No description available.

The literature shows that maxillofacial fractures in children are uncommon. Although the Department of Oral and Maxillofacial Surgery of the Faculty of Dentistry, of the University of the Western Cape, has been providing a service to the Red Cross Children&rsquo / s Hospital (RXH) for the past twenty years, no study had been undertaken to determine the age, gender, number of patients per year, aetiology, patterns, and management of maxillofacial fractures at this institution. A retrospective records based study was undertaken to determine these features. This study accessed the records of patients seen at the trauma unit at RXH, from 1994 to 2003 inclusive, and referred for maxillofacial attention.<br /> <br /> One-hundred-and-five patient records were obtained and analyzed using the SPSS statistic package. One-hundred-and-twenty-seven fractures were recorded in one hundred and five patients. The age of the patients ranged from one to thirteen. Sixty-five male and forty female patients were seen. Dentoalveolar fractures were the most common fracture seen in both the midface and mandible. Midface fractures were more common than mandibular fractures. Falls, followed by motor vehicle accidents, were the most common cause of facial fractures. Most fractures were successfully managed by closed procedures. At this institution, nasal and frontal fractures have surprisingly little or no input from the Department of Oral and Maxillofacial Surgery.

X-ray based evaluation of different stages of fracture healing is a well established clinical standard. However, several studies have shown plain radiography alone to be an unreliable method to assess healing. The advent of digital X-ray systems provides the potential to perform quantitative analysis on X-ray images without disrupting normal clinical practice. Two aspects were explored in this study. The first was the measurement of mechanical fracture stiffness under four point bending and axial loading. The second was the inclusion of an Aluminium step wedge to provide Aluminium-equivalent thickness calibration information. Mechanical sti ness studies involved the development of equipment to perform four point bending on intra-medullary (IM) nailed tibial fractures, equipment to perform axial loading on conservatively treated humeral fractures, and fracture models to ex- amine the developed systems. Computational procedures to automatically measure the angle and offset occurring at the fracture site by comparing loaded and unloaded X-ray images were developed utilising cross-correlation. The apparatus and procedures were tested using the fracture models both in X-ray and using the Zwick materials testing machine. The four point bending system was applied clinically to a series of IM nailed tibial fracture patients and the axial loading system to two conservatively treated humeral fracture patients. Mechanical stiffness results showed that the apparatus worked well in the clinical radiography environment and was unobtrusive to normal practice. The developed X-ray analysis procedure provided reliable measurements. However, in the case of IM nailed tibial fractures, both angular and displacement movements were too small to be accurately assessed or to provide reliable stiffness measurements. This indicated that this patient group was possibly unsuitable for mechanical stiffness measurements or that higher loads needed to be applied to the fracture site. The case studies of conservatively treated humeral fractures showed potential in detecting movement between loaded and unloaded X-rays and using this to provide sti ness information. Further investigation is required to show that this technique has the potential to aid fracture healing monitoring. Investigation into Aluminium step wedge calibration began with the design of different step wedges and X-ray phantoms. Initial image analysis involved studying the automatic processing applied by a digital Computed Radiography (CR) Fuji sys- tem and modelling of the inhomogeneities in X-ray images as well as investigation into the effect of and correction for scatter, overlying soft tissue and bone thickness. Computational procedures were developed to semi-automatically detect the steps of the step wedge, form an exponential Aluminium step thickness to grey level calibration graph, measure soft tissue and bone thickness, and correct for the heel effect and scatter contributions. Tests were carried out on pre-clinical models and results compared to ash weight and peripheral quantitative computed tomography (pQCT). A clinical study of radial fractures was used to investigate the effectiveness of the step wedge calibration system in monitoring fracture healing changes. Results using the step wedge indicated that the calibration technique was e ective in detecting and correcting for aspects in uencing Aluminium-equivalent thickness measures. With careful processing, useful information was obtained from digital X- rays that included the Aluminium step wedge and these correlated well with existing density measures. The use of the wedge in patient images showed that small increases in Aluminium-equivalent thickness of the fracture site could be detected. This was most useful for intra-patient comparisons throughout the course of healing rather than providing quantitative measurements which were comparable to other density measures. In conclusion, this thesis shows the potential for accurate analysis of digital X- rays to aid the monitoring of healing changes in fracture patients, particularly with application of axial loading and the use of step wedge calibration.

Compressional and shear wave velocity and attenuation measurements were obtained in the laboratory from 50 mm diameter, cylindrical, limestone core samples over a confining pressure range of 5 – 60 MPa. Normal and tangential fracture compliance values, as a function of confining pressure, were calculated for a single fracture cut perpendicular to the long axis of the core. The ratio of the normal to tangential compliance was approximately 0.4 and was independent of the applied stress. Values of normal and tangential fracture compliance calculated were of the order 10^-14 m/Pa, and decreased with an increase in confining pressure. Both Q^-1</sup>_P and Q^-1</sup>_S1/Qs were shown to be small for these samples. A borehole test site was constructed in a Carboniferous limestone quarry, at Tytherington, situated north of Bristol, UK. This quarry was chosen because the rock type was fairly homogeneous and the fractures could be mapped in the quarry walls as well as down three, 40 m vertical boreholes drilled in-line in the quarry floor. Wireline logs were obtained in all the holes and a seismic crosshole survey was carried out between the two outermost boreholes. An estimate of in-situ normal fracture compliance, Z_N, was obtained from the log and crosshole data, in 4 different ways, using effective medium theories as well as the displacement discontinuity theory. An additional estimate of Z_N was obtained from a separate borehole test site constructed in fractured Devonian meta-sediments at Reskajeage, Cornwall, UK. These fractures were much larger in size than those observed at Tytherington quarry. From the above field and laboratory measurements, fracture compliance was shown to increase approximately linearly with the size of the fractures. In addition, a study of crosshole seismic attenuation was performed at Tytherington quarry. Q was found to be frequency dependent. This frequency dependence was interpreted as being due to scattering rather than intrinsic attenuation.

Severe ankle injuries can result in ligament rupture or a fracture. A major problem after such injuries is limitation in mobility. Weight bearing tasks, such as walking, become a problem because of pain, deficits in joint range of motion and muscle strength. This thesis studies a key dilemma in early rehabilitation, whether to immobilise the ankle or allow joint motion to improve mobility outcomes. Studies have focused on two scenarios, severe ligament rupture, and unstable fractures managed through open reduction and internal fixation (ORIF). The analysis of gait outcomes was an important component of this thesis and a novel analytical method was developed to normalise gait velocity in the estimation of speed-dependent gait outcomes. A systematic review and meta-analysis was conducted including evidence to July 2014. The reporting and design of trials was universally poor. In the 6 weeks of recovery following ankle ORIF surgery, there was insufficient evidence that early ankle movements offered a benefit to mobility recovery compared with immobilisation in a cast. Ankle movements compared with immobilisation reduced the risk of venous thrombosis/thromboembolism. However, compared with cast immobilisation, the risk of deep and superficial surgical site infection and fixation-related complications were higher when ankle movements were permitted. To investigate the role of ankle supports in rehabilitation of walking after ORIF, two randomised cross-over studies were completed. In healthy participants with non-pathological gait, a walker boot induced gait abnormalities when compared with Tubigrip (elasticated bandage). There were no important differences in gait between a stirrup brace and Tubigrip. In people who had undergone ankle ORIF 6 weeks previously, a walker boot and to a lesser extent a stirrup brace offered improvements in gait symmetry and lower pain scores when compared with Tubigrip. Finally, a secondary analysis of the Collaborative Ankle Support Trial cohort (n=584) was conducted, which concluded that, in comparison to Tubigrip, 10 days of cast immobilisation provided greater probability of recovery of a range of mobility outcomes 4 weeks following injury. This thesis contributes evidence favouring a role for ankle immobilisation in improving mobility following severe ankle injury in adults. Clinicians should be aware of the benefits and risk of harms outlined, as well as the limitations in the current evidence base.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Objetivo: O presente estudo teve como objetivo verificar os efeitos do tratamento com altas e baixas doses de metotrexato (MTX) na reparação de fraturas mandibulares, num modelo experimental com ratos. Métodos: O modelo experimental empregado consiste na criação de um defeito ósseo na mandíbula do rato, semelhante a uma fratura. Oitenta ratos foram distribuídos em 4 grupos de 20 animais que receberam, por via intraperitoneal: soro fisiológico (controle) (1 ml, após a cirurgia); dexametasona (DX) (0,15 mg / kg, dose única após a cirurgia); alta dose MTX (1,6 mg / kg, semanalmente); baixa dose MTX, (0,25 mg / kg, semanalmente). Os animais foram sacrificados no dia 1º, 7º, 15º e 30º dia após a cirurgia. As mandíbulas foram submetidas à análise radiográfica para medir a distância entre os cotos ósseos e a área de osteotomia. Avaliação histomorfométrica foi realizada usando um software analisador de imagens digitalizadas para verificar a formação de cartilagem e óssea. Resultados: Os resultados revelaram não haver alterações significantes entre os tratamentos nos parâmetros avaliados nos 10 e 70 dias após a cirurgia. Animais do grupo controle sacrificados no 15º dia após a cirurgia tiveram uma redução da distância entre as extremidades ósseas e na área da osteotomia, bem como um grande aumento na formação de cartilagem. O padrão desses parâmetros nos animais tratados com baixas doses de MTX e DX não foram significativamente diferentes do grupo controle neste período. No entanto, os animais tratados com alta dose de MTX tiveram aumento da distância entre os cotos ósseos e da área da osteotomia, bem como foi praticamente nulo o aumento da formação de cartilagem. Sobre o 30º dia após a cirurgia, os animais do grupo controle tinham praticamente recuperado a região da fratura, bem como aqueles tratados com doses baixas de MTX. Os grupos tratados com a alta dose de MTX e DX mantiveram abertos os defeitos ósseos. Conclusões: Este estudo mostra claramente que a baixa dose de MTX não afetou a reparação óssea de fraturas mandibulares em ratos, em contraste com a alta dose de MTX, que afeta desfavoravelmente a regeneração óssea. / Purpose: The present study aims to verify the effect of high and low dose of methotrexate (MTX) treatment on bone repair of mandibular fractures in rats. Methods: The experimental model employed consists in creating a defect in rat mandible, similar to a fracture. Eighty rats were distributed in 4 groups of 20 animals that received, intraperitoneally: saline (1 ml, after surgery); dexametazone (DX, 0.15 mg/Kg, one dose at surgery); high dose MTX (1.6 mg/Kg, weekly); low dose MTX, (0.25 mg/Kg, weekly). Groups of five animals were sacrificed on the 1st, 7th, 15th and 30th day after surgery. Mandibles were submitted to radiographic analysis to measure the distance between bony edges and the area of osteotomy. Histopathological evaluation was performed in digitalized images using an analyzer software to examine cartilage and bone formation. Results: The treatments did not alter any evaluated parameters on days 1 and 7 after surgery. Control animals sacrificed on the 15th day after surgery had a reduction of the distance between bony ends and in the area of osteotomy, as well as a great increase in cartilage formation. The pattern of these parameters in animals treated with low dose MTX and DX did not differ from control group. However, animals treated with higher dose of MTX kept increasing the distance between bony ends and the area of osteotomy, and the increase in cartilage formation was practically inexistent. On the 30th day after surgery, control animals had pratically recovered the fracture region, as well as those treated with low dose MTX. The group treated with higher dose MTX and DX still had an open bone defect. Conclusions: This study clearly shows that low dose MTX did not affect bone healing of mandibular fractures in rats, in contrast to a higher dose, which promotes impairment of bone regeneration.

O advento da osteossíntese biológica é importante avanço no desenvolvimento da ortopedia. As vantagens que as hastes de Interlocking Nail têm demonstrado clinicamente, como método de fixação interna que promove formação de calo ósseo adequado, respeitando as premissas básicas da ortopedia moderna, com paciente retomando suas atividades de forma ativa, precoce e indolor, transportam esta técnica à condição de principal em termos de tratamento de fraturas cominutivas de fêmur em pacientes humanos e animais de companhia. No entanto, face a pouca disponibilidade de dados biomecânicos disposta em bibliografia, buscou-se, através deste estudo biomecânico não destrutivo, disponibilizar o padrão de movimentação interfragmentária do foco da fratura, mediante osteossíntese com hastes bloqueadas. Foi realizado estudo contemplando cinco grupos diferentes, com seis elementos cada, em análise in vitro, em relação a quatro diferentes possibilidades de bloqueio transcortical. Avaliou-se também comportamento do sistema quando utilizada haste de comprimento menor ao ideal, submetidos aos ensaios de compressão excêntrica, encurvamento crânio-caudal e rotação, através de análise fotogramétrica e confrontamento de dados aos obtidos pela análise de rigidez disponibilizada pela máquina universal de ensaios mecânicos Kratos® modelo 5002 dotada de célula de carga de 981 N (100 kgf). A análise dos resultados obtidos não apresentou diferença significativa entre os grupos nos ensaios propostos, tanto para análise fotogramétrica quanto análise de rigidez, sendo menor que 1,0 mm a média da movimentação interfragmentária de todos os grupos estudados. Estes dados demonstram biomecanicamente a aplicabilidade da técnica em fraturas cominutivas de terço médio de diáfise femoral em cães, possibilitando, frente à necessidade do cirurgia, optar por qualquer das técnicas de bloqueio aqui estudadas. / The advent of biological osteosynthesis is an important advance in the orthopedics development. The advantages that the rods of Interlocking Nail have clinically demonstrated, as method of internal fixation that promotes adequate bone callous formation, respecting the basic premises of the modern orthopedics, with patient retaking its activities of active, precocious and painless form, carry this technique to the first choice in terms of treatment of femoral comminutive fractures in human and small animal patients. However, face to few availability of biomechanical data disposed in bibliography, this non destructive biomechanical study had the aim to demonstrate the standard of interfragmentary motion, in Interlocking nails osteosynthesis. This research was developed contemplating five different groups, with six elements each group, in an in vitro analysis, in relation to four different possibilities of transcortical blockade. The behavior of the system when the osteosynthesis was made through one lesser length to the ideal interlocking rod was also evaluated. All groups were submitted to the assays of eccentric compression, bending and torsion, through photogrammetric analysis and comparison to the analysis of rigidity data, disposed for the Kratos® universal machine of mechanical assays, model 5002 endowed with 981 N (100 kgf) load cell. The analysis of disposed results did not present significant difference between the groups in the considered assays, neither for photogrammetric analysis nor for rigidity analysis, being the average of the interfragmentary motion lesser that one millimeter on all of the studied groups. These data biomecanically demonstrate the applicability of the interlocking nail technique in medial third cominnutive femoral fractures in dogs, including, front to the necessity of the surgeon, the possibility to opt to any of the techniques of blockade studied.

Fractures can profoundly affect the capacity of carbonate reservoirs to store and permeate fluids, depending on the properties and abundance of fractures. Fractures exist abundantly in carbonate outcrops; however, their abundance in subsurface carbonates is obscure because of the data shortages and uncertainties about the factors that drive fracturing in sedimentary basins. The objective of this research is twofold. The first is to study abundance of fractures in gently deformed carbonates, which were generally overlooked. The second is to address measuring fracture abundance using electrical borehole imaging, which is the mostly used method to describe reservoir fractures. Fractures were studied from areas in the gently folded and shallowly (less than 2 km depth) buried interiors of the Arabian Platform. The study areas include outcrops and reservoirs of the Late Jurassic Arab carbonates in the sprawling homocline of Central Arabia and a low-relief dome in Eastern Arabia. The Cenozoic Rus carbonates in the dome outcrops were also studied. Fracture abundance was measured from the outcrops using scanlines and from the reservoirs using core and borehole images of extended-reach drilling. Many systematic properties were drawn on mineralization, orientation, and abundance of fractures. The fractures were found to be opening mode, mostly barren, and exist with subvertical dips, and some regional trends. The fractures display significantly differing ranges of abundance that were controlled by the subtle structural bending of the dome and homocline, carbonate lithofacies, and paucity of fracture mineralization. The borehole imaging was found to significantly lower fracture abundance. The detection of fractures was subject to several factors including size of fracture widths, nature of fracture roughness, and present-day stress field. The results have implications for modeling of fracture systems and tectonic regimes. For example, finding that fracture abundance varies drastically in such gently deformed regions indicates that carbonates are very sensitive to fracturing processes. Moreover, the borehole imaging limitations influence the models of fracture abundance and orientations, which are often used to deduce paleo tectonic regimes and present-day geodynamics in carbonate reservoirs.

Accounting for azimuthal anisotropy is necessary for the processing and inversion of wide-azimuth and wide-aperture seismic data because wave speeds naturally depend on the wave propagation direction. Orthorhombic anisotropy is considered the most effective anisotropic model that approximates the azimuthal anisotropy we observe in seismic data. In the framework of full wave form inversion (FWI), the large number of parameters describing orthorhombic media exerts a considerable trade-off and increases the non-linearity of the inversion problem. Choosing a suitable parameterization for the model, and identifying which parameters in that parameterization could be well resolved, are essential to a successful inversion. In this thesis, I derive the radiation patterns for different acoustic orthorhombic parameterization. Analyzing the angular dependence of the scattering of the parameters of different parameterizations starting with the conventionally used notation, I assess the potential trade-off between the parameters and the resolution in describing the data and inverting for the parameters. In order to build practical inversion strategies, I suggest new parameters (called deviation parameters) for a new parameterization style in orthorhombic media. The novel parameters denoted ∈d, ƞd and δd are dimensionless and represent a measure of deviation between the vertical planes in orthorhombic anisotropy. The main feature of the deviation parameters consists of keeping the scattering of the vertical transversely isotropic (VTI) parameters stationary with azimuth. Using these scattering features, we can condition FWI to invert for the parameters which the data are sensitive to, at different stages, scales, and locations in the model. With this parameterization, the data are mainly sensitive to the scattering of 3 parameters (out of six that describe an acoustic orthorhombic medium): the horizontal velocity in the x1 direction, ∈1 which provides scattering mainly near the zero offset in the x1-x3 vertical plane, and ∈d, which is the ratio of the horizontal velocity squared in the x1 and x2 direction. Since, with this parameterization, the radiation pattern for the horizontal velocity is azimuth independent, we can perform an initial VTI inversion for two parameters (velocity and ∈1), then use ∈d to fit the azimuth variation in the data. This can be done at the reservoir level or any region of the model.