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1
Watters, Eamon Patrick John. "Wear properties of artificial hip joint materials." Thesis, Queen's University Belfast, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321968.
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Mallard, Thomas. "Development of an optimum artificial wrist joint." Thesis, University of East London, 2005. http://roar.uel.ac.uk/3409/.
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Wrist joint prostheses have developed from simple silicone joint spacers to the current state of the art where design philosophy now follows that of large joint replacement. A variety of shortcomings identified in existing designs through their clinical use led to the development of a new wrist joint prosthesis being designed. A combination of disciplines yields the necessary data and tools to develop the optimum solution to replicating the anatomical rotational centres of the healthy wrist whilst at the same time satisfying the requirements of stability, effective implantation and wear characteristics. The key tool in drawing conclusions from the articulating surfaces selected in the design proposals is Finite Element Analysis. The use of an implicit, nonlinear static contact analysis model developed and solved using MSC MARC software was used to examine the behaviour of the implant models' Ultra High Molecular Weight Polyethylene component over a large range of motion and under a compressive load. The anticipated displacements and loads caused by performing daily living tasks fall comfortably within the range of motion specified for the analyses. This, coupled with repeated analysis of the model for small geometrical alterations enabled an optimum model to be selected. The information from these analyses was used directly in making decisions on the design of the prosthesis in conjunction with cadaveric trials. The initial cadaveric trial validated the primary geometrical features of the design regarding centres of rotation and stem location and identified clear areas for design refinement. The second trial fully validated the design decisions taken. Following the analytical work on the new design, and the completion of the cadaveric trials, a comparative analysis was carried out with competing designs to further validate the design. The results of this show that the new design is competitive in terms of demonstrating low stress concentrations over a practical range of motion, and that it also has excellent stability. Beyond these features, the new implant design also facilitates secure implantation, in conjunction with a range of sizes likely to accommodate the greatest range of patient anatomical variation.
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Lam, Kwok-wai. "Design and development of a new prosthetic device for proximal interphalangeal joint replacement." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B3889161X.
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Wang, Xiaoping, and 王曉平. "Generalized artificial finger joint design process employing reverse engineering techniques." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B2953527X.
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Schumacher, Brian. "An analysis of the femoral head/stem taper lock for orthopaedic prostheses." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/18927.
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IWATA, HISASHI, SEIKI IWASADA, KOUICHI KAWAMOTO, TOSHIKI IWASE, and YUKIHARU HASEGAWA. "MACROMOTION OF THE FEMORAL COMPONENT IN ARTIFICIAL HIP JOINT." Nagoya University School of Medicine, 1996. http://hdl.handle.net/2237/16103.
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Ramjee, Shatish. "Numerical analysis of lubrication in an artificial hip joint." Pretoria : [s.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-09152008-133304/.
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Arinez, Jorge Francisco. "Reduction of friction in polymeric composites for artificial joint prostheses." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/37044.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1995.Includes bibliographical references (leaves 128-135).
Ultra-high molecular weight polyethylene has been used as a bearing material in artificial joints for more than thirty years. Despite this long period of use and the success which artificial implants have had, material failure and ultimately prosthetic failure still occurs as the result of mechanical wear of the bearing surface. Several wear mechanisms have been proposed as the main causes for failure; however, none is as dominant as the delamination wear of artificial knee prostheses. Delamination wear occurs mainly as the result of cyclic plastic deformation of the surface and subsurface layer which causes cracks to nucleate and propagate in the subsurface leading to the production of wear sheets. This research seeks a new alternative material to prevent the occurrence of delamination wear by the use of a fiber reinforced composite. The use of a fiber-reinforced composite having fibers oriented normal to the sliding direction is known to offer reduced plastic deformation resulting from the high stiffness of fibers and furthermore can inhibit crack nucleation and more importantly propagation since fibers are able to arrest the growth of cracks normal to the fiber axis. This new material has been called homo composite based on the fact that fiber and matrix are made from the same material, namely UHMWPE. This material has shown promising results in friction tests yielding coefficients of 0.05 in bovine lubricated sliding conditions. The optimization of material processing parameters with respect to friction and wear of the homocomposite is also presented.
by Jorge Francisco Arinez.
S.M.
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Opperman, Tertius. "Tribological evaluation of joint fluid and the development of a synthetic lubricant for use in hip joint simulators." Pretoria : [s.n.], 2004. http://upetd.up.ac.za/thesis/available/etd-07282005-083909.
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Szklar, O. (Oleh). "Development of an unconstrained two-force dynamic simulator for the human knee joint." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63376.
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Ma, Helen. "Quality of life changes after knee-joint replacement." Click to view the E-thesis via HKUTO, 2002. http://sunzi.lib.hku.hk/hkuto/record/B31971192.
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Peña, Vanessa 1982. "Design of a biomimetic pectoral fin joint in an artificial fish." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32775.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references (leaf 41).
A biomimetic design of the muscle joint in a pectoral fish fin was produced based on comparisons with four design models. All four design models consisted of a mechanical joint connection and incorporated the functional operation of the pectoral fish fin rays when affected by specific actuators, such as induced contractions of conducting polymer strands. Design constraints of the joint were determined by the fundamental kinematic elements of motion determined in the Bioinstrumentation Laboratory. A mechanical pin-joint provided correct simulation of movements specialized for this phase of the development of an artificial fish fin. A compression spring with a spring coefficient of K=0.45 was used as a mechanical means to imitate the biological energy conservations produced by each stroke of the pectoral fin. The joint was designed to adhere to displacements by conducting polymer actuators that induced a 2.0% maximal strain on the fish fin ray.
by Vanessa Pena.
S.B.
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Lam, Kwok-wai, and 林國偉. "Design and development of a new prosthetic device for proximal interphalangeal joint replacement." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B3889161X.
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Gale, Lorne Raymond. "Biotribological assessment for artificial synovial joints : the role of boundary lubrication." Queensland University of Technology, 2007. http://eprints.qut.edu.au/29159/.
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Biotribology, the study of lubrication, wear and friction within the body, has become a topic of high importance in recent times as we continue to encounter debilitating diseases and trauma that destroy function of the joints. A highly successful surgical procedure to replace the joint with an artificial equivalent alleviates dysfunction and pain. However, the wear of the bearing surfaces in prosthetic joints is a significant clinical problem and more patients are surviving longer than the life expectancy of the joint replacement. Revision surgery is associated with increased morbidity and mortality and has a far less successful outcome than primary joint replacement. As such, it is essential to ensure that everything possible is done to limit the rate of revision surgery. Past experience indicates that the survival rate of the implant will be influenced by many parameters, of primary importance, the material properties of the implant, the composition of the synovial fluid and the method of lubrication. In prosthetic joints, effective boundary lubrication is known to take place. The interaction of the boundary lubricant and the bearing material is of utmost importance. The identity of the vital active ingredient within synovial fluid (SF) to which we owe the near frictionless performance of our articulating joints has been the quest of researchers for many years. Once identified, tribo tests can determine what materials and more importantly what surfaces this fraction of SF can function most optimally with. Surface-Active Phospholipids (SAPL) have been implicated as the body’s natural load bearing lubricant. Studies in this thesis are the first to fully characterise the adsorbed SAPL detected on the surface of retrieved prostheses and the first to verify the presence of SAPL on knee prostheses. Rinsings from the bearing surfaces of both hip and knee prostheses removed from revision operations were analysed using High Performance Liquid Chromatography (HPLC) to determine the presence and profile of SAPL. Several common prosthetic materials along with a novel biomaterial were investigated to determine their tribological interaction with various SAPLs. A pin-on-flat tribometer was used to make comparative friction measurements between the various tribo-pairs. A novel material, Pyrolytic Carbon (PyC) was screened as a potential candidate as a load bearing prosthetic material. Friction measurements were also performed on explanted prostheses. SAPL was detected on all retrieved implant bearing surfaces. As a result of the study eight different species of phosphatidylcholines were identified. The relative concentrations of each species were also determined indicating that the unsaturated species are dominant. Initial tribo tests employed a saturated phosphatidylcholine (SPC) and the subsequent tests adopted the addition of the newly identified major constituents of SAPL, unsaturated phosphatidylcholine (USPC), as the test lubricant. All tribo tests showed a dramatic reduction in friction when synthetic SAPL was used as the lubricant under boundary lubrication conditions. Some tribopairs showed more of an affinity to SAPL than others. PyC performed superior to the other prosthetic materials. Friction measurements with explanted prostheses verified the presence and performance of SAPL. SAPL, in particular phosphatidylcholine, plays an essential role in the lubrication of prosthetic joints. Of particular interest was the ability of SAPLs to reduce friction and ultimately wear of the bearing materials. The identification and knowledge of the lubricating constituents of SF is invaluable for not only the future development of artificial joints but also in developing effective cures for several disease processes where lubrication may play a role. The tribological interaction of the various tribo-pairs and SAPL is extremely favourable in the context of reducing friction at the bearing interface. PyC is highly recommended as a future candidate material for use in load bearing prosthetic joints considering its impressive tribological performance.
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Walter, William Lindsay School of Biomechanics UNSW. "Severe biomechanical conditions in total hip replacement." Awarded by:University of New South Wales. School of Biomechanics, 2006. http://handle.unsw.edu.au/1959.4/25968.
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Hip simulators are designed to reproduce the forces and motion patterns of normal walking. In vivo demands on total hip replacements, however, are varied and often more severe than normal walking conditions. It is these severe conditions that often lead to implant failure. This is clinically based research aimed at understanding some of the more severe conditions in hips and the effect that these have on the performance of the total hip replacement. The polyethylene liner can act as a pump in an acetabular component, forcing fluid and wear particles through the holes to the retroacetabular bone causing osteolysis. Ten patients were studied at revision surgery. Pressures were measured in retroacetabular osteolytic lesions while performing pumping manouvers with the hip. Two laboratory experiments were then designed to study pumping mechanisms in vitro. In patients with contained osteolytic lesions, fluid pressure fluctuations could be measured in the lesion in association with the pumping action. Patients with uncontained osteolytic lesions showed no such pressure fluctuations. In the laboratory we identified 3 distinct mechanisms whereby fluid can be pumped from the hip joint to the retroacetabular bone. These pumping effects could be mitigated by improved implant design. Loading of the femoral head against the edge of the acetabular component produces dramatically increased contact pressures particularly in hard-on-hard bearings. In an analysis of 16 retrieved ceramic-on-ceramic bearings we were able to characterise the mechanism of edge loading based on the pattern of edge loading wear on the bearing surface. Finally in a radiographic study of patients with squeaking ceramic-on-ceramic hips. Squeaking was found to be associated with acetabular component malposition. It seems that edge loading or impingement may be an associated factor in these cases.
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Tanaka, Kenji. "Application of Ce-TZP/Al2O3 nanocomposite to bearing surfaces of artificial joint prostheses." Kyoto University, 2003. http://hdl.handle.net/2433/148683.
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Wu, Jun Jie. "The integrity of moulded ultra-high molecular weight polyethylene for joint replacement prostheses." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325574.
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Burgess, Ian C. "Tribological and mechanical properties of compliant bearings for total joint replacements." Thesis, Durham University, 1997. http://etheses.dur.ac.uk/4720/.
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The tribology of a wide range of designs of compliant layer acetabular cups has been evaluated using a simulator. The simulator applied a dynamic load of 2 kN and a sinusoidal motion of ±25 , and measured the frictional resistance directly. In general the friction developed in these joints was extremely low, with friction factors typically below 0.01. When the experimental results were compared with theoretical estimates of friction a poor correlation was found. Further analysis suggested that the design of compliant layer acetabular cups was insensitive to many of the parameters suggested by theory. In particular, the radial clearance and femoral head size were not found to be critical. In addition, methods were proposed and their effectiveness demonstrated to measure friction at the on-set of motion (start-up friction), and the steady state friction in realistic compliant layer knees. The adhesion between compliant layers and a rigid backing have been investigated, with the aim of developing a good bond between them. The peel test was used to demonstrate an excellent diffusion bond between a low modulus medical grade polyurethane, and a similar high modulus grade of polyurethane. The processing conditions used to manufacture the test piece were optimised to maximise the bond strength. The bond was found to be stable after immersion in Ringers solution at 37 C for 52 weeks, and after acetabular cups were subjected to 14 million 4 kN loading cycles. A six station knee wear simulator was designed and commissioned. The simulator applied a dynamic load and an anterior-posterior translation individually to each station, as well as a flexion-extension motion common to all six stations. The simulator was computer controlled entirely using servo hydraulics. Wear rates were obtained from tests lasting up to 8 million cycles conducted on UHMWPE joints.
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Canlas, Michael T. Jang Wooseung. "A practical approach to the cyclic multi-bin joint replenishment problem." Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/6573.
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The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on October 21, 2009). Thesis advisor: Dr. W. Jang. Includes bibliographical references.
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Migliore, Shane A. "Role of passive joint stiffness and active knee control in robotic leg swinging applications to dynamic walking /." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22684.
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Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2008.Committee Chair: DeWeerth, Stephen; Committee Member: Butera, Robert; Committee Member: Howard, Ayanna; Committee Member: Kemp, Charlie; Committee Member: Ting, Lena.
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El-Gohary, Mahmoud Ahmed. "Joint Angle Tracking with Inertial Sensors." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/661.
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The need to characterize normal and pathological human movement has consistently driven researchers to develop new tracking devices and to improve movement analysis systems. Movement has traditionally been captured by either optical, magnetic, mechanical, structured light, or acoustic systems. All of these systems have inherent limitations. Optical systems are costly, require fixed cameras in a controlled environment, and suffer from problems of occlusion. Similarly, acoustic and structured light systems suffer from the occlusion problem. Magnetic and radio frequency systems suffer from electromagnetic disturbances, noise and multipath problems. Mechanical systems have physical constraints that limit the natural body movement. Recently, the availability of low-cost wearable inertial sensors containing accelerometers, gyroscopes, and magnetometers has provided an alternative means to overcome the limitations of other motion capture systems. Inertial sensors can be used to track human movement in and outside of a laboratory, cannot be occluded, and are low cost. To calculate changes in orientation, researchers often integrate the angular velocity. However, a relatively small error or drift in the measured angular velocity leads to large integration errors. This restricts the time of accurate measurement and tracking to a few seconds. To compensate that drift, complementary data from accelerometers and magnetometers are normally integrated in tracking systems that utilize the Kalman filter (KF) or the extended Kalman filter (EKF) to fuse the nonlinear inertial data. Orientation estimates are only accurate for brief moments when the body is not moving and acceleration is only due to gravity. Moreover, success of using magnetometers to compensate drift about the vertical axis is limited by magnetic field disturbance. We combine kinematic models designed for control of robotic arms with state space methods to estimate angles of the human shoulder and elbow using two wireless wearable inertial measurement units. The same method can be used to track movement of other joints using a minimal sensor configuration with one sensor on each segment. Each limb is modeled as one kinematic chain. Velocity and acceleration are recursively tracked and propagated from one limb segment to another using Newton-Euler equations implemented in state space form. To mitigate the effect of sensor drift on the tracking accuracy, our system incorporates natural physical constraints on the range of motion for each joint, models gyroscope and accelerometer random drift, and uses zero-velocity updates. The combined effect of imposing physical constraints on state estimates and modeling the sensor random drift results in superior joint angles estimates. The tracker utilizes the unscented Kalman filter (UKF) which is an improvement to the EKF. This removes the need for linearization of the system equations which introduces tracking errors. We validate the performance of the inertial tracking system over long durations of slow, normal, and fast movements. Joint angles obtained from our inertial tracker are compared to those obtained from an optical tracking system and a high-precision industrial robot arm. Results show an excellent agreement between joint angles estimated by the inertial tracker and those obtained from the two reference systems.
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馬海倫 and Helen Ma. "Quality of life changes after knee-joint replacement." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31971192.
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Alfaro, Adrian Jesus. "Early migration and loosening of cemented femoral total hip replacement : an RSA study." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301790.
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Guo, Jiajie. "Effects of joint constraints on deformation of multi-body compliant mechanisms." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/45971.
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Motivated by the interests to understand bio-structure deformation and exploit their advantages to create bio-inspired systems for engineering applications, a curvature-based model for analyzing compliant mechanisms capable of large deformation in a three dimensional space has been developed. Unlike methods (such as finite element) that formulate problems based on displacements and/or rotational angles, superposition holds for curvatures in the case of finite rotation but not for rotational angles; thus the curvature-based formulation presents an advantage in presenting nonlinear geometries. Along with a generalized constraint that relaxes traditional boundary constraints (such as fixed, pinned or sliding constraint) on compliant mechanisms, the method of deriving the compliant members in the same global referenced frame is presented. The attractive features of the method, which greatly simplifies the models and improves the computation efficiency of multi-body system deformation where compliant beams play an important role, have been experimentally validated. To demonstrate the applicability of this proposed method to a broad spectrum of applications, three practical examples are given; the first example verifies the generalized constraint by analyzing the multi-axis rotation motion within a natural human knee joint and investigates the human-exoskeleton interactions through dynamic analysis. The second example studies a deformable bio-structure by incorporating the generalized joint constraint into the curvature-based model for automated poultry meat processing. The last example designs a bio-inspired robot with a compliant mechanism to serve as a flexonic mobile node for ferromagnetic structure health monitoring. The analytical models have been employed (with experimental validation) to investigate the effects of different joint constraints on the mechanism deformations. It is expected that the proposed method will find a broad range of applications involving compliant mechanisms.
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Wang, Allan W. "Femoral bone remodelling following cemented hip arthroplasty in a sheep model /." Title page, contents and abstract only, 1998. http://web4.library.adelaide.edu.au/theses/09PH/09phw2462.pdf.
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Ioppolo, James. "Kinematic joint measurements using radiostereometric analysis (RSA) and single-plane x-ray video fluoroscopy." University of Western Australia. Orthopaedics Unit, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0090.
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[Truncated abstract] Measuring the kinematics of joints and implants following orthopaedic surgery is important since joint motion directly influences the functional outcome of the patient and the longevity of the implant. Radiostereometric Analysis (RSA) has been used to assess the motion over time of various joints and implant designs following corrective orthopaedic and joint replacement surgery for more than 20 years in more than 10,000 patients around the world. While the use of RSA reduces the risk of implanting potentially inferior prostheses on a large scale, conventional methodological procedures are based on the acquisition of static, stereographic x-ray images that are not suitable for measuring skeletal kinematics in a dynamic manner. The purpose of this thesis was to design, validate and test a novel technique for dynamically assessing the skeletal motion of human subjects using RSA and single-plane digital x-ray video fluoroscopy. The validation procedure utilised two in-vitro phantom models of human joints capable of simulating normal kinematic motion. These phantom models were supplied with realistic spatial displacement protocols derived from cadaveric specimens. The spatial positions of a series of tantalum markers that were implanted in each skeletal segment were measured using RSA. Skeletal motion was determined in x-ray fluoroscopy images by minimising the difference between the markers measured and projected in the single image plane. Accuracy was determined in terms of bias and precision by analysing the deviation between the applied displacement protocol and measured pose estimates. ... The RSA and low dose single-plane fluoroscopy technique developed, validated and tested in this thesis is capable of dynamically measuring the kinematics of any joint in the human body, following the implantation of small metallic markers in the surrounding bone during corrective orthopaedic surgery. The kinematics of joints with replacement prostheses, such as the total knee replacement (TKR), can be analysed in addition to the kinematics of joints without replacement prostheses, such as the sacroiliac joint. The technique may be used in the future on groups of human subjects enrolled in controlled trials that are designed to analyse the kinematics of the shoulder, spine, hip, knee, patella or ankle joints for the purposes of quantitatively comparing the kinematics of different prosthesis designs and various corrective orthopaedic procedures.
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Wigfield, Crispin Campbell. "Comparative studies of an artificial cervical joint & anterior interbody fusion for the treatment of symptomatic cervical spondylosis." Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274407.
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Wachtmeister, Henrik. "Jules Verne or Joint Venture? Investigation of a Novel Concept for Deep Geothermal Energy Extraction." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-199648.
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Geothermal energy is an energy source with potential to supply mankind with both heat and electricity in nearly unlimited amounts. Despite this potential geothermal energy is not often considered in the general energy debate, often due to the perception that it is a margin energy source bound to a few locations with favorable geological conditions. Today, new technology and system concepts are under development with the potential to extract geothermal energy almost anywhere at commercial rates. The goal of these new technologies is the same, to harness the heat stored in the crystalline bedrock available all over the world at sufficient depth. To achieve this goal two major problems need to be solved: (1) access to the depths where the heat resource is located and (2) creation of heat transferring surfaces and fluid circulation paths for energy extraction. In this thesis a novel concept and method for both access and extraction of geothermal energy is investigated. The concept investigated is based on the earlier suggested idea of using a main access shaft instead of conventional surface drilling to access the geothermal resource, and the idea of using mechanically constructed 'artificial fractures' instead of the commonly used hydraulic fracturing process for creation of heat extraction systems. In this thesis a specific method for construction of such suggested mechanically constructed heat transfer surfaces is investigated. The method investigated is the use of diamond wire cutting technology, commonly used in stone quarries. To examine the concept two heat transfer models were created to represent the energy extraction system: an analytical model based on previous research and a numerical model developed in a finite element analysis software. The models were used to assess the energy production potential of the extraction system. To assess the construction cost two cost models were developed to represent the mechanical construction method. By comparison of the energy production potential results from the heat transfer models with the cost results from the construction models a basic assessment of the heat extraction system was made. The calculations presented in this thesis indicate that basic conditions for economic feasibility could exist for the investigated heat extraction system.
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Lo, Ming-yan, and 盧銘恩. "Evidence based guidelines of using music therapy in minimizing postoperative pain and promoting rehabilitation for patients aftertotal joint replacement." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B48335794.
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Introduction: Patients having total joint replacement often experience moderate to severe pain postoperatively. Postoperative pain can reduce patients’ mobility, affecting their motivation to participate in any rehabilitation activities. For patients having total join replacement, rehabilitation plays an important role in promoting their early recovery. Therefore, it is crucial for healthcare professionals to develop and evaluate intervention that can better control patients’ post-operative pain. In the clinical setting that I am working, pharmacological method is the major means of postoperative pain management. However, many Chinese patients are reluctant to use analgesic to control their post-operative pain because of the side effects and adverse reactions of the drugs. In this dissertation, music therapy, a non-pharmacological method that can be managed by nurses, is adopted for postoperative pain control. It is used to promote rehabilitation for patients who have undergone total joint replacement.
Objectives: The objectives of this study are (1) to review the published research articles that investigated the effects of music therapy in reducing the post-operative pain and promoting rehabilitation for patients having total joint replacement; and (2) to establish an evidence-based guideline for the use of music therapy by nurses to control postoperative pain and to facilitate rehabilitation for patients having total joint replacement.
Methods: A comprehensive literature search on four electronic databases including CHINAL, Medline (OvidSP), PubMed and the British Nursing Index were conducted. A total of eight RCTs and two non-randomized controlled trials were eventually identified.
Results: All the reviewed studies showed that music therapy has a statistically significant effect on reducing postoperative pain. Sedative or relaxation music (music which has no lyrics, sustained melodic quality; rate of 60-80 beats per minutes; absence of strong rhythms or percussion) are recommended in the guideline. The target setting is a total joint replacement centre in a public hospital of Hong Kong. The target clients are adult patients (aged 19 or above) that are referred by the orthopedic out-patient department and are pending for their total knee/ hip replacement in the center. The transferability and feasibility of the literature are high. The guideline is developed based on the evidence in reviewed literature. A pilot testing plan is established to detect the potential barrier and friction of the guideline before the implementation. After that, an evaluation plan for patients, healthcare providers and system outcomes was also proposed.
Conclusion: An evidence based guideline is developed for the total joint replacement center. It is anticipated that, with the use of this guideline by nurses, it will not only facilitate better rehabilitation for patients having total joint replacement, but also enhances nurses’ autonomy in their nursing practice.published_or_final_version
Nursing Studies
Master
Master of Nursing
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Deena, Salil Prashant. "Visual speech synthesis by learning joint probabilistic models of audio and video." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/visual-speech-synthesis-by-learning-joint-probabilistic-models-of-audio-and-video(bdd1a78b-4957-469e-8be4-34e83e676c79).html.
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Visual speech synthesis deals with synthesising facial animation from an audio representation of speech. In the last decade or so, data-driven approaches have gained prominence with the development of Machine Learning techniques that can learn an audio-visual mapping. Many of these Machine Learning approaches learn a generative model of speech production using the framework of probabilistic graphical models, through which efficient inference algorithms can be developed for synthesis. In this work, the audio and visual parameters are assumed to be generated from an underlying latent space that captures the shared information between the two modalities. These latent points evolve through time according to a dynamical mapping and there are mappings from the latent points to the audio and visual spaces respectively. The mappings are modelled using Gaussian processes, which are non-parametric models that can represent a distribution over non-linear functions. The result is a non-linear state-space model. It turns out that the state-space model is not a very accurate generative model of speech production because it assumes a single dynamical model, whereas it is well known that speech involves multiple dynamics (for e.g. different syllables) that are generally non-linear. In order to cater for this, the state-space model can be augmented with switching states to represent the multiple dynamics, thus giving a switching state-space model. A key problem is how to infer the switching states so as to model the multiple non-linear dynamics of speech, which we address by learning a variable-order Markov model on a discrete representation of audio speech. Various synthesis methods for predicting visual from audio speech are proposed for both the state-space and switching state-space models. Quantitative evaluation, involving the use of error and correlation metrics between ground truth and synthetic features, is used to evaluate our proposed method in comparison to other probabilistic models previously applied to the problem. Furthermore, qualitative evaluation with human participants has been conducted to evaluate the realism, perceptual characteristics and intelligibility of the synthesised animations. The results are encouraging and demonstrate that by having a joint probabilistic model of audio and visual speech that caters for the non-linearities in audio-visual mapping, realistic visual speech can be synthesised from audio speech.
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Lora-Tamayo, Morillo-Velarde Jaime. "Antimicrobial therapy in prosthetic joint infection: an approach to the most relevant and current clinical problems." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/145440.
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Prosthetic joint infections (PJI) are defined as difficult-to-treat, mainly due to the presence of bacterial biofilm and other bacterial adaptive forms. An aggressive treatment including surgery and long antimicrobial therapy must be provided, the economical burden of this complication being very important. Thus, PJI constitute a first-order health care problem, and it is expected that the number of infected devices will increase in the future.
Our knowledge on the efficacy of antimicrobial therapy in the setting of PJI mainly derives from experimental models. Clinical studies are very difficult to perform, due to the specialized nature of this infection, the need for a long follow up and the difficulties for collecting patients. Previous case series usually present with small and quite heterogeneous samples, so the conclusions drawn from these studies are not always very reliable.
The clinical studies presented in this thesis have been performed in the setting of the multidisciplinary Bone and Joint Unit of the Hospital Universitario de Bellvitge, which is integrated in the Spanish Network for the Research in Infectious Diseases (REIPI), thus allowing an appropriate clinical approach to PJI. These studies try to answer clinical questions on PJI regarding the efficacy of the antimicrobial treatment. The specific aims have been classified according to the specific surgical approach with which the patients were managed.
A. Antimicrobial therapy in PJI managed with implant retention
A.1. Infection by staphylococci
Aim 1 – To measure the impact of rifampin in the outcome of a large cohort of PJI by S. aureus
Multicenter observational retrospective study of 345 cases of PJI by S. aureus managed with implant retention, including 81 cases by methicillin-resistant S. aureus (MRSA). Overall failure was 45%. Treatment with rifampin was an independent predictor of a favourable outcome, the specific type of staphylococci having a similar
overall prognosis.
Aim 2 – To assess the efficacy of a short schedule of levofloxacin plus rifampin in staphylococcal PJI
Open, comparative, multicenter clinical trial where patients with acute staphylococcal PJI undergoing debridement plus implant retention were randomized to receive either a short treatment of 8 weeks of levofloxacin plus rifampin, or a standard long treatment of 3 months (hip prosthesis) or 6 months (knee prosthesis). Overall success rate was 93% and 65% in the per-protocol and intention-to-treat analysis, respectively, with no significant differences between the two-arms.
Aim 3 – To evaluate daptomycin plus rifampin for fluoroquinolone resistant staphylococcal PJI
Retrospective observational multicenter study of 20 patients with acute staphylococcal PJI undergoing debridement plus implant retention and treated with daptomycin (10 mg/kg/d) plus rifampin for 6 weeks. Two (10%) patients were withdrawn due to toxicity. In the other 18 patients, clinical and microbiological cure were observed in 50% and 73% of cases, respectively. There were no differences as compared with a historical cohort of cases treated with alternative rifampin-based combinations, except for a lesser rate of failure while patients were still under treatment with daptomycin plus rifampin.
A.2. Infection by Gram-negative bacilli
Aim 4 – To assess the impact of fluoroquinolones in the outcome of a large cohort of PJI by Gram-negative bacilli
Observational retrospective multicenter study of 172 cases of PJI by Gram-negative bacilli undergoing debridement plus implant retention. Overall success was 68% after a median follow-up of 25 months. Treatment with ciprofloxacin was an independent predictor of success (79% vs 41%).
A.3. Infection in the elderly
Aim 5 – Comparative evaluation of the antibiotic efficacy in patients carrying total hip prosthesis or hip hemiarthroplasties
Observational retrospective study of 210 patients with hip-PJI, comparing patients carrying either hip-hemiarthroplasties (HHA) or total hip arthroplasties (THA). Patients with HHA were older, had more underlying conditions, and infection by Gram-negative bacilli was more frequent. Overall failure of 123 patients undergoing debridement plus implant retention was 63% after a median follow up of 347 days. While the specific device (HHA or THA) was not associated with a higher likelihood of failure, crude and related mortality were significantly higher in the HHA group.
B. Antimicrobial therapy in PJI managed with implant removal
Aim 6 – To evaluate linezolid in PJI by Gram-positive microorganisms managed with a two-step exchange procedure.
Prospective non-comparative multicenter clinical trial involving 25 patients treated with linezolid for 6 weeks after prosthesis removal. Three (12%) were withdrawn due to toxicity. Among the other 22 (88%) patients, 20 (91%) were considered to be clinically cured. Among them, cultures taken at surgical site at the time of reimplantation were positive in 1 (5%) patient. Thus, clinical and microbiological cure among these 22 patients was 86%.
C. Antimicrobial activity on biofilms of multi-resistant Gram-negative bacilli
Aim 7 – To study the activity of colistin against multi-resistant P. aeruginosa biofilm in an in vitro experimental model.
Based on the CDC Biofilm reactor, the in vitro experiments were conducted during 72 hours, after an initial conditioning phase of 28 hours. Three different strains of P. aeruginosa were used: the referral strain PAO-1 (colistin- and carbapenem-susceptible) and two clinical strains (HUB-1 and HUB-2, both colistin-susceptible and carbapenemresistant).
Two clinically relevant concentrations of colistin were used at constant infusion (1.25 mg/L and 3.50 mg/L), as well as doripenem (as bolus every 8 hours, Cmax 25 mg/L). Monotherapies of colistin produced initial killing followed by regrowth and emergence of colistin-resistance. The combination with doripenem gave place to a more sustained killing and lesser rate of regrowth. Additivity and synergy were observed at different times with the combination therapy. Emergence of colistin resistance was avoided, too. These effects were also observed in the two carbapenem-resistant clinical strains.Las infecciones asociadas a prótesis articulares se han definido como de difícil tratamiento, fundamentalmente por la presencia de biopelículas bacterianas. El abordaje es complejo, pues incluye múltiples cirugías y prolongados tratamientos antibióticos. Por ello y porque se espera un incremento en el número futuro de infecciones, esta patología supone un importante problema para el sistema nacional de salud. Nuestro conocimiento sobre la eficacia del tratamiento antibiótico en estas infecciones procede fundamentalmente de modelos experimentales. La realización de estudios clínicos es complicada: la mayoría de los realizados incluyen series pequeñas y heterogéneas, y sus resultados son a menudo difíciles de interpretar. Nuestros estudios se han desarrollado en el marco de la multidisciplinar Unidad de Infección Osteoarticular del Hospital Universitario de Bellvitge, integrada en la Red Española para la Investigación en Patología Infecciosa (REIPI), lo cual constituye un marco de aproximación adecuado al problema clínico. Los estudios incluidos en la presente tesis doctoral intentan responder a distintos problemas clínicos relacionados con la eficacia del tratamiento antibiótico en la infección asociada a prótesis articular. Los objetivos específicos se han dividido de acuerdo con el abordaje quirúrgico empleado. A. Tratamiento antibiótico en la infección de prótesis articular manejada con retención del implante. A.1. Infección estafilocócica Objetivo 1 – Medir el impacto de rifampicina en el pronóstico de una gran cohorte de pacientes con infección protésica por S. aureus, incluyendo MRSA. Objetivo 2 – Evaluar la eficacia de un tratamiento corto con levofloxacino y rifampicina en la infección estafilocócica de prótesis articular. Objetivo 3 – Determinar el papel de la combinación de daptomicina más rifampicina para la infección de prótesis articular por estafilococos resistentes a fluoroquinolonas. A.2. Infección por bacilos Gram-negativos Objetivo 4 – Medir el impacto de las fluoroquinolonas en el pronóstico de una gran cohorte de pacientes con infección protésica por bacilos Gramnegativos. A.3. Infección de prótesis articular en ancianos Objetivo 5 – Análisis comparativo de la eficacia antibiótica en pacientes portadores de hemiartroplastia de cadera frente a pacientes con prótesis total de cadera. B. Tratamiento antibiótico en la infección de prótesis articular manejada con retirada del implante. Objetivo 6 – Evaluar el papel de linezolid en la infección de prótesis articular por microorganismos Gram-positivos manejada con un recambio en 2 tiempos. C. Actividad antimicrobiana en biopelículas de microorganismos Gram negativos multirresistentes. Objetivo 7 – Evaluación de la actividad de colistina frente a biofilm de P. aeruginosa multirresistente en un modelo experimental in vitro.
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Seger, Johanna. "Coagency of humans and artificial intelligence in sea rescue environments : A closer look at where artificial intelligence can help humans maintain and improve situational awareness in search and rescue operations." Thesis, Linköpings universitet, Institutionen för datavetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-157439.
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This paper aims to answer the question of how artificial intelligence could help humans maintain and/or improve situational awareness in search and rescue operations at sea, as well as where in such processes artificial intelligence could be incorporated to most efficiently compensate for human vulnerabilities and support human strengths. In order to answer this, a joint cognitive system perspective has been adopted whilst joining in search and rescue practice operations. These operations have been observed and persons participating in them have been interviewed, in order to gather insights about the process and the persons conducting it. The results from these insights coupled with experience with artificial intelligence and automation, show that artificial intelligence could help improve and/or maintain situational awareness by adopting functions which take up unnecessary time from man. According to the joint cognitive system view, these functions should never be solely performed by artificial intelligence however, but in coagency with man; allocated functions should overlap between man and machine. Suggestions have been given regarding which functions in particular an artificial intelligent agent could perform in terms of search and rescue and where these functions occur in the process. None of these suggestions are without man involvement, as they should not be. To summarise, these suggestions include; a UAV equipped with an infrared camera to search large areas quickly, a decision support system equipped with image recognition to analyse images gathered from the UAV, as well as a communication tool which allows for shared search patterns and hotspots between search and rescue units.WARA-PS
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Van, den Heever David Jacobus. "Development of patient-specific knee joint prostheses for unicompartmental knee replacement (UKR)." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/17942.
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Thesis (PhD)--Stellenbosch University, 2011.ENGLISH ABSTRACT: The knee is the largest, most complicated and incongruent joint in the human body. It sustains very high forces and is susceptible to injury and disease. Osteoarthritis is a common disease prevalent among the elderly and causes softening or degradation of the cartilage and subcondral bone in the joint, which leads to a loss of function and pain. This problem can be alleviated through a surgical intervention commonly termed a “knee replacement”. The aim of a knee replacement procedure is to relieve pain and restore normal function. Ideally, the knee replacement prosthesis should have an articulating geometry similar to that of the patient’s healthy knee, and must allow for normal motion. Unfortunately, this is often problematic since knee prostheses are supplied in standard sizes from a variety of manufacturers and each one has a slightly different design. Furthermore, commercial prostheses are not always able to restore the complex geometry of an individual patient’s original articulating surfaces. This dissertation shows that there is a significant variation between knee geometries, regardless of gender and race. This research aims to resolve the problem in two parts: Firstly by presenting a method for preoperatively selecting the optimal knee prosthesis type and size for a specific patient, and secondly by presenting a design procedure for designing and manufacturing patient-specific unicompartmental knee replacements. The design procedure uses mathematical modelling and an artificial neural network to estimate the original and healthy articulating surfaces of a patient’s knee. The models are combined with medical images from the patient to create a knee prosthesis that is patient-specific. These patient-specific implants are then compared to conventional implants with respect to contact stresses and kinematics. The dissertation concludes that patient-specific implants can have characteristics that are comparable to or better than conventional prostheses. The unique design methodology presented in this dissertation introduces a significant advancement in knee replacement technology, with the potential to dramatically improve clinical outcomes of knee replacement surgery.
AFRIKAANSE OPSOMMING: Die knie is die grootste, mees komplekse en mees ongelyksoortige gewrig in die liggaam. Osteoarthritis is ’n siekte wat algemeen by bejaardes voorkom en die versagting of agteruitgang van die kraakbeen en subchondrale bene in die gewrig tot gevolg het, wat tot ’n verlies van funksionering en pyn lei. Hierdie probleem kan verlig word deur ’n chirurgiese ingryping wat algemeen as ’n “knievervanging” bekend staan. Die doel van ’n knievervangingsprosedure is om pyn te verlig en normale funksionering te herstel. Ideaal gesproke behoort die knievervangingsprostese ’n gewrigsgeometrie te hê wat soortgelyk aan die pasiënt se gesonde knie is, en normale beweging moontlik maak. Ongelukkig is dit dikwels problematies aangesien knieprosteses in standaardgroottes en deur ’n verskeidenheid vervaardigers verskaf word, wat elkeen se ontwerp effens anders maak. Verder kan kommersiële prosteses nie altyd die komplekse geometrie van ’n individuele pasiënt se oorspronklike gewrigsoppervlakke vervang nie. Hierdie proefskrif wys dat daar ’n betekenisvolle variasie tussen knieafmetings is, afgesien van geslag en ras. Hierdie navorsing is daarop gemik om die problem op tweërlei wyse te benader: Eerstens deur ’n metode aan te bied om die optimal knieprostesetipe en -grootte vir ’n spesifieke pasiënt voor die operasie uit te soek, en tweedens om ’n ontwerpprosedure aan te bied vir die ontwerp en vervaardiging van pasiëntspesifieke unikompartementele knievervangings. Die ontwerpprosedure gebruik wiskundige modellering en ’n kunsmatige neurale netwerk om die oorspronklike en gesonde gewrigsoppervlakke van ’n pasiënt se knie te bepaal. Die modelle word met mediese beelde van die pasiënt gekombineer om ’n knieprostese te skep wat pasiëntspesifiek is. Hierdie pasiëntspesifieke inplantings word dan met konvensionele inplantings vergelyk wat kontakstres en kinematika betref. Daar word tot die slotsom gekom dat die pasiëntspesifieke inplantings oor eienskappe kan beskik wat vergelykbaar is met of selfs beter is as dié van konvensionele prosteses. Die unieke ontwerpmetodologie wat in hierdie proefskrif aangebied word, stel beduidende vordering in knievervangingstegnologie bekend, met die potensiaal om die kliniese uitkomste van knievervangingsoperasies dramaties te verbeter.
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Siores, E. "Development of a real-time ultrasonic sensing system for automated and robotic welding." Thesis, Brunel University, 1988. http://bura.brunel.ac.uk/handle/2438/5550.
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The implementation of robotic technology into welding processes is made difficult by the inherent process variables of part location, fit up, orientation and repeatability. Considering these aspects, to ensure weld reproducibility consistency and quality, advanced adaptive control techniques are essential. These involve not only the development of adequate sensors for seam tracking and joint recognition but also developments of overall machines with a level of artificial intelligence sufficient for automated welding. The development of such a prototype system which utilizes a manipulator arm, ultrasonic sensors and a transistorised welding power source is outlined. This system incorporates three essential aspects. It locates and tracks the welding seam ensuring correct positioning of the welding head relatively to the joint preparation. Additionally, it monitors the joint profile of the molten weld pool and modifies the relevant heat input parameters ensuring consistent penetration, joint filling and acceptable weld bead shape. Finally, it makes use of both the above information to reconstruct three-dimensional images of the weld pool silhouettes providing in-process inspection capabilities of the welded joints. Welding process control strategies have been incorporated into the system based on quantitative relationships between input parameters and weld bead shape configuration allowing real-time decisions to be made during the process of welding, without the need for operation intervention.
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Egilmez, Gokhan. "Road Safety Assessment of U.S. States: A Joint Frontier and Neural Network ModelingApproach." Ohio University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1374854708.
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Spirakis, Athanasios Apostolou. "A qualitative holographic study of hemipelvic and acetabular deformation caused by different hip prostheses." Master's thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/25792.
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Aseptic loosening of the components is probably the most common long-term complication resulting in failure of Total Hip Arthroplasty. The mechanical behaviour of bone under load is one of the contributory causes of loosening encountered at the prosthesis/cement/bone interface. The present study dealt with a series of invitro experiments conducted on epoxy resin models of human hemi-pelves with different commercially available acetabular components implanted in them. These are used for the construction of simplified models of the artificial hip joint (three-dimensional) and of the prosthesis/cement/bone acetabular interface (two-dimensional). Loading conditions for the models included tensioning of the simulated abductor muscles for the hemi-pelvic and femoral loading for the prosthesis/cement/bone interface study. The experimental method employed was real-time holographic interferometry, a stress analysis technique recently used in the biomechanical field, which permitted whole-field simultaneously inspection of deformation patterns. The holographic interferograms were interpreted in a qualitative rather than a quantitative manner. The models do not exactly represent the in-vivo situation. Since this study identified high stresses both in the hip bone as well as in the interface (prosthesis/bone) it is suggested that these stresses are implicated in the mechanical pathogenesis of loosening. The observed changes in stress levels detected in our models could serve as a guide for future designs of acetabular prostheses as well as guide a in surgical techniques.
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Marcinkowski, Kaaren. "Getting back to the future a grounded theory study of the patient perspective of total knee joint arthroplasty : a thesis presented in partial fulfillment of the requirements for the degree of Master of Health Science, Auckland University of Technology, March 2003." Full thesis. Abstract, 2003.
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Migliore, Shane Anthony. "Control of robotic joints using principles from the equilibrium point hypothesis of animal motor control." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5009.
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Biological systems are able to perform complex movements with high energy-efficiency and, in general, can adapt to environmental changes more elegantly than traditionally engineered mechanical
systems. The Equilibrium Point Hypothesis describes animal motor control as trajectories of
equilibrium joint angle and joint stiffness. Traditional approaches to robot design are unable to implement this control scheme because they lack joint actuation methods that can control mechanical stiffness, and, in general, they are unable to take advantage of energy introduced into the system by the environment. In this paper, we describe the development and implementation of an FPGA-controlled, servo-actuated robotic joint that incorporates series-elastic actuation with specially developed nonlinear springs. We show that the joint's equilibrium angle and stiffness are independently controllable and that their independence is not lost in the presence of external joint torques. This approach to joint control emulates the behavior of antagonistic muscles, and thus produces a mechanical system that demonstrates biological similarity both in its observable
output and in its method of control.
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McDaid, Andrew John. "Modelling and control of IPMC actuators for biomedical robotics applications : a compliant stepper motor, an artificial muscle joint, a microfluidic pump and a cell microtool/gripper and manipulator." Thesis, University of Auckland, 2011. http://hdl.handle.net/2292/8440.
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The natural progression for future robotic devices is to work closely with humans in their own environment and even become embedded with humans for improving quality of life. Some already existing biomedical devices include hearing aids, pacemakers and prosthetic limbs. The main motivation for this research was to develop new innovative biomedical robotic devices which have the ability to improve the standard of living for humanity. Traditional robotic actuators, for example electro-magnetic drives and hydraulic/pneumatic machines, have all been extensively investigated. Although these devices and their control systems are well understood and have advanced performance which can, in some aspects, surpass that of humans, they are simply inadequate for developing beneficial devices which are capable of operating together with humans to augment their capabilities. The main limiting factors for these devices are size, weight, power requirements, stiffness and scalability, most of which cannot be resolved through incremental research. New approaches to device development must therefore be taken. Bio-inspired transducers which have similar properties to human tissue and muscle, in particular mechanical compliance, structural simplicity to allow easy scalability, high power-to-weight and power-to-volume ratios, precise and embedded control capabilities are demonstrating much promise as candidates for replacing traditional robotic actuators. IPMCs, a type of EAP whose actuation mechanisms can mimic biological muscle, were utilized in this research due to their extensive desirable characteristics when compared with traditional and other smart material actuators. The aim of this research was to further the state of art in smart material transducers towards their implementation as replacements for traditional robotic actuators in real life applications, outside the laboratory. Fundamental scientific research into advanced modelling and control of IPMCs has facilitated their implementation into a new generation of biomedical robotic devices developed in this research. The first step was the development of a new conclusive scalable model to predict the actuation response of IPMC actuators. This novel model was developed based on real material parameters and physical transduction mechanisms and can predict the mechanical response with external loads and hence is very useful for designing mechanical devices. Five novel biomedical robotic devices have been designed, utilizing the developed IPMC model to optimise their performance and validate the designs before implementing the real devices. These devises are a bio-inspired compliant stepper motor, an artificial muscle finger joint, a microfluidic pump, a cell microtool/gripper and a cell micromanipulation system. Each application has specific performance specifications and so new control strategies were developed to meet these requirements. The new controllers are based on an IFT algorithm which adaptively tunes the controller to optimise device performance. The controllers extend the current capabilities of the IFT algorithm in order for it to be implemented on nonlinear systems, online throughout normal operation and to be robust by rejecting external disturbances and adapting to drift in system dynamics over time. Finally the proposed devices and their corresponding controllers have been built and implemented to verify their performance in real life situations. This has validated the entire design process from the IPMC model and mechanical system simulations through to controller performance and device functionality. By successfully developing and implementing the devices in this research the feasibility of integrating IPMCs into real world applications as solutions to engineering problems has been proven.
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Bartošík, Jan. "Vliv velikosti hlavice na procesy tření a mazání v TEP kyčle." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231946.
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This diploma thesis concerns itself with the experimental study of friction and lubrication in the artificial hip joint depending on the head size. Measurements were made in a hip joint simulator based on the principle of pendulum. For the friction measurements artificial joints, made from three material combinations and two diameters, from two companies were used. The measurements show that the material combination has a more significant effect to friction coefficient than the head size. Using a bigger head size shows a decrease in friction coefficient for all material combinations when compared to a smaller head size. For the measurement of lubrication film the colorimetric interferometry was applied. A metal-on-glass contact pair was used, where the glass cups were made according to the real measurements of the joint cups. Four types of hip replacements with diameters of 28 and 36 mm with two different diametral clearance were measured during a constant motion of 210 seconds. Measurements show, that the lubrication film in the hip joint with a small diametral clearance increases very fast over the 800 nm value. Contact surfaces in the hip joint with a large diametral clearance aren’t separated by the lubrication film, resulting in a damage of the chromium coating in cup. A thick lubrication film results in a higher friction coefficient, when compared with hip joints with a very thin or no lubrication film.
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Švachová, Michaela. "Experimentální analýza utváření mazacího filmu v náhradách kyčelního kloubu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241180.
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This diploma thesis deals with an experimental analysis of lubricant film formation in hip joint replacements. The main objective is to clarify the effect of mean speed, slide-to-roll ratio, and material of femoral head on the development of film thickness, focusing on the role of particular constituents contained in model synovial fluid, such as albumin and -globulin. For this purpose, a model ball-on-disc configuration was applied, while the development of lubricant film was evaluated using the combination of fluorescent microscopy and optical interferometry. To better understand the process, coefficient of friction between implant surfaces was later investigated as well. The effect of material, slide-to-roll ratio, mean speed and model fluid composition was analysed. Results indicate that the main parameter, influencing the character of film formation, is slide-to-roll ratio. Under most conditions, the dominant constituent responsible for the film thickness development was albumin. Coefficient of friction is affected mainly by the material of implant. The thesis contains original scientific results extending the knowledge in the area of hip joint biotribology.
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Pendelton, Alice Mae. "Biofluid lubrication for artificial joints." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3205.
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Balounová, Hana. "Studium tření náhrad kyčelního kloubu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230585.
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Diploma thesis deals with analysis of coefficient of friction in total hip prosthesis for several materials bearing with presence of bovine serum as substitute of synovial fluid occurred in natural joint. Behavior of coefficient of friction is observed on Mini Traction Machine. Results are plotted at graphs representing dependence of coefficient of friction on time. There are described effects of several kinematic conditions, the influence of used material and the effect of the method of contact lubrication. The experiments analyze how the formation of lubricant film with a layer of adsorbed protein affects coefficient of friction.
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Maier, Friedrich [Verfasser], Tobias [Akademischer Betreuer] Licha, and Martin [Akademischer Betreuer] Sauter. "Improved tracer techniques for georeservoir applications : Artificial tracer examination identifying experimentally relevant properties and potential metrics for the joint application of hydrolysis tracer and heat injection experiments / Friedrich Maier. Gutachter: Tobias Licha ; Martin Sauter. Betreuer: Tobias Licha." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2015. http://d-nb.info/1065882483/34.
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Bosák, Dalibor. "Mapování tloušťky mazacího filmu u náhrad velkých kloubů člověka." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230068.
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This master’s thesis describes mechanism of lubricating film forming and its thickness in contact of a metal hip joint ball and a glass disc with chromium layer with presence of bovine serum as substitute of synovial fluid occured in a natural joint. Lubricating film thickness is evaluated by a thin film colorimetric interferometry, results are ploted at graphs representing dependence of lubricating film thickness on experiment duration or on mutual speed of articulating surfaces. There is described the influence of concentration of bovine serum and different kinematic conditions on lubricating film forming. From observed interferograms is apparent the adsorption of proteins to glass disc and femoral head surfaces, denaturation and formation of protein aggregations affecting the residual lubricating film thickness.
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Žonda, Peter. "Konstrukce simulátoru kyčelního kloubu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241896.
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The master's thesis is concerned with design and execution of an experimental acetabulofemoral joint simulator. Its primary use is the study of lubrication film thickness in hip implants. The work first describes available hip joint simulators, which simulate particular joint positions. Next, the thesis proposes author’s own designs and solutions. The result is a produced device allowing for dynamic change of load in simulation of hip joint flexion and extension as set by ISO standard. Contact is recorded by an optical apparatus composed of a high-speed camera and a microscope. The work also includes the initial testing experiment and the complete design documentation of the device including electrical wiring diagrams.
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Dunker, Philip A. "A Biologically Inspired Robot for Lunar Exploration and Regolith Excavation." Case Western Reserve University School of Graduate Studies / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1219803272.
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Choudhury, M. "Degradation of polyethylene components in artificial knee joints." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597648.
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The consequences of irradiation on the molecular structure, crystal morphology and mechanical properties of UHMWPE, have recently been implicated as a potential major factor influencing the wear, prompting several manufacturers to consider alternative sterilisation methods. The current work has contributed to this area through investigation of the effects of irradiation dose (representative of current orthopaedic practice) and post-sterilisation ageing on subtle changes in the microstructure of UHMWPE using a wide range of experimental techniques, including X-ray diffraction, scanning electron microscopy and differential scanning calorimetry to probe the microstructure. In particular, an analysis of retrieved human knee tibial implants of both earlier designs and a recently introduced total knee system design, has been conducted using the above techniques in order to understand the fundamental wear mechanisms leading to premature failure of these components. This has been complemented with laboratory simulation tests to investigate the effects of the above physical and chemical changes on the abrasive and fatigue wear resistance of sterilised, aged and unaged UHMWPE. A new micro-scale abrasion test and a new rolling contact fatigue test have been used to achieve this. The in vivo wear mechanisms observed under these test conditions have been compared with those seen in the retrieved tibial implant material to emphasise the clinical relevance of this study. This work has shown that gamma sterilisation in air, followed by long-term shelf and/or in vivo ageing, significantly reduces the fatigue and abrasive wear resistance of UHMWPE, associated with notable changes in its microstructure. Alternative sterilisation methods which eliminate long term free radical activity have been recommended.
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Kinbrum, Amy. "Artificial joints : their tribology and wear particle analysis." Thesis, Durham University, 2008. http://etheses.dur.ac.uk/1939/.
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The wear, friction, lubrication and particle distribution of differently heat treated CoCrMo cast prostheses provided by the same supplier were analysed. Wear tests were conducted on both pin-on-plate and simulation rigs. Friction tests were also performed at intervals throughout testing. The surfaces of all bearing couples were analysed and the roughness was recorded in order to help analyse the lubrication and wear mechanism. The particles from each test were saved and frozen at -20°C, later analysis allowed further insight into the mechanism of wear of each material tested. The particles underwent protein digestion by enzymatic protocol this was the least harmful way of separating the particles from the protein. The particles were then analysed using a NanoSight LM10, this instrument can identify particles from a 0.5 ml solution by highlighting the particles with a laser and recording the movement of the particles. Using the Stokes-Einstein equation the size of the particles can be calculated by the motion recorded. Recently metal-on-plastic prostheses have not been sufficient for the younger osteoarthritic patient, therefore the market has demanded alternative, low wearing bearing couples, both metal-on-metal and ceramic-on-ceramic have come to the market as alternatives for the younger more active patient. The Birmingham Hip Resurfacing (BHR) came to the market in the early 1990's and was produced by casting methods. Theory suggested that heat treatment may improve the tribological properties of the CoCrMo alloy. This thesis set out to assess the physical mechanism of failure of these joints. This study aims to look at the problem from as many angles as possible therefore the wear rates, friction, surfaces and particle debris were analysed. The pin-on-plate tests were very useful as they allow the analysis of the surface interaction without the complication of lubrication.
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Bone, Martin. "Understanding failures of artificial joints through engineering analysis." Thesis, University of Newcastle upon Tyne, 2015. http://hdl.handle.net/10443/3055.
Full textAbstract:
The aim of joint arthroplasty is to reduce pain and improve the range of motion and functionality in joints affected by diseases such as osteoarthritis and rheumatoid arthritis. Data recorded in National Joint Registries offers the clinical perspective in relation to prosthesis failures; however, this does not explain why a prosthesis has failed. Surgeons performing revision surgery for different implants often report similar findings, despite designs of prostheses and the natural joints having numerous differences, including anatomy, loading and range of movement. The underlying factor in the majority of cases of implant failure is complications arising as a result of wear debris. To understand the failures of artificial joints, a series of studies were performed examining hip prostheses in pre-clinical and post-clinical scenarios and finger prostheses in a post-clinical scenario. The pre-clinical studies focussed on areas including: the effect of acetabular shell deformation; and validating a method to measure volumetric wear from femoral stem trunnions. The deformation studies included an investigation of how bone strength influenced deformation. The post-clinical studies involved analysing retrieved finger and hip prostheses, to quantify the damage surfaces had sustained in vivo. Analysis of the finger prostheses involved the use of a non-contacting surface profilometer, to determine the surface roughness, whilst for the hip prostheses a coordinate measuring machine was used to quantify the volumetric wear. The deformation studies found that the maximum deformation was 340 μm, which could be sufficient to disrupt the assembly process of modular acetabular components. The strength of the bone was not found to correlate with the size of the deformation. The validation study found that the coordinate measuring machine was able to measure trunnions with a maximum error of 0.13 mm³ compared with gravimetric measurements. The ex vivo cohort of trunnions had a median wear volume of 0.14 mm³ (range 0.04 – 0.28 mm³). The first finger study analysed coated, metal-on-metal prostheses finding that prostheses had suffered extensive wear on the articulating surfaces. This was hypothesised to be due to the failure of the coating interface, resulting in a hard ii “grinding paste” that wore the articulating surfaces. The second finger study examined a cohort of explanted pyrolytic carbon prostheses. Even after use in vivo the roughness average (Ra) for the articulating surfaces was below the 50 nm specified by British Standards as the maximum Ra for orthopaedic implants manufactured from metal or ceramic.