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Toksvig-Larsen, Søren. "On bone cutting." Lund : University Dept. of Orthopedics, 1992. http://books.google.com/books?id=3JBsAAAAMAAJ.
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Winnett, James. "Bone scaffolds with controllable porosity." Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/76693/.
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The Adaptive Foam Reticulation (AFR) technique, a combination of foam reticulation and freeze casting, has been investigated for producing bone repair bioscaffolds from hydroxyapatite (HA), titanium (Ti) and titanium-aluminium-vanadium (Ti-6Al-4V). Scaffolds have a network of macropores of diameter between 94 and 546 mm, with struts 20 to 118 mm thick. The structure was dependent on the template from which structures were produced, the number of coats of slurry applied to the template and the sintering temperature. The struts contained numerous micropores, the size of which was increased from 2-5 to 20-30 mm by decreasing the freezing temperature. Whilst the size of individual micropores was independent of the amount of porogen in the slurry, there was some coalescence at higher percentages. Scaffolds exhibited porosities of between 76 and 96%, with porosity consistently decreased by increasing the number of coats from one to five. The mechanical strength of all samples was determined theoretically by the novel incorporation of a shape factor conventially used for microporous structures into an existing equation used to calculate the yield stress of porous structures. In most cases this agreed with the experimentally obtained yield stress. With compressive yield stresses of 0.002 to 0.18MPa and 0.002 to 1.8 MPa respectively, HA and Ti structures are only suitable in non-load bearing situations. However Ti-6Al-4V scaffolds had yield stresses of 0.21-13.7 MPa, within the range of cancellous bone. AFR-fabricated HA scaffold offered greater in-vitro cell viability than a commercially available porous HA disc. Including a porogen offered no improvement in viability compared to structures fabricated without porogen, except at the highest inclusion where a statistically significant increase was observed. The weak compressive strength of scaffolds needs improving, and fabrications require in-vivo analyses. However, AFR could offer a viable alternative to other manufacturing techniques.
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Ahwal, Fadi Odeh. "Robotic assisted laser bone ablation for orthopaedic surgery." Thesis, University of Hull, 2006. http://hydra.hull.ac.uk/resources/hull:15104.
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The needs for better quality patient care and improved surgical procedures drive the development of new surgical tools and techniques that can augment the human surgeon capabilities. Over the past decade or so there have been significant advances in the design and development of computer assisted image guided surgery systems that can potentially perform complex tasks with high dexterity, speed and flexibility. The aim of this research work is to investigate various aspects in the design of a new computer assisted surgical tool capable of sawing, drilling and sculpturing of bone in support of image guided surgery that aims to reduce invasiveness, minimise blood loss and improve surgical outcome. The research of this thesis focuses on the design of an active positioning system (robotic end-effector) that uses a laser to cut bone to replace some of the currently available tools. This thesis starts by reviewing medical lasers and laser delivery systems, and discussing the effects of different lasers and lasers' parameters on tissue ablation time, rate and depth. It then defines criterion for the selection of the most appropriate laser and laser delivery system for bone cutting, drilling and sculpturing applications. Secondly, the thesis presents a unique design of a robotic laser end-effector. This end-effector is designed to provide accurate laser guidance for precise surgical performance (tissue ablation). This design is supported by an in-depth forward and inverse kinematic analysis to determine the end-effector workspace, resolution, positioning accuracy and manipulation flexibility. Thirdly and perhaps most importantly, the thesis presents two innovative laser feedback techniques, developed by the author, to determine the laser ablation depth and rate in real time during laser tissue interaction. These techniques are presented with complete analysis and supported by real time feedback examples. The techniques showed high measurement accuracy and reliability. Finally the thesis reviews the overall system performance supported by an error analysis model to determine the effects of different errors on the manipulation and positioning performance of the laser end-effector. It also presents some possible end-effector design modifications, alternative feedback techniques and suggestions for future work.
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Ong, Fook Rhu. "Analysis of bone drilling characteristics for the enhancement of safety and the evaluation of bone strength." Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/13900.
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Bone drilling is a major part of modern orthopaedic surgery associated with the principles of internal fixation of fractured bones. At present, information related to drilling forces, rate of drill bit penetration and drill bit rotational speed is not available to orthopaedic surgeons, clinicians and researchers as bone drilling is performed manually. This research demonstrates that orthopaedic surgery involving the drilling of bone can greatly benefit from the technology of automation/ mechatronics, which allows the collection and storage of the drilling data for analysis as well as for the improvement of the drilling procedure. The research also represents a significant contribution to the development of a drilling system for the enhancement of safety and/or as a diagnostic tool for the evaluation of bone strength. A novel automated experimental rig, which enables drilling tests to be carried out in a controlled environment, has been developed. The investigation for the enhancement of safety involves the detection of drill bit break-through on a femoral shaft in the presence of system compliance and inherent fluctuation of drilling forces. Since these two factors affect the detection of drill bit break-through, a robust and reliable method based on a modified Kalman filter has been developed. When applied to the force difference between successive samples and the rotational speed, the modified Kalman filter has been found to be very effective in establishing trends and ironing out major fluctuations caused by the system compliance and inherent drilling force fluctuation. The evaluation of bone strength related to the cancellous bone at the proximal femur has resulted in the establishment of a positive relationship between the average drilling force and bone mineral density (BMD), obtained from bone densitometry, which is used to estimate bone strength in clinical practice. The correlation has been found to depend on the direction of drilling. This is indicated by a linear relationship obtained in the anterior-posterior direction (perpendicular to the cervical axis), which is not interchangeable with the relationship in the direction of the cervical axis. Findings of this research have indicated that analysis of bone drilling forces has the potential to provide additional information about the strength of bone.
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Elbaz, Alexandre. "Implications and regulation of increasing bone marrow fat in age-related bone loss." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40765.
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The accumulation of fat in the marrow cavity is a consequence of the predominant mesenchymal stem cell differentiation into the adipocyte fate at the expense of the osteoblasts. Considering that these changes in stromal differentiation have an effect on bone health, we attempted to study bone marrow fat depots from a metabolic, lipotoxic and regulatory approach. In a fist attempt to study the potential metabolic role of bone marrow fat we observed the effect of calorie restriction (CR) on bone quality and marrow fat of aging rats subjected to a casein and soy protein diet. Bone quality and adipocyte quantification was obtained from rat tibia. Bone as well as adipogenic markers were quantified. CR was found to induce a significant decrease in bone quality. In contrast to CR rats, the ad libitum soy fed rats showed an overall better bone quality. Moreover, the results obtained showed that adipocytes were not mobilized during CR as no changes in leptin levels or adipocyte number were found. Finally we noticed that soy protein and not CR inhibited PPARgamma expression, a transcription factor required for adipogenesis. In summary, results from this first approach showed that bone marrow fat does not participate in lipid metabolism during moderate stages of starvation and that the detrimental effect of CR on bone mass could be prevented using a soy protein regime. A second approach to this subject involved looking at the mechanism through bone and fat interact within the bone marrow. We hypothesized that bone marrow adipocytes’ secretion of fatty acids (FA) induces changes in osteoblast differentiation, function and survival compatible with lipotoxicity. Using a co culture system of human pre-adipocytes and osteoblasts we showed that FAs negatively affect osteoblast differentiation and mineralization. Furthermore the effect could be prevented through the use of a FA syntase inhibitor, cerulenin. Gas chromatography/ mass spectrometry (GC\MS) analysis of co-culture suL’ostéoporose sénile est souvent associée à une augmentation de gras dans la moelle osseuse. Cette accumulation de gras est une conséquence d’une différentiation prédominante de cellules souches en adipocytes en lieu d’ostéoblastes. Prenant en considération ce changement de différentiation, nous avons décidé d’étudier le gras de la moelle osseuse de trois différentes approches : métabolique, lipo-toxique et régulatrice. Nous avons premièrement observé les effets d’une restriction calorique (RC) sur la qualité osseuse ainsi que sur le gras de la moelle osseuse de rats nourris de caséine ou de soja. Les marqueurs osseux et adipogéniques ont aussi été quantifiés. La RC fut identifiée comme une cause de réduction de qualité osseuse. Contrairement aux rats subjugués à une RC, les rats qui furent subjugués à une diète « ad libitum » de soja ont démontré une qualité osseuse supérieure. Aucuns changements n’ont été identifiés quant aux niveaux d’expression de leptin ou de cellules grasses. Ces derniers résultats indiquent que les cellules grasses de la moelle osseuse ne sont pas mobilisées pendant les périodes de RC. La diète de soja est responsable pour l’attenuation de l’expression de PPARgamma .Les résultats de l’étude ont démontré en premier lieu que le gras de la moelle osseuse ne participe pas au métabolisme de lipides pendant les périodes de famines modérées ; puis en deuxième lieu que les effets de la RC sur les os peuvent être diminués par une diète de soja. En deuxième lieu, nous avons observé le mécanisme par lequel le gras de la moelle participe à la perte osseuse associé au vieillissement. Un modèle de co-cultures cellulaires de pré-adipocytes humains ainsi que d’ostéoblastes nous a permis de démontrer que les acides gras (AG) sécrétés par les adipocytes ont un effet inhibant sur la différentiation ainsi que sur la minéralisation des ostéoblastes. Aussi, nous av
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Wermelin, Karin. "Surface bound bisphosphonate for implant fixation in bone." Doctoral thesis, Linköpings universitet, Ortopedi och idrottsmedicin, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-15310.
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During the surgical preparation of bone, prior to insertion of an implant, bone will be traumatized which leads to local resorption. Consequently, early implant fixation might be reduced. Impaired early fixation, as evidenced by radiostereometry, has been associated with increased risk of late loosening. Bisphosphonates are known to inhibit bone resorption by osteoclasts and have shown to increase implant fixation when administered systemically or locally directly at the bone prior to implant insertion. A method to bind bisphosphonates directly to the implant was developed. Stainless steel screws were coated with crosslinked fibrinogen, serving as an anchor for bisphosphonate attachment. The screws were inserted in the tibial metaphysis in rats and implant fixation was analyzed with pullout measurements. Bisphosphonate coated screws turned out to have 28 % higher pullout force at 2 weeks compared to control screws with the fibrinogen coating only. The next experiment was designed to measure at what stage in the healing process the strongest bisphosphonate effect was gained. Bisphosphonate coated screws were expected to reduce the resorption of the traumatized bone. However, no decreased fixation was found in the control group. Instead, the fixation increased with time, and so did the effect of the bisphosphonates. At 8 weeks, the pullout force was twice as high for screws with bisphosphonate compared to control screws. By histology at 8 weeks, a bone envelope was found around bisphosphonate coated screws but absent around control screws. Thus, the anti catabolic action of the bisphosphonate resulted in an increased amount of bone surrounding the bisphosphonate screws. Titanium is generally considered to be better fixated in bone compared to stainless steel. The coating technique was found to be applicable on titanium as well, again with improved fixation. A majority of fractures occur in osteoporotic bone. Despite the relatively low amount of bisphosphonates at the screws, the bisphosphonate coating improved implant fixation at 2 weeks also in rats made osteoporotic by ovariectomy. In conclusion, bisphosphonates bound to titanium or stainless steel screws coated with fibrinogen increased fixation in bone, in rats. These results suggest that the bisphosphonate and fibrinogen coating might improve the fixation of screw shaped implants and possibly also arthroplasties, in humans.
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Downer, Philip R. "Local bone graft harvest in anterior lumbar spine surgery." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0025/MQ50758.pdf.
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Downer, Philip R. "Local bone graft harvest in anterior lumbar spine surgery." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21543.
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The harvesting of a local bone graft from the lumber vertebral body adjacent to an anterior interbody fusion was suggested, to avoid secondary morbidity associated with iliac bone harvest. Instrumentation using a cannulated core drill was developed and assessed in an anatomic safety study. The biomechanical implications of plug removal were assessed in single vertebra and multisegment models. Plug removal using the tools developed was considered safe. The removal of a cylinder bone plug from the vertebral body affected flexion/compression load significantly. The yield strength of the vertebra could be restored effectively using the filler materials studied.
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Lobato, José Ventura Macieira de Sousa. "In vivo studies of bone grafts for maxillofacial surgery." Doctoral thesis, Instituto de Ciências Biomédicas Abel Salazar, 2007. http://hdl.handle.net/10216/7165.
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Lobato, José Ventura Macieira de Sousa. "In vivo studies of bone grafts for maxillofacial surgery." Tese, Instituto de Ciências Biomédicas Abel Salazar, 2007. http://hdl.handle.net/10216/7165.
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Busuttil, Naudi Kurt. "Bone bioengineering for mandibular reconstruction." Thesis, University of Glasgow, 2011. http://theses.gla.ac.uk/2419/.
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The reconstruction of critical-size bone defects following tumour resection or bone loss due to trauma is topical today and relates to the complexity of the treatment involved and poor healing outcomes. In bone bioengineering, the current trends are to explore novel methods of repairing these defects by using various bone substitutes. Various graft materials have been used for the restoration of these defects. A graft ideally needs to promote osteogenesis, osteoinduction and osteoconduction. The aim of this investigation was to assess the histological, radiographic and mechanical properties of the tissue regenerate following the application of tricalcium phosphate (TCP) scaffolding and recombinant human bone morphogenetic protein 7 (rhBMP-7) for the reconstruction of a critical-size osteoperiosteal mandibular continuity defect in the rabbit model. Highly purified and freeze dried recombinant human BMP-7 was used. It was produced by Chinese hamster ovary cells in culture and purified from the culture media. All the TCP samples had a porosity of 80% and average pore size of 100 – 500µm. For the rhBMP-7 loaded scaffolds; rhBMP-7 was reconstituted according to a recommended specification and 400ng were loaded by adsorption into the TCP scaffolds. Nine adult New Zealand white rabbits (3.0-4.0kg) were used for the planned study. In each case a unilateral osteoperiosteal mandibular body critical-size defect was created. In six cases the critical-size defect was filled with the rhBMP-7 on the TCP scaffolding, and in three cases the TCP was used alone. Assessments were made with plain radiographs at 0, 4, 8, and 12 weeks follow-up. Three months post-operatively the animals were sacrificed, the mandibles removed and the surgical sites were assessed with cone beam CT radiography, tested mechanically and analysed histologically. More bone regeneration was seen radiographically and histologically within the mandibles that received rhBMP-7 in the TCP, with evidence of both woven and lamellar bone formation. Union was obtained at the surgical site with no cartilage formation. The regenerated bone was confined to the area that had received the scaffold, with no calcification of the surrounding soft tissues. The TCP was also resorbed more completely in this experimental group. Very little bone was formed in the cases where the defect was filled with TCP alone. The mechanical properties of the regenerate in the group that received the rhBMP-7 and TCP were also significantly superior to those of the cases that received TCP alone. Histologically the overall mean of the percentage regenerated bone volume in the rhBMP-7 and TCP cases was 29.41% ± 6.25, while that for the TCP alone cases was 6.35% ± 3.08. The difference between the groups was statistically significant (p = 0.014). Mechanically the failure moments for the TCP alone cases were found to be very low (0-48mNm) while those for the rhBMP-7 and TCP cases were higher but there was considerable variation between the cases (55-2115mNm). Some of the cases in this group achieved failure moments comparable to normal untreated bone. In conclusion TCP scaffolding and rhBMP-7 can be used successfully for the reconstruction of critical-size mandibular defects in the rabbit model and TCP loaded with rhBMP-7 was significantly superior in its capacity for bone regeneration histologically when compared to TCP alone. The resultant bony regenerate could also at times have mechanical properties similar to those of natural bone. But due to the variability of the mechanical properties further investigations are required before clinical application.
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Carli, Alberto. "FGF 18 augments bone healing & osseointegration of intra-medullary femoral implants in osteopenic bone." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110402.
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Introduction:Internal fixation of fractures in the presence of osteopenia has been associated with a failure rate as high as 25%. Enhancing bone formation and osseointegration of orthopaedic hardware is a priority when treating patients with impaired bone regenerative capacity. Fibroblast Growth Factor (FGF) 18 regulates skeletal development and could therefore have applications in implant integration. This study was designed to determine if FGF 18 promotes bone formation and osseointegration in the osteopenic FGFR3-/- mouse and to examine its effect on bone marrow derived mesenchymal stem cells (MSCs).Methods: In Vivo: Intramedullary implants were fabricated from 0.4 x 10mm nylon rods coated with 300nm of titanium by physical vapour deposition. Skeletally mature, age matched female FGFR3-/- and wild type mice received bilateral intramedullary femoral implants. Left femurs received an intramedullary injection of 0.1μg of FGF 18 (courtesy Merck Serono), and right femurs received saline only. Six weeks later, femurs were harvested, radiographed, scanned by micro CT, and processed for undecalcified for histology.In Vitro: MSCs were harvested from femurs and tibiae of skeletally mature age matched FGFR3-/- and wild type mice. Cells were cultured in Alpha Modified Eagle's Medium (αMEM) to monitor proliferation or αMEM supplemented with ascorbic acid and sodium beta-glycerophosphate to monitor differentiation. Proliferation was assessed through cell counts and metabolic activity at days 3, 6 and 9. Differentiation was assessed through staining for osteoblasts and mineral deposition at days 6, 9 and 12.Results: Wild type mice exhibited more peri-implant bone formation compared to FGFR3-/- mice. Peri-implant bone formation at the proximal metaphyseal-diaphyseal junction was increased in FGF18 treated femurs compared with contralateral control femurs in wild type (p = NS) and FGFR3-/- (p = 0.04) mice. Histological analysis corroborated micro CT findings, with FGF 18 treated FGFR3-/- femurs forming peri-implant bone instead of the fibrous response seen in controls. In vitro studies showed that FGF18 significantly increased MSC proliferation and metabolism in a dose dependent manner in wild type and FGFR3-/- mice. Osteoblast differentiation was inhibited by FGF18 in wild type MSCs, while no significant effect was observed in cells harvested from FGFR3-/- mice.Conclusion: FGF 18 increases bone formation and osseointegration of intramedullary implants in osteopenic mice and increases MSC proliferation in both the presence and absence of FGFR3. FGF18 also inhibits early osteoblast differentiation in the presence of FGFR3. FGF 18 mediated MSC proliferation and osteogenesis is likely due to signalling through an alternate FGFR, likely FGFR1 or 2. Additional work is needed to confirm the identity of the alternate FGFR and to evaluate its capacity to improve osseous healing in unfavourable in-vivo environments.Introduction: La fixation interne de fractures dans la présence de l'ostéopénie a été associée à un taux d'échec aussi élevé que 25%. Amélioration de la formation osseuse et l'ostéo-intégration de matériel orthopédique est une priorité pour le traitement de patients. Facteur de croissance des fibroblastes (FGF) 18 régit le développement squelettique et pourrait donc avoir des applications dans intégration de l'implant. Cette étude a été conçue pour déterminer si le FGF 18 favorise la formation osseuse et l'ostéo-intégration dans le ostéopénique FGFR3-/- souris et d'examiner son effet sur la moelle osseuse provenant de cellules souches mésenchymateuses (CSM).Méthodes: Implants intramédullaires ont été fabriqués à partir de tiges de nylon 10mm x 0,4 revêtus de 300nm de titane par dépôt de vapeur physique. Les souris de type FGFR3-/- et souris de type sauvage a reçu des implants intramédullaires au femurs. Les fémurs gauche ont reçu une injection intra-médullaire de 0.1μg de FGF 18 (Merck Serono), et les fémurs droit ont reçu une solution saline seule. Après six semaines, les fémurs ont été récoltés, analysé par les micro CT, et préparé pour l'histologie. Les CSM ont été récoltées à partir de fémurs et les tibias de souris de type FGFR3-/ - et de type sauvage. Les cellules ont été cultivées dans 'Alpha Modified Eagle's Medium' (aMEM) pour surveiller la proliferation, ou cultivées dans un milieu 'aMEM' complété avec de l'acide ascorbique et de sodium bêta-glycérophosphate pour surveiller la différenciation. La prolifération a été évaluée par dénombrement des cellules et l'activité métabolique aux jours 3, 6 et 9. Différenciation a été évaluée par coloration pour les ostéoblastes et les dépôts minéraux aux jours 6, 9 et 12.Résultats: Les souris de type sauvage ont produit plus d'os péri-implantaire par rapport à FGFR3-/ - souris. La formation osseuse péri-implantaire à la jonction proximale métaphysodiaphysaire a été augmenté en fémurs traités avec FGF18 par rapport aux fémurs de contrôle controlatéraux dans de type sauvage (p > 0.05) et FGFR3-/ - (p = 0.04). L'analyse histologique a corroboré les conclusions micro CT. Les femurs FGFR3-/ - qui ont recus FGF 18 traités fémurs ont formé l'os autour de l'implant au lieu de la réponse fibreuse vu dans les contrôles. Des études in vitro ont montré que la proliferation du MSC ont été augmenté avec FGF18 d'une manière dose-dépendante pour les type sauvage et les type FGFR3-/ -. La différenciation des ostéoblastes a été inhibée par FGF18 pour les CSM du type sauvage. Aucun effet significatif sur la différenciation a été observé dans les cellules récoltées à partir de souris FGFR3-/ -.Conclusion: FGF 18 augmente la formation osseuse et l'ostéo-intégration des implants intramédullaires chez la souris ostéopéniques. FGF 18 augmente la prolifération des CSM à la présence et l'absence de FGFR3. FGF18 inhibe également la différenciation ostéoblastique a la présence de FGFR3. Les effets de FGF 18 sur le prolifération des CSM et l'ostéogenèse est probablement dû à la signalisation grâce à un FGFR alternative, probablement FGFR1 ou 2. Des travaux in vivo supplémentaires sont nécessaires pour confirmer l'identité de l'autre FGFR et d'évaluer sa capacité à améliorer la cicatrisation de l'os en environnements défavorable
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Mattsson, Per. "Resorbable Bone Cement for Augmentation of Hip Fracture." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5822.
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Welter, Jean F. "Vascularized vs. conventional bone grafts : an experimental comparison in large defects of weight-bearing bones." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59599.
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Early hypertrophy has justified the clinical use of vascularized bone grafts. This hypertrophy has not been established in experimental models, possibly because stress-shielded grafts were used. Our model allowed the grafts to bear weight. In 14 dogs we replaced the diaphysis of the radius with a vascularized fibula, and the diaphysis of the ulna with a conventional fibula (Group I). In 10 dogs we reversed the positions of the grafts (Group II). External fixation was used. The grafts were evaluated radiographically, mechanically and histologically. The vascularized grafts hypertrophied early, and were stronger than conventional grafts, particularly in Group I, where the former were stressed more. A previously unreported repair pattern was observed: vascularized grafts increased in size by peripheral apposition of new bone, there was no creeping substitution or weakening resorption. Conventional grafts remodeled by creeping repair, and hypertrophied slower, never reaching the size or the strength of the vascularized grafts.
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Bhumbra, Rej-Paul. "Sealing the bone-implant interface around total hip replacements using guided bone regeneration." Thesis, University of London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313796.
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Sluis-Cremer, Timothy Richard. "Minimally invasive CT-guiding excision of benign bone tumours." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29681.
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Background: The management of osteoid osteoma (OO) and other small primary benign lesions of bone has evolved over the past 50 years from open surgery with wide resection margins to less invasive surgical techniques such as image guided intralesional excision and percutaneous radiofrequency ablation. We aim to evaluate the outcomes of patients treated with computerised tomography (CT guided) intralesional excision and bone grafting of small benign lesions of bone. Method: A retrospective folder review of patients treated in a large academic hospital in Cape Town, South Africa, between March 2012 and May 2016 was performed. Patient demographics, details of presentation, clinical information and outcome following treatment were analysed descriptively. Pre-operative diagnosis based on radiological examination was compared with histological diagnosis. Result: Eleven patients (5 male) with a median age of 16 years (range 5-33) were included. Pain was the most common presenting feature. A histological diagnosis of OO was confirmed in 5 of 9 patients with a suspected diagnosis of OO preoperatively. Of the 4 patients whose diagnosis changed after the procedure the diagnoses included a benign spindle cell lesion, a benign fibrous histiocytoma, subacute osteitis and an osteochondral defect with geode cyst formation. Of the 2 patients where OO was not suspected preoperatively, chondroblastoma was confirmed in one while a benign spindle cell lesion was reported in the other. Overall histological yield was thus 100%. There were no complications or repeat procedures at a median follow up of 42 months (range 30-52 months). Conclusion: CT guided intralesional curettage is a safe and minimally invasive technique. This is especially useful in less accessible regions of the skeleton as it provides a means of accurately locating the lesion with minimal risk of complications and morbidity to the patient. We consider this to be the optimal method of treatment in our setting as it provides high success rates, few complications and a histological diagnosis without the need for any additional and expensive equipment.
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Sridharan, Srinivasan. "Porous plastic implants for bone ingrowth." Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/10101.
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Mathieson, Andrew C. "Nonlinear characterisation of power ultrasonic devices used in bone surgery." Thesis, University of Glasgow, 2012. http://theses.gla.ac.uk/3135/.
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Ultrasonic cutting has existed in surgery since the 1950s. However, it was not until the end of the 20th century that advances in ultrasonic tool design, transduction and control allowed commercially viable ultrasonic cutting devices to enter the market. Ultrasonic surgical devices, like those in other power ultrasonic applications such as drilling and welding, require devices to be driven at high power to ensure sufficient output motion is produced to fulfil the application it is designed to perform. With the advent of novel surgical techniques surgeons require tuned ultrasonic tools which can reduce invasiveness while giving access to increasingly difficult to reach surgical sites. To fulfil the requirements of novel surgical procedures new tuned tools need to be designed. Meanwhile, it is well documented that power ultrasonic devices, whilst driven at high power, are inherently nonlinear and, if no attempt is made to understand and subsequently control these behaviours, it is likely that these devices will suffer from poor performance or even failure. The behaviour of the commercial ultrasonic transducer used in bone surgery (Piezosurgery® Device) is dynamically characterised through finite element and experimental methods whilst operating in conjunction with a variety of tuned inserts. Finite element analysis was used to predict modal parameters as well as stress levels within the tuned devices whilst operating at elevated amplitudes of vibration, while experimental modal analysis validated predicted resonant frequencies and mode shapes between 0-80kHz. To investigate the behaviour of tuned devices at elevated vibrational amplitudes near resonance, responses were measured whilst the device was excited via the burst sine sweep method. In an attempt to provide an understanding of the effects that geometry, material selection and wavelength of tuned assemblies have on the behaviour of an ultrasonic device, tuned inserts consisting of a simple rod horn design were characterised alongside more complex cutting inserts which are used in maxillofacial and craniofacial surgery. From these results the aim will be to develop guidelines for design of tuned inserts. Meanwhile, Langevin transducers, commonly known as sandwich or stack transducers, in their most basic form generally consist of four parts; a front mass, a back mass, a piezoceramic stack and a stud or bolt holding the parts together under a compressive pre-load. It is traditionally proposed that the piezoceramic stack is positioned at or close to the vibrational nodal point of the longitudinal mode, however, this also corresponds with the position of highest dynamic stress. It is also well documented that piezoceramic materials possess a low linear stress threshold, therefore this research, in part, investigates whether locating the piezoceramic stack away from a position of intrinsic high stress will affect the behaviour of the device. Through experimental characterisation it has been observed that the tuned devices under investigation exhibited; resonant frequency shifts, jump amplitudes, hysteretic behaviour as well as autoparametric vibration. The source of these behaviours have been found to stem from device geometry, but also from heating within the piezoceramic elements as well as joints with different joining torques.
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Piersanti, Luigi <1973>. "New Application of Piezoelectric Ultrasounds in Maxillo-facial bone surgery." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/7118/1/New_Application_Definitivo.pdf.
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Background:
Piezoelectric instrumentation seems to offer 3 important advantages for cutting bone structures.
Be more precise because it is produced by micro-vibrations from the cutting insert.
Be safer because the ultrasonic frequency used does not affect soft tissue.
Thirdly, the less invasive cutting action produces minor tissue damage and consequently probably a better healing
Aim of the Study:
The aim of this study is to evaluate the effectiveness of piezoelectric device capability in maxillo-facial surgery, in order to take advantage of these favourable capacity.
Material and Methods:
Considering the several potential application of the piezoelectric technology in Orthognathic, Oncologic and Extractive surgery, we would like to design protocols in order to verify how this new device can modify the surgical technique, the surgical time, the patients healing and its quality of life.
Results:
Due to the precise Piezosurgery cut, we can manage the Cad-Cam-Custom Made plates protocol in Oncologic Surgery and in Orthognatic Surgery increasing our percentage of comparison between the 3D preoperative plan and the surgical execution.
We also found a better quality of life impaction in Patient who underwent and extractive surgery
Conclusion:
Piezosurgery device seems to be a strong surgical aid were safe and precise cut are needed and its capability to reduce the discomfort Patients need to be study in deep also in major surgery like Orthognatic and Oncologic surgery.
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Piersanti, Luigi <1973>. "New Application of Piezoelectric Ultrasounds in Maxillo-facial bone surgery." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/7118/.
Full textAbstract:
Background:
Piezoelectric instrumentation seems to offer 3 important advantages for cutting bone structures.
Be more precise because it is produced by micro-vibrations from the cutting insert.
Be safer because the ultrasonic frequency used does not affect soft tissue.
Thirdly, the less invasive cutting action produces minor tissue damage and consequently probably a better healing
Aim of the Study:
The aim of this study is to evaluate the effectiveness of piezoelectric device capability in maxillo-facial surgery, in order to take advantage of these favourable capacity.
Material and Methods:
Considering the several potential application of the piezoelectric technology in Orthognathic, Oncologic and Extractive surgery, we would like to design protocols in order to verify how this new device can modify the surgical technique, the surgical time, the patients healing and its quality of life.
Results:
Due to the precise Piezosurgery cut, we can manage the Cad-Cam-Custom Made plates protocol in Oncologic Surgery and in Orthognatic Surgery increasing our percentage of comparison between the 3D preoperative plan and the surgical execution.
We also found a better quality of life impaction in Patient who underwent and extractive surgery
Conclusion:
Piezosurgery device seems to be a strong surgical aid were safe and precise cut are needed and its capability to reduce the discomfort Patients need to be study in deep also in major surgery like Orthognatic and Oncologic surgery.
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Sahlin-Platt, Annika. "Bone tissue regeneration indento-alveolar surgery : clinical and experimental studies on biomaterials and bone graft substitutes." Doctoral thesis, Umeå universitet, Institutionen för odontologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-47418.
Full textAbstract:
Pathological processes in the alveolar and facial bones can lead to bone loss that may not heal with complete regeneration. Biomaterials can be used to facilitate the healing process and/or as a bone substitute, but the mechanisms are not fully understood. Persistent leakage of bacteria/bacterial toxins, after root canal treatment, may lead to a residual bone defect. The healing is dependent on a placed dental biomaterial providing a tight seal. The composition of the filling material may also influence the healing process. The general aim of this study is to investigate surface properties and biological interactions of biomaterials used in dento-alveolar surgery. A dental biomaterial, a bonded compomer (DAP) containing a corroding glass filler, was used as a root end filling material, promoting a new operation technique. The healing (assessed according to Molven´s x-ray criteria) demonstrates a significant improvement in healing results for the compomer group, compared to a commonly used technique. The surface properties and biological interactions of DAP were analyzed. ICP-OES of DAP cell culture medium extract demonstrated a significant release of Sr, Si and F from the dental biomaterial. Human periodontal ligament (PDL) cells grew on and around DAP specimens without any sign of toxic reactions. DAP extract stimulated proliferation of PDL cells, but caused an inhibition of osteoblastic gene expression in mouse bone marrow cells. The surface properties of the glass containing compomer may contribute to improved healing of the periapical lesions. A bovine inorganic bone graft substitute (BO) is commonly used as a treatment option in dento-alveolar surgery with new bone formation in immediate close contact with BO material. ICP-OES dissolution analysis of cell culture media, after incubation with BO particles, demonstrated a dosedependent release of Si and a decrease of Ca and P. An uptake of Ca from the medium to the BO particle was demonstrated with calcium-45 labeling. The Si dissolution varied between different batches, possibly reflecting a variation in food intake in the animals. Stimulated osteogenic response was seen in close contact to the BO particles in cell cultures. Furthermore, it was clearly demonstrated that the study design is a critical factor for correctly understanding biomaterials’ biological interactions. The surface properties of three bone graft substitutes reported to have good results in dento-alveolar surgery were investigated, in order to establish whether or not dissolution-precipitation reactions could contribute to the bone healing. Dissolution-precipitation extracts of BO, bioactive glass 45S5 (BG) and a marine algae hydroxyl apatite (AP) in cell culture media were analyzed. Dissolution of Si at significant levels was detected for BO and 45S5 over time. Significant uptake levels of Ca and P from the culture were seen for both 45S5, BO and AP but at different times. Surface analysis of the biomaterials with SEM/EDAX, before and after immersion in cell culture media, revealed a smoothing of the surface morphology for 45S5 over time. No obvious alterations for BO and AP were detected. Ca/P ratio decreased significantly for 45S5, but no major changes were detected by XPS for BO or AP. XPS further demonstrated a surface charge for BO, changing from negatively to positively charged when exposed to serum. 45S5 and AP had positive surface charges, both in the absence and the presence of serum. These demonstrated surface changes in biomaterials could contribute to adherence of cells and subsequently affect bone healing. Conclusion: Biomaterials used in dento-alveolar surgery interact with biological surroundings through surface and dissolution-precipitation reactions which may have implications for bone healing.
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Lughmani, Waqas A. "Experimental and numerical investigations of bone drilling for the indication of bone quality during orthopaedic surgery." Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/20567.
Full textAbstract:
Bone drilling is an essential part of many orthopaedic surgical procedures, including those for internal fixation and for attaching prosthetics. Drilling into bone is a fundamental skill that can be both very simple, such as drilling through long bones, or very difficult, such as drilling through the vertebral pedicles where incorrectly drilled holes can result in nerve damage, vascular damage or fractured pedicles. Also large forces experienced during bone drilling may promote crack formation and can result in drill overrun, causing considerable damage to surrounding tissues. Therefore, it is important to understand the effect of bone material quality on the bone drilling forces to select favourable drilling conditions, and improve orthopaedic procedures.
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Flynn, Andrew. "Bioresorbable inorganic setting systems for bone repair." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104548.
Full textAbstract:
Calcium phosphate-based materials have become the first choice for surgeons when they look for a synthetic material for the repair and augmentation of bone. Numerous studies and commercial use over the last three decades have made these materials popular options. These materials are not without their negative aspects, and properties such as poor in vivo resorption and low setting pH are well documented. Magnesium phosphates represent a poorly investigated group of materials with chemical structures similar to those of the calcium phosphates.In this thesis we investigate magnesium phosphates for use as inorganic materials for bone repair. We demonstrated that heat-treatment of magnesium phosphate created a cement reactant, which upon mixing with citric acid or sodium phosphate solutions set to form a cement. Investigation into alternate applications for the cement showed the cement could be dip-coated onto titanium rods. The dip coating formulations were also tested for their ability to release bioactive compounds, showing a relationship between initial burst and sustained release with powder-to-liquid ratio. In vitro testing of the cement showed good biocompatibility with osteoblast-like cells, inducing the expression of osteoblast markers. Preliminary in vivo data showed good material resorption and osteoconduction compared to brushite by four weeks time.Our results demonstrate that magnesium phosphate can be used in bone repair applications. Further study and development may lead to them becoming a viable alternative to calcium phosphates.Les matériaux à base de phosphate de calcium sont devenus le premier choix pour les chirurgiens quand ils choisissent un matériau synthétique pour la réparation et l'augmentation osseuse. De nombreuses études et d'utilisation commerciale au cours des trois dernières décennies ont fait de ces matériaux une option populaire. Ces matériaux ne sont pas sans désavantages, et les propriétés telles que une résorption lente in vivo et une faible mise en pH sont bien documentés. Les phosphates de magnésium représente un groupe de matériaux peu étudié avec des structures chimiques similaires à celles des phosphates de calcium. Dans cette thèse, nous avons examine les phosphates de magnésium pour l'utilisation en taut que matériaux inorganiques pour la réparation osseuse. Nous avons démontré que le traitement thermique du phosphate de magnésium crée un réactif de ciment, qui apres mélange avec de l'acide citrique ou de solutions de phosphate de sodium forment un ciment. Enquête sur les demandes de remplacement pour le ciment ont démontré que le ciment pourrait être enduit (revêti) sur des tiges de titane. Les formulations de revêtement ont également été testés pour leur capacité à libérer des composés bioactifs, démontrant une relation entre l'éclatement initial et à la libération prolongée avec un rapport poudre-liquide. Des essais in vitro ont démontré que ce ciment a une bonne biocompatibilité avec des cellules ostéoblastiques, ce qui induit l'expression des marqueurs ostéoblastiques. Les données préliminaires in vivo ont montré une bonne résorption du matériel et une ostéoconduction comparable par rapport à brushite par quatre semaines. Nos résultats démontrent que le phosphate de magnésium peut être utilisé dans des applications de réparation osseuse. Une étude plus poussée et le développement de ce matériau pourra le conduire à une alternative viable aux phosphates de calcium.
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Öberg, Sven. "Bone Healing after implantation of bone substitute materials. Experimental studies in estrogen deficiency." Doctoral thesis, Umeå University, Odontology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-138.
Full textAbstract:
Bone formation and bone healing were studied in the mandible, tibia and skull bones in adult, healthy and estrogen deficient rabbits implanted with different bone substitutes.
In the first study an evaluation of the differences in bone regeneration in and around solid (Alveograf *) and porous hydroxyapatite (Interpore 200*) was undertaken. The implant material was placed into experimentally made bone defects and in half of the defects hydroxyapatite was mixed with a fibrin sealant (Tisseel *). The material alone or mixed with Tisseel was also placed subperiostally in the mandible. The observation time was six month. No difference in bone regeneration was found between solid or porous hydroxyapatite granulas and the addition of Tisseel* did not seem to disturb the bone healing process. The implant material placed subperiostally did not induce bone formation nor did it provoke any bone resorption. The addition of Tisseel made the implant material much easier to handle and retain in the tissue during surgery.
Bone healing around hydroxyapatite implants was also evaluated in the second study. Experimental cavities in the mandible and tibia were filled with hydroxyapatite in granules or blocks (Interpore 200*) but now with or without autolyzed, antigen-extracted, allogeneic bone (AAA). Also in this study Tisseel* was used to facilitate the handling of the material. All cavities implanted with AAA-bone, regardless of the combination with hydroxyapatite or Tisseel, demonstrated excessive bone formation resembling exostosis formation. Thus, hydroxyapatite, both as granules and blocks, can be successfully combined with AAA bone utilizing the bone inductive capacity of AAA bone.
The same model was used to study the healing in ovariectomized animals in the third study. Bone cavities were implanted with or without AAA bone and left to heal. The results indicate that the osteoinductive capacity of AAA bone is in operation also in animals deprived of a normal estrogen production.
The effect of using AAA bone prior to implant insertion was studied in paper four. The bone-implant contact was significant higher when AAA bone had been used. The implant stability did not seem to be affected.
In paper five defects were made in skull and tibial bone in estrogen deficient animals. The deficiency of estrogen was confirmed through blood analysis, the decrease in the weight of uterus and bone mineral density. The whole body scanning with DEXA showed that the ovariectomized animals developed osteopenia. Various degree of bone formation was seen in the defects due to the influence of the bone inductive substance AAA bone.
The studies indicate that a conductive material like hydroxyapatite in granules or blocks could be useful in oral reconstructive surgery. The combination with AAA bone enhanced the bone formation in calvarial and tibial bone in healthy and estrogen deficient animals. Tisseel* could be used to facilitate handling and retention of the material in the intended position during the healing process without negative effects.
25
Hirvinen, Laura J. M. "Influence of bone cements on bone screw interfaces in the third metacarpal and metatarsal bones of horses." Columbus, Ohio : Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1243434636.
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Mah, Michelle Clare. "Functional outcomes and long term complications following distraction osteogenesis of the maxilla and mandible: asystematic review." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B50639626.
Full textAbstract:
Background
Distraction osteogenesis (DO) was first applied on the human craniofacial skeleton in 1992 by McCarthy et al.1 who performed lengthening of the mandible in patients with hemifacial microsomia and Nager’s syndrome. Further advances in this field have since then led to the widespread use of this modality for the treatment of numerous congenital and acquired craniofacial skeletal anomalies. In 2001, a review by Swennen et al2 concluded that up to year 1999, this form of treatment was gaining intense popularity but that the main drawbacks included insufficient data on long term results and relapse. A systematic review of the last decade on functional outcomes and long term complications following distraction osteogenesis of the facial skeleton is presented.
Methods
A structured systematic literature search, with predefined inclusion and exclusion criteria from relevant computer databases and journals were performed. The journals were evaluated and critically appraised by 2 reviewers separately in 3 rounds. Papers were categorized according to the level of evidence, the quality of methodology and the specific field of functional outcomes and long term complications. Results were then categorized according to the type of distraction movements, ie maxillary advancement and mandibular lengthening.
Results
A total of 42 papers comprising of 16 studies for maxillary advancement and 26 studies for mandibular lengthening were included in this review. Maxillary advancement was found to be beneficial in patients with cleft maxillary hypoplasia in terms of achieving aesthetic outcome but the risk for velopharyngeal insufficiency remains uncertain. The achieved maxillary advancement was stable if performed on adult patients while a recurrence of midface retrusion was noted if DO was performed on growing patients. Overcorrection was recommended in these cases to an estimated value of 20-50%. Mandibular lengthening was 99% successful in relieving respiratory obstruction in patients with isolated Pierre Robin Sequence (PRS) or syndromic micrognathic infants preventing the need for tracheostomy in the long term, and in 89% successfully decannulating infants with pre-existing tracheostomy. However, feeding and growth outcomes after airway obstruction was relieved remain unknown due to lack of sufficient evidence. Unilateral mandibular DO was successful in achieving aesthetic symmetrical facial balance in patients with hemifacial microsomia however a total loss of corrected distraction length was noted by the end of growth period if DO was performed during growth.
Conclusions
DO achieved stable results in terms of lengthening the maxilla and mandible but was also noted to cause restricted growth potential of the distracted bone. Hence, the benefits of performing DO during active growth should be weighed against the likely need for a second surgery due to a growth deficit of distracted bone and future surrounding bone growth. However DO in adults remains an alternative to conventional orthognathic surgery and choice of treatment should be patient centred.published_or_final_version
Dental Surgery
Master
Master of Dental Surgery
27
Al-Harkan, Abdullah. "Is Bio-Oss an osteoconductive material when used as an onlay bone substitute? : an experimental study in the mandible of the rabbit." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=112372.
Full textAbstract:
The present study was carried out to evaluate the osteoconductive nature of Bio-OssRTM (natural deproteinized bone mineral) when used as an onlay bone substitute in a Guided Bone Regeneration model. The lateral surface of the mandible was exposed bilaterally, in 8 rabbits. On one side of the mandible, two titanium chambers were filled with Bio-OssRTM material and the chambers were then firmly secured to the mandible using screws. The pores in the titanium chambers were covered with a layer of Bio-GideRTM material. On the opposite side of the mandible, chambers without Bio-OssRTM were placed on the lateral side of the mandible as a control. After a healing period of 3 months, histologic sections were obtained from each chamber. It was observed that new bone was generated in both test and control chambers to various degrees. In the test group, the newly generated bone was 18.41% and in the control group it was 5.31%. This difference was statistically significant. Thus, in this experiment, Bio-OssRTM was proven to be osteoconductive.
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Ljunggren, Ribom Eva. "Muscles, Estrogen, and Bone." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3779.
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Al-Khaldi, Abdulaziz A. "Therapeutic angiogenesis using autologous bone marrow stromal cells." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32749.
Full textAbstract:
Objectives. To study marrow stromal cells (MSCs) induced angiogenesis. To examine the possible mechanisms involved in the process. To evaluate neovascularization following implantation of MSCs in ischemic hind limb model.Methods and result. Using murine Matrigel angiogenesis model, we compared MSCs related angiogenesis to that produced by vascular endothelial growth factor (VEGF) and basic fibroblast growth factor. We found that MSCs result in an efficient and organized angiogenesis, arteriogenesis and vasculogenesis. MSC-related angiogenesis is VEGF dependent. MSCs in vivo produce VEGF that through paracrine effect induces local angiogenesis and through an autocrine loop stimulates FLK1+MSCs to differentiate into endothelial cells. MSCs implanted into ischemic hind limb resulted in marked improvement in blood flow and collateral vessels formation.
Conclusion. MSCs spontaneously induce efficient and mature angiogenesis in ischemic/hypoxic tissues with significant arteriolar component resulting in increased blood flow. They are also capable of spontaneous differentiation into endothelium. VEGF appears to be necessary for MSC-related angiogenesis and vasculogenesis.
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Gilbert, Stephen Gregory. "Bending fatigue of cancellous bone screws used in anterior spine surgery." Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6491.
Full textAbstract:
Bending fatigue has been noted in early clinical results of anterior spinal fixation using standard 6.5mm outside diameter (3.2mm inside diameter) cancellous bone screws. Fractography was used to qualify and quantify the failure mode. Fracture mechanics was used to determine the load level from the fractographic findings. These results were used in a test program to reproduce the fatigue failures seen in-vivo. The validity of the experimental model was investigated by varying test coupon parameters, testing the modified specimens and comparing the results to those predicted.
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Niu, Qiang. "Modeling and rendering for development of a virtual bone surgery system." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2008. http://scholarsmine.mst.edu/thesis/pdf/Niu_09007dcc8048a1fc.pdf.
Full textAbstract:
Thesis (Ph. D.)--Missouri University of Science and Technology, 2008.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed March 28, 2008) Includes bibliographical references (p. 146-154).
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Hungr, Nikolai Anthony. "Haptic emulation of hard surfaces with applications to orthopaedic surgery." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/639.
Full textAbstract:
A generally accepted goal in orthopaedic surgery today is to maximize conservation of tissue and reduce tissue damage. Bone-conserving implants have bone-mating surfaces that reproduce the natural curvature of bone structures, requiring less bone removal. No small, reliable, inexpensive and universal bone sculpting technique currently exists, however, that can both create and accurately align such complex surfaces. The goal of this thesis was to develop a haptic hard surface emulation mechanism that could be applied to curvilinear bone sculpting using a surgical robot. A novel dynamic physical constraint concept was developed that is able to emulate realistic hard constraints, smooth surface following, and realistic surface rigidity, while allowing complete freedom of motion away from the constraints. The concept was verified through the construction of a two-link manipulator prototype. Tests were run on nine users that involved each user tracing out five different virtual surfaces on a drawing surface using the prototype. The primary purposes of prototype testing were to obtain subjective data on how effectively the dynamic physical constraint concept simulates simple surfaces, to assess how it reacts to typical user interactions and to identify any unexpected behaviour. Users were 100% satisfied with the prototype’s ability to emulate realistic and stiff hard surfaces and with its ease of manipulation. The amount of incursion into each of the virtual surfaces by all the users was measured to assess the precision of the system with the goal of deciding whether this new haptic concept should be further developed specifically for precision applications such as surgery. For curvilinear surfaces, 90% of the cumulative distribution of the measured data was less than 2mm, while for linear surfaces it was less than 6mm. Four behavioural effects were noticed: lateral deflection, reverse ‘stickiness’, hysteresis and instability in certain areas. These effects were studied in detail to determine how to either eliminate them or to minimize them through system design optimization. A computer simulation was also used to model the behaviour of the prototype and to gain further understanding of these effects. These analyses showed that the concept can be successfully used in curvilinear bone sculpting.
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Thor, Andreas. "On platelet-rich plasma in reconstructive dental implant surgery /." Göteborg : Departments of Biomaterials and Oral & Maxillofacial Surgery, the Sahlgrenska Academy at Göteborg University and the Department of Surgical Sciences, Oral & Maxillofacial Surgery, Uppsala University Hospital, 2006. http://hdl.handle.net/2077/745.
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Puhulwelle, Gamage Pavan. "3D reconstruction of patient specific bone models for image guided orthopaedic surgery." Thesis, University of Auckland, 2012. http://hdl.handle.net/2292/11525.
Full textAbstract:
Visualisation of patient-specific fractured bone in 3D plays an important role in image guided orthopaedic surgery. Existing research often focuses on intra-operative registration of the patients' anatomy with pre-operatively obtained 3D volumetric data (e.g. CT scans) utilising fiduciary markers. This expensive and invasive approach is not routinely available for diagnostics, and a majority of fracture reduction procedures currently solely relies on 2D x-ray/fluoroscopic images. This research aims to assist orthopaedic surgeons in all steps of the femur fracture reduction procedure by introducing 3D anatomical visualisation. Studies conducted on femur fracture reduction has confirmed that computer-aided systems can significantly improve the accuracy of orthopaedic procedures by augmenting the current 2D image guidance with an interactive display of 3D bone models. This research indicates that the positioning errors, which generate bone misalignments and complications, will be reduced through the introduction of 3D bone fragment visualisation during surgical procedures. Consequently 3D visualisation of anatomy plays an important role in image guidedd orthopaedic surgery and most importantly contributes to minimally invasive procedures. The research goals of this thesis are achieved through the construction of a 3D model of a fractured bone, and the real-time tracking (pose estimation) of the bone segmentsintra operativelyly. The first component of the research is the innovative 3D reconstruction technique proposed for preoperative planning on procedures involving the femur, tibia and iliac. Pre-operative planning plays an essential role in the management of orthopaedic injuries because many of the technical problems that may arise during surgery can be anticipated during this preparatory phase. The novel reconstruction algorithm is based on two conventional orthogonal (in anterior and lateral views) 2D radiographic images and a 3D model of an intact (healthy) bone. This intact model is customised through a non-rigid registration process to the shape of the patient's bone. The customisation involves a fracture incorporation process that separates the bone into the proximal and distal segments and identifies the pose (position and orientation) of each fragment. This generally applicable framework is a significant contribution over current literature which is hindered by proprietary models that limit usage, are only available for small regions of the bone and have time consuming feature matching requirements. Furthermore, tests conducted involving cadaveric bone models conveyed a millimetre level accuracy in reconstruction, which is superior to comparable literature. The second component of the research is the intra-operative pose estimation conducted for cases involving bone segment motion tracking (e.g. femur shaft fracture reduction procedure). Here the pre-operatively reconstructed 3D model will be utilised intra-operatively in the 2D-3D registration process for real-time pose estimation. This novel intra-operative registration is performed solely utilising bony anatomical features extracted from fluoroscopic images. This contribution is an enhancement over the current literature which is a proponent of utilising invasive external fiduciary markers. Experiments conducted through phantom studies and cadaveric fractured bones identified a millimetre level accuracy in translation and less than a two degree level accuracy in rotation.
35
Dotsenko, Olena. "Bone marrow resident and circulating progenitor cells in patients undergoing cardiac surgery." Thesis, St George's, University of London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.530510.
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Elahi, Mohammed Mehboob. "A new predictive modality of cranial bone thickness." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ37118.pdf.
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Meredith, James O. "Biocomposites for bone tissue engineering : innovation report." Thesis, University of Warwick, 2009. http://wrap.warwick.ac.uk/36741/.
Full textAbstract:
Historically, bone defects resulting from trauma, disease or infection are treated with autograft or allograft. Autograft is bone transplanted from a non-critical area of the skeleton and allograft is bone donated from another member of the same species. The drawbacks with these treatments such as limited availability, donor site morbidity, high cost and disease transmission have driven increasing use of bone graft substitute (BGS) materials. These represent 15% of the £1.6 billion global orthobiologics market. BGS materials available to date are not suitable for use in grafts that are intrinsic to the stability of the skeleton. Thus, the aim for this project was to fabricate an off the shelf and economically viable BGS that will support the skeletal structure whilst healing occurs. This project employed an empirical approach utilising both rapid prototyping (RP) and conventional manufacturing processes to produce novel BGSs. A range of RP techniques were attempted and discovered to be unsuitable as a result of their long build and postprocessing times, poor availability of suitable materials, and undesirable surface finish. Experiments with injection moulding and laser drilling of polylactic acid (PLA) successfully produced 10 mm blocks with a compressive strength of 67 – 80 MPa and compressive modulus of 1.5 – 2.2 GPa. This line of research led to the hypothesis that ceramic extrusion, a process hitherto untested for use in bone tissue engineering (BTE), may be feasible for production of a novel and high strength BGS. In collaboration with an international expert in the manufacture of ceramic monoliths it was possible, for the first time, to manufacture hydroxyapatite (HA) monoliths by adapting the process used for manufacture of automotive exhaust catalysts. These HA monoliths exhibited a compressive strength of 142 – 265 MPa and compressive modulus of 3.2 – 4.4 GPa. The exceptional strength of these monoliths match the properties of cortical bone whilst retaining the high levels of porosity (> 60 %) found in cancellous bone. This combination of strength and porosity will enable treatment of large structural bone defects where the high strength will withstand typical skeletal forces whilst the high porosity allows blood vessels to infiltrate the monolith and begin the healing process. Furthermore, these HA monoliths support the proliferation and differentiation of human osteoblast-like MG63 cells and compare very favourably with a market leading BGS material in terms of their biological performance. It is suggested that this work will result in the development of a new family of high strength and high porosity BGSs for use in challenging clinical situations. The International Preliminary Examination Report for the patent issued to the author (WO 2007/125323) decreed that all 45 claims contained novelty and an inventive step. Two successful applications for research funding have raised nearly £50,000 that helped fund this research effort. Warwick ventures are currently involved in negotiating with medical partners to licence this technology for clinical use.
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Ke, Jin, and 柯金. "Transgenic stem cells for craniofacial bone reconstruction." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B44362973.
Full textAbstract:
Bone loss from the cranio-maxillofacial region is a major clinical problem affecting patients worldwide. Conventional treatment strategy includes the use of autogenous or allogeneic bone, biomaterials, and osteogenic growth factors. However, there has been no effective therapy for most cases so far. Stem cell-based gene therapy is the latest research method with possible applications in humans. The present study aims to (1) characterize rabbit mesenchymal stem cells (MSCs) relating to growth pattern, surface antigens, and the potential for multi-differentiation; (2) determine the transduction efficiency and duration of recombinant adeno-associated virus2 carrying enhanced green fluorescent
protein (rAAV2EGFP) reporter gene in rabbit MSCs and study the effects of rAAV2EGFP transduction on stem cells’ phenotype and capacity of multi-differentiation;
(3) evaluate the differentiation characteristics of rabbit MSCs following recombinant adeno-associated virus 2 carrying bone morphogenetic protein 2 gene (rAAV2BMP2) transduction; (4) investigate whether MSCs transduced by rAAV2BMP2 could successfully induce bone regeneration in rabbit critical-size cranial defects.
MSCs were isolated from bone marrows of rabbit tibias and cultured. Cell counting and colony-forming assays demonstrated that growth rates of MSCs dropped substantially with increasing passages. Flow cytometry on MSCs at passage 1 showed that cells expressed high level of CD49a and low level of CD44 as well as stage-specific embryonic antigen 4 (SSEA4). Multi-differentiation and reverse transcriptase-polymerase chain reaction (RTPCR) tests demonstrated that rabbit MSCs were capable to differentiate into osteocytes, chondrocytes and adipocytes. Immunofluorescence microscopy showed that rabbit MSCs produced a series of hematopoietic growth factors, including stem cell factor (SCF), vascular endothelial growth factor-A (VEGFA) and granulocyte macrophage colony-stimulating factor (GMCSF).
Subsequently, rabbit MSCs were transduced with rAAV2EGFP in vitro. By comparing the transduction efficiency with different doses of rAAV2EGFP particles, multiplicity of infection (MOI) of 1 x 10 4 was identified as an optimal parameter for the transduction of rAAV2 in rabbit MSCs. Fluorescent microscopy demonstrated long-term expression of EGFP in rabbit MSCs after transduction both in vitro and in vivo. In addition, cell proliferation assay, adipogenic induction test and flow cytometry showed that rAAV2EGFP transduced MSCs exhibited a similar pattern with non-transduced cells on the cell growth, capacity of adipogenic differentiation and expression of surface antigens, indicating that rabbit MSCs maintain their stem cell properties after rAAV2EGFP transduction.published_or_final_version
Dentistry
Doctoral
Doctor of Philosophy
39
McCord, J. Fraser. "An investigation into the effects of two bioceramics on rat mandibular bone." Thesis, University of Edinburgh, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377509.
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Lisbona, Allan Elie. "Apoptosis at the pseudomembrane-bone interface of failed total hip arthroplasties." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21596.
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The terminal events leading to periprosthetic osteolysis are multifactorial and attempts to modulate this process after the stage of modulator release have been futile. Cell death at the osteolytic interface of failed total hip arthroplasties (THAs) may occur via one of two modes---Apoptosis (programmed cell death/cellular suicide) vs. Necrosis. Apoptosis (PCD) is an active form of cell death that results in---among other things---orderly fragmentation of DNA and specific protein synthesis. The purpose of this study was to determine the mode of cell death at this interface. TdT-mediated dUTP nick end-labeling (TUNEL) stain and immunodetection of terminin protein were used to identify apoptosis.Our studies demonstrated that 31% (range 7--56%) of cells of pseudomembrane were positive for TUNEL stain. Moreover, the presence of apoptosis was the same at both the femoral and acetabular sides of the prostheses. In addition, pseudomembrane (PM) specimens stained for the 30 kDa terminin protein, an apoptosis-specific protein. The results demonstrate that apoptosis is occurring at the PM-bone interface of THAs suggesting that apoptosis, related events may be associated with periprosthetic osteolysis.
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許顯名 and Hin-ming Hui. "The morbidity of anterior iliac bone harvesting for maxillofacial grafting procedures." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B38628211.
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楊國泰 and Kwok-tai Cathay Yeung. "Finite element modeling of bone cement for vertebroplasty." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B31228021.
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Husseini, Abdallah. "Bone formation during fracture repair in mice deficient for the cyp24a1 gene." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=106532.
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Vitamin D is a key regulator of mineral and bone homeostasis. The enzyme CYP24A1 is responsible for transforming vitamin D into 24,25(OH)2D. The putative biological activity of 24,25(OH)2D remains unclear. Previous studies showed an increase in the circulating levels of this metabolite following a fracture in chicks. Our laboratory has engineered a mouse model deficient for the Cyp24a1 gene for studying the role of 24,25(OH)2D. We set out to study the role of 24,25(OH)2D in endochondral and intramembranous bone formation in mammalian fracture repair in this mouse model. Methods: Wild-type and Cyp24a1-deficient mice were subjected to two surgical procedures to simulate bone development and fracture repair. To mimic endochondral ossification, we devised a modified technique to perform intramedullary nailing of a tibia followed by an osteotomy. To evaluate intramembranous ossification, we applied distraction osteogenesis to tibiae using a mini Ilizarov external fixator. Histomorphometric parameters and gene expression differences in fracture repair between the mutant mice and the wild-type controls were measured using micro computed tomography, histology and reverse-transcription quantitative PCR. Results: Quantitative histomorphometric results showed a delay in endochondral fracture repair in the mutant as compared to wild-type mice. In the same model, gene expression of collagen type X in the callus was lower in the mutant mice. These significant differences were fully rescued by injecting the mutant mice with exogenous 24,25(OH)2D. In the intramembranous bone formation model, we found a trend towards reduced bone formation in the gap created by the distraction process in the mutant mice as compared to the wild-type mice. Conclusions: Our results support a role for CYP24A1 and its product 24,25(OH)2D in fracture repair which is more dominant in a chondrocyte-mediated bone formation pathway like endochondral ossification. Further study of the role of 24,25(OH)2D in bone healing has the potential to support novel approaches in accelerating bone formation and fracture repair.La vitamine D est un régulateur important de l'homéostasie minérale et osseuse. L'enzyme CYP24A1 métabolise la vitamine D en 24,25(OH)2D. L'activité biologique de la 24,25(OH)2D demeure imprécise. Des études ont démontré que la 24,25(OH)2D est un métabolite important pour la réparation des fractures chez le poulet. Notre laboratoire a conçu un modèle de souris déficientes pour le gène Cyp24a1 afin d'étudier le rôle de la 24,25(OH)2D. Nous avons entrepris d'étudier le rôle de ce métabolite dans l'ossification endochondrale et intramembranaire pendant la réparation des fractures dans ce modèle de souris. Méthodes: les souris sauvages et Cyp24a1-mutantes ont été soumises à deux différentes procédures chirurgicales pour simuler la formation d'os pendant la réparation des fractures. Pour imiter l'ossification endochondrale, nous avons utilisé un clou intramédullaire afin de stabiliser le tibia après la fracture. Pour évaluer l'ossification intramembranaire, nous avons appliqué l'ostéogénèse par distraction sur le tibia à l'aide d'un appareil de fixation externe. Les paramètres histomorphométriques et l'expression génique au cours de la réparation de la fracture chez les souris mutantes et sauvages ont été mesurés par microtomographie, histologie et PCR quantitative (qRT-PCR), respectivement. Résultats: l'analyse histomorphométrique démontre un retard dans la réparation des fractures stabilisée par clou intramédullaire chez les souris mutantes par rapport au type sauvage. Dans le même modèle, l'expression du collagène de type X était plus élevée chez les souris de type sauvage. Ces différences significatives ont été entièrement corrigées par l'injection de 24,25(OH)2D exogène chez les souris mutantes. Dans le modèle d'ostéogénèse par distraction, nous avons trouvé une tendance vers la formation osseuse réduite chez les souris mutantes comparativement aux souris de type sauvage. Cependant, les différences observées n'étaient pas statistiquement significatives. Conclusion: Nos résultats suggèrent un rôle pour CYP24A1 et la 24,25(OH)2D dans la réparation des fractures par ossification endochondrale. Une étude plus approfondie du rôle de la 24,25(OH)2D pourrait conduire à l'utilisation de ce métabolite afin d'accélérer la formation osseuse et la réparation des fractures.
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Dunlop, D. G. "Mechanical and biological aspects of impaction bone grafting in revision hip surgery and the use of a new synthetic bone graft." Thesis, University of Edinburgh, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.649798.
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This thesis examines, in three phases, the biological and mechanical properties of impacted morcellised bone graft and the use of synthetic additives. Phase I. The mechanical strengths of different mixtures of bone graft were found to follow sound Engineering principles. The distribution of particle sizes from different bone mills determines the mechanical strength of graft from that mill. Theoretical increases in strength by improving particle size distribution were confirmed by mechanical tests Washing the graft or the addition of synthetic additives (Controlled Release Glass - Corglaes(r) (Giltech Ltd. Ayr, Scotland) & Tricalcium Phosphate/Hydroxyapatite - TCP/HA (Stryker Howmedica Osteonics, Berkshire, England)) also improved strength. Phase II. An in-vivo ovine defect model allowed biological assessment of impacted pellets, made of mixtures found in Phase I to be mechanically strong. Bone densitometry and histological analysis were used. Phase III. An ideal mixture of bone graft and an additive was compared with allograft bone alone, in an ovine femoral revision hip replacement model. The subsistence over time and 3D micromotions under load of the implant were similar between the two groups. Histological analysis showed increased biological activity around the proximal femur in contrast to the relative isolation of the distal graft. These experiments highlight potential mechanisms with which to improve impacted bone graft strength and support further analysis of Corglaes(r) and TCP/HA as bulking agents and/or bone graft enhancers.
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Hellström, Hans-Olov. "Bone and Aluminium." Doctoral thesis, Uppsala University, Department of Surgical Sciences, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8181.
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Osteoporosis is a major health care problem, by reason of its devastating consequences, in particular hip fractures. Worldwide it has been estimated that the incidence of hip fracture will increase to more than 6 million per year by 2050 compared to 1.7 million per year in 1990. Osteoporosis can be caused by various factors namely, genetic, lifestyle and environmental factors, and since the rising incidence of its consequences is not fully explained by the growing age of the population, there is an urgent need to identify individual causal factors of this condition.
The present research has focused on aluminium, one potential environmental factor of importance for bone disease, and its possible relation to osteoporosis, since it is known to cause osteoporosis-like bone disease and has been associated with induction of progressive central nervous system diseases.
Aluminium is the third most common element in the earth’s crust and the most abundant metal (8%). It is widely utilized industrially and it is also naturally present in many foods. Although aluminium is ubiquitous in the human environment, evolution has not given it an essential biological function.
The aluminium content of bone was measured by inductively coupled mass spectrometry in a large group of patients suffering from hip fractures, high energy fractures and osteoarthrosis. An exponential increase in aluminium content of bone with age was found (p=0.0004). However, no significant association of aluminium in bone with occurrence of hip fracture or dementia could be found, and no indirect evidence was obtained, e.g. through bone mineral density or biomechanical properties, that aluminium is involved in the pathogenesis of osteoporosis. Although we accumulate aluminium in bone throughout our lives, and there are experimental suggestions that aluminium induces premature cell death, the body content of this metal does not seem to influence the overall mortality risk.
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Conway, Jordan C. "Highly silicated hydroxyapatite : synthesis, characterisation and evaluation." Thesis, University of Aberdeen, 2017. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=235581.
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Chua, Hannah Daile P. "Distraction osteogenesis versus orthognathic surgery which is better for cleft lip and palate patients? /." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B41758195.
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Campisi, Paolo. "Characterization of the expression of bone morphogenetic proteins during distraction osteogenesis of the mandible." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32980.
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Distraction osteogenesis is a form of in vivo tissue engineering used to lengthen bone. Bone morphogenetic proteins (BMPs) are known mediators of bone formation during the distraction of enchondral bones. Their role in the distraction of membranous bones remains unknown. A rabbit model was used to characterize the expression of BMP-2, 4 and 7 during mandibular distraction osteogenesis. Fourteen animals were subjected to a defined distraction protocol. At weekly intervals, two rabbits were sacrificed and the generate bone harvested for radiographic, bone densitometric, histologic and immunohistochemical analyses. The results demonstrate that during distraction, bane forms primarily by intramembranous ossification. BMP-2 and 4 were maximally expressed in osteoblastic cells during the distraction period and in chondrocytes during the consolidation period. The pattern of mandibular BMP expression was different than previously described for long bones. Understanding the pattern of BMP expression may guide the strategic administration of recombinant BMPs to enhance the rate and quality of bone formation during distraction osteogenesis thereby shortening the time required for consolidation of the generate bone.
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Creamer, Kyle William. "Utilizing pQCT and Biomarkers of Bone Turnover to Study Influences of Physical Activity or Bariatric Surgery on Structural and Metabolic Status of Bone." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/64865.
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Bone health in the context of two common maladies, osteoporosis and obesity, has spurred research in the area of physical activity (PA) and bariatric surgery (BarS).
Objectives: To examine: 1) relationships between PA and the skeleton utilizing the peripheral Quantitative Computed Tomography (pQCT) and Dual-energy X-ray Absorptiometry (DXA) in pre-menopausal women; 2) effects of adjustable gastric banding (AGB) vs. Roux-en-Y gastric bypass (RYGB) surgeries on pQCT and DXA measures; 3) 6-month time course changes on serum biomarkers of bone turnover and associated adipokines induced by AGB vs. RYGB.
Methods: Standard DXA and pQCT measurements were taken for all subjects. PA tertiles (PA-L, PA-M, PA-H) were based on a calculated average MET-min/day determined from 4-d self-reported PA and pedometer step counts. For BarS subjects, bone measurements were taken pre-surgery, 3- and 6-months post-surgery along with serum (or plasma) from fasting blood draws, with ELISA assays for total OC, undercarboxylated OC, CTx, adiponectin, and leptin.
Results: Minimal DXA differences between the highest and lowest PA tertiles were seen, while pQCT tibial measures and polar strength-strain index (SSIp) indicated differences along the tibial shaft. Comparing the two instruments and adjusting for BMI, the DXA leg and hip BMD and BMC showed differences (p<0.05) between PA-M and PA-L as well as PA-H and PA-L. Similarly, the pQCT tibial cortical area, BMC, and SSIp were progressively greater for the different levels of PA (p<0.05).
3- and 6-months post-BarS weight, fat-free mass, fat mass, central body fat, tibial and radial subcutaneous fat, and radial MCSA decreased (p<0.05). Comparing the AGB and RYGB and adjusting for weight, DXA BMC showed decreases (p<0.01) at both time points for RYGB. RYGB demonstrated differences (p<0.05) in bone measures at 3- and 6-months post-surgery along the tibial shaft that are indicative of increases in bone strength, and at 6-months, total OC, undercarboxylated OC, and HMW adiponectin increased, while leptin decreased.
Conclusions: PA is associated with increases in bone, but pQCT data are more discriminatory and sensitive. 6-months post-RYGB, pQCT measures indicate increases in bone strength parameters, and greater bone adaptation was evidenced by biomarkers of increased osteoblastic activity.Ph. D.
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Bittira, Bindu. "Bone marrow stromal cells in the tissue repair process following myocardial infarction." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32763.
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Marrow stromal cells (MSCs) are pluripotent stem cells which may participate in the repair of damaged organs. We tested the hypothesis that MSCs can be recruited to the heart upon myocardial infarction, and play pathophysiological roles in the subsequent healing and adaptation process. An animal model was created with labeled MSCs in its bone marrow and then a myocardial infarction produced. Donor MSCs from isogenic Lewis rats were harvested, multiplied in culture and labelled. Labelled cells were intravenously injected into the recipient rats and one week later upon the engraftment of these labelled MSCs within the bone marrow, rats underwent a coronary artery ligation or sham operation. The hearts were removed at various time points and the presence of labelled cells in the heart was confirmed and their phenotypes identified. We confirmed the presence of labelled cells in the rat bone marrows and the presence of labelled cells in the infarcted myocardium at all time points studied, but not in the normal hearts. There was evidence for myogenic differentiation with some labelled cells expressing smooth muscle/myofibroblast phenotypes and appearing to participate in vasculogenesis. Our evidence is consistent with the hypothesis that myocardial infarction may send a signal to recruit MSCs to the injured heart, where they undergo milieu-dependent differentiation. The ability of these cells to express various phenotypes may allow them to participate in the pathophysiology of post-infarct remodeling and angiogenesis. Therapeutic implantation of MSCs thus may further enhance such effects.