Orientador: Francisco de Assis Mollo Júnior / Resumo: O objetivo neste estudo foi avaliar in vitro a precisão entre técnicas de moldagem convencional e os diferentes scanners digitais em reabilitações protéticas sobre implantes. Um modelo anatômico metálico de maxila desdentada com quatro implantes, simulando o sistema All-on-four, foi escaneado com um scanner de contato (MDX-40, Roland) e utilizado como modelo mestre para posterior comparação com outros scanners odontológicos. Sobre os implantes do modelo mestre foram instalados scanbodies para permitir a digitalização da posição dos implantes. Dois scanners de bancada e um scanner intraoral foram utilizados para a digitalização do modelo mestre e posterior sobreposição das imagens com o objetivo de comparar o posicionamento em 3D dos análogos em relação à posição dos implantes no modelo mestre e avaliar a precisão dos scanners. Ainda, utilizando o modelo mestre foram realizadas 10 moldagens com a técnica convencional (moldeira aberta), que foram vazadas e os modelos obtidos foram digitalizados com o scanner de contato. As imagens obtidas em formato STL foram exportadas para o programa Bio-CAD para avaliação e comparação da precisão entre as técnicas de moldagem convencional e a moldagem digital. A análise da sobreposição das imagens foi guiada pela pirâmide presente no modelo mestre, o que permitiu avaliar a diferença na posição dos análogos em 3D nos eixos X, Y e Z. Os valores médios dos desvios (μm) da posição do modelo mestre em relação a posição das imagens dos diferentes ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This study aims to evaluate in vitro the accuracy between conventional impression techniques and different digital scanners in prosthetic implant rehabilitation. A metallic anatomical model of a edentulous maxilla with four implants, simulating the All-on-four system, was scanned by a contact scanner and used as a control group for later comparison with dental scanners. On the implants of the master model were installed scanbodies to allow the digitalization of the position of the implants. Two laboratory scanners and an intraoral scanner were used for the digitalization of the master model and later overlap of the images in order to compare the 3D position of the analogs in relation to the position of the master model and evaluate the accuracy of this scanners. Subsequently, from the master model, 10 casts were made using the conventional technique (pick-up technique). The models were created with plaster and the obtained models were scanned by the contact scanner. The images obtained in STL format were exported to the Bio-CAD program for evaluation and comparison of the precision between the conventional and impression technique. The analysis of the superimpose of the images was guided by the pyramid present in the master model, so it was possible to evaluate the difference in a 3D position of the analogues in the X, Y and Z axes. The mean values of the deviations (μm) in relation to the virtual position of the images obtained by the different scanners of the components on ... (Complete abstract click electronic access below) / Mestre

Introduction: Aseptic loosening is the most common indication for revision surgery of hipimplants. However, sometimes diagnosis from planar radiography is uncertain, makingdecision regarding revision surgery problematic. Implant Movement Analysis (IMA) is anewly introduced method of analysing uncertain aseptic loosening of hip prostheses. It usescomputer tomography with rotational provocation to expose movement of the implantrelatively to the surrounding bone. Aim: To evaluate the role of IMA as a complementary method to planar radiography indiagnosing aseptic loosening of total hip artroplasty (THA) at Lindesberg Hospital. 1) HasIMA improved diagnosing of uncertain cases of aseptic loosening? 2) Has IMA reduced thenumber of unnecessary THA revision surgeries? Methods: Retrospective cohort study analysing 43 cases of uncertain aseptic looseningexamined with IMA at Lindesberg Hospital. Paired results from planar radiography and IMAwere statistically compared with McNemar’s test, IMA held as the reference. Additional datawas also collected (i.e. age and symptoms). Results: Planar radiography had 70 % sensitivity and 65 % specificity compared to certainresults from IMA. IMA provided diagnoses in 84 % of the cases and changed the diagnosisfor 33 % compared to planar radiography. Eight cases got their diagnosis changed from looseto not loose. Conclusions: IMA has improved diagnosing cases of uncertain aseptic loosening and cantherefore be seen as a good complementary method to planar radiography in these cases.However, as it is a new method further evaluation is needed.

Bibliography: leaves 184-190 / viii, 190 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Applied Mathematics, 1987

Based on a thesis in Electrical Engineering, 1965. / Bibliography: p.79-86. / Contract DA-36-039-AMC-03200(E).

The ability to control balance and stability are essential to prevent falls during locomotion. Maintenance of stable locomotion is challenging especially when complicated by amputation and prosthesis use. Humans employ several motor strategies to maintain stability during walking on complex terrain: decreasing walking speed, adjusting stride length and stance width, lowering the center of mass, and prolonging the double support time. The mechanisms of selecting these motor strategies by the primary motor cortex are unknown and cannot be studied directly in humans. There is also little information about dynamic stability of prosthetic gait with bone-anchored prostheses, which are thought to provide sensory feedback to the amputee through osseoperception. Therefore, the Specific Aims of my research were to (1) evaluate dynamic stability and the activity of the primary motor cortex during walking with different constraints on the base of support and (2) develop an animal model to evaluate mechanics and stability of prosthetic gait with a bone-anchored prosthesis. To address these aims, I developed a feline model that allows for investigating (1) the role of the primary motor cortex in regulation of dynamic stability of intact locomotion, (2) skin and bone integration with a percutaneous porous titanium implant facilitating prosthetic attachment, and (3) dynamic stability of walking on a bone-anchored prosthesis. The results of Specific Aim 1 demonstrated that the area and shape of the base of support influence the margins of dynamic stability during quadrupedal walking. For example, I found that the animal is dynamically unstable in the sagittal plane and frontal plane (although to a lesser degree) during a double-support by a forelimb and the contralateral hindlimb. Elevated neuronal activity from the right forelimb representation in the primary motor cortex during these phases suggests that the motor cortex may contribute to selection of paw placement location and thus to regulation of stability. The results of Specific Aim 2 on the development of skin-integrated bone-anchored prostheses demonstrated the following. Skin ingrowth into 3 types of porous titanium pylons (pore sizes 40-100 μm and 100-160 μm and nano-tubular surface treatment) implanted under skin of rats was seen 3 and 6 weeks after implantation, and skin filled at least 30% of available implant space. The duration of implantation, but not implant pore size (in the studied range) or surface treatment statistically influenced skin ingrowth; pore size and time of implantation affected the implant extrusion length (p<0.05). The implant type with the slowest extrusion rate (pore size 40-100 μm) was used in a feline model of prosthetic gait with skin-integrated bone-anchored prosthesis. The developed implantation methods, rehabilitation procedures and feline prostheses allowed 2 animals to utilize skin- and bone-integrated prostheses for dynamically stable locomotion. Prosthetic gait analysis demonstrated that the animals loaded the prosthetic limb, but increased reliance on intact limbs for weight support and propulsion. The obtained results and developed animal model improve the understanding of locomotor stability control and integration of skin with percutaneous implants.

The Niagara Foot (NF) is a relatively new prosthetic design, primarily intended for use in developing countries. It combines low cost and durability with high performance energy return features. The design has been successfully tested mechanically and in field trials, but to date there has been little quantitative gait data describing the performance of the foot. Biomechanical gait analysis techniques will be used to extract quantitative gait measures. The current study is designed to characterize the effect of heel section stiffness parameter differences between a NF normal heel and a NF with a reduced material heel section., on gait characteristics in persons with unilateral trans-tibial amputations (TTA). Standardized biomechanical gait analysis techniques, adapted for this population, were used to extract quantitative gait measures. Five persons with TTA performed walking tasks while 3D ground reaction forces were recorded via an embedded force platform. A motion capture system also recorded the 3D segmental motion of the lower limbs and torso of each subject. These were combined to calculate net joint moments and mechanical power at the hip and knee of both limbs. These data were compared between a normal NF and a NF with a modified heel. Each participant had a period of two-week adaptation prior to any testing. An EMG system and a prosthesis evaluation questionnaire were used to help analyze the condition. The overall hypothesis of this study was that modification of the heel section stiffness would change several aspects of gait. Although the gait pattern differences between participants and the low participant number produced no significant differences between the conditions for all variables, trends were observed in multiple outcomes. These results report preliminary evidence that for some participants the heel material reduction does impact their gait by showing a different loading phase during the transition between the heel strike and the full contact with the ground. The NF2 may move the gait toward a more flexed knee position. Furthermore, despite a reduction in the material of the heel section results showed that the overall foot stiffness increased. This may be the result of the one-piece design and mechanics of the NF. Further investigations with a bigger cohort of people with TTA are required to look at the importance of the impact of the prosthetic foot heel stiffness.

El ciprofloxacino marcado con tecnecio-99m (99mTc-ciprofloxacino) es un radiofármaco cuyo interés radica en el diagnóstico y control terapéutico de las infecciones. El marcaje de este antibiótico ya se ha llevado a cabo por diferentes grupos de investigación pero es necesario el desarrollo de nuevos métodos de preparación y control de calidad para obtener un radiofármaco lo más puro posible así como para evaluar la acumulación in vitro en bacterias. Este radiofármaco debe cumplir los requisitos más estrictos de pureza y calidad si se pretende su aplicación en la práctica clínica y poder competir con las pruebas ya existentes en el campo de la infección. Para el marcaje, en este trabajo se ha usado ciprofloxacino clorhidrato, ácido clorhídrico, cloruro de estaño, ácido tartárico, agua inyectable, cloruro sódico 0,9% y tecnecio. El control de calidad se ha basado en cromatografía en capa fina combinando dos de sílica gel y una en fase reversa. El estudio del marcaje propuesto para el radiofármaco muestra una clara influencia de la concentración de ácido tartárico durante la reacción mostrándose un equilibrio entre 99mTc-ciprofloxacino y 99mTc-tartrato. Usando una relación molar ciprofloxacino / ácido tartárico de 50 a 100, el producto mayoritario es el esperado (99mTc-ciprofloxacino). En cambio, con relaciones molares ciprofloxacino / ácido tartárico menores de 10 se obtienen grandes cantidades de 99mTc-tartrato. Sin embargo, a medida que disminuimos la concentración de ácido tartárico aumenta la proporción de especies coloidales, las cuales son impurezas a evitar en esta exploración diagnóstica, debido a la posibilidad de falsos positivos. La acumulación in vitro en bacterias se llevó a cabo mediante dos cepas (con y sin mecanismos de resistencia) de Staphylococcus aureus y Pseudomonas aeruginosa a los 5 y 30 minutos. La evaluación de la acumulación de tecnecio libre se realizó para demostrar si toda la señal radiactiva intracelular era debida al antibiótico marcado. El 99mTc-ciprofloxacino se acumuló por igual en todas las cepas bacterianas estudiadas mientras que el tecnecio libre (99mTcO4-) no mostró acumulación. El estudio clínico se realizó en 40 pacientes con sospecha clínica y/o analítica de aflojamiento séptico en prótesis osteoarticulares de cadera, rodilla y hombro. La adquisición de imágenes consistió en una gammagrafía ósea convencional y en la combinación de una gammagrafía con leucocitos marcados con 99mTc-HMPAO y una gammagrafía medular (99mTc-coloide). La prueba con 99mTc-ciprofloxacino se realizó a las 1, 4 y 24 horas post inyección intravenosa de 370MBq. El diagnóstico final de infección de prótesis osteoarticular se estableció cuando en 2 cultivos de tejido periprotésico de 6 sean positivos para el mismo microorganismo o haya evidencia macroscópica de material purulento. De los 40 pacientes incluidos en el estudio se documentó infección en 16 correspondientes a las prótesis en 8 caderas, 6 rodillas y 2 hombros. De los microorganismos aislados, 9 fueron resistentes a ciprofloxacino. En los 24 casos restantes se excluyó el diagnóstico de infección. Los mejores resultados de la gammagrafía con 99mTc-ciprofloxacino en pacientes se obtienen en las imágenes a las 24 horas, con una sensibilidad del 88%, una especificidad del 71%, un valor predictivo positivo del 67% y un valor predictivo negativo del 89%. La gammagrafía con 99mTc-ciprofloxacino puede ser una alternativa útil a la gammagrafía con leucocitos marcados en la evaluación de la sospecha de infección de prótesis de cadera. La especificidad encontrada no es adecuada para recomendarla en el diagnóstico de infección en prótesis de rodilla. / 99mTc-ciprofloxacin is a radiopharmaceutical used in the detection of osteoarticular prosthesis infection. In this work, a labelling procedure using tin(II) chloride and L-tartaric acid instead of tin(II) tartrate is reported. Quality control is based on thin layer chromatography. Intracellular accumulation of the labelled antibiotic and free pertechnetate (99mTcO4-) in bacteria was also analyzed. Finally, a clinical trial was performed. The study of the influence of tartaric acid concentration during the labelling reaction showed the existence of an equilibrium between 99mTc-ciprofloxacin and 99mTc-tartrate. When using a molar ratio ciprofloxacin/tartaric acid from 50 to 100, 99mTc-ciprofloxacin is the main product. Significant amounts of 99mTc-tartrate were observed when the ciprofloxacin/tartrate ratio is minus or equal than 10 and it can become the main compound at lower values. Radiocolloid quantity becomes important at high ratio values. The study of the intracellular accumulation of ciprofloxacin, 99mTc-ciprofloxacin and 99mTcO4- was performed in Staphylococcus aureus and Pseudomonas aeruginosa strains with and without the presence of an efflux pump as a mechanism of resistance. Accumulation of 99mTcO4- was performed to ensure that the entire radioactivity signal was due to the 99mTc-ciprofloxacin. Also, the accumulation of non-labelled ciprofloxacin was done to ensure that the strains were able to pump out the antibiotic. 99mTc-ciprofloxacin accumulated equally intracellularly in all the strains tested while 99mTcO4- did not show accumulation. Forty patients (26 women, 14 men) with local pain in the hip (21), knee (16), or shoulder (3) prosthesis were recruited. 99mTc-ciprofloxacin scintigraphy was performed at 1, 4, and 24h after intravenous injection of 370MBq. A routine bone scan, 99mTc-HMPAO leukocyte scan and 99mTc-colloid scan were performed. Diagnosis of arthroplasty infection was established in 16 out 40 cases: 8 hips, 6 knees, 1 shoulder. From the isolated microorganisms, 9 were resistant to ciprofloxacin. 99mTc-ciprofloxacin scintigraphy showed the 24h image to be the best acquisition time-point. The sensitivity, specificity, negative predictive value and positive predictive value at 24h were 88, 71, 67, and 89%. 99mTc-ciprofloxacin scintigraphy can be a useful alternative in the diagnosis of arthroplasty infection of the hip. The lack of specificity of makes this technique inadequate for knee prostheses.

In this master thesis the connection between the two major parts of an osseointegrated prosthesis system for lower limb amputees has been investigated by finite element (FE) analysis. The prosthesis system is developed by Integrum and the current design consists of a fixture, which is integrated in the residual bone, an abutment that penetrates the skin and an abutment screw that holds the parts together. The connection between the fixture and the abutment has a hexagonal section and a press-fit section that together form the connection. Due to wear and fracture problems it is desired to improve the connection. A tapered connection could be an alternative and three different taper angles, the effect of the length of the taper and the smoothness of the outer edge of a tapered fixture have been investigated. The results show that the taper has potential to function well and that a longer connection will give lower stresses in the system, but further investigations are needed.

The Niagara Foot (NF) is a relatively new prosthetic design, primarily intended for use in developing countries. It combines low cost and durability with high performance energy return features. The design has been successfully tested mechanically and in field trials, but to date there has been little quantitative gait data describing the performance of the foot. Biomechanical gait analysis techniques will be used to extract quantitative gait measures. The current study is designed to characterize the effect of heel section stiffness parameter differences between a NF normal heel and a NF with a reduced material heel section., on gait characteristics in persons with unilateral trans-tibial amputations (TTA). Standardized biomechanical gait analysis techniques, adapted for this population, were used to extract quantitative gait measures. Five persons with TTA performed walking tasks while 3D ground reaction forces were recorded via an embedded force platform. A motion capture system also recorded the 3D segmental motion of the lower limbs and torso of each subject. These were combined to calculate net joint moments and mechanical power at the hip and knee of both limbs. These data were compared between a normal NF and a NF with a modified heel. Each participant had a period of two-week adaptation prior to any testing. An EMG system and a prosthesis evaluation questionnaire were used to help analyze the condition. The overall hypothesis of this study was that modification of the heel section stiffness would change several aspects of gait. Although the gait pattern differences between participants and the low participant number produced no significant differences between the conditions for all variables, trends were observed in multiple outcomes. These results report preliminary evidence that for some participants the heel material reduction does impact their gait by showing a different loading phase during the transition between the heel strike and the full contact with the ground. The NF2 may move the gait toward a more flexed knee position. Furthermore, despite a reduction in the material of the heel section results showed that the overall foot stiffness increased. This may be the result of the one-piece design and mechanics of the NF. Further investigations with a bigger cohort of people with TTA are required to look at the importance of the impact of the prosthetic foot heel stiffness.

Neural prostheses are being developed to provide motor capabilities to patients who suffer from motor-debilitating diseases and conditions. These brain-computer interfaces (BCI) will be controlled by activity from the brain and bypass damaged parts of the spinal cord or peripheral nervous system to re-establish volitional control of motor output. Spike sorting is a technologically expensive component of the signal processing chain required to interpret population spike activity acquired in a BCI. No systematic analysis of the need for spike sorting has been carried out and little is known about the effects of spike sorting error on the ability of a BCI to decode intended motor commands. We developed a theoretical framework and a modelling environment to examine the effects of spike processing on the information available to a BCI decoder. Shannon information theory was applied to simulated neural data. Results demonstrated that reported amounts of spike sorting error reduce mutual information (MI) significantly in single-unit spike trains. These results prompted investigation into how much information is available in a cluster of pooled signals. Indirect information analysis revealed the conditions under which pooled multi-unit signals can maintain the MI that is available in the corresponding sorted signals and how the information loss grows with dissimilarity of MI among the pooled responses. To reveal the differences in non-sorted spike activity within the context of a BCI, we simulated responses of 4 neurons with the commonly observed and exploited cosine-tuning property and with varying levels of sorting error. Tolerances of angular tuning differences and spike sorting error were given for MI loss due to pooling under various conditions, such as cases of inter- and/or intra-electrode differences and combinations of various mean firing rates and tuning depths. These analyses revealed the degree to which mutual information loss due to pooling spike activity depended upon differences in tuning between pooled neurons and the amount of spike error introduced by sorting. The theoretical framework and computational tools presented in this dissertation will BCI system designers to make decisions with an understanding of the tradeoffs between a system with and without spike sorting. / Dissertation