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Delhaas, Tammo. "Regional subepicardial mechanics under normoxic and ischemic circumstances relation with hemodynamics, and regional electrical activation and oxygen uptake /." Maastricht : Maastricht : Rijksuniversiteit Limburg ; University Library, Maastricht University [Host], 1993. http://arno.unimaas.nl/show.cgi?fid=5756.
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Snijders, Johannes Maria Abraham. "The triphasic mechanics of the intervertebral disc a theoretical, numerical and experimental analysis /." [Maastricht : Maastricht : Universitaire Pers Maastricht] ; University Library, Maastricht University [Host], 1994. http://arno.unimaas.nl/show.cgi?fid=7912.
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Rijcken, Johannes Matthias. "Optimization of left ventricular muscle fiber orientation." [Maastricht : Maastricht : Universiteit Maastricht] ; University Library, Maastricht University [Host], 1997. http://arno.unimaas.nl/show.cgi?fid=5914.
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Yousefi, Koupaei Atieh. "Biomechanical Interaction Between Fluid Flow and Biomaterials: Applications in Cardiovascular and Ocular Biomechanics." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1595335168435434.
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Jang, Sae, Rebecca R. Vanderpool, Reza Avazmohammadi, Eugene Lapshin, Timothy N. Bachman, Michael Sacks, and Marc A. Simon. "Biomechanical and Hemodynamic Measures of Right Ventricular Diastolic Function: Translating Tissue Biomechanics to Clinical Relevance." WILEY, 2017. http://hdl.handle.net/10150/626001.
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Background Right ventricular (RV) diastolic function has been associated with outcomes for patients with pulmonary hypertension; however, the relationship between biomechanics and hemodynamics in the right ventricle has not been studied. Methods and Results Rat models of RV pressure overload were obtained via pulmonary artery banding (PAB; control, n=7; PAB, n=5). At 3 weeks after banding, RV hemodynamics were measured using a conductance catheter. Biaxial mechanical properties of the RV free wall myocardium were obtained to extrapolate longitudinal and circumferential elastic modulus in low and high strain regions (E-1 and E-2, respectively). Hemodynamic analysis revealed significantly increased end-diastolic elastance (E-ed) in PAB (control: 55.1 mm Hg/mL [interquartile range: 44.785.4 mm Hg/mL]; PAB: 146.6 mm Hg/mL [interquartile range: 105.8155.0 mm Hg/mL]; P=0.010). Longitudinal E1 was increased in PAB (control: 7.2 kPa [interquartile range: 6.718.1 kPa]; PAB: 34.2 kPa [interquartile range: 18.144.6 kPa]; P=0.018), whereas there were no significant changes in longitudinal E-2 or circumferential E-1 and E-2. Last, wall stress was calculated from hemodynamic data by modeling the right ventricle as a sphere: (stress = Pressure x radius/2 x thickness Conclusions RV pressure overload in PAB rats resulted in an increase in diastolic myocardial stiffness reflected both hemodynamically, by an increase in E-ed, and biomechanically, by an increase in longitudinal E-1. Modest increases in tissue biomechanical stiffness are associated with large increases in E-ed. Hemodynamic measurements of RV diastolic function can be used to predict biomechanical changes in the myocardium.
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Bucci, Francesca. "Personalized biomechanical model of a patient with severe hip osteoarthritis for the prediction of pelvic biomechanics." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15879/.
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L’articolazione dell'anca è un'articolazione sinoviale sferica che costituisce la connessione primaria tra gli arti inferiori e lo scheletro della parte superiore del corpo. Durante le attività quotidiane di routine, carichi anormali ripetuti sull'anca possono portare alla danneggiamento della cartilagine articolare e conseguentemente , all’osteoartrite (OA).
L'OA dell'anca è una condizione muscolo-scheletrica cronica e progressiva, il cui trattamento per i pazienti severi è l'artroplastica totale dell'anca (THA). Il centro dell'articolazione dell'anca (HJC) ha grande importanza nell’analisi della biomeccanica dell’anca, così come il suo spostamento, che puo’ essere dovuto a patologie, come OA, o alla chirurgia, THA.
Per valutare la biomeccanica del bacino in questa tesi sono stati implementati un modello muscoloscheletrico (NMS) personalizzato statistical shape e modelli ad elementi finiti (FE) di un paziente con grave OA mono-laterale dell'anca.
Viene discussa l'accuratezza relativamente al modello scalato generico nella predizione delle grandezze biomeccaniche piu’ importanti, durante la deambulazione.
Attraverso i modelli FE, è stato studiato l'effetto di una cattiva stima e/o dello spostamento del centro dell'articolazione dell'anca nelle direzioni antero-posteriore, mediolaterale o infero-superiore per valutare lo stato di sollecitazione della pelvi.
Infine sono presentati i risultati di un approccio multiscala integrato, per valutare le caratteristiche biomeccaniche del suddetto paziente, passando dalla modellazione NMS, all’analisi del modello FE della pelvi, per effettuare un’analisi comparativa dell’arto osteoartritico con il modello dall’arto controlaterale prima dell’intervento e dopo lo stesso
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Denning, Matthew M. "The Effects of Aquatic Exercise on Physiological and Biomechanical Responses." DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/670.
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Due to recent advances in aquatic research, technology, and facilities, many modes of aquatic therapy now exist. These aquatic modes assist individuals (e.g., osteoarthritis patients) in the performance of activities that may be too difficult to complete on land. However, the biomechanical requirements of each aquatic therapy mode may elicit different physiological and functional responses. Therefore, the purpose of this thesis was to: (a) provide a review of the physiological and biomechanical differences between aquatic and land based exercises, and (b) examine the acute effects of underwater and land treadmill exercise on oxygen consumption (VO2), rating of perceived exertion (RPE), perceived pain, mobility, and gait kinematics for patients with osteoarthritis (OA). Methods consisted of the retrieval of experimental studies examining the physiological and biomechanical effects of deep water running (DWR), shallow water running (SWR), water calisthenics, and underwater treadmill therapy. The methods also examined the physiological and biomechanical effects on 19 participants during and after three consecutive exercise sessions on an underwater treadmill and on a land-based treadmill. Based on the studies reviewed, when compared to a similar land-based mode, VO2 values are lower during both DWR and SWR, but can be higher during water calisthenics and underwater treadmill exercise. RPE responses during DWR are similar during max effort, and stride frequency and stride length are both lower in all four aquatic modes than on land. Pain levels are no different between most water calisthenics, and most studies reported improvements in mobility after aquatic therapy, but no difference between the aquatic and land-based modes. The OA participants achieved VO2 values that were not different between conditions during moderate intensities, but were 37% greater during low intensity exercise on land than in water (p = 0.001). Perceived pain and Time Up & Go scores were 140% and 240% greater, respectively, for land than underwater treadmill exercise (p = 0.01). Patients diagnosed with OA may walk on an underwater treadmill at a moderate intensity with less pain and equivalent energy expenditures compared to walking on a land-based treadmill.
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Orekhov, Greg. "Hip and Knee Biomechanics for Transtibial Amputees in Gait, Cycling, and Elliptical Training." DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/2010.
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Transtibial amputees are at increased risk of contralateral hip and knee joint osteoarthritis, likely due to abnormal biomechanics. Biomechanical challenges exist for transtibial amputees in gait and cycling; particularly, asymmetry in ground/pedal reaction forces and joint kinetics is well documented and state-of-the-art passive and powered prostheses do not fully restore natural biomechanics. Elliptical training has not been studied as a potential exercise for rehabilitation, nor have any studies been published that compare joint kinematics and kinetics and ground/pedal reaction forces for the same group of transtibial amputees in gait, cycling, and elliptical training. The hypothesis was that hip and knee joint kinematics and kinetics and ground and pedal reaction forces would differ due to exercise (gait, cycling, elliptical) amputee status (amputated, control [non-amputated]), and leg (dominant [intact], non-dominant [amputated]). Ten unilateral transtibial amputees and ten control participants performed the three exercises while kinematic and kinetic data were collected. Hip and knee joint flexion angle, resultant forces, and resultant moments were calculated by inverse dynamics for the dominant and non-dominant legs of both participant groups. Joint biomechanics and measured ground/pedal reaction forces were then compared between exercises, between the dominant and non-dominant legs within each participant group, and across participant groups. Significant differences in hip and knee joint flexion angles and timing, compressive forces, extension-flexion (EF) and adduction-abduction (AddAbd) moments, and anterior-posterior (AP) and lateral-medial (LM) reaction forces were found. Particularly, transtibial amputees showed maximum knee flexion angle asymmetry as compared to controls in all three exercises. Maximum hip and knee compressive forces, EF moments, and AddAbd moments were lowest in cycling and highest in gait. Asymmetry in amputee midstance knee flexion and timing in v gait, coupled with low maximum EF moment for the non-dominant leg, suggests that amputees avoid contraction of the non-dominant quadriceps muscle. Knee flexion angle and EF moment asymmetry in elliptical training suggests that a similar phenomenon occurs. Asymmetry in AP and LM reaction forces in gait, but not other exercises, suggests that exercises that constrain kinematics reduce loading imbalances. The results suggest that cycling and elliptical training should be recommended to transtibial amputees for rehabilitation due to reduced hip and knee joint forces and moments. Elliptical training may be preferred over gait due to decreased joint loading and loading asymmetry, but some asymmetry and differences from control participants still exist. Non-weight bearing exercises such as cycling may be best at reducing overall joint loading and joint load asymmetry but do not eliminate all kinematic and temporal asymmetries. Current state-of-the-art prosthetic leg design is insufficient in restoring natural biomechanics not only in gait but also in cycling and elliptical training. Improved prosthesis kinematics that restore non-dominant knee flexion in amputees to normal levels could help reprogram quadriceps muscle patterns in gait and elliptical training and hip and knee joint biomechanical asymmetries. Further work in comparing contralateral and prosthesis ankle joint biomechanics would help to elucidate the relationship between prosthesis design and its impact on lower limb joint biomechanics.
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Reinert, Senia Smoot. "Enhancing Posturography Stabilization Analysis and Limits of Stability Assessment." University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1470227622.
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Gutierrez-Franco, Juan. "THE EFFECTS OF OBESITY ON RESULTANT KNEE JOINT LOADS FOR GAIT AND CYCLING." DigitalCommons@CalPoly, 2016. https://digitalcommons.calpoly.edu/theses/1624.
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Osteoarthritis (OA) is a degenerative disease of cartilage and bone tissue and the most common form of arthritis, accounting for US$ 10.5 billion in hospital charges in 2006. Obesity (OB) has been linked to increased risk of developing knee OA due to increased knee joint loads and varus-valgus misalignment. Walking is recommended as a weight-loss activity but it may increase risk of knee OA as OB gait increases knee loads. Cycling has been proposed as an alternative weight-loss measure, however, lack of studies comparing normal weight (NW) and OB subjects in cycling and gait hinder identification of exercises that may best prevent knee OA incidence. The objective of this work is to determine if cycling is a better weight-loss exercise than gait in OB subjects as it relates to knee OA risk reduction due to decreased knee loads. A stationary bicycle was modified to measure forces and moments at the pedals in three dimensions. A pilot experiment was performed to calculate resultant knee loads during gait and cycling for NW (n = 4) and OB (n = 4) subjects. Statistical analyses were performed to compare knee loads and knee angles, and to determine statistical significance of results (p < 0.05). Cycling knee loads were lower than gait knee loads for all subjects (p < 0.033). OB axial knee loads were higher than NW axial knee loads in gait (p = 0.004) due to the weight-bearing nature of gait. No differences were observed in cycling knee loads between NW and OB subjects, suggesting cycling returns OB knee loads and biomechanics to normal levels. The lack of significant results in cycling could be due to the small sample size used or because rider weight is supported by the seat. Limitations to this study include small sample size, soft tissue artifact, and experimental errors in marker placement. Future studies should correct these limitations and find knee joint contact force rather than knee resultant loads using v EMG-driven experiments. In conclusion, cycling loads were lower than gait loads for NW and OB subjects suggesting cycling is a better weight-loss exercise than gait in the context of reducing knee OA risk.
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Mandaltsi, Aikaterini. "Modelling the mechanobiological evolution of aneurysms : an integrative in vivo, in vitro and in silico approach." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:08d7dde3-2501-4bb4-a229-40225f75efec.
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In silico models of intracranial aneurysm (IA) evolution aim to reliably represent the mechanical blood flow environment, the biology of the arterial wall and, crucially, the complex link between the two, namely the mechanobiology of healthy and diseased arteries. The ultimate goal is to create diagnostic tools for personalized management and treatment of aneurysm disease. Towards that target, the work presented in this thesis aims to establish a directly interactive link between experimental (in vivo and in vitro) and computational work for biologically and clinically relevant research on aneurysm disease. Mechanobiological hypotheses were firstly investigated in a novel 1D mathematical conceptual model of aneurysm evolution: for the first time these included representations of endothelial heterogeneity and smooth muscle cell (SMC) active stress response and apoptosis. The 1D investigations analysed and assessed the role of wall shear stress (WSS) homeostasis in elastin degradation, and the evolving role of the adventitia as a protective sheath in health and primary load-bearer in disease. The 1D framework was applied to a specific patient's aneurysm using both imaging and histological data to parameterise the model, calculating a material parameter for the adventitital collagen. The predicted evolution captured aspects of tissue changes measured with time focusing on the remodelled tissue wall thickness consistent with the experimental measurements, and physiological cyclic deformation in order to propose an approach to modelling adventitia's adaptive role to load bearing. Furthermore, an existing Fluid-Solid-Growth (FSG) computational framework was adapted and calibrated for the same patient-specific case with the help from the experimental data and the analysis from the 1D framework. This FSG model quantifies the arterial mechanical environment and captures the mechanical response of the fibrous arterial constituents. Comparing 1D and 3D investigations to establish consistency for our models, the 3Dmodel tested the hypothesis of WSS homeostasis, additionally introducing the element of spatial heterogeneity in the definition, and a new hypothesis linking cyclic deformation with collagen growth that ensures a physiological mechanical environment in stabilised aneurysms. Moreover, the FSG framework was applied in a specific rabbit aneurysm case and extended to link growth and remodeling to the detailed representation of the pulsatile blood flow mechanical environment. This research illustrates the power of computational modelling when coupled with rich data sets on the physiology, histology and geometry of healthy and diseased vascular tissue. In particular, the integrative modelling framework provides the foundation for establishing mechanobiological links crucial to aneurysm progression, and a basis for further research towards creating reliable aneurysm clinical tools.
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Skaro, Jordan M. "Knee Angles and Axes Crosstalk Correction In Gait, Cycling, and Elliptical Training Exercises." DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/1922.
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When conducting motion analysis using 3-dimensional motion capture technology, errors in marker placement on the knee results in a widely observed phenomenon known as “crosstalk” [1-18] in calculated knee joint angles (i.e., flexion-extension (FE), adduction-abduction (AA), internal-external rotation (IE)). Principal Component Analysis (PCA) has recently been proposed as a post hoc method to reduce crosstalk errors and operates by minimizing the correlation between the knee angles [1, 2]. However, recent studies that have used PCA have neither considered exercises, such as cycling (C) and elliptical training (E), other than gait (G) nor estimated the corrected knee axes following PCA correction. The hypothesis of this study is that PCA can correct for crosstalk in G, C, and E exercises but that subject-specific PCA corrected axes differ for these exercises.
Motion analysis of the selected exercises were conducted on 8 normal weight (body mass index (BMI) = 21.70 +/- 3.20) and 7 overweight participants (BMI = 27.45 +/- 2.45). An enhanced Helen Hayes marker set with 27 markers was used to track kinematics. Knee joint FE, AA, and IE angles were obtained with Cortex (Motion Analysis, Santa Rosa, CA) software and corrected using PCA to obtain corrected angles for each exercise. Exercise-specific corrected knee joint axes were determined by finding axes that reproduced the shank and ankle body vectors taken from Cortex when used with the PCA corrected angles. Then, PCA corrected gait axes were used as a common set of axes for all exercises to find corresponding knee angles. Paired t-tests assessed if FE-AA angle correlations changed with PCA. Multivariate Paired Hotelling’s T-Square tests assessed if the PCA corrected knee joint axes were similar between exercises. ANOVA was used to assess if Cortex angles, PCA corrected angles, and knee angles using PCA corrected gait axes were different.
Reduced FE-AA angle correlations existed for G (p<0.001 for Cortex and p=0.85 for PCA corrected), C (p=0.01 for Cortex and p=0.77 for PCA corrected), and E (p<0.001 for Cortex and p=0.77 for PCA corrected). Differences in the PCA corrected knee axes were found between G and C (p<0.0014). Then, differences were found between Cortex, PCA corrected, and C and E knee angles using the PCA corrected G axes (p<0.0056).
The results of this study suggest that if PCA is used to reduce crosstalk errors in motions other than G then it is recommended to adopt the use of a PCA corrected axes set determined from G to produce the PCA corrected angles.
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Said, Munzir. "Computational optimal control modeling and smoothing for biomechanical systems." University of Western Australia. Dept. of Mathematics and Statistics, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0082.
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[Truncated abstract] The study of biomechanical system dynamics consists of research to obtain an accurate model of biomechanical systems and to find appropriate torques or forces that reproduce motions of a biomechanical subject. In the first part of this study, specific computational models are developed to maintain relative angle constraints for 2-dimensional segmented bodies. This is motivated by the fact that there is a possibility of models of segmented bodies, moving under gravitational acceleration and joint torques, for its segments to move past the natural relative angle limits. Three models to maintain angle constraints between segments are proposed and compared. These models are: all-time angle constraints, a restoring torque in the state equations and an exponential penalty model. The models are applied to a 2-D three segment body to test the behaviour of each model when optimizing torques to minimize an objective. The optimization is run to find torques so that the end effector of the body follows the trajectory of a half circle. The result shows the behavior of each model in maintaining the angle constraints. The all-time constraints case exhibits a behaviour of not allowing torques (at a solution) which make segments move past the constraints, while the other two show a flexibility in handling the angle constraints more similar to a real biomechanical system. With three computational methods to represent the angle contraint, a workable set of initial torques for the motion of a segmented body can be obtained without causing integration failure in the ordinary differential equation (ODE) solver and without the need to use the “blind man method” that restarts the optimal control many times. ... With one layer of penalty weight balancing between trajectory compliance penalty and other optimal control objectives (minimizing torque/smoothing torque) already difficult to obtain (as explained by the L-curve phenomena), adding the second layer penalty weight for the closeness of fit for each of the body segments will further complicate the weight balancing and too much trial and error computation may be needed to get a reasonably good set of weighting values. Second order regularization is also added to the optimal control objective and the optimization has managed to obtain smoother torques for all body joints. To make the current approach more competitive with the inverse dynamic, an algorithm to speed up the computation of the optimal control is required as a potential future work.
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Clarke, Amy W. "A method for testing the amount of deformation and level of force required to produce permanent injury to the dentition." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/97989/4/Amy_Clarke_Thesis-1.pdf.
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Sporting injuries are the cause of up to a third of dental injuries each year. There is a 95% chance of permanent disfigurement to the most visible upper front teeth due to an impact to the mouth. This project developed a methodology to investigate the biomechanics of the teeth and their supporting structures in post-mortem human specimens. Using this method controlled loads can be applied to the teeth and their deformation and movement in the maxilla measured. Development of this methodology producing a robust and repeatable method capable of measuring injury thresholds will help to design better dental protective devices.
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Muschner, Anne. "Entwicklung eines Modells zur biomechanischen Untersuchung verschiedener Osteosynthesesysteme am Os scaphoideum." Doctoral thesis, Universitätsbibliothek Leipzig, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-82392.
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Die Kahnbeinfraktur ereignet sich als die häufigste Fraktur innerhalb der Handwurzelknochen. Als Pathomechanismus wird hauptsächlich der Sturz auf die nach dorsal hyperextendierte ulnar abduzierte Hand angesehen. Bei rechtzeitiger Diagnose und sofortiger Intervention lassen sich sehr gute Heilungsergebnisse erzielen und eine Pseudarthrosebildung verhindern. Für die akute dislozierte B2-Fraktur nach Herbert hat sich die intraossäre Fixation als bewährtes Behandlungs-verfahren etabliert. In der Klinik stehen dafür eine Vielzahl von intraossären Schrauben zur Verfügung, die sich in ihren technischen Eigenschaften teilweise stark unterscheiden. Ziel dieser Arbeit ist die Entwicklung eines biomechanischen Versuchsaufbaues, das im experimentellen Vergleich verschiedener Osteosynthese-verfahren am Os scaphoideum Anwendung finden soll. Die experimentell ermittelten Ergebnisse ermöglichen eine Aussage über die Primärstabilität, die allein durch die Verankerung des Implantats im Knochen erreicht wird.
In der hier vorliegenden in vitro Studie wurden sechs unversehrte anomaliefreie humane Kahnbeine der Hand, gestellt durch das Institut für Anatomie der Universitätsklinik Leipzig, vollständig von Bändern und umgebenden Weichteil-gewebe befreit. Zur Vermeidung eines Positionsverlustes beider Fragmentenden erfolgte zunächst die Osteosynthese durch Insertion einer Herbertschraube und anschließend die Osteotomie mittels oszillierender Knochensäge im Sinne einer nicht-dislozierten Fraktur im mittleren Drittel.
Die verwendete Herbertschraube der Firma Martin® war 21 mm lang und zählt zu den Standardimplantaten. Sie verfügt über zwei endständige Gewinde, die sich in Durchmesser und Gewindesteigung jeweils unterscheiden. Über einen Führungs-draht kann eine exakte Positionierung des kanülierten Implantats erreicht werden. Durch selbstbohrende und selbstschneidende Eigenschaften wird eine regelrechte Schraubenimplantation bei nur minimaler Knochensubstanzreduktion ermöglicht.
Die Knochen-Implantat-Verbindung wurde zweizeitig unter penibler Aussparung des Frakturspaltes in je 2 kubische eiserne Pfannen mit den Abmaßen 2,0 cm x 2,0 cm x 2,0 cm geklebt. Hierfür diente Sikadur®-31 CF Normal, ein lösemittelfreier, thixotroper Zweikomponentenkleber auf Epoxidharzbasis. In Zusammenarbeit mit der HTWK Leipzig erfolgte nach vollständiger Aushärtung der gesamten Testeinheit die Einspannung und Ausrichtung in die elektromechanische Prüfmaschine vom Typ LFM-H der Firma Walter + Bai AG. Zur Datenerhebung diente eine in den Versuchs-aufbau eingebrachte Kraftmessdose, die nach Einspannung des Testobjektes kalibriert wurde. An den beiden Eisenpfannen wurden zwei Branchen des Wegmess-systems platziert. Der Weg wurde als Regelgröße festgelegt. Die drei Kanäle speicherten 1-Zeitwerte, 2- Kraftwerte und 3- Wegwerte.
Wichtige Kriterien für das Design einer biomechanischen Studie sind das Einhalten standardisierter Bedingungen und die Reproduzierbarkeit der Ergebnisse. Nach Abschluss der Vorversuche und Auswertung der Ergebnisse ergaben sich folgende Erkenntnisse:
1) Zyklisch eingeleitete Kraft in Form von sinusförmigen Schwingungen ermöglichen eine standardisierte Verifizierbarkeit der Ergebnisse. Innerhalb dieser Studie wurde die Frequenz der wechselnden Belastungsrichtung auf 0,5 Hz festgelegt. Ein Belastungzyklus umfasste 100 sinusförmige Schwingungen.
2) Die Krafteinleitung soll über einen definierten Weg geschehen, damit Stadien vor dem definitiven Implantatversagen erfasst werden können.
3) Nach Abschluss eines Belastungszyklus soll die Auslenkung auf das nächsthöhere Belastungsniveau um einen definierten Weg erfolgen. Aus den Erkenntnissen des letzten Vorversuches profitierend wurde eine Auslenkungs-erhöhung um je 10 µm festgelegt.
4) Für die experimentelle Testung der Primärfestigkeit zwischen Os scaphoideum und intraossärem Implantat empfiehlt sich neben der exakten Schraubeninsertion eine Ausrichtung des Testkörpers entsprechend der Krafteinleitung, da somit ein Entstehen von Momenten innerhalb der Knochen-Implantat-Verbindung verhindert werden kann.
5) Damit in der biomechanischen in vitro Testung nur die Primärfestigkeit zwischen Knochen und Implantat gemessen wird, sollten die Versuche auf Zugbelastungen beruhen. Die Analyse des Kraftflusses im Versuchsaufbau ergab, dass während der Druckbelastung teilweise Kräfte gemessen worden sind, die keine Aussage über die Festigkeit der Knochen-Implantat-Verbindung erlauben. Darüber hinaus erwiesen sich die Druckversuche sogar als Ursache für ein schneller voranschreitendes Implantatversagen.
6) Die Verwendung einer Prüfmaschine ist für die komplexe Testung und die Auswertung der Ergebnisse empfehlenswert.
7) Die klinische Übertragbarkeit ist auf Grund des nicht berücksichtigten anatomisch funktionellen Zusammenwirkens mit angrenzendem Weichteil-gewebe und Knochen eingeschränkt.
Biomechanische Untersuchungen zur Primärstabilität können bei der Auswahl des „idealen“ Implantats hilfreich sein. Der direkte experimentelle Vergleich verschiedener intraossärer Schrauben und die Analyse ihrer technischen Eigenschaften können dazu beitragen, dass bei der Wahl des Implantats bessere Heilungserfolge in der operativen Versorgung der Kahnbeinfraktur erzielt werden und dass sich somit das Risiko einer Pseudarthrosenbildung vermindert.
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Salinas, Manuel. "Movement Effects on the Flow Physics and Nutrient Delivery in Engineered Valvular Tissues." FIU Digital Commons, 2014. http://digitalcommons.fiu.edu/etd/1924.
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Mechanical conditioning has been shown to promote tissue formation in a wide variety of tissue engineering efforts. However the underlying mechanisms by which external mechanical stimuli regulate cells and tissues are not known. This is particularly relevant in the area of heart valve tissue engineering (HVTE) owing to the intense hemodynamic environments that surround native valves. Some studies suggest that oscillatory shear stress (OSS) caused by steady flow and scaffold flexure play a critical role in engineered tissue formation derived from bone marrow derived stem cells (BMSCs). In addition, scaffold flexure may enhance nutrient (e.g. oxygen, glucose) transport. In this study, we computationally quantified the i) magnitude of fluid-induced shear stresses; ii) the extent of temporal fluid oscillations in the flow field using the oscillatory shear index (OSI) parameter, and iii) glucose and oxygen mass transport profiles. Noting that sample cyclic flexure induces a high degree of oscillatory shear stress (OSS), we incorporated moving boundary computational fluid dynamic simulations of samples housed within a bioreactor to consider the effects of: 1) no flow, no flexure (control group), 2) steady flow-alone, 3) cyclic flexure-alone and 4) combined steady flow and cyclic flexure environments. We also coupled a diffusion and convention mass transport equation to the simulated system. We found that the coexistence of both OSS and appreciable shear stress magnitudes, described by the newly introduced parameter OSI-t , explained the high levels of engineered collagen previously observed from combining cyclic flexure and steady flow states. On the other hand, each of these metrics on its own showed no association. This finding suggests that cyclic flexure and steady flow synergistically promote engineered heart valve tissue production via OSS, so long as the oscillations are accompanied by a critical magnitude of shear stress. In addition, our simulations showed that mass transport of glucose and oxygen is enhanced by sample movement at low sample porosities, but did not play a role in highly porous scaffolds. Preliminary in-house in vitro experiments showed that cell proliferation and phenotype is enhanced in OSI-t environments.
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Jennings, Dalton James. "USE OF BODY COMPOSITION IMAGING TO CALCULATE 3-D INERTIAL PARAMETERS FOR INVERSE DYNAMIC ANALYSIS OF YOUTH PITCHING ARM KINETICS." DigitalCommons@CalPoly, 2020. https://digitalcommons.calpoly.edu/theses/2122.
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The objectives of this study were to 1) calculate participant-specific segment inertial parameters using dual energy X-ray absorptiometry (DXA) data (referred to as full DXA-driven parameters) and compare the pitching arm kinetic predictions using full DXA-driven inverse dynamics vs scaled, DXA mass-driven (using DXA masses but scaled centers of mass and radii of gyration), and DXA scaled inverse dynamics(ID) (using the full DXA-driven inertial parameters averaged across all participants), 2) examine associations between full DXA-driven kinetics and body mass index (BMI) and 3) examine associations between full DXA-driven kinetics and segment mass index (SMI). Eighteen 10- to 11- year-olds pitched 10 fastballs. DXA scans were conducted and examined to obtain 3D inertial parameters of the upper arm, forearm, and hand. Full DXA-driven and scaled inertial parameters were compared using paired t-tests. Pitching arm kinetic predictions calculated with the four methods (i.e. scaled ID, DXA mass-driven ID, full DXA-driven ID, and DXA scaled ID) were compared using a repeated measures ANOVA with Tukey post-hoc tests. The major results were that 1) full DXA-driven participant specific inertial parameters differed from scaled inertial parameters 2) kinetic predictions significantly varied by method and 3) full DXA-driven ID predictions for shoulder compression force and shoulder internal rotation torque were significantly associated with BMI and/or SMI.
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Vosynek, Petr. "Deformačně-napěťová analýza povrchové náhrady kyčelního kloubu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-227873.
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Today is the surface hip repacement very often surgery becouse of new studies and improvements. For young and active people it's the best way to delay implantation of a total hip replacement. The objective of this study was to perform finite-element analyses of computational model of the partial/total surface replacement, conventional partial/total replacement and physiological hip joint. We obtained strain-stress states from these analyses. All results were compared one another and then were confronted with results of the physiological hip joint. The three-dimensional computational model consists of these components: sacral, pelvic and femoral bone, muscles, artificial socket, and surface hip replacement. We were using FEM system ANSYS. The geometrical models of bones were generated by means of computed tomography (CT) images. The FE model of bone reflects two types of the bone tissues (trabecular and cortical bone) and muscles which are important when standing on one leg. The model of the muscle corresponds to isometric contraction. The implants material and bone tissues were modelled as isotropic linear elastic material. The model was loaded by force, corresponding to load by standing on one leg.
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Koehler, Amy. "Biomechanical Modeling of Manual Wheelchair Propulsion:Force Capability Investigation for Improved Clinical Fitting Procedures." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1494193078750548.
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Stewart, Kevin Matthew. "MECHANICAL SIMULATION OF ARTICULAR CARTILAGE BASED ON EXPERIMENTAL RESULTS." DigitalCommons@CalPoly, 2009. https://digitalcommons.calpoly.edu/theses/93.
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Recently, a constituent based cartilage growth finite element model (CGFEM) was developed in order to predict articular cartilage (AC) biomechanical properties before and after growth. Previous research has noted limitations in the CGFEM such as model convergence with growth periods greater than 12 days. The main aims of this work were to address these limitations through (1) implementation of an exact material Jacobian matrix definition using the Jaumann-Kirchhoff (J-K) method and (2) quantification of elastic material parameters based upon research findings of the Cal Poly Cartilage Biomechanics Group (CPGBG). The J-K method was successfully implemented into the CGFEM and exceeded the maximum convergence strains for both the “pushed forward, then differentiated” (PFD) and “differentiated, then pushed forward” (DPF) methods, while maintaining correct material stress responses. Elastic parameters were optimized for confined compression (CC), unconfined compression (UCC), and uniaxial tension (UT) protocols. This work increases the robustness of the CGFEM through the J-K method, as well as defines an accurate starting point for AC growth based on the optimized material parameters.
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Ramsey, Glenn. "Equine hoof biomechanics." Thesis, University of Auckland, 2011. http://hdl.handle.net/2292/11469.
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The biomechanics of the equine hoof are not well understood. Therefore biomechanical models of the hoof were developed, using finite element analysis and finite deformation elasticity, to provide a means of analysing the mechanisms underlying hoof function and dysfunction. One goal of the research was to investigate the biomechanical effects of different hoof shapes. A parametric geometry model that could be configured to represent commonly observed variations in hoof shape was developed for this purpose. Tissue behaviour models, accounting for aspects of the nonlinearity, inhomogeneity due to a moisture gradient and anisotropy of the tissues, were developed and configured using data from the literature. A method for applying joint moment loads was incorporated into the model to allow the direct use of published hoof load data. These aspects of the model were improvements over previously published hoof models. Both hoof capsule deflections and stored elastic energy were predicted to be increased by increased moisture content and by caudal movement of the centre of pressure of the ground reaction force. These results confirm that hoof deflections may play an important role in attenuating potentially damaging load impulse energy and support the geometry hypothesis to explain the mechanism by which the hoof expands under load. Further analyses provided insights into aspects of hoof mechanics that challenge conventional beliefs. The model predicts that load in the dorsal lamellar tissue is increased, rather than decreased, when hoof angle is increased. Simulations of different ground surface shapes indicate that hoof deformability and not ground deformability, may be responsible for the concave quarter relief observed in naturally worn hooves. A hypothesis is proposed for the mechanism by which heel contraction occurs and implicates heel unloading due to bending of the caudal hoof capsule and contraction under load bearing of the caudal coronet as probable causes. Biomechanical analyses of this kind enable improved understanding of hoof function, and a rational, objective basis for comparing the efficacy of different therapeutic strategies designed to address hoof dysfunction.
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Wetzel, Franziska. "Biomechanical Phenotyping of Cells in Tissue and Determination of Impact Factors." Doctoral thesis, Universitätsbibliothek Leipzig, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-144866.
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Diese Arbeit beinhaltet Ergebnisse der ersten klinischen Studie zur Charakterisierung der mechanischen Eigenschaften von Zellen in einem Tumor mit der dafür notwendigen Probengröße. Dies ermöglichte die Erstellung eines umfassenden Bildes von Subpopulationen innerhalb eines Tumors mit großem diagnostischem Potential. Die Änderung der Einzelzellmechanik von Tumorzellen wird durch Veränderung des Zytoskeletts, einem komplexes Polymernetzwerk in Zellen, hervorgerufen. Mit Hilfe von Zellgiften wurde das Zytoskelett gezielt manipuliert, um den Einfluss einzelner Faktoren auf die Biomechanik zu bestimmen.
Aus Gewebeproben von Brustkrebspatienten wurden Zellen mit Hilfe enzymatischer Aufspaltung des extrazellulären Kollagennetzwerkes isoliert. Als Kontrollsystem wurden Primärzellen aus Brustreduktionsgewebe und aus Fibroadenomen, gutartigen Gewebeneubildungen der Brustdrüse, verwendet. Unter Einsatz des Optischen Stretchers, einer Zweistrahl-Laserfalle, wurden suspendierte Zellen für zwei Sekunden einer konstanten Zugspannung ausgesetzt und das Deformations- wie auch das anschließende Relaxationsverhalten beobachtet.
Dabei ergaben sich wesentliche Unterschiede zwischen Tumor- und Kontrollproben. Neben Zellen mit ähnlichen Steifigkeiten, enthielten Tumorproben Subpopulationen sehr weicher Zellen, wie sie in Normalgewebe nicht zu finden sind. Desweiteren war das Relaxationsverhalten der Tumorzellen stärker elastisch dominiert. Einzelne Zellen kontrahierten sogar aktiv gegen die Zugspannung. Versuche, das Zytoskelett mittels Zellgiften künstlich in einem Zustand zu bringen, der in Krebszellen beobachtet wurde, ergaben zwar ebenfalls die Zunahme weicherer Zellen, jedoch war das Relaxationsverhalten eher viskos dominiert. Fluoreszenzaufnahmen des Aktin-Zytoskeletts sowie der fokalen Adhäsionen, die das Aktin-Netzwerk der Zelle mit dem Substrat verankern, zeigten Veränderungen bei Krebszellen im Vergleich zu Kontrollen.
Darüber hinaus wurden Einflussfaktoren auf die Zellmechanik untersucht. Neben Kulturbedingungen, beeinflussen auch Alter und Medikation das biomechanische Verhalten. Die Steifigkeit der Krebszellen scheint vom Ursprungsgewebe beeinflusst zu werden, sodass Zellen verschiedener Krebsarten Steifigkeiten in unterschiedlichen Regimes zeigen.
Die Ergebnisse dieser Arbeit liefern wichtige Informationen für unser Verständnis der Karzinogenese und bilden die Grundlage für eine neue diagnostische Methode zur Bestimmung der Tumoraggressivität. Eine gezielte Untersuchung der gefundenen Subpopulationen in einem Tumor könnte dabei helfen, neue Therapieansätze zu entwickeln und damit die hohen Rezidivraten aggressiver Tumore zu vermindern.
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Bartoňová, Petra. "Analýza vlivu mechanických vlastností komponent patologické stěny tepny na její napjatost." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-418194.
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The thesis deals with measurements of the atherosclerothic carotid plaques mechanical properties with wiew towards the improvements of their constitutive models and then towards the impact of application of those constitutive models in fibrous cap. The introductory part provides a brief summary of medical knowledge needed to understand atheroma formation and the risks involved. Next, there's a survey of plaque mechanical testing methods and the obtained results on tissue properties. The previously used constitutive models of atherosclerothic tissues are listed as well. Main body of the thesis describes the preparation of testing samples from obtained atheroma, methodology and course of experiments execution and subsequent processing of the experimental data to evaluate the behavior of the atheromatous tissue individual parts. Then the discussion and evaluation of our results and findings is given. Along with the evaluated mechanical properties, experimental data fitted to models are presented with respect to their predictive abilities. The final part is dedvoted to the finite element analysis of an idealized 2D model with emphasis on the effect of necrotic core and fibrous tissue properties on von Mises equivalent stress in the fibrous cap.
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Konz, Suzanne M. "Technique and Performance Level Comparisons of Male and Female Hammer Throwers." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1660.pdf.
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Schmidt, Sebastian, Tobias Kießling, Enrico Warmt, Anatol Fritsch, Roland Stange, and Josef A. Käs. "Complex thermorheology of living cells." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-173543.
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Temperature has a reliable and nearly instantaneous influence on mechanical responses of cells. As recently published, MCF-10A normal epithelial breast cells follow the time-temperature superposition (TTS) principle. Here, we measured thermorheological behaviour of eight common cell types within physiologically relevant temperatures and applied TTS to creep compliance curves. Our results showed that superposition is not universal and was seen in four of the eight investigated cell types. For the other cell types, transitions of thermorheological responses were observed at 36 °C. Activation energies (EA) were calculated for all cell types and ranged between 50 and 150 kJ mol-1. The scaling factors of the superposition of creep curves were used to group the cell lines into three categories. They were dependent on relaxation processes as well as structural composition of the cells in response to mechanical load and temperature increase. This study supports the view that temperature is a vital parameter for comparing cell rheological data and should be precisely controlled when designing experiments.
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Lambach, Mark D. "Distribution of Chondrocyte Cell Death in Medial and Lateral Femoral Condyles in Porcine Knees after Sub-impact Loading." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1338354533.
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Halliday, Suzanne Elizabeth. "Biomechanics of ergometer rowing." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270367.
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Jacob, Hilaire A. C. "Biomechanics of the forefoot." Thesis, University of Strathclyde, 1989. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21307.
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The work reported in this thesis was carried out to investigate the kinematic and dynamic behaviour of the forefoot during normal locomotion activities. An extensive literature review on the subject is presented and the need for further investigations shown. Fresh autopsy specimens were studied to determine the course taken by tendons in relation to the joints of the forefoot, and the topography of joint surfaces mapped. The overall geometries of the first and second rays have been described too. Also, an experimental investigation has shown that without muscular activity the metatarsal bones are mainly loaded in bending. Locomotion studies have shown that the average peak ground forces under the pad of the great toe, the head of the 1st metatarsal, the pad of the 2nd toe, the head of the 2nd metatarsal and the head of the 5th metatarsal measure about 30% body weight (BW), 15% BW, 6% BW, 30% BW and 15% BW, respectively. Temporal graphs of these forces show their behaviour during the gait cycle. Furthermore, the magnitudes of these forces when wearing shoes-with stiff soles, when climbing up and down stairs, as well as when walking up and down a slope of 15° are reported. Based on the external forces measured, the internal forces acting along the flexor tendons and across joint surfaces of the 1st and 2nd rays during gait are estimated. The stresses that thereby develop in the shanks of the metatarsal bones indicate that the 1st metatarsal bone is subjected mainly to compression while the 2nd metatarsal bone is exposed to a high degree of bending. The relationship between the results of this study and clinical problems is considered and especially a hypothesis has been advanced to explain how under edge-loading conditions localised necrosis of the metatarsal heads could occur, thus giving rise to Koehler-Freiberg's disease.
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Morrison, Andrew Paul. "Golf coaching biomechanics interface." Thesis, Ulster University, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.680144.
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Gladchenko, O. R., and A. E. Serik. "Biomechanical principles in badminton." Thesis, Сумський державний університет, 2014. http://essuir.sumdu.edu.ua/handle/123456789/34847.
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Human psychophysiology forms mutually agreed unity where targeted development of one of the components can ensure the development of the other. Mass character and attractiveness of physical culture and sports as leisure components make urgent the task to develop intellectual abilities.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/34847
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Holub, Ondrej. "Biomechanics of spinal metastases." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/7315/.
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The lack of suitable models for prediction of the vertebral body (VB) failure load for a variety of pathologies hampers the development of indications for surgical and pharmaceutical interventions and the assessment of novel treatments. Similar models would also be of benefit in a laboratory environment in which predictions of failure load could aid experimental design when using cadaveric tissue. Finite element modelling shows great potential but the expertise required to effectively deploy this technology in a clinical environment precludes its routine use at the present time. Its deployment within the laboratory environment is also time consuming. An alternative approach may be the use of composite beam theory structural analysis that takes into account both vertebral geometry and the bone mineral density (BMD) distribution and they are utilised to predict the loads at which vertebrae will fail. As a part of this work, vertebrae suffering from three distinct pathologies (osteoporosis, multiple myeloma (MM) and metastases) were tested in a wedge compression loading protocol (WCF) as a determinant for vertebroplasty treatment. MM bone was first tested for changes at the bone tissue level by means of depth-sensing micro-indentation testing. In the second part more than one hundred VBs were subjected to a destructive in-vitro WCF experiment, while CT images were used for in-silico structural and morphological assessment. In the last part, two vertebroplasty cements, calcium phosphate and PMMA, were tested. At the tissue level MM bone shows rather moderate changes which are of such small magnitude that alone would not be sufficient to change the overall vertebral strength. Relatively good predictions of VB strength were obtained when using image-based fracture prediction suggesting that bone distribution and pathological alterations to its structure make a significant contribution to overall VB strength. The results of VB reinforcement using either of the cements show increased strength while stiffness was restored only when PMMA cement was injected in lower porosity samples.
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Marine, Brandon K. "A Computational Study of the Kinematics of Femoroacetabular Morphology During A Sit-to-Stand Transfer." VCU Scholars Compass, 2017. https://scholarscompass.vcu.edu/etd/5189.
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Computational modeling in the field of biomechanics is becoming increasingly popular and successful in practice for its ability to predict function and provide information that would otherwise be unobtainable. Through the application of these new and constantly improving methods, kinematics and joint contact characteristics in pathological conditions of femoroacetabular impingement (FAI) and total hip arthroplasty (THA) were studied using a lower extremity computational model. Patients presenting with FAI exhibit abnormal contact between the femoral neck and acetabular rim leading to surrounding tissue damage in daily use. THA is the replacement of both the proximal femur and acetabular region of the pelvis and is the most common surgical intervention for degenerative hip disorders. A combination of rigid osteoarticular anatomy and force vectors representing soft tissue structures were used in developing this model. Kinematics produced by healthy models were formally validated with experimental data from Burnfield et al. This healthy model was then modified to emulate the desired morphology of FAI and a THA procedure with a range of combined version (CV) angles. All soft tissue structures were maintained constant for each subsequent model. Data gathered from these models did not provide any significant differences between the kinematics of healthy and FAI but did show a large amount of variation in all THA kinematics including incidents of dislocation with cases of lower CV angles. With the results of these computational studies performed with this model, an increased understanding of hip morphology with regards to STS has been achieved.
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Wangerin, Spencer D. "Development and validation of a human knee joint finite element model for tissue stress and strain predictions during exercise." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1129.
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Osteoarthritis (OA) is a degenerative condition of cartilage and is the leading cost of disability in the United States. Motion analysis experiments in combination with knee-joint finite element (FE) analysis may be used to identify exercises that maintain knee-joint osteochondral (OC) loading at safe levels for patients at high-risk for knee OA, individuals with modest OC defects, or patients rehabilitating after surgical interventions. Therefore, a detailed total knee-joint FE model was developed by modifying open-source knee-joint geometries in order to predict OC tissue stress and strain during the stance phase of gait. The model was partially validated for predicting the timing and locations of maximum contact parameters (contact pressure, contact area, and principal Green-Lagrangian strain), but over-estimated contact parameters compared with both published in vivo studies and other FE analyses of the stance phase of gait. This suggests that the model geometry and kinematic boundary conditions utilized in this FE model are appropriate, but limitations in the material properties used, as well as potentially the loading boundary conditions represent primary areas for improvement.
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Frampton, Peter. "Tonometry : a study in biomechanical modelling : appraisal and utility of measurable biomechanical markers." Thesis, Aston University, 2017. http://publications.aston.ac.uk/33115/.
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Goldmann Applanation Tonometry (GAT) is the recognised ‘Gold Standard’ tonometer. However this status is refuted by eminent authors. These contradictory views have driven the initial goal to assess, from first principles, the evolution of GAT and to experimentally evaluate its utility and corrections. Subsequently, an important caveat became the evaluation of Corneal Hysteresis and Corneal Resistance Factor. Chapter 1. Biomechanical building blocks are defined and constitutive principles incorporated into continuum modelling. The Imbert-Fick construct is re-interpreted a simple biomechanical model. GAT corrections are also appraised within a continuum framework; CCT, geometry and stiffness. These principles enable evaluation of alternative tonometer theory and the evolving biomechanical markers, Corneal Hysteresis (ORA-CH) and Corneal Resistance Factor (ORA-CRF). Chapter 2 appraises corneal biomechanical markers, CCT, curvature, ORA-CH and ORA-CRF in 91 normal eyes and the impact these have on three tonometers: GAT, Tonopen and Ocular Response Analyser (ORA). Tonopen was the sole tonometer not affected by biomechanics. CCT was confirmed the sole measurable parameter affecting GAT. ORA did not demonstrate improved utility. ORA-CH and ORA-CRF do not appear robust biomechanical measures. Chapter 3 assessed agreement between GAT, the ORA measures and Tonopen. Tonopen is found to measure highest and raises the question should a development goal emphasise GAT agreement or improvement? Chapter 4 assessed repeatability of the three tonometers and biomechanical measures keratometry, pachymetry, ORA-CH and ORA-CRF on 35 eyes. Coefficients of Repeatability (CoR) of all tonometers are wide. Effects assessed in Chapter 5 may be masked by general noise. ORA does not appear to enhance utility over GAT. Isolation of corneal shape change via Orthokeratology (Chapter 5) demonstrate ORACH and ORA-CRF reflect, predominantly, a response to corneal flattening. It is proposed they do not significantly reflect corneal biomechanics. After reviewing models for tear forces (Chapter 6), a refined mathematical model is presented. Tear bridge attraction is minimal and cannot explain under-estimation of IOP by GAT in thin corneas. CCT corrections and the Imbert-Fick rules are incompatible. Chapter 7 summarises findings. The supremacy of GAT is likely to remain for some time, reflecting the sheer magnitude of overturning 60 years of convention, historical precedent, expert opinion as well as the logistical and educational difficulties of redefining standards and statistical norms.
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Schöne, Martin. "Possibilities of Articular Cartilage Quantification Based on High-Frequency Ultrasound Scans and Ultrasound Palpation." Doctoral thesis, Humboldt-Universität zu Berlin, 2020. http://dx.doi.org/10.18452/21781.
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In der Diagnostik und Reparatur von hyalinem Gelenkknorpel sind neue Methoden zur Quantifizierung von Struktur und mechanischer Belastbarkeit gefragt, um die Behandlung von Knorpelschäden an Millionen von Patienten weltweit zu verbessern.
Mittels hochfrequentem, fokussierten Ultraschall werden Oberflächenparameter für Reflektivität und Rauheit an Gelenkknorpel bestimmt. Es wird gezeigt wie die Oberflächenneigung kontrolliert werden kann. Die Ergebnisse vermitteln ein besseres Verständnis über die Zusammensetzung der Ultraschallsignale aus reflektierten und gestreuten Komponenten.
3D Ultraschallscans von Knorpelregeneraten erlauben die Defektstellen volumetrisch zu Quantifizieren. Die Proben wurden zusätzlich nach etablierten Bewertungssystemen benotet, welche auf makroskopischer Beurteilungen, MRT-Scans und Histologie basieren. Die ultraschallbasierten Volumendaten zeigten dabei gute Korrelationen mit den Punktwertungen.
Die im Labor verwendeten Messaufbauten zur biomechanischen Charakterisierung von Gelenkknorpel können am Patienten nicht angewandt werden. Daher können Ärzte die Festigkeit von Knorpel bisher nur mittels manueller Palpation abschätzen. Diese Arbeit entwickelt eine Methode der Ultraschall-Palpation (USP), die es erlaubt, die während der manuellen Palpation erzeugte Kraft und Deformation, basierend auf Ultraschallechos, aufzunehmen. Es wurde einen Prototyp entwickelt womit gezeigt werden konnte, dass USP eine ausreichende Genauigkeit und Reproduzierbarkeit aufweist. Wiederholte Messungen können zusätzlich zeitabhängige biomechanische Parameter von Knorpel ableiten.
Zusammenfassend zeigt diese Arbeit verbesserte und neue Möglichkeiten zur strukturellen und biomechanischen Charakterisierung von hyalinem Gelenkknorpel bzw. den Ergebnissen von Knorpelreparatur basierend auf Ultraschalldaten. Diese Methoden haben das Potenzial die Diagnostik von Gelenkknorpel und die Quantifizierung von Knorpelreparatur zu verbessern.In the diagnostics and repair of hyaline articular cartilage, new methods to quantify structure and mechanical capacity are required to improve the treatment of cartilage defects for millions of patients worldwide. This thesis uses high frequency focused ultrasound to derive surface parameters for reflectivity and roughness from articular cartilage. It is shown how to control the inclination dependency to gain more reliable results. Furthermore, the results provided a better understanding of the composition of ultrasonic signals from reflected and scattered components. 3D ultrasound scans of cartilage repair tissue were performed to quantify defect sites after cartilage repair volumetrically. The samples were also graded according to established scoring systems based on macroscopic evaluation, MRI scans and histology. The ultrasound-based volumetric parameters showed good correlation with these scores. Complex biomechanical measurement setups used in laboratories cannot be applied to the patient. Therefore, currently physicians have to estimate the stiffness of cartilage by means of manual palpation. In the last part of this thesis, a method denoted as ultrasound palpation is developed, which allows for measuring the applied force and strain during manual palpation in real time, solely based on the evaluation of the time of flight of ultrasound pulses. A prototype was developed and its measurement accuracy and reproducibility were characterized. It could be shown that ultrasound palpation has sufficient accuracy and reproducibility. Additionally, by repeated measurements it was possible to derive time-dependent biomechanical parameters of cartilage. In summary, this work shows improved and new possibilities for structural and biomechanical characterization of hyaline articular cartilage and the outcomes of cartilage repair based on ultrasound data. The methods have the potential to improve the diagnostics of articular cartilage and quantification of its repair.
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Barbarino, Casey Michael. "Design and Development of a Stair Ascension Assistive Device for Transfemoral Amputees." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/942.
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Transfemoral amputees around the world experience increased difficulty in climbing stairs due to lack of muscle, balance, and other factors. The loss of a lower limb greatly diminishes the amount of natural force generation provided that is necessary to propel oneself up stairs. This study investigated possible solutions to the problem of stair ascension for transfemoral amputees by the means of designing and developing an externally attachable device to a prosthesis. The number of amputations from military service has greatly increased since 2008, which shows there is a clear need for assistive devices (Wenke, Krueger, & Ficke, 2012). With the number of amputations rising and no current externally attachable products on the market to aid in stair ascension for transfemoral amputees, the need for this specific device has become more prominent.
Research, previous work, and preliminary testing provided a basis for design and development of a new prototype. Bench top testing was conducted to review concepts in the prototype and provide data for further modifications. Results from testing of previous work, as well as testing of new concepts and modifications, provided a framework for designing a new externally attachable device for assistance in stair ascension. A new prototype was then designed, manufactured, and tested with bench models as well as real-time testing with amputees. Success of the device’s performance was based on bench top results and feedback from amputees, noting both the advantages and shortcomings of the new prototype. Testing provided results and feedback that the device was well built and functioned properly, but did not perform satisfactorily, particularly in the categories of force generation and balance.
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Davis, Kermit G. "Interaction between biomechanical and psychosocial workplace stressors : implications for biomechanical responses and spinal loading /." The Ohio State University, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486397841222912.
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Huber, Zach Elijah. "Creation and Validation of a Dynamic, EMG-Driven Cervical Spine Model." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1365680628.
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Kiapour, Ata. "Non-Contact ACL Injuries during Landing: Risk Factors and Mechanisms." University of Toledo / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1368186846.
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Lamrich, Martin. "Deformačně napěťová analýza femuru s vnitrodřeňovým hřebem a fixačními pásky." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230513.
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The presented Master’s Thesis aims at determining stress and strain analysis of femur with fracture fixed by intramedullary nail and cerclage cable. The one of the goals of this work was create computational model which will be able simulate problem. Computational model consist of model of femur , it’s geometry was created on basis of CT data, than there was created model of intramedullary nail and cerclage cable on a basis of real objects. In this work was created simply model of femur with the same material features and characteristic proportions as analyzed model of femur. On this model was investigated direct impact of cerclage cables on deformation, respectively displacement in a surroundings of femoral fracture. On a final model were applied the real loads conditions. Preload in a cerclage cable was simulated by cooling down to a temperature from analytical calculation. Concluding analysis was powered by Finite Element Method (FEM) applied in system ANSYS Workbench 14.5 . Due to a results of analysis, we could say that using cerclage cables in combination with intramedullary nail is an effective way for healing femoral shaft fractures.
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Flick, Kevin Charles. "Biomechanics and dynamics of turning /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/5221.
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Lee, Angela Wing Chung. "Breast image fusion using biomechanics." Thesis, University of Auckland, 2011. http://hdl.handle.net/2292/10277.
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Breast cancer is a leading cause of cancer mortality in women worldwide. Biophysical mathematical models of the breast have the potential to aid in the diagnosis and treatment of breast cancer. This thesis presents research on the development and validation of biomechanical models of the breast subject to gravity and compressive loads. The finite element method was used to implement the theory of finite elasticity coupled with contact mechanics in order to simulate the large non-linear deformations of the breast tissues. Initially, validation studies were conducted using a breast phantom, which was placed in different orientations with respect to the gravity loading and compressed using a custom made device. A novel application of a block matching image processing method was used to quantitatively assess the accuracy of the biomechanics predictions throughout the entire phantom. In this way, systematic changes to the assumptions, parameters, and boundary constraints of the breast models could be quantitatively assessed and compared. Using contact mechanics to model the interactions between the ribs and breasts can improve the accuracy of simulating prone to supine deformations due to the relative sliding of the tissues, as was observed using MRI studies on volunteers. In addition, an optimisation framework was used to estimate the heterogeneous mechanical parameters of the breast tissues, and the improvements to the models were quantified using the block matching comparison method. A novel multimodality framework was developed and validated using MR and X-ray images of the breast phantom before being applied to clinical breast images. Using this framework, it was shown that the parameters of the model (boundary conditions, mechanical properties) could be estimated and the image alignment improved. The biomechanical modelling framework presented in this thesis was shown to reliably simulate both prone to supine reorientation, and prone to mammographic compression, deformations. This capability has the potential to help breast radiologists interpret information from MR and X-ray mammography imaging in a common visualisation environment. In future, ultrasound imaging could also be incorporated into this modelling framework to aid clinicians in the diagnosis and management of breast cancer.
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Kilic, Osman. "Biomechanical Modeling Of Human Hand." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12608906/index.pdf.
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This thesis analyzes the wrist joint of the human hand by using a realistic threedimensional wrist model. Load distributions among carpal bones, forces on ligaments and joints were examined by using three-dimensional model. Wrist
injuries and required surgical operations were examined with the model. The most crucial point of the study was that, using three-dimensional model of the wrist, hand surgeons would be able to predict results of surgical operation. Surgery
planning may be done and mechanical results may be Evaluated on the wrist model.
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Heistand, Mark Richard. "Biomechanics of the lens capsule." Texas A&M University, 2004. http://hdl.handle.net/1969.1/2726.
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Knowledge of the mechanics of the lens capsule is crucial for improving cataract surgery as well as understanding better the physiological role of the lens capsule in the process of accommodation. Previous research on the mechanical properties of the lens capsule contains many gaps and contradictions due to experimental limitations and inappropriate assumptions. Thus, the goal of this work is to quantify fully the regional, multiaxial mechanical behavior of the lens capsule and to calculate the change in stress and strain fields as a result of cataract surgery.
Determining in situ the multiaxial mechanical behavior of the lens capsule required the design and construction of an experimental device capable of altering stresses in the capsule while measuring localized surface deformations. Tests performed on this device reveal that the meridional and circumferential strains align with the principal directions and are equivalent through most of the anterior lens capsule, except close to the equator where the meridional strain is greater. Furthermore, preconditioning effects were also found to be significant. Most importantly, however, these tests provide the data necessary for calculating material properties.
This experimental system is advantageous in that it allows reconstruction of 3D geometry of the lens capsule and thereby quantification of curvature changes, as well as measurement of surface deformations that result from various surgical interventions. For instance, a continuous circular capsulorhexis (CCC) is commonly used during cataract surgery to create a hole in the anterior lens capsule (typically with a diameter of 5 mm). After the introduction of a CCC, strain was found to redistribute evenly from the meridional direction (retractional strain) to the circumferential direction (extensional strain), where both directional components of strain reached magnitudes up to 20% near the edge of the CCC. Furthermore, the curvature was found to increase at the edge of the CCC and remain the same near the equator, indicating that the mere introduction of a hole in the lens capsule will alter the focal characteristics of the lens and must therefore be considered in the design of an accommodative intraocular lens.
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Senavongse, Wongwit. "Biomechanics of the patellofemoral joint." Thesis, Imperial College London, 2002. http://hdl.handle.net/10044/1/7378.
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Borse, Vishal Harish. "In-vitro biomechanics of vertebroplasty." Thesis, University of Leeds, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.713483.
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Osteoporotic vertebral compression fractures are a major burden worldwide. Percutaneous vertebroplasty is a recognised treatment option for these fractures but there is conflicting evidence regarding the optimum amount of cement to use and there is little evidence regarding the best surgical approach to treating these fractures. Newer techniques are available which expand on the basic premise of percutaneous vertebroplasty. This project aimed to provide the basic science to answer the questions of cement fill, approach and the use of modern adjuncts to traditional percutaneous vertebroplasty. The first phase looked at approaches and cement fill and found that a 30% fill via a unipedicular approach , gave the best biomechanical outcome combined with the lowest theoretical risk and that the interaction between the cement and the vertebral endplate was important for syength restoration. Phase 2 expanded on the work carried out earlier in this study and looked at the response to dynamic loading of augmented and unaugmented vertebra. It reinforced the findings of phase 1 that 30% was the key figure and the endplate-bolus interaction was key. Finally phase 3 took the work carried out in the study so far and compared cavity creation vertebroplasty using a contour osteotome with traditional balloon kyphoplasty in, a static loading environment. It demonstrated equivocal strength restoration between the two but with lower incidence of implant induced fracture in the contour group. The culmination of this project provides guidelines for the effective use of cement augmentation by percutaneous vertebroplasty as a method for restoring strength post vertebral fracture in osteoporotic patients.
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Ferguson, Stephen John. "Biomechanics of the acetabular labrum." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0020/NQ54413.pdf.
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Gratz, Kenneth R. "Biomechanics of articular cartilage defects." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3284116.
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Thesis (Ph. D.)--University of California, San Diego, 2007.Title from first page of PDF file (viewed January 9, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Bogie, Katherine Mary. "Biomechanical considerations in seating design." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390455.
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Stefanakis, Manos. "Biomechanics of intervertebral disc pain." Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556723.
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'Background: Back pain is strongly (but variably) associated with degeneration of intervertebral discs. Mechanical loading has long been considered one of the causes of disc pathology and pain, but its precise role is poorly understood. In particular the spatial relation between load distribution inside the disc, the disc matrix changes as a result of load and their relationship with pain has not been researched. Methods: Distribution of compressive stress inside intervertebral discs from all regions of the spine was studied using stress profilometry in cadaveric motion segments. Matrix pathological changes were studied using simple histology and light microscopy in two groups of surgically removed discs: 'painful' discs from patients undergoing surgery for suspected discogenic pain, and 'control' discs from patients undergoing surgery for scoliosis or spondylolisthesis reduction. Ingrowth of nerves and blood vessels into the annulus was studied by immunohistochemistry with an endothelial and a general neuronal marker. Stress reduction inside annulus fissures were investigated using stress profilometry. Proteoglycan reduction within annulus fissures was studied by means of a novel, semi-quantitative method involving simple histology and image analysis. Although semi-quantitative, the technique had great spatial resolution and allowed integration with the results from the mechanical experiments. Results: High stress concentrations were localised in the middle annulus and increased with disc degeneration. Associated stress gradients appeared early in the degeneration process and were not diminished in late stage degeneration when substantial compressive loading is transferred to the neural arch. Nerve and blood vessel ingrowth increased with degeneration, but were confined to the outermost 4mm of the annulus. Other cellular changes such as apoptosis, cellular infiltration and proliferation were mostly confined to the annulus. Annulus fissures were found to represent focal regions of low proteoglycan content, and also of low compressive stress, especially when the nucleus was also decompressed. Conclusions: Results suggest that high stress gradients play an important role in progressive annulus disruption, and that annulus fissures provide a microenvironment that is mechanically and chemically conducive to the ingrowth of nerves and blood vessels. Co-localisation of nerves, blood vessels and stress concentrations in the middle-outer annulus suggest that this is the most likely site of discogenic pain. Pain is associated with annulus disruption and the attempted healing rather than age-related degenerative changes in the nucleus.