification of kick force and mechanical stress and strain due to fetal movements in the human skeleton in utero, thus advancing our understanding of the biomechanical environment of the uterus. Further, by revealing a potential link between fetal biomechanics and skeletal malformations, our work will stimulate future research in tissue engineering and mechanobiology.
Villette CC, Castilho M, Malda J, et al., Heterogeneous design optimisation of tissue engineering scaffolds: in-vitro assessment of a digital design framework, 15th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering, Publisher: Taylor & Francis, ISSN: 1025-5842
Phillips A, 2017, Engineering design, research and education: Breaking in and out of liminal space, IABSE Conference, Bath 2017: Creativity and Collaboration, Pages: 286-287
Engineering educators, researchers and designers are all stakeholders in the development of undergraduate engineering degrees, which seek to equip graduates with the knowledge and understanding, skills, attitudes and experience required in the profession. These stakeholders are often in conflict when considering the desired learning outcomes for graduate engineers. Breaking in and out of liminal space is presented as the core skill which we wish to pass on to engineering graduates. It provides a focus for constructive discussions on curriculum, activities and assessment on engineering degree courses.
Villette CC, Phillips ATM, 2017, Microscale poroelastic metamodel for efficient mesoscale bone remodelling simulations., Biomechanics and Modeling in Mechanobiology, Vol: 16, Pages: 2077-2091, ISSN: 1617-7940
Bone functional tissue adaptation is a multiaspect physiological process driven by interrelated mechanical and biological stimuli which requires the combined activity of osteoclasts and osteoblasts. In previous work, the authors developed a phenomenological mesoscale structural modelling approach capable of predicting internal structure of the femur based on daily activity loading, which relied on the iterative update of the cross-sectional areas of truss and shell elements representative of trabecular and cortical bones, respectively. The objective of this study was to introduce trabecular reorientation in the phenomenological model at limited computational cost. To this aim, a metamodel derived from poroelastic microscale continuum simulations was used to predict the functional adaptation of a simplified proximal structural femur model. Clear smooth trabecular tracts are predicted to form in the regions corresponding to the main trabecular groups identified in literature, at minimal computational cost.
Favier C, McGregor A, Phillips A, Development of a combined MSK and FEA model of the lower back, 13th Annual Bath Biomechanics Symposium
Verbruggen SVW, Oyen M, Phillips A, et al., 2017, Function and failure of the fetal membrane: Modelling the mechanics of the chorion and amnion, PLOS One, Vol: 12, ISSN: 1932-6203
The fetal membrane surrounds the fetus during pregnancy and is a thin tissue composed of two layers, the chorion and the amnion. While rupture of this membrane normallyoccurs at term, preterm rupture can resultin increased risk of fetal mortality and morbidity, as well as danger of infection in the mother. Although structural changes have been observed in the membrane in such cases, the mechanical behaviour of the human fetal membrane in vivoremains poorly understoodand is challenging to investigate experimentally.Therefore,the objectiveof this study wasto developsimplifiedfinite element models toinvestigatethe mechanical behaviourand ruptureof the fetal membrane, particularlyits constituent layers,under variousphysiological conditions.It was found that modelling the chorion and amnion as a single layer predicts remarkably different behaviourcompared with a more anatomically-accurate bilayer, significantly underestimating stress in the amnion and under-predicting the risk ofmembrane rupture. Additionally,reductions in chorion-amnion interface lubrication and chorion thickness (reported in cases of preterm rupture)both resultedin increasedmembrane stress. Interestingly, the inclusion of a weak zone in the fetal membrane that has been observed to develop overlying the cervix would likelycause it to fail atterm,during labour. Finally, these findings support the theory that the amnion is the dominant structural component of the fetal membrane and is required to maintain its integrity. The results provide a novel insight into the mechanical effect of structural changes in the chorion and amnion, in cases of bothnormal andpreterm rupture.
Favier C, Phillips A, Musculoskeletal Model of Lumbar Spine and Lower Limb, XXVI Congress of the International Society of Biomechanics
Phillips ATM, 2017, Engineering education, research and design: breaking in and out of liminal space, Journal of Professional Issues in Engineering Education and Practice, Vol: 143, ISSN: 1943-5541
Liminality is presented as a concept familiar to engineering educators, researchers anddesigners, as a state of challenge and discomfort that we must fluxin and out of in orderto advance our respective aims. Common areas for discussion in familiarising engineeringlearners with liminality are sought. Threshold concepts, divergent-convergent thinking, andthe concept of design, research and education as iterative processes associated with breakingin and out of liminal space are explored. The duality of learning is discussed through theacquisition and participation metaphors. The use of design coursesin leading learners into and out of liminal space, and in particular the Group Design Projects on the ImperialCivil Engineering MEng degree are discussed. In closing the informedcreative, as opposedto routine design process, viewed from an engineering and a psychology perspective is brieflycharacterised, along with the skills and experiences that the engineering community wouldwish engineering graduates to have.
Phillips AT, Impagliazzo J, 2015, Toward an multidisciplinary curriculum in cyberscience
© 2015 IEEE. This conference presentation describes a process for developing a multidisciplinary curriculum in cyberscience. The process presented is a broad-based approach designed to support a four-year undergraduate cyberscience curriculum applicable to diverse institutions of higher learning.
Geraldes DM, Modenese L, Phillips ATM, 2015, Consideration of multiple load cases is critical in modelling orthotropic bone adaptation in the femur, Biomechanics and Modeling in Mechanobiology, Vol: 15, Pages: 1029-1042, ISSN: 1617-7959
Functional adaptation of the femur has beeninvestigated in several studies by embedding bone remodellingalgorithms in finite element (FE) models, with simpli-fications often made to the representation of bone’s materialsymmetry and mechanical environment. An orthotropicstrain-driven adaptation algorithm is proposed in order topredict the femur’s volumetric material property distributionand directionality of its internal structures within a continuum.The algorithm was applied to a FE model of the femur,with muscles, ligaments and joints included explicitly. Multipleload cases representing distinct frames of two activitiesof daily living (walking and stair climbing) were considered.It is hypothesised that low shear moduli occur in areasof bone that are simply loaded and high shear moduli inareas subjected to complex loading conditions. In addition,it is investigated whether material properties of differentfemoral regions are stimulated by different activities. The loading and boundary conditions were considered to providea physiological mechanical environment. The resultingvolumetric material property distribution and directionalitiesagreed with ex vivo imaging data for the whole femur.Regions where non-orthogonal trabecular crossing has beendocumented coincided with higher values of predicted shearmoduli. The topological influence of the different activitiesmodelled was analysed. The influence of stair climbing onthe properties of the femoral neck region is highlighted. It isrecommended that multiple load cases should be consideredwhen modelling bone adaptation. The orthotropic model ofthe complete femur is released with this study.
Fetal movements in the uterus are a natural part of development, and are known to play an important role in normal musculoskeletal development. However, very little is known about the biomechanical stimuli that arise during movements in utero, despite these stimuli being crucial to normal bone and joint formation. Therefore the objective of this study is to create a series of computational steps by which the forces generated during a kick in utero could be predicted from clinically observed fetal movements using novel cine-MRI data of three fetuses, aged 20-22 weeks. A custom tracking software was designed to characterise the movements of joints in utero, and average uterus deflection of 6.95 ± 0.41 mm due to kicking was calculated. These observed displacements provided boundary conditions for a finite element model of the uterine environment, predicting an average reaction force of 0.52 ± 0.15 N generated by a kick against the uterine wall. Finally, these data were applied as inputs for a musculoskeletal model of a fetal kick, resulting in predicted maximum forces in the muscles surrounding the hip joint of approximately 8 N, while higher maximum forces of approximately 21 N were predicted for the muscles surrounding the knee joint. This study provides a novel insight into the closed mechanical environment of the uterus, with an innovative method allowing elucidation of the biomechanical interaction of the developing fetus with its surroundings.
Villette CC, Phillips ATM, 2015, Informing phenomenological structural bone remodelling with a mechanistic poroelastic model, Biomechanics and Modeling in Mechanobiology, Vol: 15, Pages: 69-82, ISSN: 1617-7959
t Studies suggest that fluid motion in the extracellularspace may be involved in the cellular mechanosensitivityat play in the bone tissue adaptation process. Previously,the authors developed a mesoscale predictive structuralmodel of the femur using truss elements to represent trabecularbone, relying on a phenomenological strain-basedbone adaptation algorithm. In order to introduce a responseto bending and shear, the authors considered the use of beamelements, requiring a new formulation of the bone adaptationdrivers. The primary goal of the study presented herewas to isolate phenomenological drivers based on the resultsof a mechanistic approach to be used with a beam elementrepresentation of trabecular bone in mesoscale structuralmodelling. A single-beam model and a microscale poroelasticmodel of a single trabecula were developed. A mechanisticiterative adaptation algorithm was implemented based onfluid motion velocity through the bone matrix pores to predictthe remodelled geometries of the poroelastic trabeculaunder 42 different loading scenarios. Regression analyseswere used to correlate the changes in poroelastic trabeculathickness and orientation to the initial strain outputsof the beam model. Linear (R2 > 0.998) and third-orderpolynomial (R2 > 0.98) relationships were found betweenchange in cross section and axial strain at the central axis,and between beam reorientation and ratio of bending strainto axial strain, respectively. Implementing these relationships into the phenomenological predictive algorithm for themesoscale structural femur has the potential to produce amodel combining biofidelic structure and mechanical behaviourwith computational efficiency.
Geraldes D, Phillips A, 2015, The influence of different load cases in orthotropic bone adaptation in the femur, International Society of Biomechanics 2015
Montanino A, Modenese L, Gopalakrishnan A, et al., Smoothing or filtering marker trajectories? The effects on calculated joint moments, XXV Congress of the International Society of Biomechanics
Villette CC, Phillips ATM, Zaharie DT, Frangible optimised lower limb surrogate for assessing underbelly blast injury, International Research Council on Biomechanics of Injury
Phillips ATM, Villette CC, Modenese L, 2015, Femoral bone mesoscale structural architecture prediction using musculoskeletal and finite element modelling, International Biomechanics, Vol: 2, Pages: 43-61, ISSN: 2333-5432
Through much of the anatomical and clinical literature bone is studied with a focus on its structural architecture, while it is rare for bone to be modelled using a structural mechanics as opposed to a continuum mechanics approach in the engineering literature. A novel mesoscale structural model of the femur is presented in which truss and shell elements are used to represent trabecular and cortical bone, respectively. Structural optimisation using a strain-based bone adaptation algorithm is incorporated within a musculoskeletal and finite element modelling framework to predict the structure of the femur subjected to two loading scenarios; a single load case corresponding to the frame of maximum hip joint contact force during walking and a full loading regime consisting of multiple load cases from five activities of daily living. The use of the full loading regime compared to the single load case has a profound influence on the predicted trabecular and cortical structure throughout the femur, with dramatic volume increases in the femoral shaft and the distal femur, and regional increases at the femoral neck and greater trochanter in the proximal femur. The mesoscale structural model subjected to the full loading regime shows agreement with the observed structural architecture of the femur while the structural approach has potential application in bone fracture prediction, prevention and treatment. The mesoscale structural approach achieves the synergistic goals of computational efficiency similar to a macroscale continuum approach and a resolution nearing that of a microscale continuum approach.
Villette CC, Phillips ATM, Predictive mesoscale structural modelling of bone informed by microscale poroelastic analyses, XXV congress of the International Society of Biomechanics
Zaharie D, Villette C, Phillips A, FRANGIBLE OPTIMISED LOWER LIMB SURROGATE FOR ASSESSING INJURY CAUSED BY UNDERBELLY BLAST, XV International Symposium on Computer Simulation in Biomechanics
Gopalakrishnan A, Modenese L, Phillips ATM, 2014, A novel computational framework for deducing muscle synergies from experimental joint moments, Frontiers in Computational Neuroscience, ISSN: 1662-5188
Prior experimental studies have hypothesized the existence of a ‘muscle synergy’ based control scheme for producing limb movements and locomotion in vertebrates. Such synergies have been suggested to consist of fixed muscle grouping schemes with the co-activation of all muscles in a synergy resulting in limb movement. Quantitative representations of these groupings (termed muscle weightings) and their control signals (termed synergy controls) have traditionally been derived by the factorization of experimentally measured EMG. This study presents a novel approach for deducing these weightings and controls from inverse dynamic joint moments that are computed from an alternative set of experimental measurements – movement kinematics and kinetics. This technique was applied to joint moments for healthy human walking at 0.7 and 1.7 m/s, and two sets of ‘simulated’ synergies were computed based on two different criteria (1) synergies were required to minimize errors between experimental and simulated joint moments in a musculoskeletal model (pure-synergy solution) (2) along with minimizing joint moment errors, synergies also minimized muscle activation levels (optimal-synergy solution). On comparing the two solutions, it was observed that the introduction of optimality requirements (optimal-synergy) to a control strategy solely aimed at reproducing the joint moments (pure-synergy) did not necessitate major changes in the muscle grouping within synergies or the temporal profiles of synergy control signals. Synergies from both the simulated solutions exhibited many similarities to EMG derived synergies from a previously published study, thus implying that the analysis of the two different types of experimental data reveals similar, underlying synergy structures.
Gopalakrishnan A, Modenese L, Phillips ATM, 2014, A dynamic simulation approach for computing muscle synergies from joint moments, 12th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering
Gopalakrishnan A, Phillips ATM, Higginson JS, et al., 2014, Predictive simulations of movement for informing rehabilitation programmes, 12th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering
Geraldes DM, Phillips ATM, 2014, A comparative study of orthotropic and isotropic bone adaptation in the femur, International Journal for Numerical Methods in Biomedical Engineering, Vol: 30, Pages: 873-889, ISSN: 2040-7947
Functional adaptation of the femur has been studied extensively by embedding remodelling algorithms in finite element models, with bone commonly assumed to have isotropic material properties for computational efficiency. However, isotropy is insufficient in predicting the directionality of bone's observed microstructure. A novel iterative orthotropic 3D adaptation algorithm is proposed and applied to a finite element model of the whole femur. Bone was modelled as an optimised strain-driven adaptive continuum with local orthotropic symmetry. Each element's material orientations were aligned with the local principal stress directions and their corresponding directional Young's moduli updated proportionally to the associated strain stimuli. The converged predicted density distributions for a coronal section of the whole femur were qualitatively and quantitatively compared with the results obtained by the commonly used isotropic approach to bone adaptation and with ex vivo imaging data. The orthotropic assumption was shown to improve the prediction of bone density distribution when compared with the more commonly used isotropic approach, whilst producing lower comparative mass, structurally optimised models. It was also shown that the orthotropic approach can provide additional directional information on the material properties distributions for the whole femur, an advantage over isotropic bone adaptation. Orthotropic bone models can help in improving research areas in biomechanics where local structure and mechanical properties are of key importance, such as fracture prediction and implant assessment.
Barzan M, Modenese L, Gopalakrishnan A, et al., The effect of footwear on the running kinematics, kinetics and knee internal loads: a preliminary study., 7th World Congress of Biomechanics
Villette CC, Phillips ATM, Modenese L, Combined musculoskeletal and finite element predictive modelling of bone structure and simple fracture analysis, 12th international symposium on Computer Methods in Biomechanics and Biomedical Engineering
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