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Model-based radiostereometric analysis (MBRSA) of a total ankle arthroplasty (TAA) prosthesis was studied for the first time. The TAA MBRSA system precision was determined from the double exams of 20 patients implanted with the Mobility(TM). The MTE for any direction was 0.07mm for the tibial component. The MTE was 0.09mm and the MRE was 0.51° for the talar component. The MTPM detection limits were 0.22mm and 0.85mm for the tibial and talar components. Both components followed the typical subsidence-stabilization pattern. There was little detectable continuous migration at one to two years. The median(range) MTPM at two years was 0.96mm(0.17-2.28mm) and 1.23mm(0.39-1.9 mm) for the tibial and talar components. There was no detectable inducible displacement observed for any components at two years, except one talar component. The median(range) MTPM induced by the loading at two years was 0.08mm(0.03-0.18mm) and 0.39mm(0.27-1.06mm) for the tibial and talar components.

The history of total knee arthroplasty stretches back over 70 years. Many studies have shown that TKA is, in general, a successful operation for the relief of joint pain, with patient satisfaction rates of 90-95% and implant survival rates at 10-15 years of greater than 90%. However, a number of studies have also shown the potential for failures or complications arising post-implantation leading to revision surgery. This thesis presents finite element (FE) models of the distal femur following primary and revision total knee arthroplasty. Pre-arthroplasty models are also developed for comparison. Particular attention is given to how femoral component design and method of fixation impacts the mechanical environment of the distal femur and stability of the prosthesis. FE analyses with fully bonded interfaces indicate that femoral components are subject to areas of low stress (stress shielding) immediately under the anterior flange and chamfer regardless of internal implant features. However, internal implant features were found to play a role in the pattern and magnitude of stress concentrations. Both stresses and motions were observed to increase with increasing flexion angle, indicating the importance of testing at multiple angles. The initial models of the distal femur were extended to incorporate the effects of ageing and endosteal thinning of the femoral cortex, through novel application of pre-existing FE modelling techniques, specifically the ability to assign variable material properties corresponding to the nodal temperatures output from a heat transfer analysis. The findings from this study indicate that older patients with osteoporosis may be at increased risk of periprosthetic fracture compared to younger healthy patients. The use of a revision femoral component with a cemented stem as a means to mitigate this fracture risk was also investigated. FE analyses using frictional interfaces were employed to determine the influence of femoral component design on micromotion at the interface. These models showed that all primary implants were subject to similar magnitudes of relative motion at the interface, however, the distinct internal implant features led to very different regional variations. Furthermore, certain internal implant features (i.e. femoral box) were found to be highly sensitive to errors in surgical bone cuts. This aspect of the thesis also concluded that the addition of a stem served to significantly reduce motions at the interface in comparison to primary stemless implants. Long stemmed prostheses were found to result in the smallest levels of interface motion. This study also detailed the design and creation of an in vitro test setup for the purposes of determining the influence of stem length and fixation on the stability of revision prostheses. Experimental results using this test rig showed that a cemented short stem provides as much initial stability as the uncemented long stem, and is easier to fit surgically. Corresponding FE models incorporating a virtual representation of the test rig and in vitro loading conditions revealed that the relative motion at the multi-planar bone-prosthesis interface cannot be adequately described using a single reference point. However, in vitro setups may be used to predict a general measure of implant stability and to provide a source of calibration for FE. The distal femur models were further modified to investigate how the presence of condylar defects as classified by AORI defect classification system (Engh 2006) and weak osseous support due to osteoporosis may adversely affect the survival of the prosthesis. These investigations revealed that fixation of the femoral component, the presence of a large condylar defect and the level of osseous support all had an impact on stress in the implant, it is concluded that a non-modular approach should be adopted in older patient groups with severe osteoporosis to mitigate the risk of component junction failure and distal femoral fracture.

This thesis deals with the analysis of micromotion of a single charged calcium ion trapped inside the linear Paul's ion trap and the influence of residual micromotion on the systematic frequency shifts of the clock transition of calcium ion. The fundamental properties of the motion of an ion confined within linear Paul's ion trap are shown in general using a theoretical description. The micromotion component of the overall motion is especially emphasized. A model expressing micromotion in the axial direction of the trap is introduced on the basis of the results of the numerical calculation of electric fields inside the trap. The model is compared to the reality experimentally. Then, the photon-correlation method of detection of micromotion is introduced and subsequently used to minimize and to estimate a measure of residual micromotion in all spacial directions. According to the achievable measure of residual micromotion, the systematic frequency shifts caused by this micromotion are estimated. It can be seen that we are able to reach uncertainties of the relative frequency shifts due to micromotion below 10^20. We expect that uncertainty of total motional systematic frequency shift is in our case limited by thermal motion.

Aseptic loosening of the tibial component is an important cause of failure after total knee arthroplasty. Bone destruction often claimed to be caused by the cement makes the revision difficult. In order to treat younger patients, uncemented fixation has been introduced, but the etiology to loosening is multifactorial and only partly known. Early detection of implant migration facilitates research in this field but is difficult using conventional techniques. In this study modified versions of roentgen stereophotogrammetric analysis (RSA) were developed to obtain accurate and standardized evaluations facilitating comparison between prosthetic designs. The method was used to record the efficacy of cemented and uncemented fixation of different designs of the tibial component, to determine the accuracy of scintimetry in the detection of early aseptic loosening, and to analyse the in vivo kinematics of knee arthroplasties with different design and stability between the joint surfaces. Forty-three arthroplasties with comparatively high inherent stability of the joint surfaces were randomized to cemented or uncemented fixation of the tibial component. In all groups micromovements were rather large, but with no differences between the cemented and uncemented components. The preoperative diagnosis (arthrosis OA, n=25; rheumatoid arthritis RA, n=18) did not influence the magnitude of micromotion. 20 arthroplasties with the same design as above but equipped with an intramedullary stem, were randomized to cemented or uncemented fixation in patients with RA. Cement improved the fixation. Uncemented stemmed components displayed micromovements seemingly larger than unstemmed ones. 34 arthroplasties with an unconstrained design of the joint area and fixed to the tibia with four pegs were randomized to cemented or uncemented fixation in patients with OA. When used uncemented 4 screws were added. Compared with previously investigated designs small micromotions were recorded, and especially in the cemented cases. Uncemented components with thin polyethylene inserts displayed larger initial micromotions. The preoperative deformity influenced the direction of the micromotion. 33 knees were followed prospectively with RSA and scintimetry to evaluate any correlation between these methods. Low activity under the tibial component at 2 years implied prosthetic stability, whereas high activity indicated instability or high bone remodelling caused by the preoperative malalignment. The in vivo kinematics in three different designs of knee arthroplasties were analyzed during active flexion and extension without weight-bearing. Each type of prosthesis displayed design-specific abnormalities when compared with a normal material. Pronounced posterior tibial translations were recorded during flexion regardless whether the posterior cruciate ligament had been sacrificed or not. Data from the kinematic and the fixation studies suggest that movements restricted by the design of the joint area are transmitted to the bony interface with design-specific micromotions as the result. Analysis of knee joint kinematics during extension and weight-bearing revealed small alterations compared with non-weight-bearing. Evaluation of the three-dimensional movements in terms of helical axis rotations and translations confirmed the constrained or unconstrained in vivo behaviour of the designs under study. This analysis also facilitated the interpretation of the kinematic behaviour of the prosthetic knees and may be of value in the evaluation of new designs. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1992, härtill 7 uppsatser.</p> / digitalisering@umu

Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are relatively new biomedical techniques developed during the last century, which are frequently recommended for patients with joint diseases. In spite of their success and huge popularity, the postoperative failure rates for these procedures remain significant. Migration and micromotion of the implant are the primary indicators of its postoperative stability and many in vitro measurement techniques have been discussed. However, effective, practical methods to measure these metrics in vivo have proven elusive and the evolution of such a technique is the subject of this thesis. An implantable, remotely interrogated electronic system for the in vivo measurement of both micromotion and migration in the axial direction is proposed. The main purpose of the device is to improve the ability of clinicians to assess the longterm stability of orthopaedic implants and also to plan and optimise patients’ rehabilitation protocols. The system is based on a modified form of differential variable reluctance transducer (DVRT) in which the nullpoint of the system set automatically by means of a selfcalibration process. Simulations and preliminary in vitro measurements on the bench show that the selfcalibration algorithm works correctly in spite of component tolerances and initial set up errors, allowing a gross displacement (migration) to be measured with a resolution of 15 �m and a range from 0 to 4 mm, and that the device can measure micromotion with an amplitude as low as 1 �m in the range from 200 �m to 200 �m. Accuracy of less than 10 % are achieved in both micromotion and migration measurements. Prototypes of all the major components and subsystems have been fabricated in CMOS integrated circuit (IC) technology as part of the project. Measurements support the feasibility of constructing an integrated version of the complete system for implantation and in vivo use in the future.

Synthetic Aperture Radar (SAR) imaging is a well-known technique in the domain of remote sensing, aerospace surveillance, geography and mapping. To obtain images of high resolution under noise, taking into account of the characteristics of targets in the observed scene, the different uncertainties of measure and the modeling errors becomes very important.Conventional imaging methods are based on i) over-simplified scene models, ii) a simplified linear forward modeling (mathematical relations between the transmitted signals, the received signals and the targets) and iii) using a very simplified Inverse Fast Fourier Transform (IFFT) to do the inversion, resulting in low resolution and noisy images with unsuppressed speckles and high side lobe artifacts.In this thesis, we propose to use a Bayesian approach to SAR imaging, which overcomes many drawbacks of classical methods and brings high resolution, more stable images and more accurate parameter estimation for target recognition.The proposed unifying approach is used for inverse problems in Mono-, Bi- and Multi-static SAR imaging, as well as for micromotion target imaging. Appropriate priors for modeling different target scenes in terms of target features enhancement during imaging are proposed. Fast and effective estimation methods with simple and hierarchical priors are developed. The problem of hyperparameter estimation is also handled in this Bayesian approach framework. Results on synthetic, experimental and real data demonstrate the effectiveness of the proposed approach.

The investigations conducted within this dissertation centers around the use of electric cell-substrate impedance sensing (ECIS). This system is able to characterize in real-time analysis, the adhesion of cells to their substrate and neighboring cells. With this, valuable information can be gathered with in-vitro experiments regarding a tissue culture's response to physiological stimulation. This dissertation has taken advantage of ECIS' ability to analyze toxicology, barrier function, and cancer invasion on a tissue culture. With proper analysis modifications, trans-epethelial resistance (TER) can be used as a cytotoxicity assay with higher sensitivity than previously thought. In vitro assessment of cytotoxicity based on TER needs more quantitative methods to analyze the alteration of cell morphology and motility. Here, we applied ECIS to evaluate dose-dependent responses of human umbilical vein endothelial cells (HUVEC) and mouse embryonic fibroblasts (NIH 3T3) exposed to cytochalasin B and protein kinase inhibitor H7. To detect subtle changes in cell morphology, the frequency-dependent impedance data of the cell monolayer were measured and analyzed with a theoretical cell-electrode model. To detect the alternation of cell micromotion in response to cytochalasin B and H7 challenge, time-series impedance fluctuations of cell-covered electrodes were monitored and the values of power spectrum, variance, and variance of the increment were calculated to verify the difference. While a dose-dependent relationship was generally observed from the overall resistance of the cell monolayer, the analysis of frequency-dependent impedance and impedance fluctuations distinguished cytochalasin B levels as low as 0.1µM and H7 levels as low as 10 µM for HUVEC and 3T3 layers. Even though overall resistance values are relatively small for 3T3 layers, and frequency scan measurements are negligible, impedance fluctuation analysis reveals significant micromotion for cytotoxic detection. Our results show that cytochalasin B and H7 causes a decrease of junctional resistance between cells and an increase of membrane capacitance. Cigarette smoke is cytotoxic and tumorigenic. Initial studies were conducted to evaluate the cytotoxicity of cigarette smoke condensate (CSC) on HUVEC layers. The focus was then turned to investigations involving in vitro cancer invasion assays with CSC on HUVEC layers. ECIS is an excellent investigative device that can be utilized to observe cancer invasion on normal tissue cultures due to the significantly higher impedance signature of cancer cells. The investigation in this dissertation focused on cigarette smoke's influence on cellular mechanics of endothelial cells and the invasive potential of two ovarian cancer cell lines (ALST and OVCA429) against a fully active endothelium. The HUVEC cultures responded to CSC with an increase in junctional binding, where as ALST and OVCA429 relieved adhesion thereby providing an improved motility when evaluated in wound healing assays. Transmigration of the HUVEC layer by ALST cells exhibit a pre-CSC exposure time-dependence affecting the effectiveness of ALST transmigration. The HUVEC layer's decreased tight junction binding that resulted from CSC exposure, allowed for a more aggressive ALST layer formation that occurred during simulated intravasation. Increased HUVEC layer tight junction binding that occurred in the first five hours in response to CSC during extravasation contributes to impeding ALST transmigration at high concentrations of CSC. Overall, CSC has an impeding effect on ALST transmigration during extravasation while causing aggressive transmigration during intravasation.

Les systèmes composés d'atomes et d'ions ultrafroids ont étés un sujet d'intérêt pour les physiciens atomiques et, plus récemment, pour la communauté des ions froids (simulation et calcul quantique avec des ions piégés). Ils sont considéré la possibilité d'utiliser un gaz d'atomes ultrafroids pour refroidir sympathiquement les ions car la modulation intrinsèque du mouvement, le micromouvement, représente une source de décohérence dans les applications des ions froids. L'intérêt envers ce système mixte est aussi motivé par l'étude de la physique d'impuretés et par une meilleure compréhension des réactions entre espèces ioniques et neutre ayant pour but la création d'ions moléculaires. Cette thèse a pour objectif d'étudier les effets du micromouvement dans les collisions atome-ion. Nous traitons au préalable les collisions à 1D d'une particule dans un piège harmonique (un ion) et d'un particule libre (une atome) en utilisant différentes approches numériques. Ce système est intéressant en soi en raison de la dimensionnalité mixte 0D-1D. Le potentiel atome-ion est modélisé par une interaction à portée nulle tout au cours de ce travail. Par la suite, nous traitons un problème similaire mais dans le cas d'une particule dans un piège harmonique décrivant un piège de Paul. Enfin, nous généralisons l'étude du micromouvement à un système modèle 3D avec un ion dans un piège de Paul sphérique 3D et un atome lourd au centre du piège. Nous discutons de l'influence du micromouvement en vue d'applications potentielles de ce système telle que la porte logique de phase. / Ultracold atom-ion systems have been a topic of interest for atomic physicists studying chemical reactions and since recently, the cold ion community (ion trap quantum computation and simulation). They have been looking at the possibility of using an ultracold atom gas to sympathetically cool ions since intrinsic motional modulation i.e micromotion is an inherent cause of decoherence in coherent applications of cold ions. Interest is also piqued by the possibility of using this hybrid system for studying impurity physics and to better understand ion-neutral reactions aimed at creation of molecular ions. In this thesis, we aim to study the effect of ion micromotion in atom-ion collision. As a prelude, we treat the 1D collision of a particle in a harmonic trap (ion) and a free particle (atom) using different numerical schemes. This system is of interest in its own right due to the mixed 0D-1D dimensionality. Atom-ion potential is simplified to a zero range potential all through out the work. Next we deal with a similar problem but with the trapped particle in a time dependent harmonic trap identical to an ion Paul trap. Finally we extend the study of micromotion to a model system in 3D with an ion in a 3D spherical Paul trap and a heavy atom at the trap centre. We discuss the effect micromotion has on potential applications of such a system, like a quantum phase gate.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22659号 / 工博第4743号 / 新制||工||1741(附属図書館) / 京都大学大学院工学研究科電子工学専攻 / (主査)教授 山田 啓文, 教授 川上 養一, 准教授 杉山 和彦 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM