The fossil sirenian material from the upper Oligocene Linz Sands of Upper Austria is reviewed and re-described in detail following a recent approach on the invalidity of the genus Halitherium Kaup, ...1838. This morphological study provides the first evidence for the synonymy of “Halitherium” cristolii Fitzinger 1842, “H.” abeli Spillmann, 1959 and “H.” pergense (Toula, 1899), supporting the hypothesis that only a single species inhabited the late Oligocene shores of present-day Upper Austria. In the course of the taxonomic revision of the “Halitherium” species-complex, this taxon is now assigned to the new genus Lentiarenium Voss gen. nov. It represents a more derived sirenian compared to Eocene and early Oligocene taxa distributed across Central Europe and North Africa, which is in accordance with the stratigraphical data. An updated inventory list of all identifiable and referable skeletal material is provided, including a detailed synonymy list for the new taxonomic combination.
OBJECTIVESThe aim of this study was to simulate different entry points and investigate potential angulation errors of the intramedullary device and resulting changes in the distal femoral cut using a ...computer-aided design (CAD) approach. MATERIALS AND METHODSWe used a CAD approach to simulate various distal femoral entry points for intramedullary instrumentation. Simulations were performed on (i) a commercially available three-dimensional (3D) CAD model of a human femur (DigitalFemur) and (ii) a digital 3D model of an analogue large femur model produced using a coordinate measuring machine (FaroFemur). Divergent insertion points medial, lateral, anterior and posterior to the ideal position were simulated. Angulation deviations of the resulting positions of the intramedullary rod were measured and changes in the anatomical-mechanical axis angle were calculated. Differences between the two simulation models were quantified. RESULTSThe ideal entry point in the FaroFemur was 9.9 mm anterior and 4.3 mm medial to the apex of the intercondylar notch, and 9.2 mm anterior and 3.6 mm medial in the DigitalFemur. A medial entry point increased the angle between the anatomical femoral axis and the alignment rod in the FaroFemur and DigitalFemur (with 5 mm displacement 2.510° and 2.363°, respectively; with 10 mm displacement 3.239° and 3.283°, respectively). In contrast, a lateral entry point decreased the angle between the anatomical femoral axis and the alignment rod (with 5 mm displacement 2.267° and 2.262°, respectively; with 10 mm displacement 3.158° and 3.731°, respectively). An anterior entry point changed the angle between the anatomical femoral axis and the alignment rod towards extension (1.802° in the FaroFemur; 2.142° in the DigitalFemur), while a posterior entry point generated a deviation toward flexion (2.045° in the FaroFemur; 2.055° in the DigitalFemur). The mean difference between the two models was 0.108±0.121° with the highest difference for anterior displacement. CONCLUSIONMinor deviations of the entry point for intramedullary instrumentation during total knee arthroplasty can result in malalignment of several degrees.
Europe's new security challenges Gärtner, Heinz; Hyde-Price, Adrian; Reiter, Erich ...
European Political Science,
12/2007, Letnik:
6, Številka:
4
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