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Bruno, Alexander G. "Investigation of spine loading to understand vertebral fractures." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98727.
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Thesis: Ph. D., Harvard-MIT Program in Health Sciences and Technology, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references.
Vertebral fractures are the most common complication of osteoporosis and are associated with significant pain, height loss, disfigurement, respiratory impairment, depression, and decreased life span. Despite the high personal and societal costs of vertebral fractures, little is known regarding their biomechanical etiology. In particular, whereas much is known about the determinants of vertebral strength, little is known about the in vivo loading of the spine that may contribute to vertebral fracture. Prior efforts to understand the possible contribution of spine mechanics to vertebral fractures have been limited by the inability to accurately assess in vivo spinal loading, especially in the thoracic region. Thus, the overall goal of this work was to improve the understanding of vertebral fractures through detailed analysis of spinal loading. We first developed and validated a novel musculoskeletal model capable of predicting forces in the thoracolumbar spine during daily activities. Model-derived predictions of vertebral compressive loading and trunk muscle activity were highly correlated with previously collected in vivo measurements of pressure, vertebral compression from telemeterized implants, and trunk muscle myoelectric activity from electromyography. To gain insights into how individual variation in trunk anatomy influences vertebral loading, we developed a robust set of methods for rapid, automated generation of subject-specific musculoskeletal models of the thoracolumbar spine using computed tomography based measurements of spine curvature and trunk muscle morphology. Using these subject-specific models, we found that normal variations in spine curvature and muscle morphology in the adult population have a large effect on vertebral loading predictions. Specifically, we found that increasing thoracic kyphosis and reducing lumbar lordosis, changes that commonly occur with age, were both associated with higher spinal loads. Lastly, we used our musculoskeletal model to describe how vertebral loading and the factor-of-risk (load-to-strength ratio) vary along the spine for a large number of activities. For a majority of activities, the highest loads and factor-of- risk were in the thoracolumbar region, which is the spine region with the highest incidence of vertebral fracture. Further, we identified a unique biomechanical mechanism responsible for the high loads in this region.
by Alexander G. Bruno.
Ph. D.
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Kalyan, Raman. "Predictors of outcome in stable thoraco-lumbar spine fractures." Thesis, Queen's University Belfast, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437740.
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Ali, Amira I. Hussein. "3-D visualization and prediction of spine fractures under axial loading." Thesis, Boston University, 2013. https://hdl.handle.net/2144/10927.
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Thesis (Ph.D.)--Boston UniversityVertebral fractures are the hallmark of osteoporosis, yet the failure mechanisms involved in these fractures are not well understood. Current approaches to predicting fracture risk rely on average measures of bone mineral density in the vertebra, which are imperfect predictors of vertebral strength and poor predictors of fracture risk. Prior research has established that substantial regional variations in density exist throughout the vertebra and has suggested several biomechanical consequences of these variations. The overall goal of this dissertation was to characterize failure mechanisms in human vertebrae, with specific emphasis on the role of intra-vertebral heterogeneity in density and microstructure and on identifying clinically feasible techniques for predicting fracture risk. Using images obtained from micro-computed tomography (μCT) and quantitative computed tomography (QCT), the intra-vertebral heterogeneity in bone density was quantified in cadaveric specimens. Quantitative measures of this heterogeneity improved predictions of vertebral strength as compared to predictions based only on mean density. Subsequently, the intra-vertebral heterogeneity in density was measured via QCT in a cohort of post-menopausal women and was found to be lower in those who had sustained a vertebral fracture vs. in age-matched individuals without fracture. The next set of studies focused on assessing the accuracy of finite element (FE) models for predicting vertebral failure. Digital volume correlation (DVC) was used to measure the deformations sustained throughout the vertebra during compression tests. These results were compared against deformation patterns predicted using FE models created from QCT images of the vertebrae. Good agreement was found between predicted and measured deformations when the boundary conditions were accurately defined, despite simplifications made in representing material properties. The outcomes from this dissertation demonstrate that the intra-vertebral heterogeneity in density contributes to bone strength and has promise as a clinically feasible indicator of fracture risk. OCT-based FE models, which by definition account for this heterogeneity, are another promising technique, yet will likely require non-invasive techniques for estimating vertebral loading to provide the requisite accuracy in failure predictions. These two engineering approaches that account for the spatial heterogeneity in density within the vertebra may lead to more sensitive and specific indicators of fracture risk.
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Hussein, Ali Amira I. "3-D visualization and prediction of spine fractures under axial loading." Thesis, Boston University, 2013. https://hdl.handle.net/2144/12124.
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Thesis (Ph.D.)--Boston UniversityVertebral fractures are the hallmark of osteoporosis, yet the failure mechanisms involved in these fractures are not well understood. Current approaches to predicting fracture risk rely on average measures of bone mineral density in the vertebra, which are imperfect predictors of vertebral strength and poor predictors of fracture risk. Prior research has established that substantial regional variations in density exist throughout the vertebra and has suggested several biomechanical consequences of these variations. The overall goal of this dissertation was to characterize failure mechanisms in human vertebrae, with specific emphasis on the role of intra-vertebral heterogeneity in density and microstructure and on identifying clinically feasible techniques for predicting fracture risk. Using images obtained from micro-computed tomography (μCT) and quantitative computed tomography (QCT), the intra-vertebral heterogeneity in bone density was quantified in cadaveric specimens. Quantitative measures of this heterogeneity improved predictions of vertebral strength as compared to predictions based only on mean density. Subsequently, the intra-vertebral heterogeneity in density was measured via QCT in a cohort of post-menopausal women and was found to be lower in those who had sustained a vertebral fracture vs. in age-matched individuals without fracture. The next set of studies focused on assessing the accuracy of finite element (FE) models for predicting vertebral failure. Digital volume correlation (DVC) was used to measure the deformations sustained throughout the vertebra during compression tests. These results were compared against deformation patterns predicted using FE models created from QCT images of the vertebrae. Good agreement was found between predicted and measured deformations when the boundary conditions were accurately defined, despite simplifications made in representing material properties. The outcomes from this dissertation demonstrate that the intra-vertebral heterogeneity in density contributes to bone strength and has promise as a clinically feasible indicator of fracture risk. OCT-based FE models, which by definition account for this heterogeneity, are another promising technique, yet will likely require non-invasive techniques for estimating vertebral loading to provide the requisite accuracy in failure predictions. These two engineering approaches that account for the spatial heterogeneity in density within the vertebra may lead to more sensitive and specific indicators of fracture risk.
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Ochia, Ruth Shada. "Mechanisms of axial compressive fracture in human lumbar spine /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/7997.
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Davis, Johan H. "Thoracolumbar injuries : short segment posterior instrumentation as standalone treatment - thoracolumbar fractures." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/5351.
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Thesis (MMed (Surgical Sciences. Orthopaedic Surgery))--University of Stellenbosch, 2010.Objective: This research paper reports on the radiographic outcome of unstable thoracolumbar injuries with short segment posterior instrumentation as standalone treatment; in order to review rate of instrumentation failure and identify possible contributing factors. Background: Short segment posterior instrumentation is the treatment method of choice for unstable thoracolumbar injuries in the Acute Spinal Cord Injury Unit (Groote Schuur Hospital). It is considered adequate treatment in fracture cases with an intact posterior longitudinal ligament, and Gaines score below 7 (Parker JW 2000); as well as fracture dislocations, and seatbelt-type injuries (without loss of bone column - bearing integrity). The available body of literature often states instrumentation failure rates of up to 50% (Alanay A 2001, Tezeren G 2005). The same high level of catastrophic hardware failure is not evident in the unit researched. Methods: Sixty-five consecutive patients undergoing the aforementioned surgery were studied. Patients were divided into two main cohorts, namely the “Fracture group” (n=40) consisting of unstable burst fractures and unstable compression fractures; and the “Dislocation group” (n=25) consisting of fracture dislocations and seatbelt-type injuries. The groups reflect similar goals in surgical treatment for the grouped injuries, with reduction in loss of sagittal profile and maintenance thereof being the main aim in the fracture group, appropriately treated with Schantz pin constructs; and maintenance in position only, the goal in the dislocation group, managed with pedicle screw constructs. Data was reviewed in terms of complications, correction of deformity, and subsequent loss of correction with associated instrumentation failure. Secondly, factors influencing the aforementioned were sought, and stratified in terms of relevance. Results: Average follow up was 278 days for the fracture group and 177 days for the dislocation group (all patients included were deemed to have achieved radiological fusion – if fusion technique was employed). There was an average correction in kyphotic deformity of 10.25 degrees. Subsequent loss in sagittal profile averaged 2 degrees (injured level) and 5 degrees (thoracolumbar region) in the combined fracture and dislocation group. The only factor showing a superior trend in loss of reduction achieved was the absence of bone graft (when non-fusion technique was employed). Instrumentation complications occurred in two cases (bent connection rods in a Schantz pin construct with exaggerated loss in regional sagittal profile, and bent Schantz pins). These complications represent a 3.07% hardware failure in total. None of the failures were considered catastrophic. Conclusion: Short segment posterior instrumentation is a safe and effective option in the treatment of unstable thoracolumbar fractures as a standalone measure.
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Gallagher, Sean. "Effects of torso flexion on fatigue failure of the human lumbosacral spine." Connect to this title online, 2003. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1070310033.
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Thesis (Ph. D.)--Ohio State University, 2003.Title from first page of PDF file. Document formatted into pages; contains xvii, 238 p.; also includes graphics (some col.). Includes abstract and vita. Advisor: William S. Marras, Dept. of Industrial and Systems Engineering. Includes bibliographical references (p. 204-238).
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Robinson, Anna-Lena. "Axis Fractures in Elderly : Epidemiology and Treatment related outcome." Doctoral thesis, Uppsala universitet, Ortopedi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-333901.
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Background: Axis fractures are a common injury in the elderly population. Treatment is often complicated due to osteoporosis and patient comorbidity. Knowledge of the incidence of these fractures, as well as their treatment, outcome and mortality rate, will improve knowledge and decision-making processes for this fragile group of patients. Objectives: This thesis aims (1) to review the literature on the non-surgical and surgical treatment of odontoid fractures type 2 in the elderly population, (2) to provide an updated overview of axis fracture subtypes, their incidence and their treatment in a cohort in two university cities, (3) to map the incidence of fractures and the treatment of these patients in Sweden, (4) to investigate the effect on mortality of both the surgical and non-surgical treatment of axis fractures and (5) to present the protocol for a randomized controlled trial (RCT) on the treatment of odontoid fractures type 2 in the elderly population. Methods: A systematic review was performed using the MeSH keywords “odontoid AND fracture AND elderly”. The data for the cohort study were extracted from the regional hospital information system. The radiographs were reviewed retrospectively. Data were extracted from the Swedish National Patient Registry (NPR) and the mortality registry for the national registry studies. Finally, the RCT protocol was carried out according to the SPIRIT and CONSORT statements for clinical trial reporting. Results and conclusions: So far, there has been a scarcity of existing evidence on treatment of odontoid fractures type 2 in the elderly population. In this thesis, we found in two university cities an increased incidence, and a trend towards more surgical treatment of type 2 and 3 odontoid fractures 2002-2014. Between 1997 and 2014 in Sweden, there was an increasing incidence of C2 fractures, but the treatment trend went towards more non-surgical treatment. Surgically treated patients had a greater survival rate than non-surgically treated patients. Among those over 88 years of age, surgical treatment lost its effect on survival. In the RCT we will study the function of patients with odontoid fractures type 2 and by comparing non-surgical treatment with posterior C1-C2 fusion, the cost-effectiveness of the treatment options.
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Wilson, Sara E. (Sara Ellen). "Development of a model to predict the compressive forces on the spine associated with age-related vertebral fractures." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/11673.
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KATO, FUMIHIKO, NAOKI ISHIGURO, MASAAKI MACHINO, KEIGO ITO, YASUTSUGU YUKAWA, and HIROAKI NAKASHIMA. "COMBINED POSTERIOR-ANTERIOR SURGERY FOR OSTEOPOROTIC DELAYED VERTEBRAL FRACTURE WITH NEUROLOGIC DEFICIT." Nagoya University School of Medicine, 2014. http://hdl.handle.net/2237/20549.
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Lison, Almkvist Viktor. "FE-Analysis of Stabilization of Cervical Spine Fracture in Ankylosing Spondylitis." Thesis, KTH, Hållfasthetslära (Inst.), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-175357.
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Ankylosing Spondylitis (AS), or Bechterew’s disease, is an inflammatory rheumaticdisease that through the formation of additional bone tissue in the spine eventuallyleads to the complete fusion of the vertebrae, in effect turning the spine into one longbone. Due to the reduced flexibility of the spine with the long lever arms, spinalfractures in AS-patients are relatively common even after minor trauma. The aim of this thesis was to use an existing finite element model of a healthy spineand adapt it to the conditions of AS, thus gaining some insight into the effects ofsurgical stabilization of cervical fractures, using posterior screws and rods. Althoughthis type of surgery is often performed, it has not been previously investigated in abiomechanical model. This thesis should be considered as a starting point for how afinite element model of the spine could be used to investigate the effect of spinalimplants in the case of a fracture in the ankylosed spine. An existing FE-model was modified to some of the conditions of AS: The vertebraewere fused by adding ossifications at the intervertebral discs (with the Head-C1 andC1-C2 joints left mobile). A fracture was simulated at the C6C7 disc level. Fourdifferent implant configurations were tested: Short instrumentation C6C7, mediuminstrumentation C5toT1, long instrumentation C3toT3, and a long instrumentationC3C6C7T3 with skipped intermediate levels. Three loads (1.5g, 3.0g, 4.5g) wereapplied according to a specific load curve. Kinematic data such as the gap distance inthe fracture site were obtained. Furthermore the stresses in the ossified parts of thediscs were evaluated. It was shown that the chosen methods of adapting the model to the AS conditions, andmodeling the fracture and implant, changed the kinematics so that less movementoccurred between the vertebra, which is typical for AS. Measured as fracture gap, alltested implant configurations were equally good at stabilizing the fracture, althoughthey all allowed more movement than the non-fractured AS-model did. All implantconfigurations were also able to stabilize the fracture in terms of the horizontal translation in the fracture. The disc ossifications were somewhat shielded from stress for those ossifications that were within the range of the implant. This was so for all implant configurations. No increased stress was observed in the ossifications immediately outside the range for the implants, relative the non-fractured AS-model. For the C6C7 and C5toT1 implant configurations as well as the non-fractured ASmodel,the stresses were highest at the T1T2 level. Stresses in the ossifications in the thoracic spine were generally low, apart from the T1T2 level. The results show that the chosen AS-adaptations and the modeled implant seem reasonable for testing some of the considerations of cervical fractures in the ankylosed spine as well as for some implant configurations. The results also make it possible to speculate about the optimal type of implant. The effects of screw placement and anchoring, osteoporosis, muscle activation and possible spinal deformity on the implant stability were not investigated, and should be a matter for further studies.Ankyloserande Spondylit (AS), eller Bechterew’s sjukdom, är en inflammatorisk, reumatisk sjukdom som innebär att ny benvävnad formas i ryggraden. Detta leder till att kotorna slutligen smälter samma. I praktiken leder detta till att ryggraden fogas samman till ett enda långt ben. Vid en reducerad flexibilitet med långa hävstänger är frakturer i kotpelaren relativt vanliga för patienter med AS även vid mindre trauma. Syftet med denna uppsats var att använda en existerande FE-modell av en frisk rygg och nacke, och anpassa den till det tillstånd som är typiskt för AS. Vidare var syftet att erhålla insikt om hur kirurgisk stabilisering med skruvar och stänger av en fraktur i nacken beter sig. Trots att denna typ av operation utförs förhållandevis ofta, så har detta inte tidigare undersökts i någon biomekanisk modell. Denna uppsats kan ses som en utgångspunkt för hur en FE-modell av ryggraden kan användas för att undersöka effekten av stabiliserande implantat av en fraktur vid AS. En existerande FE-modell modifierades för att överensstämma med några av de villkor som gäller vid AS: Kotorna fogades samman via förbeningar i diskarna. (Huvud-C1 och C1-C2-lederna lämnades rörliga). En fraktur simulerades i C6C7- nivån. Fyra olika konfigurationer av implantat provades: Kort implantat C6C7, mellanlångt implantat: C5tillT1, långt implantat C3tillT3 och ett långt implantat C3C6C7T3 där mellanliggande kotor hoppades över. Tre lastfall (1.5g, 3.0g, 4.5g) applicerades enligt en specifik lastkurva. Kinematisk data såsom “fracture gap distance” i frakturen registrerades. Vidare registrerades också spänningarna i de förbenade delarna av diskarna. Det var möjligt att, genom att anpassa modellen till AS och modellera fraktur och implantat, påverka nackens kinematik så att mindre rörelse skedde mellan kotorna, vilket är typiskt för AS. Med utgångspunkt i mätningarna av “fracture gap distance”, var det möjligt för alla konfigurationer av implantat att stabilisera frakturen, även om implantaten tillät mer rörelse än AS-modellen som saknade fraktur. Detta gällde även för horisontell translation i frakturen. Vad gällde spänningarna i förbeningarna så avlastades dessa för de förbeningar som var belägna inom implantatets räckvidd. Detta gällde för alla implantatkonfigurationer. Inga spänningskoncentrationer observerades i förbeningarna precis utanför implantatens räckvidd i förhållande till AS-modellen utan fraktur. Vad gällde C6C7 och C5toT1 implantaten, liksom ASmodellen utan fraktur, så registrerades de högsta spänningarna i T1T2-nivån. Spänningarna i förbeningarna i bröstryggen var generellt låga, bortsett från T1T2- nivån. Resultaten visade att de valda anpassningarna till AS och sättet att modellera implantaten verkade vettiga för att undersöka några av de överväganden som uppstår vid nackfrakturer i en ankyloserad kotpelare, samt ett par implantatvarianter. Resultaten möjliggör även spekulationer kring vilken typ av implantat som är optimal. Huruvida implantatstabiliteten påverkades av placeringen av skruvar, infästningen i benvävnaden, osteoporos, muskelaktivering och möjlig missbildning av ryggen undersöktes inte. Detta kan undersökas i framtida studier.
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Fuster, Obregón Salvador. "Estudio experimental sobre diferentes métodos de osteosíntesis del raquis dorsolumbar." Doctoral thesis, Universitat de Barcelona, 1987. http://hdl.handle.net/10803/295120.
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1) INTRODUCCIÓN
Hemos estudiado los traumatismos de la columna dorsolumbar basándonos en los estudios biomecánicos de Junghans 1931, Rolander 1966, Farfan 1970 y White y Panjabi 1978, entre otros. Definimos la inestabilidad ajustándonos a los criterios de White y Panjabi 1978, y las clasificamos según Denis 1984. Estadísticas diversas concuerdan con el estudio de Laborde y cols. 1980, aceptando que la inmensa mayoría de las fracturas son por flexión y no se acompañan de déficits neurológicos, aunque algunas son inestables mecánicamente y requieren tratamiento quirúrgico. Precisarían una osteosíntesis anterior que ejerciera la función que llevaban a cabo los elementos destruidos, pero la mayor morbimortalidad de las terapéuticas anteriores nos derivan a la búsqueda de técnicas quirúrgicas de implantación posterior que, desde una vía de abordaje menos problemática, sean igualmente eficaces en la resolución de estos casos.
2) HIPÓTESIS DE TRABAJO
Las fracturas de la columna dorsolumbar por mecanismo de flexión-compresión, que afectan a la columna anterior y media, son inestables y precisan, como método de osteosíntesis idóneo, una técnica anterior que remedie la función de las estructuras afectas. En estas fracturas, los métodos de implantación posterior no trabajan en las condiciones biomecánicas adecuadas para soportar esfuerzos de flexión-compresión, y por tanto, aportarán más estabilidad aquellos sistemas que combinen compresión interfragmentaria y distracción. Idearemos el método experimental necesario para ensayar una técnica original de compresión interfragmentaria más distracción, comparándola con las osteosíntesis más preconizadas,
3) MATERIAL Y MÉTODOS
Se han utilizado especímenes frescos de columna de cerdo conteniendo las vértebras D9 a L5, ambas inclusive. Se ha diseñado un utillaje original para fijar el espécimen a la bancada de pruebas, obteniéndose cinco vértebras libres donde se implantarán las osteosíntesis a estudio. Se efectúa una fractura experimental que afecta al cuerpo vertebral de Ll, claramente inestable. Al especímen preparado se le implantan sucesivamente, y siempre por el mismo orden, los métodos de Kostiuk-Harrington, Roy-Camille, doble Harrington a distracción (HDR), Harrington- Luque, Luque y la técnica de doble HDR modificada por Villanueva. Este autor ha utilizado la barra de Harrington diseñada para efectuar compresión intertransversaria en las escoliosis y la ha aplicado en compresión sobre la línea media posterior. Inmediatamente efectúa distracción con barra a ambos lados.
Se han efectuado 36 ensayos sobre 8 especímenes, aplicándose esfuerzos de flexión-compresión descentrada. Se han medido la fuerza aplicada, la distancia de aplicación de la fuerza, el desplazamiento sufrido por el segmento lesionado y la tensión soportada por los implantes. A tal fin, se han dispuesto galgas extensométricas en los materiales de osteosíntesis y se han tomado instantáneas fotográficas en cada variación del esfuerzo aplicado. A partir de estos parámetros se han calculado cinco variables: ángulo girado por el segmento lesionado, momento soportado por la fijación, momento soportado por la columna, fuerza soportada por la fijación y fuerza soportada por la columna. Se han construido gráficos calculando la pendiente para estas variables y para el nivel de tensión soportado por los implantes.
4) RESULTADOS
La comparación de los seis sistemas estudiados en base a las variables escogidas indica que el sistema de Kostuik-Harrington implantado por vía anterior es el que aporta más rigidez a la columna y mejora la descarga, trabajando con bajas tensiones. Entre las técnicas posteriores, las placas de Roy-Camille estabilizan mucho la muestra y soportan bajos niveles de tensión, mientras que el HDR-Villanueva es la técnica que más descarga la columna, con bajos guarismos de tensión, aunque rigidifique poco el espécimen. Los sistemas que utilizan lazadas de Luque descargan poco la columna y soportan altas tensiones con valores de rigidez intermedios. El HDR tradicional padece altas tensiones de material, no rigidifica apenas y descarga poco al espécimen.
5) DISCUSIÓN
Owen y cols. 1984, no encuentran diferencias significativas entre el cerdo, Sus scrofa domesticus, y el Homo sapiens, en la anatomía comparada. Los estudios se han hecho "in vitro" dado que no se comparan aspectos clínicos sino las prestaciones de diversas técnicas ante solicitaciones iguales. La fractura experimental es inestable siguiendo cualquier criterio de clasificación (Holdsworth 1963, Louis 1977, Denis 1984). Los mejores resultados del sistema de Kostuik-Harrington se deben a su localización anterior que le permite trabajar como un puntal, mientras que los implantes posteriores lo hacen como tirantes externos.
Los métodos que utilizan distracción obtienen peores resultados que los implantados en neutralización, puesto que al aplicar los esfuerzos la columna se comprime anteriormente y se tracciona posteriormente, lo que descarga el método estabilizador. Con el sistema HDR-Villanueva este efecto desaparece por la presencia de fuerzas compresoras que se contraponen a las fuerzas distractoras y permiten descargar mucho la muestra con niveles de tensión muy bajos. Al efectuar esfuerzos de flexión y compresión las fuerzas compresoras excedentes se desplazan a la porción anterior del cuerpo sin que aparezcan pérdidas de reducción posteriores, en un mecanismo intermitente de compresión dinámica.
6) CONCLUSIONES
Para el modelo experimental propuesto, el mejor método de osteosíntesis es aquel que sustituye la función de las estructuras lesionadas. De entre las técnicas posteriores los mejores resultados los ofrecen las placas de Roy-Camille. Los métodos que se colocan en compresión ven reforzada su misión, mientras que los que se colocan en distracción pierden su acción estabilizadora. La estabilidad de un sistema no depende tanto del número de puntos de apoyo que tome en la región instrumental izada sino en las fuerzas que genere para rigidificar el segmento.
La combinación de compresión y distracción establece un equilibrio de fuerzas que disminuye los niveles de tensión en el implante. La compresión interfragmentaria complementando un sistema distractor genera una dinámica de fuerzas que proporciona altos niveles de descarga de la columna lesionada. Los métodos que utilizan lazadas de Luque rigidifican mucho a expensas de altas fatigas del material y mínimo reposo por lesión. Por otro lado no existen diferencias significativas entre el Harrington- Luque que utiliza distracción, y el Luque en neutralización, lo que refuerza la poca relevancia de las fuerzas a distracción para la estabilización del modelo ensayado.We compared the biochemical behaviour of different methods of osteosynthysis of dorsolumbar rachis under flexion and compression stress testing, while stabilizing an expenmentally produced unstable lesion. The method of choice was the "in vitro" experimental study on specimens of the pig spinal column, including vertebra IX (a)D to V(a)L. An unstable fracture was produced in the anterior and mid-segment of the vertebra I(a)L also involving the intervertebral disc XII(o) D-I(o) L, and was osteosynthesized with the following methods: Kostuik-Harrington, Roy-Camille, Harrington's Distraction, Harrington-Luque, Luque and Harrington modified by Villanueva as an original technique not experimentally verified. Thirty-six trials were carried out on eight specimens and the following parameters were measured for each stepped-up load applied: the force supported by the specimen, the distance from the axial axis of load to the posterior wall of the lesioned vertebra, the angle turned by the involved segment and tensions supported by the implantations. The measurement of displacement undergone by the specimen and the tensions supported by the various methods of osteosynthesis were carried out by instantaneous photograph taken with each new load introduced and by the extensometric gauge implanted in the trial methods. Deformation variables, force borne by the column and tensions suffered due to the implantation were calculated and compared. The best method for the experimental model chosen was seen to be that of Kostuik-Harrington as it made the lesion very rigid, relieved the load from the column and functioned under low tensions. This was followed by the Roy-Camille plates which brougth about great rigidity of the instrumented segment with low tensions of the material. Harrington's method, modified by Villanueva, which combines interfragmentary compression and distraction, provided the greatest unloading of the lesioned column and shown little wear of material, although rigidity was low. Sublaminar segmentation techniques caused great rigidity of the column but brought about very high tensions of material and unloading was minimal. Harrington's Distraction method unloaded the column only very slightly, did not bring about rigidity and supported high tensions of materials.
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Shea, Thomas Michael. "Localized Expansion of Pedicle Screws for Increased Stability and Safety in the Osteoporotic Spine." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5308.
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When a patient is diagnosed with various spinal injuries, deformities, or advanced degeneration, it is commonly suggested that he/she undergoes surgery for spinal fusion. Most current procedures in spinal fusion restrict mobility in one or multiple levels of the spine so that, over time, new bone will grow between the levels creating a single motionless unit of bone. The bilateral pedicle screw system (BPSS) has long been considered to be the "gold standard" in spinal fusion. However, for patients with osteoporosis, adequate fixation within the bone-screw interface has continuously been difficult to achieve or has come with high risk of other forms of catastrophic damage. Reflecting this, a new pedicle screw design was developed and evaluated against current standard pedicle screws commonly used in spinal surgery. All screw designs were also tested with a common cement augmentation technique surrounding the circumference of the screw. All tests measured pullout strength, stiffness, energy to failure, toughness, and the amount of destruction to the surrounding synthetic bone. While the newly designed pedicle screw failed to produce significantly stronger pullout forces in comparison to the standard screws, it did show evidence of a longer lasting residual axial resistance and a safer mode of failure than the standard screw, hinting that the design may benefit individuals who experience screw pullout and are awaiting reinstrumentation.
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Figueiredo, Adriana Valente de. "Estudo biomecânico ex vivo em coluna tóraco-lombar de cães com técnicas de estabilização utilizando Placa Bloqueada, Clamp Rod Internal Fixation, Pino com Cimento Ósseo e Técnica Segmentar Modificada." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/10/10137/tde-20082014-145759/.
Full textAbstract:
Fraturas e luxações vertebrais decorrente de trauma consistem afecção neurológica frequente na prática clínica veterinária, sendo a coluna tóraco-lombar a mais comumente afetada em cães, e em muitos casos o tratamento cirúrgico é de eleição. Existem diversas técnicas propostas a realizar estabilização vertebral, entretanto, estudos em coluna tóraco-lombar não foram realizados para avaliar as propriedades biomecânicas de cada técnica. Baseado nisso, nossa pesquisa teve como objetivo fazer uma avaliação biomecânica comparando a força e rigidez promovidas por cinco diferentes técnicas de estabilização em coluna toracolombar (Pinos com Cimento Ósseo, Técnica Segmentar Modificada, Placa Bloqueada e Clamp Rod Internal Fixation utilizando parafusos monocorticais e bicorticais) frente às forças de compressão e flexão. Foram utilizadas 34 colunas tóraco-lombares de cães, divididas em cinco grupos. Para realização dos testes biomecânicos, foi utilizada a máquina de ensaios Kratos (modelo KE3000MP) e célula de carga de 100 kg. Para cada corpo de prova, três testes biomecânicos foram realizados, o controle, no segmento íntegro, após desarticulação de T13/L1 e após realização de uma das técnicas de estabilização propostas. Os dados foram exportados para análise estatística para o programa Statistical Package for the Social Sciences (SPSS) versão 18.0. Os resultados permitiram concluir que, apesar de não haver diferença estatística significativa, a Placa Bloqueada foi a técnica que promoveu maior rigidez e estabilidade nas vértebras lesionadas, seguida do CRIF bicortical, técnica Segmentar Modificada e Pinos e Cimento Ósseo. Estatisticamente, a Placa Bloqueada e o CRIF com parafusos bicorticais apresentaram maior rigidez e estabilidade em T13/L1 quando comparados com a técnica CRIF monocortical, que por sua vez, não alcançou rigidez necessária para adequada estabilização das vértebras.Spinal fractures and luxations resulting from trauma consist frequent disorder in clinical veterinary practice, being thoracolumbar spine the region that is the most commonly affected in canines, thus in many cases surgical treatment is necessary. There are several proposed techniques of implants to perform spinal stabilization; however, few studies of the thoracolumbar spine were carried out to evaluate the biomechanical properties of each technic. Therefore, the objective of the present study is to analyze biomechanical effects comparing the strength and the stiffness promoted by five different technics of stabilization in the thoracolumbar spine (pin with bone cement, modified segmental stabilization, locking plate and clamp rod internal fixation) under compression and bending forces. In the study, thirty four thoracolumbar dog spines were used, dividing the specimens in five groups. In order to perform the biomechanical tests, it was used a Kratos testing machine (model KE3000MP) and loading cell of 100 Kg. Each body of proof was submitted to three biomechanical tests, the control, in the segment intact, after disarticulation of the T13/L1 and after the realization of one of the proposed technics. Data were exported to statistical analyses to the Statistical Package for the Social Sciences (SPSS) version 18.0. The results led to the conclusion that despite there was no statistically significant difference between the techniques, the Locking Plate was the technique that promoted greater rigidity and stability in the injured vertebrae, followed by the Clamp Rod Internal Fixation bicortical, Modified Segmental Instrumentation and Pins with Bone Cement. Statistically, the locking plate and the Clamp Rod Internal Fixation with bicortical pins showed more stiffness and stability in T13/L1 when compared to the Clamp Rod Internal Fixation monocortical, which did not achieved the adequate rigidity for the stabilization of the vertebrae.
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Wilson, Sara E. (Sara Ellen). "Analysis of the forces on the spine during a fall with applications towards predicting vertebral fracture risk." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/33545.
Full textAbstract:
Thesis (Ph.D.)--Harvard--Massachusetts Institute of Technology Division of Health Sciences and Technology, 1999.Includes bibliographical references.
Age-related vertebral fractures are a common public health problem for the elderly with an estimated 27 percent of U.S. women aged 65 years and over thought to have at least one vertebral fracture. It is important, therefore, to characterize the "at risk" patient and to find methods of reducing that risk. Fracture risk has been defined as the ratio of applied loads to the force required to fracture a bone. Although studies have examined the force required to fracture, few studies have tried to assess the applied loads associated with fractures. Epidemiological studies have found that as many as 30 to 50 percent of vertebral fractures are associated with falls. This work examines the forces on the spine during a backward fall. Models of a passive fall, without tension in the torso musculature, were constructed in order to examine the peak axial forces on the spine as a result of a passive fall. Muscle tension elements were added to examine the effect of pre-compression of the spine by the musculature. Three experimental and observational studies were performed to examine the input parameters of these models. This included an experimental measurement of the stiffness and damping of the spine segments, measurement and modeling of the fall dynamics in a backward fall, and measurement of the geometry of the torso musculature. The peak axial forces on the spine were found to range from 1100 Newtons to 3500 Newtons depending on a number of factors including the fall impact dynamics (fall velocity and torso angle), the body weight of the individual, the properties of the soft tissue of the pelvis and spine, and the amount of muscle tension in the torso musculature. These forces can be compared to a mean compressive failure force around 2000 N in elderly thoracolumbar vertebrae. This puts a portion of the elderly population at risk for a fracture simply from an upright passive fall of average velocity. The highest forces were found in upright, fast falls in which the individual had a high upper body weight and very tense torso musculature and little damping in the spine.
by Sara E. Wilson.
Ph.D.
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Junior, Jefferson Rosi. "Ocorrência de traumatismo raquidiano em doentes em coma decorrente de traumatismo cranioencefálico." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/5/5138/tde-25042012-093451/.
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Foi realizado estudo prospectivo com o objetivo de se determinar a ocorrência de traumatismo raquidiano (TR) em 355 doentes em coma decorrente de traumatismo cranioencefálico (TCE) resultante de acidente de tráfego atendidos no Pronto Socorro de Neurocirurgia do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (PSNCHCFMUSP) de 1° de setembro de 2003 a 31 de dezembro de 2009. Todos os doentes foram submetidos ao exame físico e neurológico e à tomografia computadorizada (TC) do corpo inteiro para diagnosticar-se e avaliar-se a gravidade das lesões traumáticas encefálicas, vertebrais ou de outras regiões no momento da admissão ao PSNCHCFMUSP. Em 69 (19,4%) doentes, foi(ram) diagnosticada(s) lesão(ões) na coluna vertebral com o exame de TC da coluna vertebral. As idades dos doentes variaram de 12 a 55 anos (média de 29,0 anos). Eram do sexo masculino 57 (82,6%) doentes. As causas do(s) traumatismo(s) foi(ram) acidente(s) envolvendo motocicleta em 28 (40,6%) casos, atropelamento em 21 (30,5%), colisão de automóvel, caminhão ou caminhonete, em 18 (26,1%) ou acidente com bicicleta em dois (2,9%). Hemorragia subaracnóidea traumática foi a anormalidade intracraniana traumática mais evidenciada no exame de TC do crânio; ocorreu em 57 (82,6%). O(s) processo(s) transverso(s) foi(ram) o(s) segmento(s) vertebral(is) mais acometido(s) pela(s) fratura(s). A sétima vértebra cervical foi a mais lesada; nela identificaram-se fraturas em 24 (34,8%) doentes. Evidenciou-se que a distribuição das fraturas foi similar ao longo das demais vértebras da coluna cervical, quatro primeiras vértebras torácicas e vértebras lombares. Em oito (11,6%) doentes a(s) lesão(ões) neurológica(s) foi(ram) classificada(s) como Frankel A, e nos demais 61(88,4%), como Frankel não-A. Houve necessidade de cirurgia espinal em 24 (34,8%) doentes e de neurocirurgia craniana em 18 (26,0%) doentes. A Escala de Recuperação de Glasgow foi aplicada para avaliar-se as condições neurológicas do doente no momento da alta hospitalar e revelou ocorrência de óbito em dois (2,9%) doentes. Concluiuse que é recomendada a avaliação clínica e também com métodos de imagem da coluna vertebral nos doentes em coma decorrente de TCEThe author presents a prospective study aiming the evaluation of coexistence of spinal injury (SI) in 355 patients presenting coma due to craniocerebral trauma assisted at the Emergency Room of the Hospital das Clínicas of the University of São Paulo Medical School, from September, 1st, 2003 to december, 31th,2009. All patients underwent physical and neurological examination and had computed tomography (CT) scanning of the entire body to diagnose and evaluate the severity of brain and spinal injury at the time of admission. Traumatic lesions of the spine were diagnosed in 69 (19.4%) patients. The ages of patients ranged from 12 to 55 years (mean = 29,0 years).The SI predominated in males, corresponding to 57 (82.6%) patients. The causes of the trauma were motorcycle accident in 28 (40.6%) cases, running over in 21(30.5%), car collision 18 (26.1%) cases and bicycle accident in two (2.9%). Traumatic subarachnoid hemorrhage was the most common traumatic intracranial abnormality in the CT images; it was identified in 57 (82.6%) patients. The transverse process was the most common vertebral part presenting fracture(s). The 7th cervical vertebra was individually the most commonly affected; traumatic lesion of this vertebra presented in 24 (34.8%) patients. The diagnosis of fracture(s) was similar in the other cervical vertebrae and occurred also in the first four thoracic and in the lumbar vertebrae. Severe neurological deficit secondary to spine fracture was diagnosed in eight (11.6%) patients, classified as Frankel A. The others 61(88.4%) patients did not present complete spinal cord or spinal roots neurological deficits were classified as Frankel non A. The Recovery Scale of Glasgow was used to evaluate the neurological status at discharge from hospital. Two (2.9%) patients died. Spinal surgery was necessary in 24 (34.8%) patients and cranial surgery in 18 (26.0%). It was concluded that in addition to clinical evaluation, the CT imaging of the spine is recommended in patients in coma due to mechanical traumatic head injury
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López, Alejandro. "Injectable Biomaterials for Spinal Applications." Doctoral thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-215606.
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The use of injectable biomaterials is growing as the demands for minimally invasive procedures, and more easily applicable implants become higher, but their availability is still limited due to the difficulties associated to their design. Each year, more than 700,000 vertebral compression fractures (VCF’s) are reported in the US and 500,000 VCF’s in Europe due to primary osteoporosis only. VCF’s can compromise the delicacy of the spinal canal and also cause back pain, which affects the patient’s quality of life. Vertebroplasty was developed in the 80’s, and has proven to be a safe minimally invasive procedure that can, quickly and sustainably, relieve the pain in patients experiencing VCF’s. However, biomaterials for vertebroplasty still have limitations. For instance, ceramic bone cements are difficult to distinguish from the bone using X-ray techniques. On the other hand, acrylic bone cements may cause adjacent vertebral fractures (AVF’s). Large clinical studies have indicated that 12 to 20% vertebroplasty recipients developed subsequent vertebral fractures, and that 41 to 67% of these, were AVF’s. This may be attributed to the load shifting and increased pressure on the adjacent endplates reached after vertebroplasty with stiff cements. The primary aim of this thesis was to develop better injectable biomaterials for spinal applications, particularly, bone cements for vertebroplasty. Water-soluble radiopacifiers were first investigated to enhance the radiopacity of resorbable ceramic cements. Additionally, different strategies to produce materials that mechanically comply with the surrounding tissues (low-modulus bone cements) were investigated. When a suitable low-modulus cement was produced, its performance was evaluated in both bovine bone, and human vertebra ex vivo models. In summary, strontium halides showed potential as water-soluble radiocontrast agents and could be used in resorbable calcium phosphates and other types of resorbable biomaterials. Conversely, linoleic acid-modified (low-modulus) cements appeared to be a promising alternative to currently available high-modulus cements. It was also shown that the influence of the cement properties on the strength and stiffness of a single vertebra depend upon the initial bone volume fraction, and that at low bone volume fractions, the initial mechanical properties of the vertebroplasty cement become more relevant. Finally, it was shown that vertebroplasty with low-modulus cements is biomechanically safe, and could become a recommended minimally invasive therapy in selected cases, especially for patients suffering from vertebral compression fractures due to osteoporosis.
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Schulze, Danny. "Einsatz und Wertigkeit der CT-gestützten Navigation bei der operativen Versorgung instabiler thorakolumbaler Wirbelfrakturen." Doctoral thesis, Universitätsbibliothek Leipzig, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-105098.
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Durch die Entwicklung moderner Technologien konnte die Unfallchirurgie in der vergangenen Dekade enorme Fortschritte in der operativen Behandlung von Frakturen im Bereich der zervikalen, thorakalen und lumbalen Wirbelsäule verzeichnen. In allen operativen Behandlungsverfahren ist der Einsatz der computergestützten Navigationstechnik möglich. Anhand der vorliegenden Arbeit wird die Wertigkeit der CT-gestützten Navigation bei der operativen Behandlung thorakolumbaler Wirbelkörperfrakturen hinsichtlich der klinischen Bedeutsamkeit in der alltäglichen Anwendung untersucht. Als wesentliche Aspekte wurden dabei Genauigkeit, Reproduzierbarkeit, mögliche Risiken und Fehlerquellen sowie Anforderungen an das behandelnde Personal integriert.
Im Rahmen einer retrospektiv-deskriptiven Studie wurden im Zeitraum März 2002 und Juli 2004 insgesamt 97 (64 männliche, 33 weibliche) Patienten an der Klinik für Unfall-, Wiederherstellungs- und Plastische Chirurgie des Universitätsklinikums Leipzig operativ mit CT-gestützter Navigationstechnik mit Frakturen der thorakolumbalen Wirbelsäule versorgt und hinsichtlich des perioperativen und poststationären Verlaufes einschließlich potentieller Komplikationen nachuntersucht. Sowohl traumatisch (n= 83) als auch nichttraumatisch bedingte (n= 14) Frakturen der Wirbelsäule sind mit Einsatz der genannten Techniken versorgt worden.
Während der größere Teil der Patienten im Alter bis 65 Jahren männlich ist, überwiegen im Alter ab 65 Jahren weibliche Patienten. Am häufigsten ist der Bereich 12. BWK und 1. LWK (70,3%) betroffen. Als Frakturursachen dominieren Stürze aus der Höhe. Unter den pathologischen Frakturen kommen vor allem Wirbelkörpermetastasen vor.
Die Klassifizierung der Frakturen erfolgte anhand der Einteilung nach Magerl et al. OP-Indikationen liegen für Frakturen A2.3 - A3.3 sowie für alle B – und C-Frakturen vor. Ausnahmen stellten stark kyphosierte A1.2-Frakturen (>15-20° Kyphosewinkel, hier wurde die operative Stabilisierung vorgenommen) und wenig kyphosierte A3.1-Frakturen dar (hier wurde das konservative Vorgehen bevorzugt).
Die operativen Möglichkeiten zur Stabilisierung reichen von isoliert dorsaler Versorgung mittels Fixateur interne (n=14) über isoliert ventrale (n=26) bis hin zu kombiniert dorsoventralen (n=57) Verfahren. Die am häufigsten durchgeführten dorsoventralen Operationen wurden überwiegend zweizeitig (70,2% der dorsoventralen OP´s ) durchgeführt.
Postoperativ wurden die Patienten ab dem 1. postoperativen Tag mobilisiert. Anhand von Scoresystemen (Visuelle Analogskala, Hannover Wirbelsäulenscore, Frankel-Score (ASIA), Kraftgradeinteilung nach Janda, SF-36-Fragebogen) konnte der postoperative Verlauf im Rahmen der Nachuntersuchung nachvollzogen und dokumentiert werden. Röntgenbilder und CT-Aufnahmen ermöglichten ebenfalls eine Verlaufsbeobachtung.
Die Integration der Navigation in etablierte OP- Verfahren stellte einen erhöhten Aufwand im Rahmen der OP- Vorbereitung als auch bei Durchführung der Operation selbst dar. Besonders in anatomisch kritischen Regionen und speziellen anatomischen Gegebenheiten zeigte sich der Nutzen dieser neuen Methode durch die zusätzliche vom Chirurgen nutzbare axiale Bildebene.
Verschiedene Einflussfaktoren können dazu führen, dass eine Weiterverwendung des Navigationssystems für den Fortlauf der Operation nicht möglich und ein Umstieg auf konventionelle Verfahren notwendig ist. In der vorliegenden Arbeit lagen Ungenauigkeiten durch technische Probleme vor allem beim Matching (n=4) vor, seltener eine auffällige Fehllage bei der Pedikelschraubenimplantation (n=2), sowie intrapleurale Verwachsungen im Rahmen ventraler navigationsgestützter Eingriffe bei 2 Patienten. Navigationsbedingte Komplikationen traten bei der ventralen Versorgung nicht auf. Besonderes Augenmerk lag auf der Präzision bei der Implantation von Pedikelschrauben. Vor allem im mittleren und oberen BWS-Bereich zeigte sich die dorsale Navigation aufgrund der besonderen anatomischen Situation mit engen Pedikeln hilfreich. Aber auch im unteren BWS- und im gesamten LWS-Bereich kann die Navigation die hohen Ansprüche an die Präzision und Sicherheit für den Operateur und den Patienten steigern. Von 124 Pedikelschrauben bei traumatisch bedingten Frakturen wurden 98 optimal zentral eingebracht. 19 Schrauben davon ließen B-Perforation und 7 Schrauben eine C-Perforation erkennen. Unter den 24 eingebrachten Pedikelschrauben bei pathologischen Frakturen waren 19 in zentraler Lage. Somit können zwar Perforationen nicht gänzlich vermieden werden, jedoch wird die Wahrscheinlichkeit für das Auftreten von Pedikelperforationen durch den Einsatz der modernen Technik insbesondere an der oberen BWS gesenkt. Zu beachten ist allerdings die nicht zu vernachlässigende verlängerte Vorbereitungszeit für die Operation (Erstellung des Datensatzes), die verlängerte OP-Dauer (Matching, initialisieren der Technik) und der erhöhte Material- und Personalaufwand.
Die Durchleuchtungszeit bei der Insertion von Pedikelschrauben war an der oberen BWS (BWK 1-8) signifikant länger als an der unteren BWS und LWS. Im Vergleich zwischen navigierten und nicht navigiert implantierten Pedikelschrauben zeigte sich im beobachteten Zeitraum kein signifikanter Unterschied.
Nahezu allen Patienten wurden ambulante oder stationäre Rehabilitationsmaßnahmen bewilligt. Bei polytraumatisierten Patienten war die Rehabilitationsdauer im Vergleich zu Monoverletzungen verlängert. Mit guten Behandlungsergebnissen steigt die Wahrscheinlichkeit für eine zeitnahe Wiedereingliederung ins Arbeitsleben. Die kürzeste Krankheitsdauer wurde unter den isoliert ventral versorgten Patienten festgestellt. Insgesamt waren 2 Jahre postoperativ 69% aller präoperativ arbeitstätigen Patienten wieder in den alten Beruf zurückgekehrt. Von den übrigen 31% wurden 14,3 % in andere Berufe umgeschult, 4,8 % wurden berufsunfähig, 2,4 % waren noch krankgeschrieben und 9,5 % waren arbeitslos. Lag ein Arbeitsunfall vor, war die Krankheitsdauer tendenziell verlängert.
Betrachtet man das Schmerzempfinden, gaben überwiegend die isoliert dorsal versorgten Patienten auch postoperativ einen hohen Schmerzmittelbedarf an. Die Zugangsstelle an sich war davon eher nicht betroffen. Durch die Anwendung der Minithorakotomie beim ventralen Zugang wurden Postthorakotomiesyndrome nicht beobachtet. Durch den SF-36-Bogen wurde auch die Patientenzufriedenheit abgebildet. Am zufriedensten schnitt dabei die Gruppe der isoliert ventral versorgten Patienten ab. Mit der Entwicklung von OP-Techniken mit möglichst kleinem minimal invasivem Zugang wurde die Zufriedenheit gesteigert und das Schmerzempfinden der Patienten gesenkt. Weitere Möglichkeiten zur Steigerung der Patientenzufriedenheit bestehen durch begleitende psychosoziale Therapien.
Zusammenfassend stellt die Anwendung der Navigationstechnik eine interessante neue Facette im Bereich der Wirbelsäulenchirurgie dar. Zu beachten ist jedoch, dass bei der CT- basierten Technik die Abbildungen auf dem Monitor nur einer virtuellen Welt entsprechen aber dem Operateur eine sinnvolle und zuverlässige Unterstützung bieten können. Den entscheidenden Einfluss auf den Verlauf der Operation hat auch weiterhin allein der Operateur. Daher gehört die moderne Technik in die Hände erfahrener Operateure und sollte nicht von Anfängern allein bedient werden. Anhand evidenzbasierter Untersuchung ist auch weiterhin eine Überprüfung auf Effektivität und Nutzen neu etablierter Behandlungsverfahren erforderlich um die hohe Behandlungsqualität aufrecht zu erhalten. Interessante Neuerungen stellen die nächste Generation der 3D-Bildwandler mit Flat- Panel-Technologie als auch das intraoperative CT mit Navigationsanbindung dar.
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López, Picazo Mirella. "3D subject-specific shape and density modeling of the lumbar spine from 2D DXA images for osteoporosis assessment." Doctoral thesis, Universitat Pompeu Fabra, 2019. http://hdl.handle.net/10803/666513.
Full textAbstract:
Osteoporosis is the most common bone disease, with a significant morbidity and mortality caused by the increase of bone fragility and susceptibility to fracture. Dual Energy X-ray Absorptiometry (DXA) is the gold standard technique for osteoporosis and fracture risk evaluation at the spine. However, the standard analysis of DXA images only provides 2D measurements and does not differentiate between bone compartments; neither specifically assess bone density in the vertebral body, which is where most of the osteoporotic fractures occur. Quantitative Computed Tomography (QCT) is an alternative technique that overcomes limitations of DXA-based diagnosis. However, due to the high cost and radiation dose, QCT is not used for osteoporosis management. In this thesis, a method providing a 3D subject-specific shape and density estimation of the lumbar spine from a single anteroposterior DXA image is proposed. The method is based on a 3D statistical shape and density model built from a training set of QCT scans. The 3D subject-specific shape and density estimation is obtained by registering and fitting the statistical model onto the DXA image. Cortical and trabecular bone compartments are segmented using a model-based algorithm. 3D measurements are performed at different vertebral regions and bone compartments. The accuracy of the proposed methods is evaluated by comparing DXA-derived to QCT-derived 3D measurements. Two case-control studies are also performed: a retrospective study evaluating the ability of DXA-derived 3D measurements at lumbar spine to discriminate between osteoporosis-related vertebral fractures and control groups; and a study evaluating the association between DXA-derived 3D measurements at lumbar spine and osteoporosis-related hip fractures. In both studies, stronger associations are found between osteoporosis-related fractures and DXA-derived 3D measurements compared to standard 2D measurements. The technology developed within this thesis offers an insightful 3D analysis of the lumbar spine, which could potentially improve osteoporosis and fracture risk assessment in patients who had a standard DXA scan of the lumbar spine without any additional examination.La osteoporosis es la enfermedad ósea más común, con una morbilidad y mortalidad significativas causadas por el aumento de la fragilidad ósea y la susceptibilidad a las fracturas. La absorciometría de rayos X de energía dual (DXA, por sus siglas en inglés) es la técnica de referencia para la evaluación de la osteoporosis y del riesgo de fracturas en la columna vertebral. Sin embargo, el análisis estándar de las imágenes DXA solo proporciona mediciones 2D y no diferencia entre los compartimentos óseos; tampoco evalúa la densidad ósea en el cuerpo vertebral, que es donde se producen la mayoría de las fracturas osteoporóticas. La tomografía computarizada cuantitativa (QCT, por sus siglas en inglés) es una técnica alternativa que supera las limitaciones del diagnóstico basado en DXA. Sin embargo, debido al alto costo y la dosis de radiación, la QCT no se usa para el diagnóstico de la osteoporosis. En esta tesis, se propone un método que proporciona una estimación personalizada de la forma 3D y la densidad de la columna vertebral en la zona lumbar a partir de una única imagen DXA anteroposterior. El método se basa en un modelo estadístico 3D de forma y densidad creado a partir de un conjunto de entrenamiento de exploraciones QCT. La estimación 3D personalizada de forma y densidad se obtiene al registrar y ajustar el modelo estadístico con la imagen DXA. Se segmentan los compartimentos óseos corticales y trabeculares utilizando un algoritmo basado en modelos. Se realizan mediciones 3D en diferentes regiones vertebrales y compartimentos óseos. La precisión de los métodos propuestos se evalúa comparando las mediciones 3D derivadas de DXA con las derivadas de QCT. También se realizan dos estudios de casos y controles: un estudio retrospectivo que evalúa la capacidad de las mediciones 3D derivadas de DXA en la columna lumbar para discriminar entre sujetos con fracturas vertebrales relacionadas con la osteoporosis y sujetos control; y un estudio que evalúa la asociación entre las mediciones 3D derivadas de DXA en la columna lumbar y las fracturas de cadera relacionadas con la osteoporosis. En ambos estudios, se encuentran asociaciones más fuertes entre las fracturas relacionadas con la osteoporosis y las mediciones 3D derivadas de DXA en comparación con las mediciones estándar 2D. La tecnología desarrollada dentro de esta tesis ofrece un análisis en 3D de la columna lumbar, que podría mejorar la evaluación de la osteoporosis y el riesgo de fractura en pacientes que se sometieron a una exploración DXA estándar de la columna lumbar sin ningún examen adicional.
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Von, Forell Gregory Allen. "Computational and Experimental Study of Degeneration, Damage and Failure in Biological Soft Tissues." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3951.
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The purpose of this work was to analyze the biomechanics of degeneration, damage, and failure in biological soft tissues both experimentally and computationally to provide insight into tendon or ligament tearing, tendo-achilles lengthening and lumbar spine dysfunction. For soft tissue tearing, experimental studies for calculating fracture toughness were performed and determined that tendons and ligaments are able to completely resist tear propagation. For tendo-achilles lengthening, a damage model was developed to mimic the behavior of the lengthening that occurs as a result of the percutaneous triple hemisection technique. The model provided insight for predicting the amount of lengthening that occurs during the procedure. For lumbar spine dysfunction, a finite element model was validated against experimental testing and simulated using boundary conditions representing physiological loading. The model was able to predict how biomechanical changes can lead to pain and how the prevalence of Schmorl's nodes can be predicted. For each of the situations, the best verification and validation methods were selected and are presented throughout the research to demonstrate the predictive capabilities and limitations of the work. Results of these studies are presented along with how those results influence the clinical endeavors associated with the degeneration, damage and failure of soft tissues.
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Seyed, Vosoughi Ardalan. "Mitigating the Biomechanical Complications Following Pedicle Subtraction Osteotomy: A Finite Element Analysis." University of Toledo / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1503598742789914.
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Guenoun, Daphné. "Etude du rachis et des vertèbres : outils diagnostics de la vertèbre ostéoporotique : prévention et traitement de la fracture à l'aide de nouveaux biomateriaux." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0620/document.
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L’ostéoporose est définie par une diminution de la masse osseuse et une altération de la structure osseuse. L’évaluation de l’architecture de l’os trabéculaire vertébral est un des enjeux majeurs de recherche actuels visant à la caractérisation des modifications du tissu osseux liées au vieillissement. Par ailleurs, le traitement de la fracture vertébrale ostéoporotique par vertébroplastie a démontré son efficacité. Le ciment actuel utilisé pour la vertébroplastie est le polyméthylméthacrylate. Ce ciment est efficace pour stabiliser la vertèbre et diminuer la douleur mais il existe une toxicité pour les tissus mous avoisinant, notamment la moelle en cas de fuite, et des inquiétudes quant au risque de fracture des vertèbres adjacentes. De nouveaux ciments biointégrables du type ciments phosphocalciques supplémentés en bisphosphonates pourraient avoir leur place à l’avenir dans le traitement des vertèbres.Notre travail de thèse s’est inscrit dans un projet pluridisciplinaire de recherche sur les altérations de la structure de l’os trabéculaire vertébral, reposant sur une analyse en imagerie médicale et une étude biomécanique, et sur le développement d’un nouveau ciment phosphocalcique supplémenté en bisphosphonates.L’ensemble de nos résultats pourra nous permettre :-D’améliorer la prédiction du risque de fracture vertébrale ostéoporotique-D’optimiser les nouveaux ciments biointégrablesThe current definition of osteoporosis is a low bone mass associated with a microarchitecture deterioration. Vertebral trabecular bone microarchitecture assessment is an important research topic aiming at the characterization of the modifications of the bone tissue bound to ageing. On the other hand, the vertebral fracture treatment by vertebroplasty is known to be effective. Currently the cement used in vertebroplasty is the polymethylmetacrylate (PMMA). This cement stabilizes the vertebral fracture and decreases the pain, but there are a toxicity for nearby soft tissues, in particular spinal marrow in case of leakage, and concerns as for the risk of fracture of the neighboring vertebrae. In the future, new biointegrable calcium phosphate cement supplemented in bisphosphonate could be used in the vertrebrae treatment.Our work was based on a multidisciplinary project which aimed firstly at evaluating trabecular vertebral bone microarchitecture using medical imaging and biomechanical testing in this crucial anatomical region, secondly at developing a new calcium phosphate cement supplemented in bisphosphonate. Our results may lead to:- improve the fracture risk prediction in osteoporotic vertebra- improve the new biointegrable cements
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Song, Zhaobin. "Fracture analysis of bridges by spline finite strip method." Thesis, University of Ottawa (Canada), 2004. http://hdl.handle.net/10393/29168.
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The primary objective of this thesis is to develop crack strip method and verify the convergency of the method, finally to perform fracture analysis of bridge structures using spline finite strip method. In this thesis, combining the shape function of spline finite strip with the eigenfunction expansions at a crack tip, three types of crack strips, namely anti-plane shear crack strip, plane crack strip and bending crack strip, have been developed, in which cracks are perpendicular to the longitudinal axis of strips and the stress intensity factors can be computed directly. Based on plane crack strips and bending crack strips, the flat shell crack strip is developed for the fracture analysis of box girder bridges. Several case studies have demonstrated the satisfactory convergence of the proposed method. The fracture analysis of different types of bridges have been successfully conducted using these crack strips.
In Chapter 3, the basic model of the crack strip is farmed. Substructure technique and extra knots are employed to enhance the efficiency and the convergence of this model. Two Gaussian quadratures for improper integrals are introduced to calculate the singular integral in the crack strip. The efficiencies of these two methods are compared through case studies.
On the basis of anti-plane eigenfunction expansion derived by Tilley (1978), plane eigenfunction expansion by Williams (1957) and bending eigenfunction expansion by Williams (1961) in the area around the crack tip, anti-plane shear crack strip, plane crack strip and bending crack strip are developed in Chapter 4 to 6, respectively. The convergence of the proposed models is generally good as shown by case studies.
In Chapter 7, these crack strip models are applied to the fracture analysis of bridge structures. Based on the plane crack strip and the bending crack strip, flat shell crack strip is formed for the fracture analysis of box girder bridges. The fracture analysis of different types of bridges, such as slab bridge, continuous slab bridge, single - cell box girder bridge and continuous bridge with top-open box girder, are successfully conducted using these crack strips. The leading diagonal terms are replaced by large numbers to deal with those restraints in the continuous bridges.
The present method, i.e., combining the spline finite strip method with the analytical solution for the area around crack tip, provides a new and efficient approach for fracture analysis of structures, especially for the fracture analysis of bridge structures.
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Travert, Christophe. "Estimation du risque de fracture ostéoporotique du rachis thoraco-lombaire par un modèle en élément finis personnalisé." Phd thesis, Paris, ENSAM, 2012. http://pastel.archives-ouvertes.fr/pastel-00834740.
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L'ostéoporose est une maladie du squelette caractérisée par une perte de la qualité osseuse qui entraîne un risque de fracture accru, notamment au niveau vertébral. Des modèles en éléments finis basés sur la tomodensitométrie permettent d'estimer la résistance vertébrale, et donc le risque de fracture, mais leur utilisation en routine clinique est limitée par le coût et l'irradiation engendrée par la tomodensitométrie. L'estimation la résistance vertébrale à partir d'un modèle en éléments finis basés sur l'imagerie basse dose, telle que l'absorptiométrie biphotonique à rayons X, ou la stéréo-radiographie EOS en double énergie, permettrait une utilisation en routine clinique. Cette thèse contribue au développement de la modélisation à partir de l'imagerie basse dose pour la prédiction du risque de fracture. Un modèle en éléments finis de résistance vertébrale y est évalué par rapport à un modèle basé sur la tomodensitométrie, et une étude de sensibilité identifie les facteurs importants du modèle sont analysés. Des méthodes de maillage hexaédrique morpho-réalistes à partir de la reconstruction 3D, et d'estimation de la distribution de densité à partir d'image 2D de densité y sont développées. De plus, profitant des possibilités du système EOS qui permet de radiographier le patient de la tête aux pieds, une méthode préliminaire est proposée pour estimer l'effort exercé sur les vertèbres in vivo. Nous espérons que nos méthodes pourront être utilisées très prochainement in vivo, et contribuer à l'estimation du risque de fracture ostéoporotique, et à la prise en charge des patients à risque de fracture.
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King, Jason. "Energy Release Management Through Manipulated Geometries of Surgical Devices." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1342730044.
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Siddall, Daniel Jonathan. "Patient specific spine models : the development of a laboratory validation spine." Thesis, University of Hull, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396751.
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Liu, Jianzhi. "A two-dimensional human spine simulation and three-dimensional spine model construction." [Gainesville, Fla.] : University of Florida, 2001. http://purl.fcla.edu/fcla/etd/UFE0000329.
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Thesis (M.S.)--University of Florida, 2001.Title from title page of source document. Document formatted into pages; contains xi, 114 p.; also contains graphics. Includes vita. Includes bibliographical references.
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Silva, Carmem Lúcia Cadurim da. "Traumatismo raquimedular por mergulho em águas rasas: proposta de um programa de prevenção." Universidade de São Paulo, 1998. http://www.teses.usp.br/teses/disponiveis/82/82131/tde-16102017-085725/.
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Este trabalho avaliou a incidência de pacientes com lesão traumática da coluna cervical causada por mergulho em águas rasas, que foram atendidos nos Hospitais da cidade de Ribeirão Preto-SP, entre janeiro de 1989 a dezembro de 1996. O estudo epidemiológico foi realizado mediante investigação feita nos prontuários médicos desses pacientes. Complementou-se as informações por meio de uma entrevista realizada com 12 deles. Com base nos números apresentados, elaborou-se um programa de prevenção decorrente desses traumatismos a implantou-se uma Campanha de prevenção das lesões cervicais por mergulho em águas rasas em Ribeirão Preto. Um Programa de Campanha foi encaminhado à Assembléia Legislativa do Estado e transformado em Projeto de Lei. Os resultados mostraram que, dos 355 casos estudados, 69 deles foram por acidentes em águas rasas, a dentre estes, 58% tiveram danos neurológicos. Os locais mais freqüentes dos acidentes foram rios, córregos, lagos, cachoeiras,com a ocorrência de 75,4% dos casos, enquanto que a incidência em piscinas foi de 24,6%. A média de idade variou entre 10 a 30 anos, havendo diferença significativa com outras faixas etárias. Quanto ao sexo, 92,8% ocorreram em homens a 7,2% com mulheres. Em relação ao estado civil, 68,2% eram solteiros e 31,9% eram casados. O período do ano em que houve um número mais elevado dos traumatismos da coluna cervical causado pelo mergulho nas chamadas águas rasas foi nos meses de estações mais quentes na região (primavera, verão a outono). Dos 17,4% dos pacientes entrevistados de um total de 40 que tiveram lesão medular, todos mostraram desconhecimento desse tipo de acidente, bem como suas conseqüências. A Campanha de prevenção teve início em setembro de 1996 e está em fase de desenvolvimento em Ribeirão Preto. O Projeto de Lei estadual nº 183 aguarda aprovação da Assembléia. Conclui-se que, a incidência de acidentes com lesão traumática da coluna cervical por mergulho em águas rasas é elevada, sendo a terceira causa de danos traumáticos. A desinformação da população no que diz respeito ao perigo de um mergulho em águas rasas é elevado. A redução deste tipo de acidente pode acontecera partir de um processo educacional da população a da atuação decisiva do poder público.This study is an evaluation of the incidence of patients treated in the hospitals in Ribeirão Preto - SP for traumatic injury of the cervical cord caused by diving in shallow waters. The epidemiological study was held by means of an investigation of the medical charts of patients who underwent treatment from January 1989 to December 1996. The information on the charts was complemented through interviews held with 12 of these patients. Based on the results of these investigations, a campaign to prevent cervical injury caused by diving into shallow waters was elaborated and sent to the State Legislature, where it was transformed into a bill. The study revealed that in the 355 cases of cervical injury investigated, 69 were the result of accidents in shallow waters, and of these, 58% suffered neurological dysfunction. Rivers, lakes and waterfalls were most frequently cited as locations for the occurrence of these injuries (75,4% of the cases), with the incidence of accidents in swimming pools at 24,6%. The average age of patients varied between 10 to 30 years of age, with a significant difference in other age groups. In relation to sex, 92,8% of the accidents occurred in men, and only 7,2% in women. As to marital status, 68,2% were single and only 31,9% were married. The greatest number of cases of trauma of the cervical cord caused by diving in shallow waters occurred in the warmer seasons of the year (spring summer and fall). 17,4% of the patients interviewed out of a total of 40 with medullar injury, claimed not to know about this kind of accident and its consequences. The Prevention Campaign began in September 1996 and is presently being carried out in the city of Ribeirão Preto. The Bill of Law no. 183 awaits approval from the State Legislature. One may conclude that the incidence of traumatic injury of the cervical cord due to diving in shallow waters is high (third place as the cause of injury). The lack of information on the part of the population regarding the dangers of this type of accident may be one of the reasons behind these high statistics. The reduction of this type of accident may occur as the result of an educational process involving the population as well as decisive action on the part of the government.
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Axelsson, Paul. "On lumbar spine stabilization." Lund : Dept. of Orthopedics, Lund University Hospital, 1996. http://catalog.hathitrust.org/api/volumes/oclc/38045390.html.
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Benner, Nicole. "Explorations of the Spine." Thesis, Southern Illinois University at Edwardsville, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10130722.
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Ceran, Murat. "Parametric human spine modelling." Thesis, Loughborough University, 2006. https://dspace.lboro.ac.uk/2134/7958.
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3-D computational modelling of the human spine provides a sophisticated and cost-effective medium for bioengineers, researchers, and ergonomics designers in order to study the biomechanical behaviour of the human spine under different loading conditions. Developing a generic parametric computational human spine model to be employed in biomechanical modelling introduces a considerable potential to reduce the complexity of implementing and amending the intricate spinal geometry. The main objective of this research is to develop a 3-D parametric human spine model generation framework based on a command file system, by which the parameters of each vertebra are read from the database system, and then modelled within commercial 3-D CAD software. A novel data acquisition and generation system was developed as a part of the framework for determining the unknown vertebral dimensions, depending on the correlations between the parameters estimated from existing anthropometrical studies in the literature. The data acquisition system embodies a predictive methodology that comprehends the relations between the features of the vertebrae by employing statistical and geometrical techniques. Relations amongst vertebral parameters such as golden ratio were investigated and successfully implemented into the algorithms. The validation of the framework was carried out by comparing the developed 3-D computational human spine models against various real life human spine data, where good agreements were achieved. The constructed versatile framework possesses the capability to be utilised as a basis for quickly and effectively developing biomechanical models of the human spine such as finite element models.
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Mihcin, Senay. "Spine modelling for lifting." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/8065.
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Mathematical modelling is widely used in the field of biomechanics. The traditional approach to investigate spine related injuries is to check the strength of the components of the spine. Spinal stability approach focuses on the force polygons formed by the body weight, muscle forces, ligament forces and external load. This force polygon is expected to stay within the boundaries of the spine to ensure stability. Proving the possibility of one force polygon within the spine boundaries proves the stability of the spine. This study focuses on the full curvature of the spine for spinal stability investigations in a lifting activity. An experiment has been designed to investigate the postural differences in males and females by measuring the full spinal curvature with a skin surface device. Distributed body weight force, with increased detail of muscle and ligament forces acting on the spine have been modelled by writing a code in Visual Basic, while lifting a load from the boot of a car in the sagittal plane. This model is flexible enough to reflect changes in body weight parameter. Results show that there is a difference between male and female postures during the full span of lifting activities. Application of individual muscle forces provides greater control of stability at each vertebral level. By considering the elongation of the ligaments and the force requirements of the muscle groups, it is possible to diagnose soft tissue failure. The differences in posture result in different moment arms for muscles and ligaments causing different loading on the spine. Most critical postures have been identified as the fully flexed postures with external load acting on the spine. Conceptual design ideas have been proposed to assist lifting a load from the boot of a car to eliminate the excessive flexion and loading on the spine.
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Hastings, Elizabeth. "FRACTURES." Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3136.
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A stoplight at night. A dim bedroom. The smell of smoke and loss in summer. In winter, the crackle of snow underfoot, the city cold as a lavender planet. These are the settings within Fractures, and it is to these backdrops that the conflicts of the poems' speakers bare themselves. In the glow of these places, the truth of fractures, the gaps and slivers within us all, are illuminated. Below the visible wholeness of life lies a masked truth, the truth of a world that exists as a collection of fragments, of lives, of stories that connect, intersect, and sometimes overlap to create the tapestry of life as we know it. Each of us, in our own way, is fractured: in our minds, bodies, families, or relationships. And yet we live with these breakages, embrace them, even, because these splinters--personalities, moments, obstacles--are what make us whole. Fractures is a collection of poems that examines these pieces that characterize human life. The events and speakers in this manuscript are fictional, yet, like all fiction, they reflect some remnants of reality, some recognizable truths of ourselves stitched throughout. Each section of the collection can be viewed as a separate fracture, and each poem may also be a fracture. Some poems are broken even further: within stanzas, within lines, sometimes within the mind of the speaker. The poems do not tell a linear story, but rather tell bits of stories that often overlap. These narrative gaps too are indicative of a fracture as they mirror the disconnect, both physical and emotional, that frequently occurs in the stories of one's life. The sections of Fractures address different topics, ranging from loss to love to self destruction. The speakers are linked by a sense of searching, a self-awareness of being splintered, and, as one poem states, of recognizing a "hunger" for something more. One has lost a dear friend; another destroys her body in a quest for beauty. Some reflect on their families. Others mourn for lovers past, while one clings to a fleeting moment of love in its perfection. Just as the body suffers its broken bones that heal with time, so too these speakers suffer rifts that mend but are not forgotten. In this way, Fractures is a dissection, an X-ray of its speakers, each break a lit scar, fluorescent on the page.M.F.A.
Department of English
Arts and Humanities
Creative Writing MFA
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Loutzenheiser, Max J. "Fractures." Kent State University Honors College / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ksuhonors1463053698.
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Fathallah, Fadi A. "Coupled spine motions, spine loading and risk of occupationally- related low back disorders /." The Ohio State University, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487867541730726.
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Hodges, Paul William. "Neuromechanical control of the spine /." Stockholm, 2003. http://diss.kib.ki.se/2003/91-7349-552-2/.
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Przybyla, Andrzej Stefan. "Biomechanics of the cervical spine." Thesis, University of Bristol, 2005. http://hdl.handle.net/1983/845f95ee-39dd-4418-b6ed-200d749f87ae.
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Yu, Yuk-ling. "The use of computerised tomography in cervical spondylotic myelopathy and radiculopathy." [Hong Kong : University of Hong Kong], 1985. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12315904.
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Blackwelder, Reid B. "Wrist Fractures." Digital Commons @ East Tennessee State University, 1995. https://www.amzn.com/0721651925/.
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Book Summary: The 451 chapters in this introductory text are organized by organ system, and provide data on 318 specific diseases and disorders - including their aetiology, symptoms, clinical findings, laboratory tests, differential diagnosis, treatment and follow-up. Nearly 60 office procedures are described in detail, with discussions of indications, contraindications, preparation, equipment, anaesthesia, precautions, technique and follow-up. A complete list of procedures and ICD-9 codes is also included.
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Blackwelder, Reid B. "Wrist Fractures." Digital Commons @ East Tennessee State University, 2000. https://www.amzn.com/072168002X.
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Book Summary: The New Edition provides the latest, essential information on the symptoms, diseases, treatments, and procedures most commonly encountered in everyday practice. It features step-by-step clinical guidance for more than 320 common diseases and disorders, as well as explicit guidelines for over 60 office procedures. An organ-system organization, extensive alphabetical index, and cross references within the individual chapters make the information easy to find.
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Zhou, Lei. "Molecular mechanisms regulating dendritic spine morphology." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=106328.
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In the central nervous system, chemical synapses are highly specialized junctions that are known to be critical for communication between neurons. The ability of synapses to change their physiological and structural properties, known as synaptic plasticity, is important for storing information in neural connections. Dendritic spines are small protrusions on dendrites where the majority of glutamatergic synapses form in the brain. In general, a dendritic spine has an enlarged head region that is connected to the dendritic shaft by a narrow neck. This geometry allows spines to function as individual biochemical compartments and control postsynaptic signaling events. Recent evidence indicates that structural remodeling of spines and the formation of new synaptic contacts may lead to long-term changes in synaptic function including long-term potentiation (LTP) and long-term depression (LTD). These forms of synaptic plasticity are believed to contribute to cognitive processes such as learning and memory. Interestingly, the actin cytoskeleton is enriched in dendritic spines and its turnover contributes to spine shape and motility. A variety of signaling proteins associate with the actin cytoskeleton and are likely critical for controlling the morphological plasticity of spines. However, the molecular mechanisms that regulate actin-based spine dynamics remain unclear. My studies revealed novel pathways downstream of the EphA class of receptor tyrosine kinases that are important for regulating spine plasticity. I showed that PLCγ1 physically interacts with the EphA4 receptor tyrosine kinase and links EphA4 to the downstream actin depolymerizing/severing protein, cofilin. PLCγ1 signaling is critical for maintaining spine morphology and PLC activity is required for spine retraction caused by ephrin ligand binding to EphA4. Remarkably, the amount of cofilin associated with the cell membrane is regulated by PLC and EphA4 activity. Furthermore, I found that ephrin binding to EphA receptors cause the dephosphorylation and activation of cofilin through the phosphatases slingshot (SSH) and calcineurin. Both of the phosphatases are needed for EphA-mediated reorganization of actin filaments and dendritic spine remodeling. These studies contribute new insight into the intricate signaling mechanisms downstream of EphA receptors that control the local remodeling of the actin cytoskeleton in dendritic spines and structural plasticity of excitatory synapses in the central nervous system.Les synapses chimiques sont des jonctions hautement spécialisées du système nerveux central ayant un rôle déterminant pour la communication entre les neurones. Ces dernières sont capables de changer leurs propriétés structurales et physiologiques. Ce phénomène, appelé la plasticité synaptique, est important pour le stockage de l'information. Les épines dendritiques sont de petites saillies sur les dendrites des neurones où la majorité des synapses glutamatergiques du cerveau se forment. De manière générale, une épine dendritique se compose d'une large tête connectée à l'arbre dendritique par une structure plus étroite appelée cou. Cette géométrie permet le fonctionnement des épines comme des compartiments biochimiques indépendant, pouvant ainsi contrôler les événements de transmission synaptique localement, soit au niveau postsynaptique. De récentes évidences expérimentales indiquent que les réarrangements structurels des épines et la formation de nouvelles synapses qui en découle pourraient induire des changements persistant du fonctionnement de la synapse. Ces changements sont de deux types : la potentialisation à long terme (PLT) et la dépression à long terme (DLT). Ce sont deux formes de plasticité synaptique connues pour contribuer aux processus cérébraux de la cognition tels que l'apprentissage et la mémoire. Il est intéressant de noter que le cytosquelette d'actine est très dense dans les épines dendritiques et que son turnover contribue à la morphologie ainsi qu'à la motilité de ces dernières. Une grande variété de protéines de signalisation sont connues pour s'associer avec le cytosquelette d'actine et ont donc probablement un rôle crucial pour le contrôle de la plasticité morphologique des épines. Néanmoins, les mécanismes moléculaires qui régulent la dynamique des épines basée sur le cytosquelette d'actine restent obscurs à ce jour. La présente étude révèle de nouvelles voies de signalisation moléculaire en aval de la classe EphA des récepteurs à la tyrosine kinase ayant un rôle dans la régulation de la plasticité des épines dendritiques. Cette étude montre que la PLCγ1 interagit physiquement avec le récepteur EphA4 tyrosine kinase et relie, en aval, EphA4 à la cofiline, une protéine ayant un pouvoir polymérisant ou dépolymérisant sur les filaments d'actine. De plus, elle démontre que la PLCγ1 est essentielle pour le maintien de la morphologie des épines car la rétraction de celles-ci observée lors de la liaison de l'ephrine à son récepteur EphA4 nécessite une activité des PLC. La quantité de cofiline s'associant à la membrane cellulaire est apparue comme étant régulée de façon remarquable par l'activité de la PLC et du EphA4. Finalement, la démonstration que la liaison de l'ephrine à son récepteur EphA cause la déphosphorylation et l'activation de la cofiline par la phosphatase slingshot (SSH) et la calcineurine a été effectuée. Ces deux phosphatases sont apparues essentielles pour la réorganisation des filaments d'actines et des modifications morphologiques des épines dendritiques induites par EphA. Cette étude contribue donc à la compréhension des mécanismes de signalisation complexes prenant place en aval des récepteurs EphA lors des modifications structurales des épines observées lors des phénomènes de plasticité des synapses excitatrices du système nerveux central.
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Mameren, Hendrik van Lieshout F. van. "Motion patterns in the cervical spine." Maastricht : Maastricht : Rijksuniversiteit Limburg ; University Library, Maastricht University [Host], 1988. http://arno.unimaas.nl/show.cgi?fid=5445.
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Norris, Christopher Michael. "Functional rehabilitation of the lumbar spine." Thesis, Staffordshire University, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493646.
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Côrte, Ana Filipa Terleira Camacho da. "Cervical spine instability in rheumatoid arthritis." Dissertação, Faculdade de Medicina da Universidade do Porto, 2010. http://hdl.handle.net/10216/61051.
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Rose, Joseph D. "Carrying and Loading of the Spine." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1356475691.
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Hueston, Susan. "Anthropometric Analysis of the Cervical Spine." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1315947078.
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Makola, Mbulelo T. "Cervical Spine Biomechanical Behavior and Injury." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1316534684.
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Côrte, Ana Filipa Terleira Camacho da. "Cervical spine instability in rheumatoid arthritis." Master's thesis, Faculdade de Medicina da Universidade do Porto, 2010. http://hdl.handle.net/10216/61051.
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Behnami, Delaram. "Joint multimodal registration of medical images to a statistical model of the lumbar spine for spine anesthesia." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/59570.
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Facet joint injections and epidural needle insertions are widely used for spine anesthesia. Needle guidance is usually performed by fluoroscopy or palpation, resulting in radiation exposure and multiple needle re-insertions. Several ultrasound (US)-based guidance approaches have been proposed to eliminate such issues.However, but they have not widely accepted in clinics due to difficulties in interpretation of the complex spinal anatomy in US, which leads to clinicians' lack of confidence in relying only on information derived from US for needle guidance.
In this thesis, a model-based multi-modal joint registration framework is introduced, where a statistical model of the lumbar spine is concurrently registered to intraprocedure US and easy-to-interpret preprocedure images. The goal is to take advantage of the complementary features visible in US and preprocedure images, namely Computed Topography (CT) and Magnetic Resonance (MR) scans. Two versions of a lumbar spine statistical model are employed: a shape+pose model and a shape+pose+scale model. The underlying assumption is that the shape and size of the spine of a given subject are common amongst all imaging modalities . However, the pose of the spine changes from one modality to another, as the patient's position is different at different image acquisitions. The proposed method has been successfully validated on two datasets: (i) 10 pairs of US and CT scans and (ii) nine US and MR images of the lumbar spine. Using the shape+pose+scale model on the US+CT dataset, mean surface distance error of 2.42 mm for CT and mean Target Registration Error (TRE) of 3.14 mm for US were achieved. As for the US+MR dataset, TRE of 2.62 mm and 4.20 mm for the MR and US images, respectively. Both models models were equally accurate on the US+CT dataset. For US+MR, the shape+pose+scale model outperformed the shape+pose model. The joint registration allows augmentation of important anatomical landmarks in both intraprocedure US and preprocedure domains. Furthermore, observing the patient-specific model in preprocedure domains allows the clinicians to assess the local registration accuracy qualitatively. This can increase their confidence in using the US model for deriving needle guidance decisions.Applied Science, Faculty of
Graduate
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Mouginot, Rémi. "Fractures d'indentation élastique." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37616694v.
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