This Thesis presents a design innovation in arthroscopic forceps. Based on surveying the subject-matter literature on arthroscopic surgery of the knee, design changes are proposed to alter the cutting geometry of the functional end of the instrument to improve its utility. The proposed changes are imple-mented in a prototype, which is then compared with the current design. The comparison is made by testing the functioning of the instrument and the force required to shear the test material.

In der vorliegenden Arbeit konnten erstmals der TGF-β-Signalweg und dessen Smad- Signalmoleküle innerhalb der MPCs nachgewiesen werden. Dieser Nachweis erfolgte sowohl auf zellulärer und Gewebeebene als auch auf Gen- und Proteinebene. Zusätzlich konnte auf Gen- und Proteinebene gezeigt werden, dass die Signalmoleküle Smad2, Smad3 und Smad4 in MPCs aus gering erkranktem Meniskusgewebe eine vermehrte Expression aufweisen im Vergleich zu den MPCs aus hochgradig erkranktem Meniskusgewebe. Diese Erkenntnis weist auf eine mögliche protektive Funktion des TGF- β-Signalwegs während degenerativer Prozesse im Meniskusgewebe hin. Um die Effekte des TGF-β-Signalwegs und dessen Smad-Signalmoleküle genauer zu verstehen und besser beschreiben zu können, wurde eine Überexpression der Smad-Signalmoleküle innerhalb von MPCs durchgeführt und die Auswirkungen dieser auf die Kollagen I- und Kollagen II-Synthese genauer beleuchtet. Infolgedessen konnte sowohl eine vermehrte Kollagen I-Synthese als auch eine vermehrte Kollagen II-Synthese festgestellt werden. Dies bestätigt die Annahme, dass dem TGF-β-Signalweg und dessen Smad-Signalmolekülen eine zentrale, protektive Funktion während der Meniskusdegeneration zukommt. Durch die vermehrte Synthese von Matrixkomponenten wird den Degenerationsprozessen innerhalb des Meniskusgewebes entgegengewirkt. Ein nicht degenerierter bzw. ein regenerierter Meniskus besitzt eine biomechanische Schutzfunktion für das Kniegelenk und wirkt somit einer Kniegelenkarthrose entgegen. In Zukunft könnte der TGF-β-Signalweg  einen möglichen Ansatzpunkt für therapeutische Behandlungen bei Meniskusläsionen darstellen. Da Meniskusdefekte häufig direkt mit einer Osteoarthrose im Kniegelenk assoziiert sind, spielt die durch den TGF-β-Signalweg induzierte Regeneration von Meniskusgewebe auch in der Prävention der Osteoarthrose eine zentrale Rolle.

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The diploma thesis deals with The study of transition between fully flooded and starved regimes in EHL Contact. The work is focused on problems of starved contact and surface texturing of rubbing surfaces. Surface texturing of rubbing surfaces is one of the adjustments that cause in a sense improved lubricity and reduce friction and wear. The aim of this study is to compare numerical models with real experimental results measured on the Experimental apparatus.

<p>Uvod: magnetno rezonantni imidžing (MR) je u &scaron;irokoj uporebi u dijagnostici patolo&scaron;kih poremećaja ekstremiteta. Postoji interes da se redukuje vreme trajanja snimanja tokom pregleda kako bi se povećao komfor pacijenata i redukovali problemi koji su u vezi sa klaustrofobijom i artefaktima koji nastaju pri pomeranju pacijenta tokom dugih snimanja. Trodimenzionalne (3D) izovoksel sekvence pokazale su značajne mogućnosti u redukciji vremena snimanja MR pregledom zgloba kolena bez smanjenja kvaliteta dijagnostičkih mogućnosti. Cilj: uporediti dijagnostičke mogućnosti rutinskog, 2D MR protokola, na 3.0 Tesla MR aparatu, sa 3D True fast imaging, TrueFISP, izovoksel sekvencom u detekciji hondralnih o&scaron;tećenja, ruptura prednjeg ukr&scaron;tenog ligamenta (LCA), ruptura meniskusa i abnormalnosti subhondralne kosti, u korelaciji sa artroskopijom, kao referentnim standardom. Materijal i metode: Studija je odobrena od institucionalnog etičkog odbora. Pacijenti su informisani o studiji i potpisali pristanak za uče&scaron;će u istraživanju. 76 zgloba kolena kod 76 pacijenata (34 ženskog pola; prosečne starosti 36 godina) uključeno je u prospektivnu studiju, snimljeno je standardnim 2D MR protokolom snimanja i 3D TrueFISP sekvencom u sagitalnoj ravni. Svim pacijentima je urađena artroskopija u periodu od maksimum 30 dana nakon snimanja. Dva radiologa, nezavisno jedan od drugog, su evaluirala dobijene snimke. Preciznost u detekciji hondralnih o&scaron;tećenja, ruptura LCA i meniskusa, i abnormalnosti subhondralne kostne srži je određena podudarno&scaron;ću radiolo&scaron;kih i artroskopskih nalaza kao i proverom podudaranja ove dve metode snimanja. Rezultati: prosečna senzitivnost i specifičnost 3DTrueFISP sekvence je bila 75%, 94% respektivno, u dijagnostici o&scaron;tećenja hrskavice, 97%, 97% u detekciji ruptura LCA, 65%, 89% u postavljanju dijagnoze ruptura meniskusa, a dobra podudarnost radiolo&scaron;kih nalaza je dobijena u interpretaciji o&scaron;tećenja subhondralne kosti. Standardnim 2D MR protokolom prosečna senzitivnost i specifičnost je bila 70%, 93%, respektivno, u postavljanju dijagnoze hondralnih o&scaron;tećenja, 94% i 100% u postavljanju dijagnoze rupture LCA, 65%, 88% u detekciji ruptura meniskusa. Zaključak: dijagnostičke mogućnosti upotrebom 3DTrueFISP sekvence su uporedive sa standardnim, 2D, MR protokolom u snimanju zgloba kolena.</p> / <p>Introduction: Magnetic resonance imaging (MR) is widely used to assess internal derangements of the extremities. There is an interest in decreasing examination times to improve patient comfort and reduce the problems related to claustrophobia and motion artifacts, which occur more commonly with long examinations. The three-dimensional (3D) isovoxel true FISP sequence facilitates a noticeable reduction in acquisition time for MR imaging of the knee without reducing diagnostic performance. Objective: To compare the diagnostic performance of conventional, 2D, MR protocol, at 3.0 Tesla MR, with 3D water-excitation true fast imaging with steady-state precession, TrueFISP, an isotropic resolution sequence for detecting articular cartilage defects, anterior crucial ligament tears, meniscal tears and subhondral bone changes of the knee joint, with arthroscopy as reference standard. Materials and methods: The study was institutional review board approved. Written informed consent was obtained from all patients. 76 knees of 76 patients (34 females; mean age 36 years) were prospectively examined by using a conventional 2D MR protocol and sagittal 3D TrueFISP sequence. All patients underwent arthroscopy within a maximum period of 30 days after imaging. Two blinded readers evaluated the MR images. Accuracy for detection of cartilage defects, anterior cruciate ligament and meniscal tears, and subchondral bone abnormalities interobserver agreement, and intermethod agreement were calculated. Results: Overall sensitivity and specificity of 3DTrueFISP sequence were, respectively, 75%, 94% for diagnosis cartilage defects, 97%, 97%, for a diagnosis ACL tears, 65%, 89% for diagnosis of meniscal tears and with good interobserver agreement in interpretation of subhondral bone abnormalities. The standard MR protocol had overall sensitivities and specificities 70%, 93%, respectively, for diagnosis of cartilage defects, 94% and 100% for diagnosis ACL tears and 65%, 88% for diagnosis meniscal tears. Conclusion: The diagnostic perfomance of knee MR imaging performed by using a 3DTrueFISP sequence is comparable to the diagnostic performance of the conventional, 2D, MR protocol.</p>