Rotator cuff repair: an analysis of failure mechanisms and predictors of structural and clinical repair outcomes

Post-operative Re-Rupturen stellen die wohl grösste Herausforderung bei der chirurgischen Versorgung von Rotatorenmanschettenrupturen dar. Inwieweit diese Re-Defekte klinische Relevanz haben, wird derzeit kontrovers diskutiert. Diese Dissertation untersucht mögliche Mechanismen, welche zur Entstehung von Re-Defekten führen. Um die klinische Relevanz dieser Mechanismen zu bewerten, das Verhältnis von strukuturellem und klinischem Operationsergebnis zu untersuchen und mögliche Ergebnisprediktoren zu identifzieren, wurde eine Meta-Analyse von 31 klinischen Studien durchgeführt. Die Daten dieser Analyse bewiesen, dass auch in Patienten mit post-operativer Re-Ruptur, eine signifikante Verbesserung klinischer Symptome erzielt wird. Jedoch zeigte der Vergleich der Daten re-rupturierter und intakter Sehnen, einen statistisch signifikanten Unterschied zu Gunsten post-operativ intakter Manschetten. Hinsichtlich predominanter Fehlermechanismen konnte die Analyse klinischer Studien nur begrenzt Aufschluss geben. Nach Zusammenfassung der klinischen Daten, sowie den Ergebnissen einer generellen Literaturrecherche, konnten bestimmte Problemzonen heutiger Behandlungstechniken identifiziert werden. Abschliessend wird ein ovines Manschettenmodel präsentiert, welches in erster Linie die Untersuchung einer post-operativen Lückenbildung zwischen der re-inserierten Sehne und ihrem knöchernen Ursprung ermöglicht. Zudem erlaubt es die Untersuchung genereller Aspekte der Heilung reparierter Manschetten. Post-operative re-tearing represents a major challenge in the surgical treatment of rotator cuff tears. Whether or not re-torn cuffs inevitably cause inferior clinical outcomes is temporarily a subject of controversial debate. This thesis investigates the occurrence of rotator cuff re-tearing by analyzing the repair components of current surgical concepts and discussing potential failure mechanisms. In order to evaluate the clinical relevance of these mechanisms, investigate the relation of structural repair failure and clinical outcome and furthermore identify predictors of structural and clinical outcomes, a meta-analysis of 31 studies (3611 shoulders in total) was performed. The data showed significant relief of clinical symptoms and an increase in shoulder function in both, patients with intact repairs and those showing cuff re-tears. However, it also confirmed a correlation between re-torn cuffs and generally lower clinical results. The meta-analysis of patient, surgical, imaging and clinical follow-up data could only very limitedly provide information about the underlying mechanisms of failure. When synthesizing results from the clinical study meta-analysis and general research including animal and ex-vivo studies, several hot spots in current concepts were identified. Finally, an ovine model is presented that allows further investigation of repair site gap formation and assessment of general aspects and timing of rotator cuff healing

Method for cryopreservation of Paramoeba perurans

Paramoeba perurans causes amoebic gill disease (AGD), which is a major problem in aquaculture worldwide. The parasite can be cultured in vitro, but to this date, no method for long-term storage of the clones exists. In this study, we describe a method for cryopreservation of Paramoeba perurans. The method was successfully employed on four out the five clones we tested. The thawing success rate, that is the percentage of successfully thawed vials relative to the total number of vials that were thawed, differed for the clones and ranged from 25% to 100%. The age of the clones seemed to have a negative impact on the ability to survive cryopreservation.publishedVersio

Identifying the BLE Advertising Channel for Reliable Distance Estimation on Smartphones

Estimating the distance between two smartphones plays an important role in a host of applications. For this purpose, smartphones emit and scan for Bluetooth Low Energy (BLE) signals. When a device is detected, the distance is estimated by evaluating the received strength of these signals. The main insight that is exploited for distance estimation is that the attenuation of a signal increases with the distance along which it has traveled. However, besides distance, there are multiple additional factors that impact the attenuation and hence disturb the distance estimation procedure. Among them, frequency-selective hardware and signal propagation belong to the most significant ones. For example, a BLE device transmits packets on three different frequencies (channels), while the transmit power and the receiver sensitivity depend on the frequency. As a result, the received signal strength varies for each channel, even when the distance remains constant. However, the information on which wireless channel a packet has been received is not made available to a smartphone. Hence, this error cannot be compensated, e.g. by calibration. In this paper, we for the first time provide a solution to detect the wireless channel on which a packet has been received by a smartphone application. We experimentally evaluate our proposed technique on multiple different smartphone models. Our results help to make distance estimation on smartphones more robust and accurate