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We measured the thickness and the dry weight of recently deposited sediment along several transects across Lake Arendsee in order to quantify the sedimentation rate and its local variability. As a time marker, we used an artificial marl layer that was deposited by a remediation program in the year 1995. A portion of the sediment deposited during the year was transported from the littoral and the top of the submerged hills to the foot of the slope, where we found the greatest deposition. Within the same lake, the deposited sediment layer varied by a factor of 4 between minimal and maximal values over the same time periods. Lake Arendsee is a holomictic and eutrophic lake with depletion of oxygen in summer time.

Zusammenfassung Ziel der Studie war die Beschreibung einer neuen minimal-invasiven Operationstechnik zur retrograden Anbohrung osteochondraler Lasionen am oberen Sprunggelenk. Unter der Nutzung von computertomographischer (CT) Bildgebung und robotischer Assistenz konnte in vier Fallen eine erfolgreiche retrograde Anbohrung am Talus (2) und an der distalen Tibia (2) durchgefuhrt werden. Wir konnten zeigen, dass dieses neuartige Verfahren bei geeigneter Indikation eine sichere und klinisch anwendbare Behandlungsmethode der osteochondralen Lasionen des oberen Sprunggelenks darstellt. Die Unterstutzung mittels INNOMOTION-Roboter kombiniert mit einer exakten Darstellung der knochernen Anatomie mittels CT erlaubt einen prazisen Eingriff und stellt eine Alternative zur herkommlichen arthroskopischen Methode dar

Many researchers have shown the importance of water chemistry and benthic habitat characteristics for the conservation of the freshwater macroinvertebrate biodiversity. However, few authors have examined the physical effect of extreme water-level fluctuations in lakes. The present study set out to determine, through a comparative study between a regulated lake (Laja Lake, LL) and an unregulated lake (Icalma Lake, IL) of the Andean zone of southern Chile, how man-made disturbances of the natural hydrological regime affect the structure of the benthic macroinvertebrate community. The results showed LL had very low values for species richness, density and biomass in comparison with IL, and the community was composed mainly of few individuals belonging to opportunistic taxa such as Chironomidae and Naididae. We suggest that the low values in the regulated lake are potentially explained by littoral zone factors driven by the water-level fluctuations such as: desiccation, freezing of the biota, removal of organic particles from the sediment and absence of aquatic macrophytes.

Osteochondral lesions of the talus are often located posteromedially requiring open surgery to facilitate solid and complete osteochondral reconstruction. The aim of the study was to identify the optimal anatomical site for medial malleolar osteotomy based on the criteria of minimal cartilage damage (Study I) and to report on the morbidity in patients receiving osteotomy performed at the previously identified site (Study II). For Study I, cartilage coverage of the tibiofibular ankle joint facet was measured in 40 cadaveric ankles (20 cadaver specimens). In Study II, we assessed clinical (VAS pain score, AOFAS score, range of motion) and radiological outcome measures (SPECT-CT) in 17 patients (mean age, 36.8 ± 10.8 years) undergoing medial malleolar osteotomy. The medial edge in the transition zone of the tibial plafond to the medial malleolus showed less than 75 % of cartilage coverage in 62.5 % of cadavers (Study I). Surgery resulted in lower pain levels (2.4 ± 2.6 compared with 6.3 ± 1.8 points; p

Background: The specific morphological and biomechanical characteristics of the osteochondral unit of the ankle joint are not yet fully understood. This anatomical study aimed to map regional thickness of the articular hyaline uncalcified cartilage and its adjacent layers of mineralized cartilage and subchondral bone as well as to measure the regional indentation stiffness of human ankle joint cartilage. Materials and Methods: A total of 20 pairs of human cadaver ankle joints (median age: 78 years) were evaluated by histomorphometry and multidetector row double-contrast CT arthrography for cartilage thickness in 17 distinct anatomical regions. In addition, regional distribution of the subchondral bone plate and of the mineralized cartilage was scrutinized histologically. Cartilage indentation stiffness was measured using an arthroscopic handheld device (Artscan200), especially validated for use in thin cartilage. The correlation between the thickness of different components of the osteochondral unit and the cartilage indentation stiffness was evaluated. Results: The thinnest uncalcified cartilage was measured at the anterior talar dome and the distal fibula. The thickest uncalcified cartilage was found in the mid and posterior talar dome, as well as in the tibial plafond. Mineralized cartilage and subchondral bone showed highest values at the anteromedial talar dome. Cartilage indentation stiffness showed a bicentric distribution pattern in 14/20 ankle pairs and was highest in regions with thin cartilage. Positive correlation between the thickness of the mineralized cartilage and the subchondral bone plate was found. No correlation between the thickness of the uncalcified and the mineralized cartilage could be identified. Conclusion: This anatomical study provides a comprehensive mapping of the osteochondral unit of the human ankle joint in elderly people. Articular hyaline uncalcified cartilage and the subchondral bone plate showed clear regional differences and were reciprocally distributed. Cartilage indentation stiffness was inversely correlated to cartilage thickness in elderly people. Clinical Relevance: Thorough understanding of the osteochondral unit of the ankle joint could be helpful for clinicians and researchers in the development of improved operative repair techniques for osteochondral defects in the ankle joint, for example, in constructing specific tissue-engineered osteochondral plugs.

The aim of this case report is to describe a novel technique for treatment of large osteochondral lesions of the talus using autologous matrix-induced chondrogenesis with a collagen I/III membrane.

Processed bovine cancellous bone (PBCB) is an attractive material for tissue engineering of bone. It is biocompatible, osteoconductive, nonimmunogenic, and porous and its biomechanical properties are close to those of native bone. In this study, differentiation of primary rat osteoblasts (rOBs) incubated on PBCB was investigated in vitro. rOBs were isolated and expanded in two-dimensional culture. Expanded rOBs were seeded into PBCB disks and cultured either in basal medium (BM) or differentiation medium (DM) containing ascorbic acid, beta-glycerol phosphate, and dexamethasone. Alkaline phosphatase (ALP) activity and RNA expression of ALP, bone sialoprotein (BSP), collagen type I (COL1), osteocalcin (OC), and osteopontin (OPN) were assessed by chemiluminescence assay and quantitative real-time RT-PCR over 14 days. Histologic analysis was performed on day 14. ALP increased over the observation period independent of stimulation. OPN and BSP expression was significantly higher in the DM group whereas COL1 and OC expression was significantly higher in the BM group. Matrix calcification was detectable only in the DM group by von Kossa stain. The observed expression patterns suggest a physiological response of rOBs to the differentiation stimulus. PBCB is a suitable matrix for in vitro differentiation of osteoblasts. Cell-seeded PBCB is a potential osteogenic construct for in vivo application.