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The primary anti-rotational stability is critical to preventing cup tilting failure following revision total hip arthroplasty, but is frequently compromised by severe ischial bone loss. A novel technique of "inferior extended fixation" was introduced by securing a porous metal augment into the deficient ischium. This study evaluated the effect of this technique on primary anti-rotational stability in revision total hip arthroplasty. Composite hemipelvis specimens, acetabular components and "lotus" augments were used to simulate total hip arthroplasty surgeries. Three different cementless operative settings of cup implantation were simulated: (1) native ischium without defects; (2) ischium with a defect not reconstructed; (3) ischial defect reconstructed with inferior extended fixation using a lotus augment. Lever-out testing was used to examine primary anti-rotational stability, which was measured as interface stiffness and yield moment. Compared with the native ischium setting, the mean interface stiffness decreased by 53.1% in the ischial defect setting (p < 0.001). In the inferior extended fixation setting, the mean value was 110% greater than that in the ischial defect setting (p = 0.014), and comparable to that in the native ischium setting (p = 1). Similar results were observed for the yield moment (declined by 63.1%, p < 0.001; 200% higher, p < 0.001; and p = 0.395; respectively). In revision total hip arthroplasty with severe ischial defects, inferior extended fixation with a lotus porous titanium augment restores anti-rotational stability of the acetabular component to the level of that with a native ischium, which provides the mechanical environment for bone ingrowth and prevents cup tilting failure. • Ischial bone defects compromise the initial fixation stability of acetabular cups. • Inferior extended fixation effectively restored interface stiffness of rotation. • Inferior extended fixation effectively improved yield point of rotation. • Inferior extended fixation improved anti-rotational stability of acetabular cups. [ABSTRACT FROM AUTHOR]

Fossil ostracode assemblages were investigated in three sediment cores from the Chukchi Plateau, in the western Arctic Ocean, in order to reconstruct its late Quaternary paleoceanographic history. The cores were obtained from water depths of 435–741 m, within the range of modern Atlantic Water (AW). The ostracode abundance shows distinct glacial/interglacial fluctuations, suggesting the suppression of benthic bioproductivity during glacial periods, probably associated with the development of perennial sea ice. Based on the modern ostracode distribution in the Arctic Ocean, 11 common ostracode taxa out of a total of 33 are related to specific water mass or sea ice conditions. Analyses of key ostracode species and a benthic foraminifera species, Cassidulina teretis , reveal a pronounced faunal turnover between MIS 3 and MIS 1. A distinct assemblage dominated by Polycope spp. and accompanied by other species preferring Arctic Intermediate Water (AIW) (Microcythere medistriatum , Pseudocythere caudata , Cytheropteron sedovi , C. scoresbyi , and Pedicythere spp.) characterizes the period between late MIS 5 and MIS 3, whereas MIS 1 is characterized by a rise in Krithe spp. and two species associated with AW (Cytheropteron perlaria and Cassidulina teretis). The faunal turnover indicates an upward shift of AIW and a decline of the influence of warm AW during the period between late MIS 5 and MIS 3, presumably caused by a weakening or cessation of the westward dispersion of AW. The distributions of two sea-ice related species, Acetabulastoma arcticum and Rabilimis mirabilis , indicate minimal perennial sea-ice cover and probably summer sea-ice-free conditions throughout MIS 1 and the development of a summer sea-ice margin environment during interglacial/interstadial periods. • The first study on fossil ostracodes from the Chukchi Plateau, western Arctic Ocean. • The Atlantic Water may have declined between late MIS 5 and MIS 3 in this area. • The area was probably in a summer sea-ice-free condition throughout MIS 1. [ABSTRACT FROM AUTHOR]

Abstract In this report, we describe the first discovery of two living ostracods from the Japanese archipelago, Sinocytheropteron ignobile and Sinocytheridea impressa , which are typically continental faunal elements from China, during our research on the distribution of ostracod assemblages in the Ariake and Yatsushiro Seas in southwest Japan. The (palaeo-) biogeographical data from recent and fossil records indicate that S. ignobile and S. impressa migrated through land bridges during past decreases in sea levels. We also discovered Xestoleberis ryukyuensis , which has been reported from the Ryukyu Islands; its discovery in our study area indicates the current northernmost distribution of the species and suggests that it migrated from the Ryukyu Islands to the study area using the Tsushima Warm Current, a branch of the main Kuroshio Current. This evidence suggests that the migration of shallow-marine ostracods between the continents and their adjacent islands affect not only global oceanic current but also global decreases in sea levels and the (palaeo-) geography of adjacent seas. Thus, ostracods living within the continental coasts provide powerful evidence for reconstructing the connection between the continent and its adjacent islands. Highlights • A total of 155 ostracode species were identified from the Ariake and Yatsushiro Seas. • We discovered living specimens of two Chinese continental taxa. • These Chinese continental taxa do not transported by oceanic current. • The continental taxa living in Japan migrated there during past geological periods. [ABSTRACT FROM AUTHOR]