The objective of this study was to determine elution properties of meropenem and compare the elutions of meropenem impregnated PMMA beads without sterilization (PMMA-Cont) to those sterilized with steam (PMMA-Auto) and ethylene oxide gas (PMMA-EO). Four groups of beads were produced: one group without antibiotic and three groups of meropenem impregnated beads: PMMA-Cont, PMMA-Auto, and PMMA-EO. Antibiotic concentrations in eluent samples were determined using a microbiological assay at different time intervals. The microbiological assay resulted in no zone of inhibition at all time periods for the PMMA-Auto samples and the samples of PMMA without antimicrobial. The meropenem concentration on the eluent remained above 4 mcg/ml for 15 days in the PMMA-Cont group and until day 18 for PMMA-EO group. The meropenem incorporated in the PMMA beads elutes effectively and gradually decreases after the 24 hour peak. Ethylene oxide does not adversely affect meropenem’s elution.

Einführung Die Kranioplastik (KP) nach Kraniektomie dient der Wiederherstellung der Funktionalität und Ästhetik des Schädels. Obwohl es sich um einen Routineeingriff handelt, wurden hohe Komplikationsraten beschrieben, die zum Teil auf die unterschiedlichen Arten des verwendeten Implantatmaterials zurückzuführen sind. Wir haben diese Studie durchgeführt, um intraoperativ-geformte (Palacos®) und CAD-CAM-PMMA-Implantate bei Patienten/-innen nach Kraniektomie hinsichtlich perioperativer Modalitäten, kurz- und langfristiger Komplikationsraten und ästhetischer Ergebnisse zu vergleichen. Methoden Diese retrospektive Single-Center-Analyse wurde an 350 Patienten mit 359 Kranioplastiken durchgeführt, die sich in 133 Palacos®-Fälle (01/2005-12/2012) und 226 CAD-CAM-Fälle (01/2010-12/2018) aufteilten. Postoperative Komplikationen wurden in kurzfristige (≤ 30 Tage) und langfristige (> 30 Tage) unterteilt. Die ästhetischen Ergebnisse wurden per Telefoninterview erhoben und auf einer 5-Punkte-Skala bewertet. Ergebnisse CAD-CAM-Patienten hatten eine kürzere Operationszeit (p < 0.001), einen geringeren intraoperativen Blutverlust (p < 0.001) und einen kürzeren postoperativen Krankenhausaufenthalt (p < 0.005) als Palacos®-Patienten. Operative Revisionen nach CP mussten bei 12,8 % der Patienten durchgeführt werden. Implantatinfektionen traten bei 3,8 % der Palacos®-Fälle und 1,8 % der CAD-CAM-Fälle auf. Wundheilungsstörungen traten bei CAD-CAM-Patienten häufiger auf, was mit einer höheren Anzahl an kraniellen Vor-Operationen und Vorinfektionen einherging. Palacos®-Patienten hatten signifikant mehr Implantatdislokationen (p < 0.05). CAD-CAM-Patienten berichteten von einem besseren ästhetischen Ergebnis im Vergleich zu Palacos®-Patienten. Fazit Diese Studie zeigt eine Überlegenheit der CAD-CAM-PMMA-Implantate im Vergleich zu Palacos®-Implantaten hinsichtlich peri- und postoperativer Faktoren, sowie dem ästhetischen Ergebnis. CAD-CAM-Implantate haben geringere Komplikations- und Infektionsraten als Palacos®-Implantate und zeigten positive Wirkungen, wenn sie in vorinfiziertes Gewebe implantiert wurden. Die langfristigen Komplikationsraten von CAD-CAM-Implantaten müssen weiter evaluiert werden. / Introduction Cranioplasty (CP) after craniectomy restores the functionality and aesthetic of the patient’s cranial vault. Although it is a routine procedure, high complication rates have been described, partly related to the different type of implant material used. We conducted this study to compare intraoperative-moulded (Palacos®) and CAD-CAM-PMMA implants in patients underwent craniectomy regarding perioperative modalities, short- and long-term complication rates and aesthetic results. Methods This retrospective single-center-analysis was conducted on 350 patients with 359 cranioplasties, dividing into 133 Palacos® cases (01/2005-12/2012) and 226 CAD-CAM cases (01/2010-12/2018). Postoperative complications were divided into short-term (> 30 days) and long-term (< 30 days). Aesthetic results were evaluated via telephone interview on a 5-item scale. Results CAD-CAM patients had a shorter surgery time (p < 0.001), a lower intraoperative blood loss (p < 0.001) and shorter postoperative hospitalization (p < 0.005) than Palacos® patients. Operative revisions after CP had to be carried out at 12.8% of patients. Implant infections occurred in 3.8% of Palacos® cases and 1.8% of CAD-CAM cases. Wound healing disorders occurred more frequently in CAD-CAM patients, which was associated with higher cranial pre-operation and pre-infection rates. Palacos® patients had significantly more implant dislocations (p < 0.05). CAD-CAM patients reported a better aesthetic result compared to Palacos® patients. Conclusion This study shows superior peri-, postoperative and aesthetic results for CAD-CAM-implants compared to Palacos®. CAD-CAM implants have lower complication and infection rates than Palacos® implants and showed positive effects when implanted in pre-infected tissue. Long-term complication rates of CAD-CAM implant need to be further evaluated.

Several methods of surgical stabilization of the atlantoaxial joint are described in the veterinary literature. Threaded acrylic pins placed ventrally together with polymethylmethacrylate (PMMA) is a well-established technique that has been widely used in clinical cases. However, Kishigami tension bands are a less technically demanding procedure with potentially fewer complications. The purpose of this study was to biomechanically compare these two techniques in ventral-to-dorsal bending in both mature and immature dogs. Seventeen normal canine cadavers <15kg were collected and radiographed to determine skeletal maturity. The cervical spines were dissected leaving bony and ligamentous structures intact. Eight mature spines and 9 immature spines were randomly divided into two groups. In one group a Kishigami tension band was applied over the dorsal arch of the atlas and attached to the spinous process of the axis using orthopedic wire. In the second group, six acrylic pins were placed ventrally in the atlas, axis, and transarticularly. The pins were then cut and covered with PMMA. The specimens were potted in custom steel pots and biomechanically analyzed in ventral-to-dorsal four-point bending. Load-displacement curves representing the degree of stiffness were compared between the groups. Stabilization using ventral pins and PMMA had a significantly greater stiffness than a Kishigami tension band when bending in ventral to dorsal bending. Within the stabilized vertebral segment, there was no significant difference between the stiffness of immature vs. mature bone. Further analysis in torsion and analysis in abnormal dogs will be helpful in establishing the clinical significance of these findings. / Master of Science

published_or_final_version / Orthopaedics and Traumatology / Master / Master of Philosophy

M.Phil.(Optometry) / The concept of contact lenses was conceived over 500 years ago and has now evolved into a fundamental component of optometric practice. Soft contact lenses have become a convenient, aesthetically pleasing and comfortable alternative to spectacles that are becoming increasingly popular. The use of rigid contact lenses is imperative in the management of conditions such as keratoconus due to spectacles being insufficient in providing adequate vision. Placing a contact lens onto the cornea is an invasive procedure. The contact lens is a foreign body to the eye hence it is expected that the eye would react to that foreign body. Literature has revealed that the general reactions of the eye to contact lens wear are initial tearing, alteration of the tear layer and oedema due to reduced oxygen transmission but these are just a few of the known consequences amongst the multitude of the unknown consequences. What exactly goes on under a contact lens remains an enigma which contact lens researchers have strived to uncover over the past century. The consequence of contact lens wear is a vast area of research and can best be investigated by focusing on one aspect at a time. The aim of this study was to use dioptric power matrices and multivariate statistics to explore the effects of both gas permeable and gas non-permeable rigid contact lenses on corneal curvature. This study involves auto-keratometric measurements of the corneal curvature before and after lens wear to establish if there are any curvature changes induced by the contact lens. Keratometric data was collected with an automated keratometer (Nidek ARK-700) and was analysed correctly and completely using multivariate statistics. This thesis presents the findings of a study done in an effort to establish the short-term effects of rigid contact lens wear on keratometric behaviour by using complete methods of multivariate statistical analysis. Twenty four subjects were equally divided into three groups. One group wore polymethyl methacrylate (PMMA) rigid lenses, another group wore rigid gas permeable (RGP) contact lenses and the third group served as the control. The control group was included in the study to establish a reference for normal diurnal changes in keratometric behaviour. Fifty autoii keratometric measurements were taken before and immediately after three hours of rigid contact lens wear for the experimental groups and 50 auto-keratometric measurements were taken before and immediately after three hours of no lens wear for the control group. Data collected was analysed using multivariate statistical methods that in the past have been used infrequently in this area of research.

O objetivo do presente estudo foi avaliar a resposta tecidual e clínica a um implante orbitário de polimetilmetacrilato (PMMA), oco e multiperfurado em sua porção posterior em modelo animal de evisceração. Dezesseis coelhos da raça Nova Zelândia foram submetidos à evisceração do globo ocular direito. Todos receberam implante de polimetilmetacrilato de 12 mm de diâmetro multiperfurado em sua semiesfera posterior. O estudo foi dividido em avaliação clínica e histopatológica. A avaliação clínica foi diária até 14 dias pós-evisceração e, a cada sete dias, até completar 180 dias. Os animais foram divididos em grupos de quatro animais e cada um foi submetido à exenteração com 07, 30, 90 e 180 dias e depois à eutanásia. A análise histopatológica teve por fim caracterizar o padrão inflamatório, a estrutura do colágeno e o grau de neovascularização. Para isso, além da tradicional coloração pela hematoxilina-eosina (HE), utilizou-se o corante Picrosirius Red (PSR) e imunohistoquímica com o marcador CD34. Não houve sinais de infecção, exposição ou extrusão do implante em nenhum animal durante o estudo. Já no sétimo dia, o tecido neoformado migrou para dentro do implante formando uma rede fibrovascular através dos canais posteriores. A resposta inflamatória diminuiu ao longo do tempo avaliado e não foram encontradas células gigantes multinucleadas. O implante analisado é biocompatível, inerte e sua estrutura permite a sua integração aos tecidos orbitários pelo crescimento fibrovascular. / The objective of the present study was to evaluate the tissue and clinical response to a hollow and multiperforated polymethylmethacrylate (PMMA) orbital implant in its posterior portion in an evisceration animal model. Sixteen New Zealand rabbits were submitted to evisceration of the right eyeball. All animals were implanted with 12 mm diameter of PMMA multiperforated in their posterior hemisphere. The study was divided into clinical and histopathological evaluation. The clinical evaluation was daily during the 14 days after evisceration, and every seven days until completing 180 days. The animals were divided into groups of four animals and each was exenterated at 07, 30, 90 and 180 days and then at euthanasia. Histopathological analysis was aimed at characterizing the inflammatory pattern, the collagen structure and the degree of neovascularization. For this, in addition to the traditional hematoxylin-eosin staining (HE), we used the Picrosirius Red dye (PSR) and immunohistochemistry with the CD34 marker. There were no signs of infection, exposure or extrusion of the implant in any animal during the study. On the seventh day, the newly formed tissue migrated into the implant, forming a fibrovascular network through the posterior channels. The inflammatory response decreased over time and no multinucleated giant cells were found. The implant analyzed is biocompatible, inert and its structure allows its integration into the orbital tissues by fibrovascular growth.

Thesis (M.S.)--Ohio State University, 2009. / Title from first page of PDF file. Includes vita. Includes bibliographical references (p. 35-41).

Not available / text

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Peter F. Green. Vita. Includes bibliographical references.

Techn. Universiẗat, Diss., 2004--Darmstadt.