Femoral shaft fractures are commonly encountered in orthopaedics and are typically treated using intramedullary (IM) nailing under fluoroscopic guidance. Inaccuracies in the location of the entry point of the nail and the alignment of the reduced fracture are not uncommon during this procedure. This can greatly increase the risk of iatrogenic fractures, malunions and, potentially, secondary degenerative joint disease. Fluoroscopy-based computer-assisted navigation workflows have been developed but are, as yet, not widely used. As such, there is a need to investigate the performance of these systems as well as the possibility of using newer imaging methods to enhance the reduction accuracy. This body of work investigated the impact of off-angle fluoroscopic images on the accuracy and precision of the selection of the entry points used in IM nailing and found that, while images were considered to be clinically acceptable, they resulted in large deviations in the selection of the entry point. Although higher precision was achieved with navigation, it did not improve the accuracy. This work extended the investigation of off-angle images by investigating the impact of the variation in the landmarks used by current navigation methods on quantification of femoral anteversion. The observed landmark variations were propagated through the calculation of femoral anteversion and yielded errors exceeding current clinical tolerances. As an alternative to fluoroscopy, this work developed two, semi-automated algorithms to quantify femoral shaft fracture alignment in six degrees of freedom (6DOF) based on a single, intraoperative cone-beam CT scan. Both algorithms were able to accurately quantify malalignment in all 6DOF with high repeatability and limited user interaction over a range of complex femoral shaft fractures, even in cases with severe comminution. The time requirements for the utilization of these algorithms were reasonable with respect to the time required for current, fluoroscopy-based navigation. Therefore, both of these algorithms would provide an efficient, robust and accurate alternative for the quantification of malalignment in 6DOF. Such an accurate and robust quantification of malalignment, when paired with the high precision tracking in current navigation systems, may enable the improvement of reduction accuracy in the treatment of complex femoral shaft fractures.

Thesis (M.S.E.C.E.)--University of Massachusetts Amherst, 2009. / Includes bibliographical references (p. 66-71).

Com a grande procura da sociedade moderna pela estética perfeita a cirurgia ortognática para conseguir melhores resultados e mais precisos, começou a planejar e diagnosticar os casos clínicos utilizando medidas obtidas de grandezas do perfil tegumentar dos pacientes com o auxílio de imagens digitais empregadas em softwares de planejamento, Neste estudo foi proposto aferir as medidas de brasileiros leucodermas de descendência européia e compará-las com as medidas já padronizadas por ARNETT, com o intuito de criar novas medidas para serem seguidas por brasileiros utilizando-se o software Dolphin Imaging 9.0 de predicção cirúrgica. Foi utilizado na metodologia radiografias cefalométricas de 60 pacientes com oclusão classe I de Angle e harmonia facial. Todas as radiografias foram digitalizadas e inseridas no software Dolphin 9.0 e um total de 16 pontos de tecido mole e 22 pontos do esqueleto facial foram marcados, seguindo exatamente as marcações da análise de Arnett & McLaughlin presentes no programa. Os resultados obtidos foram avaliados estatisticamente e mostram que o perfil do brasileiro é quase totalmente diferente do perfil norte-americano, exceção feita a apenas quatro pontos para os homens e outros quatro, para as mulheres. Os brasileiros apresentam uma face menos protruída, um perfil mais convexo e menor proeminência do queixo do que o grupo controle. Os dados obtidos mostram a necessidade de realizar algumas mudanças nas grandezas numéricas para que um perfeito diagnóstico e planejamento possa ser realizado em brasileiros, criando assim o padrão do perfil facial do brasileiro leucoderma de descendência européia. / Considering that modern orthognatic surgery is mainly concerned in planning and diagnosing clinical cases by the use of patients\' soft tissue measurements obtained from digital images employed in planning software, the aim of this study is to establish Caucasian Brazilians measures and to compare them to the standard North American measures. For this, a total of 60 Angle\'s class I patients not previously submitted to orthodontic treatment and presenting harmonious facial features were invited to participate in the study as volunteers. The patients were initially photographed in frontal and lateral views and, afterwards, cephalograms were obtained. The images were digitized, adjusted and indexed in Dolphin\'s image software. In order to procede cephalometric analysis, a total of 16 soft tissue profile points and 22 hard tissue profile points were demarcated, accordingly to North American original measurements used in Dolphin\'s digital image program. After, all cephalograms were again evaluated to determine intra-examiner error according to paired Student\'s t test. Mean and standard error measures were obtained and compared to American measures by unpaired Student\'s t test with 95% confidence level. The results obtained have shown that all measurements, except for four points in male and four points in female, are significantly different (p < 0.05) between Brazilian and American samples. Datas show that Brazilians\' soft tissue profile is almost completely different from North Americans\', with a less protrusive face, shorter chin projection and a more convex profile. This suggests the necessity of performing some changes in numerical values to obtain an ideal diagnosis and planning of orthognatic surgery in Caucasian Brazilians.

A generally accepted goal in orthopaedic surgery today is to maximize conservation of tissue and reduce tissue damage. Bone-conserving implants have bone-mating surfaces that reproduce the natural curvature of bone structures, requiring less bone removal. No small, reliable, inexpensive and universal bone sculpting technique currently exists, however, that can both create and accurately align such complex surfaces. The goal of this thesis was to develop a haptic hard surface emulation mechanism that could be applied to curvilinear bone sculpting using a surgical robot. A novel dynamic physical constraint concept was developed that is able to emulate realistic hard constraints, smooth surface following, and realistic surface rigidity, while allowing complete freedom of motion away from the constraints. The concept was verified through the construction of a two-link manipulator prototype. Tests were run on nine users that involved each user tracing out five different virtual surfaces on a drawing surface using the prototype. The primary purposes of prototype testing were to obtain subjective data on how effectively the dynamic physical constraint concept simulates simple surfaces, to assess how it reacts to typical user interactions and to identify any unexpected behaviour. Users were 100% satisfied with the prototype’s ability to emulate realistic and stiff hard surfaces and with its ease of manipulation. The amount of incursion into each of the virtual surfaces by all the users was measured to assess the precision of the system with the goal of deciding whether this new haptic concept should be further developed specifically for precision applications such as surgery. For curvilinear surfaces, 90% of the cumulative distribution of the measured data was less than 2mm, while for linear surfaces it was less than 6mm. Four behavioural effects were noticed: lateral deflection, reverse ‘stickiness’, hysteresis and instability in certain areas. These effects were studied in detail to determine how to either eliminate them or to minimize them through system design optimization. A computer simulation was also used to model the behaviour of the prototype and to gain further understanding of these effects. These analyses showed that the concept can be successfully used in curvilinear bone sculpting.

A generally accepted goal in orthopaedic surgery today is to maximize conservation of tissue and reduce tissue damage. Bone-conserving implants have bone-mating surfaces that reproduce the natural curvature of bone structures, requiring less bone removal. No small, reliable, inexpensive and universal bone sculpting technique currently exists, however, that can both create and accurately align such complex surfaces. The goal of this thesis was to develop a haptic hard surface emulation mechanism that could be applied to curvilinear bone sculpting using a surgical robot. A novel dynamic physical constraint concept was developed that is able to emulate realistic hard constraints, smooth surface following, and realistic surface rigidity, while allowing complete freedom of motion away from the constraints. The concept was verified through the construction of a two-link manipulator prototype. Tests were run on nine users that involved each user tracing out five different virtual surfaces on a drawing surface using the prototype. The primary purposes of prototype testing were to obtain subjective data on how effectively the dynamic physical constraint concept simulates simple surfaces, to assess how it reacts to typical user interactions and to identify any unexpected behaviour. Users were 100% satisfied with the prototype’s ability to emulate realistic and stiff hard surfaces and with its ease of manipulation. The amount of incursion into each of the virtual surfaces by all the users was measured to assess the precision of the system with the goal of deciding whether this new haptic concept should be further developed specifically for precision applications such as surgery. For curvilinear surfaces, 90% of the cumulative distribution of the measured data was less than 2mm, while for linear surfaces it was less than 6mm. Four behavioural effects were noticed: lateral deflection, reverse ‘stickiness’, hysteresis and instability in certain areas. These effects were studied in detail to determine how to either eliminate them or to minimize them through system design optimization. A computer simulation was also used to model the behaviour of the prototype and to gain further understanding of these effects. These analyses showed that the concept can be successfully used in curvilinear bone sculpting.

Com a grande procura da sociedade moderna pela estética perfeita a cirurgia ortognática para conseguir melhores resultados e mais precisos, começou a planejar e diagnosticar os casos clínicos utilizando medidas obtidas de grandezas do perfil tegumentar dos pacientes com o auxílio de imagens digitais empregadas em softwares de planejamento, Neste estudo foi proposto aferir as medidas de brasileiros leucodermas de descendência européia e compará-las com as medidas já padronizadas por ARNETT, com o intuito de criar novas medidas para serem seguidas por brasileiros utilizando-se o software Dolphin Imaging 9.0 de predicção cirúrgica. Foi utilizado na metodologia radiografias cefalométricas de 60 pacientes com oclusão classe I de Angle e harmonia facial. Todas as radiografias foram digitalizadas e inseridas no software Dolphin 9.0 e um total de 16 pontos de tecido mole e 22 pontos do esqueleto facial foram marcados, seguindo exatamente as marcações da análise de Arnett & McLaughlin presentes no programa. Os resultados obtidos foram avaliados estatisticamente e mostram que o perfil do brasileiro é quase totalmente diferente do perfil norte-americano, exceção feita a apenas quatro pontos para os homens e outros quatro, para as mulheres. Os brasileiros apresentam uma face menos protruída, um perfil mais convexo e menor proeminência do queixo do que o grupo controle. Os dados obtidos mostram a necessidade de realizar algumas mudanças nas grandezas numéricas para que um perfeito diagnóstico e planejamento possa ser realizado em brasileiros, criando assim o padrão do perfil facial do brasileiro leucoderma de descendência européia. / Considering that modern orthognatic surgery is mainly concerned in planning and diagnosing clinical cases by the use of patients\' soft tissue measurements obtained from digital images employed in planning software, the aim of this study is to establish Caucasian Brazilians measures and to compare them to the standard North American measures. For this, a total of 60 Angle\'s class I patients not previously submitted to orthodontic treatment and presenting harmonious facial features were invited to participate in the study as volunteers. The patients were initially photographed in frontal and lateral views and, afterwards, cephalograms were obtained. The images were digitized, adjusted and indexed in Dolphin\'s image software. In order to procede cephalometric analysis, a total of 16 soft tissue profile points and 22 hard tissue profile points were demarcated, accordingly to North American original measurements used in Dolphin\'s digital image program. After, all cephalograms were again evaluated to determine intra-examiner error according to paired Student\'s t test. Mean and standard error measures were obtained and compared to American measures by unpaired Student\'s t test with 95% confidence level. The results obtained have shown that all measurements, except for four points in male and four points in female, are significantly different (p < 0.05) between Brazilian and American samples. Datas show that Brazilians\' soft tissue profile is almost completely different from North Americans\', with a less protrusive face, shorter chin projection and a more convex profile. This suggests the necessity of performing some changes in numerical values to obtain an ideal diagnosis and planning of orthognatic surgery in Caucasian Brazilians.

Abstract Magnetic resonance imaging (MRI) has excellent soft tissue contrast, which can be enhanced by different contrast agents, multiplanar imaging capability and high temporal and spatial resolution. Even blood vessels can be easily visualised, and MRI parameters are sensitive to temperature. Therefore, MRI has the greatest potential for guiding and monitoring interventional and surgical procedures. The aim of this study was to design and evaluate new solutions for MR-guided procedures and surgery, to develop the technique and to assess the feasibility of MR-guided nerve root infiltration, bone biopsy and sacroiliac (SI) joint arthrography. The possibilities for versatile use of MR scanners were studied with a setup where an MR scanner with a 0,23 T open magnet was installed in a full-scale operating room (OR) to allow diagnostic MRI examinations, research, radiological interventions and neurosurgical operations to be performed in the same facility. All of the 144 MR-guided radiological interventions and neurosurgical operations performed in Oulu University Hospital between February 1999 and September 2000 were included in the study. The studied setup was a functionally feasible solution for combined neurosurgical and radiological use. To further improve MR-guided interventions, a new user interface was developed and preliminary tested with simulated clinical experiments. The new user interface seemed to be easily adobted by radiologists for interventional procedures. MR-guided nerve root infiltrations were studied by using MRI guidance on 34 consequent patients referred for first sacral root infiltration. Needle placement into the first sacral nerve root sheath was successful in 34 of the 35 (97%) cases, and the average duration of the procedure was 32 minutes. Bone biopsies were performed using a bone biopsy set designed in our institution to be connected to an optical tracking system. The feasibility of this new guiding system was evaluated with biopsies from five different anatomical areas. The bone biopsy system was successfully applied to all patients and provided a safe and accurate guidance method for all phases of the procedure. Twenty patients with low back pain suspected to arise from the SI joint underwent MR-guided SI joint arthrography. The procedure was successfully performed in all cases. The needle guiding with optical tracking inside the soft tissues proved to be accurate enough for successful procedures. In conclusion, versatile use of MR scanners for diagnostic imaging, radiological procedures and neurosurgery is feasible if planned properly. The prototype of a new user interface for MR-guided procedures allows radiologist to fully control the MR-scanner during the procedure. MRI is a suitable and accurate guidance method for musculoskeletal interventions.

A generally accepted goal in orthopaedic surgery today is to maximize conservation of tissue and reduce tissue damage. Bone-conserving implants have bone-mating surfaces that reproduce the natural curvature of bone structures, requiring less bone removal. No small, reliable, inexpensive and universal bone sculpting technique currently exists, however, that can both create and accurately align such complex surfaces. The goal of this thesis was to develop a haptic hard surface emulation mechanism that could be applied to curvilinear bone sculpting using a surgical robot. A novel dynamic physical constraint concept was developed that is able to emulate realistic hard constraints, smooth surface following, and realistic surface rigidity, while allowing complete freedom of motion away from the constraints. The concept was verified through the construction of a two-link manipulator prototype. Tests were run on nine users that involved each user tracing out five different virtual surfaces on a drawing surface using the prototype. The primary purposes of prototype testing were to obtain subjective data on how effectively the dynamic physical constraint concept simulates simple surfaces, to assess how it reacts to typical user interactions and to identify any unexpected behaviour. Users were 100% satisfied with the prototype’s ability to emulate realistic and stiff hard surfaces and with its ease of manipulation. The amount of incursion into each of the virtual surfaces by all the users was measured to assess the precision of the system with the goal of deciding whether this new haptic concept should be further developed specifically for precision applications such as surgery. For curvilinear surfaces, 90% of the cumulative distribution of the measured data was less than 2mm, while for linear surfaces it was less than 6mm. Four behavioural effects were noticed: lateral deflection, reverse ‘stickiness’, hysteresis and instability in certain areas. These effects were studied in detail to determine how to either eliminate them or to minimize them through system design optimization. A computer simulation was also used to model the behaviour of the prototype and to gain further understanding of these effects. These analyses showed that the concept can be successfully used in curvilinear bone sculpting. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

No description available.

Considerando as dificuldades que ocorrem com a localização e o posicionamento de implantes e, ainda, o risco de deslocamento das guias, tomográfica e cirúrgica, durante os procedimentos de diagnóstico e cirúrgico, foi objetivo desta pesquisa avaliar, se a alternativa de introduzir dispositivos para retenção e suporte, nas guias da técnica de cirurgia guiada convencional, interfere na posição e inclinação de implantes no momento da sua colocação. Foram confeccionados 10 modelos simulando tecido ósseo, divididos aleatoriamente em 2 grupos: 5 com a guia tomográfica e cirúrgica da técnica convencional, denominado grupo controle (M); 5 com as guias fixadas a ortoimplantes modificados associados ao sistema de encaixe o ring, representando o grupo experimental (MI). A avaliação dos resultados foi pela sobreposição dos planejamentos virtuais (Implant Viewer), derivados de tomografias computadorizadas pré-cirúrgicas, com as realizadas após a colocação dos implantes. Os resultados obtidos mostraram que não houve diferenças estatisticamente significantes para os desvios angulares (Teste Tukey F= 1,06 e p= 0, 3124) e lineares (Teste ANOVA F = 2,54 e p = 0,11). No entanto, os valores angulares individuais do grupo experimental (MI), mostraram ser mais próximos entre si, com menor variabilidade, quando comparados ao grupo controle. Concluiuse, que o uso de ortoimplantes associados ao sistema de encaixe o ring, pode trazer benefícios à técnica da cirurgia guiada convencional, reduzindo as alterações de posicionamento dos implantes no momento da sua colocação. / Computer guided surgery is an excellent alternative to the proper insertion of implants in patients with an edentulous arch or a partially edentulous area and with appropriate quantity of bone. Considering the difficulties that occur with implants placement and the risk of displacement of radiographic and surgical template during the diagnostic and surgical procedures, the aim of this research was to assess if an alternative devices for retention of radiographic and surgical templates can bring benefits for a more accurate implant placement. Ten models made by a material that simulates bone tissue were randomly divided into 2 groups: 5 with the conventional radiographic and surgical guide, which was called control group (M); 5 with modified orthodontic implants that fixed the radiographic and the surgical templates, representing the experimental group (MI). The evaluation of the results was by matching virtual plans (Implant Viewer), derived from pre-operative cone-beam CT images, with post-operative ones to calculate the deviation between planned and installed implants. The results showed that there was no statistically significant differences for angular (Tukey F = 1.06 and p = 0, 3124) and linear deviations (test ANOVA F = 2.54 and p = 0.11). However, the individual angular values of experimental group (MI) showed to be closer to each other, with lower variability when compared to control group. It was concluded that the use of modified orthodontic implant with o ring attachment can bring benefits to conventional guided surgery technique, reducing changes in ideal implant position.