Dissertation submitted in partial compliance with the requirements for the Master’s Degree in Technology: Chiropractic Faculty: Health Sciences, Durban University of Technology, 2009 / Aim To determine the profile of traumatic cervical spine fractures with respect to the epidemiology, clinical presentation, types of fractures, conservative and surgical intervention, short-term post-intervention (i.e. post-conservative and post-surgical) complications and short-term post-surgical rehabilitation of patients presenting at the Spinal Unit of King George V Hospital over a 12-week period. Methods Patients who presented to the King George V Hospital Spinal Unit from surrounding hospitals with traumatic cervical spine fractures were evaluated by the medical staff. Data concerning the epidemiology, clinical presentation, types of fractures, conservative and surgical intervention, short-term post-intervention (i.e. post-conservative and postsurgical) complications and short-term post-surgical rehabilitation data were recorded by the researcher. A p-value of <0.05 was considered as statistically significant. Appropriate statistical tests were applied to the hypothesis-testing objectives. These involved the Pearson’s Chi Square Tests for categorical variables or Fisher’s Exact Tests as appropriate where sample sizes were small. Paired t-tests were done to compare preand- post-surgical Frankel grading and Norton Pressure Sore Assessment scores. Results The number of patients who presented to the Spinal Unit over a 12-week period was 20, of this number 17 were males, three were females and all were black. Eleven patients were treated surgically while nine patients were treated conservatively. The most frequent aetiology of cervical spine fractures was motor vehicle accidents (n = 10) followed by falls (n = 9). The most common co-existing medical conditions were smoking (n = 7), HIV (n = 5), alcohol abuse (n = 3) and obesity (n = 3). The most frequent locations of cervical spine fractures were C2 (n = 6), C1 (n = 4) and the posterior column of C6 (n = 3), while dislocations occurred primarily at the C5-C6 levels (n = 5) of the lower cervical spine. Odontoid fractures (n = 6), Jefferson’s fractures (n = 4) and unilateral facet dislocations (n = 6) were the most common fractures and dislocations v observed. Head injuries (n = 4) and lower limb fractures (n = 3) were the most common extra-spinal fractures. All subjects who sustained head injuries also had associated C1 or C2 fractures. Neurological complications most frequently involved the upper limb where loss of motor function (n = 8) and weakness (n = 4) were observed. The majority of the patients (n = 8) reported a Frankel Grading of E. There were no significant associations between types of fracture and gender with the exception of fracture/dislocation observed in two females. There was a statistically significant difference in the NPSA score (p = 0.004). Conservative care utilized included soft collar (n = 6), cones calipers (n = 6), physiotherapy (n = 4), Minerva jacket (n = 4) and SOMI (sterno-occipital mandibular immobilization) brace (n = 1) while surgical intervention included anterior decompression (n = 8), anterior fusion (n = 8), allograft strut (n = 8), discectomy (n = 8), anterior cervical plating (n = 8), anterior screw fixation (n = 2), a transoral approach (n = 1) and a corpectomy (n = 1). The short-term post-conservative care complications observed in this study were an occipital pressure sore (n = 1), severe discomfort (n = 1) as well as severe neck pain (n = 1), while the short-term post-surgical complications were severe neck pain (n = 2), oral thrush (n = 1), pneumonia (n = 1), odynophagia (n = 1) and hoarseness (n = 1). Of the 11 patients who underwent cervical spine surgery, ten were sent for physiotherapy and one for occupational therapy. No significant associations were seen between the type of cervical spine fracture and the age of the subject. There was a significant association between fracture/dislocation and the female gender (p = 0.016). There was significant negative association between odontoid fracture and: anterior decompression, anterior fusion, allograft strut, discectomy and anterior cervical plating (p = 0.006). Conclusion The results of this study reflect the presentation and management of cervical spine fractures at a referral spinal unit of a public hospital in KwaZulu Natal. The impact of HIV and other co-existing medical conditions were not determined due to the small sample size in this study. Further epidemiological studies are required to be conducted in the Spinal Units of all South African public hospitals in order to confirm or refute the observation of this study. / National Research Foundation (NRF)

published_or_final_version / Orthopaedic Surgery / Master / Master of Philosophy

Background: Severe facial trauma is often associated with intracerebral injuries. So it seemed to be of interest to study stress propagation from face to neurocranium after a fistlike impact on the facial skull in a finite element analysis. / Hintergrund: Frakturen des Gesichtsschädels gehen häufig mit intrakraniellen Verletzungen einher. Deshalb erschien es interessant, die Weiterleitung und Verteilung von Spannungen, wie sie bei einem Faustschlag auftreten, vom Gesichtsschädel zum Hirnschädel in einer Finite Elemente Analyse zu untersuchen.

In simulation of closely- or separately-joined rock masses, stability of rock blocks is of primary concern. However, there seems to be no approach that can handle general modes of simultaneous sliding and truly large rotation under general forces, including non-conservative forces such as water forces. General causes of failure for rock blocks, such as limit points, bifurcation points, and dynamic instability (divergence and flutter), have never been addressed. This research implements a formulation, called BS3D(an incremental-iterative algorithm introduced by Tonon), for analyzing general failure modes of rock blocks under conservative and non-conservative forces. Among the constitutive models for rock fractures developed over the years, Barton's empirical model has been widely used because it is easy to apply and includes several important factors associated with fracture characteristics. Although Barton's failure criterion predicts peak shear strength of rock fractures with acceptable precision, it has some weaknesses in estimating the peak shear displacement, post-peak shear strength, dilation, and surface degradation in unloading and reloading. In this dissertation, modifications are made to Barton's original model in order to address these weaknesses. The modified Barton’s model is validated by a series of direct shear tests on rock fractures and implemented in BS3D to consider the dilatant behavior of fractures. The mechanical behavior of a rock block formed in the roof of a tunnel is governed by its geometry, the mechanical characteristics and the deformability of the fractures forming the block, the deformability of the block and that of the surrounding rock mass, and the stresses within the rock. BS3D, after verification and validation, is used to investigate the effect of dilatancy on stability of rock blocks formed in the roof of a circular tunnel. High-velocity plunging jets, issuing from hydraulic artificial or natural structures, can result in scouring of the rock riverbed or the dam toe foundation. Assessment of the extent of scour is necessary to ensure the safety of the dam and to guarantee the stability of its abutments. BS3D is used to investigate effect of high-velocity jet impact on stability of rock blocks in plunge pools. / text

Fractures can increase the permeability and producability of reservoirs by acting as fluid and gas conduits to wells. Networks of fractures are most important in reservoirs where little to no matrix permeability exists such as tight gas sandstones. Two significant variables, fracture length and the abundance of fractures, are not readily measurable from subsurface observations such as those obtained from cores or well logs. Numerical models suggest natural fracture apertures and lengths follow systematic power-law (Marrett, 1996; Olson, 2007) and negative exponential distributions (Olson, 2004); fracture trace lengths are interrogated. This study tests those propositions through study of fractures in outcrop. Outcrops of the Cretaceous Frontier Formation at Oyster Ridge in southwest Wyoming and Oil Mountain near Casper, in central Wyoming provide evidence of reservoir scale fracture networks in sandstones. In the subsurface the Frontier Formation sandstones are reservoirs that produce gas and oil in several Wyoming basins. I mapped fracture patterns at twenty locations at Oyster Ridge and Oil Mountain and measured fracture trace length distributions and abundance (intensity). Fracture cumulative length distribution plots illustrate systematic length distributions. Trace length distributions of every fracture network follow negative exponential distributions regardless of the number of fractures (N = 39 to N = 394) or the size of the outcrop (1.3 to 710 m²). Results show that the fractures follow a negative exponential distribution over a range of lengths of a few centimeters to tens of meters. These trace length distributions are consistent with geomechanical model fracture pattern simulation results by Olson (2004) that suggests negative exponential trace length distribution result from fracture to fracture interaction during fracture formation. Length distributions from my field study are inconsistent with pattern simulation results by Marrett (1996) and Olson (2007) and others that produce power-law length distributions. This inconsistency suggests that the model assumptions of Olson (2004) best account for the patterns I observed. Two dimensional fracture intensity, defined as the total fracture trace length divided by the map area, was measured for each outcrop to determine how structural position affects fracture abundance patterns. Two-dimensional fracture intensity measurements collected at thirteen structural locations around Oil Mountain show higher values of fracture intensity near the fold-axial-trace compared to fold limbs. The difference is as much as 7.4 fractures per meter near fold hinges compared to 0.63 fractures per meter in fold limbs. Outcrops near small faults, with displacement of a few meters, show an increase in fracture intensity from background values around 4.8 fractures per meter to values nearly three times as high (13 fractures per meter) near faults. Values of fracture intensity that are more elevated near small tear faults imply that faulting has a greater influence on fracture intensity than folding. / text

Defects in bone are a constant and serious problem. They occur as a result of high energy trauma, congenital conditions or are created surgically to treat bone tumours or infection. Currently the treatment for these conditions is awkward for the patient, takes a long time and has a high complication rate. An elegant solution would be to mend the bone defect using the patient own cells; osteoblasts or mesenchymal stem cells seeded onto a supportive material scaffold. For successful regeneration of bone structures, a scaffold production technique has to be adopted that can precisely control porosity, internal pore architecture and fibre thickness, as well as maximising media diffusion and optimising scaffold mechanical properties so that the scaffold can withstand bone bearing pressures. It would also be beneficial if the scaffold uniformly distributed surface strain along the fibres throughout the entire scaffold as this would encourage more even cell proliferation/differentiation in the structure. This was addressed by performing a series of finite element analyses on the computer aided design model where the mechanical properties of the natural or synthetic polymer used have been incorporated to yield an accurate strain profile of the entire scaffold. The process used here to generate the scaffolds is a Rapid Prototyping method that creates a three-dimensional object through the repetitive deposition of fibres in layers via extrusion. Due to the high accuracy and versatility of the extruder, the diameter of the pores can be precisely controlled to an accuracy of 10μm, in the manufactured scaffolds the pore size ranges from 100 to 300μm as that is what is found in trabecular bone. Natural and synthetic polymers were plotted which altered the biodegradability properties of the scaffold and the degrees of cell adhesion, proliferation and differentiation in the structure. Scaffolds were manufactured that demonstrated compatibility with cell adhesion, proliferation and osteogenic differentiation. On completion of the scaffolds, the latter were seeded with osteoblasts or marrow stromal cells and put into a mechanically stimulating bioreactor machine to induce a small strain in the scaffold; this was performed to encourage cell proliferation/differentiation. The structure was left until the osteoblasts or marrow stromal cells modified the scaffold through bone deposition. In-vivo experiments were then undertaken. Preliminary data indicated an effect of mechanical stimulation of the cell/scaffold construct on the degree of mineralization of cell matrix generated by human osteogenic cells.

The West Elk Breccia has been studied since the late 1800’s with many interpretations regarding its origin. One unrecognized possibility is that parts of it are debris-avalanche deposits. This study has recognized evidence for this interpretation at three scales: volcano scale, outcrop scale, and intra-outcrop scale. At the volcano scale, a scarp in the old volcano reveals underlying Mesozoic bedrock, suggesting sector collapse. At the outcrop scale, megablocks of the original edifice, up to hundreds of meters in length, have atypical orientations and are surrounded by a gravel matrix. At the intra-outcrop scale, jigsaw-fit fracturing and rip-up clasts are common in distal deposits, which are documented in analogous debris-avalanche deposits. Similar to the debris-avalanche deposit at Mt. Shasta, medial-to-distal-matrix volcaniclast content decreases by 23%; Paleozoic and Mesozoic clasts increase by 5%; and the size of megablocks decreases. The geochemical and petrographic signatures reveal breccia blocks composed of pyroxene-andesite, a more silicic matrix facies, and the andesitic-to-dacitic East Elk Creek Tuff, all compositions that corroborate previous work on this northern extension of the San Juan volcanic field. Measured sections in the 100-km² study area allow for an estimation of total formation volume of approximately 8.5 km3.

Aufgrund der Tatsache, dass die Wahl der Therapie bei Wirbelfrakturen der Klasse A3 nach Magerl et al. (1994) weiterhin kontrovers diskutiert wird, wurden in dieser Arbeit die Patientenfälle der Abteilung Orthopädie und Unfallchirurgie der Universitätsmedizin Göttingen betrachtet, die im Zeitraum von 2008 bis 2013 eine Wirbelfraktur im Bereich der Brust- und Lendenwirbelsäule erlitten. Das gesamte Kollektiv umfasst 475 Patienten, von denen 266 männlich und 209 weiblich sind. Es wurden objektive Daten wie GDW, Kyphosewinkel und Wirbelkörperhöhenminderung zu fest definierten Zeitpunkten erhoben. Anhand dieser Daten konnte der Verlauf der Stabilität und sowohl der Korrekturgewinn durch die Therapie als auch der Korrekturverlust während der Nachsorge für die jeweiligen Therapiemethoden erfasst werden. Die Therapiemethoden, die hier verglichen werden, sind die konservative Therapie, die Kyphoplastie, die dorsale und die kombiniert dorsoventrale Stabilisierung. Die in der radiologischen Verlaufskontrolle erhobenen Parameter zeigen, dass bei Frakturen der Klassen A1 und A2, die als stabil gelten, die konservative Therapie zu einem guten Ergebnis führt. Bei A3- Frakturen, bei denen in der internationalen Literatur starke Unstimmigkeit darüber besteht, ob diese Frakturen als stabil oder instabil gelten und wie solche Frakturen im allgemeinen zu behandeln sind, bringt die operative Vorgehensweise klare Vorteile. Zudem können bei kombiniert dorsoventraler Operation noch stabilere Ergebnisse erzielt werden. Für die Rotationsfrakturen stellt sich heraus, dass nach der Entfernung des eingebrachten Osteosynthesematerials ein größerer Korrekturverlust eintritt. Abschließend lässt sich sagen, dass bei isolierten Berstungsfrakturen ohne Beteiligung des Bandapparates die Indikation für die kombiniert dorsoventrale Operation häufiger und frühzeitiger gestellt werden sollte. Außerdem sollte beachtet werden, dass bei instabilen Frakturen die Verlängerung der Tragezeit des Fixateurs einen positiven Einfluss auf den Korrekturerhalt hat.

Small mammals, namely those species larger than microfauna like rats and murids but smaller than medium, sheep-size fauna, are generally one of the less studied areas of zooarchaeology. While this may be partly influenced by modern cultural biases, it is more often because finding small, rabbit-sized, mammal remains in archaeological deposits presents a problem in accurately differentiating between those arising from natural, biological and anthropogenic agencies. This thesis tackles this subject using a synthesis of different methods, examining the exploitation and role of small, non-ungulate mammals in early Western European prehistory by combining existing ethnographic knowledge and archaeological research with actualistic experiments and bone assemblage analysis. It first presents a detailed summary of the various taphonomic effects on bone from natural, biological and human action, with particular reference to those of small mammals, using empirical evidence to describe the processes and likely resultant effects. Small mammal utilisation is then contextualised using archaeological and ethnographic evidence to examine past and present practices in Europe and other areas of the world. Different acquisition methods, such as hunting and trapping, are described, and using small mammals for dietary and non-dietary purposes is outlined, along with the rationale for such utilisation given their size. Also considered are other, more abstract ideological and symbolic roles they fulfilled within different cultures, whether physically using parts of the animal, or conceptually. To extend the existing methods available to zooarchaeologists, and improve identifying human exploitation of these species, the ‘chaîne opératoire’ of small game use is examined from an osteological perspective, starting with acquisition, through processing, cooking and consumption to discard, using a series of experiments and microscopic analysis to explore potential bone modification signatures and fracture patterns arising from such activities. Finally, it places these results into broader context by comparing the fracture patterns with bones from British and North American archaeological sites, to demonstrate that similar changes can be seen.

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