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Total knee arthroplasty (TKA) in patients with established knee osteoarthritis and major varus, mostly due to constitutional proximal deformity, remains a challenging procedure. Orthogonal cuts result in asymmetric bone resection and subsequent bone-related laxity or difficult release. A procedure that combines opening high tibial osteotomy (HTO) and TKA in the same sitting to address such major deformities is possible. But for this combined operation, precise planning and an exact intraoperative transformation of the planning is required. The assumption that the results could be predicted better by means of a navigation system was analyzed.The precision of surgery with computer-based navigation was compared to conventional surgery. A comparative prospective study was conducted using an expert surgeon. Between 2005 and 2015, we performed 20 procedures on knees with average preoperative 18° (range, 15-25°) varus. Tibial valgus osteotomy plus TKA was performed in one sitting. It allows the surgeon to do a more sparing medial release and to achieve proper realignment with a concomitant well-balanced prothesis. A group of 10 patients had conventional surgery and the other 10 had surgery performed with computer-based navigation for both osteotomy and TKA. By means of this system, the desired mechanical axis is obtained with real-time monitoring of the coronal and sagittal plane on the navigation without intraoperative x-ray control. The positioning of the saw-jigs for the femoral and tibial cuts of the arthroplasty was also performed with the help of the navigation system.Postoperative mean femorotibial varus was 1.5° (range, 0-5°) with better alignment for the computer-based navigation. The mean correction following osteotomy was 16° (range, 12-24°). The intraarticular part of the deformity due to cartilage wear was addressed by the TKA. No release was done during surgery. The patients were mobilized early with limitation in range of motion up to 90° of flexion during the two weeks and were allowed full weight after. No instability and no complications were observed. On assessing radiological coronal alignment of the prostheses, there was better alignment of 0.5° varus (range, 0-3° of varus) in the computer navigation group compared to the traditional group (2.5° varus; range, 1-5° of varus). The navigation group showed better tibial slope maintenance (mean change, + 0.5°, p=0.732), whereas it was increased significantly in the conventional group (mean change, +4.2°, p0.01). The average number of fluoroscopy shots for the computer navigation group was 2.8 (95% CI, 1.2-6.5) versus 9.4 in the control group (95% CI, 5.3-12.4). This represented a shorter (p0.001) time of 11.4 seconds of irradiation for the computerized navigation technique compared to 36.2 seconds of irradiation for the traditional technique.Computer navigation improved precision with less radiation. The findings of this study suggest that computer navigation may be safely used in a complex procedure when combined with total knee arthroplasty and opening wedge high tibial osteotomy in one sitting.

Purpose The current pandemic caused by COVID-19 is the biggest challenge for national health systems for a century. While most medical resources are allocated to treat COVID-19 patients, fractures still need to be treated, as some patients with non-deferrable pathologies. The aim of this paper is to report the early experience of an integrated team of orthopaedic surgeons during this period. Material and methods This is a mono-geographic, observational, retrospective, descriptive study. We collected data from the beginning of the epidemic (1 March 2020), during the pandemic lockdown period (declared in the country on March 16, 2020) until the end of our study period on April 15, 2020. All the 140 patients presented to the Emergency Department of the hospital during this period with a diagnosis of fracture, or trauma (sprains, dislocations, wounds) were included in the cohort. In addition, 12 patients needing hospitalization for planning a non-deferrable elective surgical treatment were included. A group of patients from the two same hospitals and treated during the same period (1st March 2018 to April 15, 2018) but previously was used as control. Results Of these 152 patients (mean age 45.5 years; range 1 to 103), 100 underwent a surgical procedure and 52 were managed non-operatively. Twenty-eight were children and 124 were adults. The COVID-19 diagnosis was confirmed for four patients. The frequency of patients with confirmed COVID-19 diagnosis among this population treated in emergency was ten fold higher (2.6%; 4 among 152) than in the general population (0.30%) of the country. The mortality rate for patients with surgery was 2% (2 of 100 patients) and 50% (2 of 4) for those older than 60 years with COVID-19; it was null for patients who were managed non-operatively. As compared to the year 2018, the number of patients seen with trauma had decreased of 32% during the epidemic. Conclusion Staying home during the COVID-19 pandemic decreased trauma frequency of 32%. The structural organization in our hospital allowed us to reduce the time to surgery and ultimately hospital stay, thereby maximizing the already stretched medical resources available to treat all the patients who needed orthopedic care during this period.

International audience; We present the latest version of the ISBA‐CTRIP land surface system, focusing on the representation of the land carbon cycle. We review the main improvements since the year 2012, mainly added modules for wild fires, carbon leaching through soil and transport of dissolved organic carbon to the ocean, and land cover changes but also improved representation of photosynthesis, respiration, and plant functional types. This version of ISBA‐CTRIP is fully described in terms of land carbon pools, fluxes, and their interactions. Results are compared with the previous version in an off‐line mode forced by observed climate during the historical time period. The two simulations are presented to demonstrate the model performance compared to an ensemble of observed and observation‐derived data sets for gross and net primary productivity, heterotrophic and autotrophic respiration, above and below ground biomass, litter, and soil carbon pools. New developments specific to the new version such as burned area, fire emissions, carbon leaching, and land cover are also validated against observations. The results show clearly that the latest version of ISBA‐CTRIP outperforms the former version and reproduces generally well the observed mean spatial patterns in carbon pools and fluxes, as well as the seasonal cycle of leaf area index. The trends of the global fluxes over the last 50 years agree with other global models and with available estimates. This comparison gives us confidence that the model represents the main processes involved in the terrestrial carbon cycle and can be used to explore future global change projections.

Permafrost soils and arctic wetlands methane emissions represent an important challenge for modeling the future climate. Here we present a process-based model designed to correctly represent the main thermal, hydrological, and biogeochemical processes related to these emissions for general land surface modeling. We propose a new multilayer soil carbon and gas module within the Interaction Soil-Biosphere-Atmosphere (ISBA) land-surface model (LSM). This module represents carbon pools, vertical carbon dynamics, and both oxic and anoxic organic matter decomposition. It also represents the soil gas processes for CH4, CO2, and O2 through the soil column. We base CH4 production and oxydation on an O2 control instead of the classical water table level strata approach used in state-of-the-art soil CH4 models. We propose a new parametrization of CH4 oxydation using recent field experiments and use an explicit O2 limitation for soil carbon decomposition. Soil gas transport is computed explicitly, using a revisited formulation of plant-mediated transport, a new representation of gas bulk diffusivity in porous media closer to experimental observations, and an innovative advection term for ebullition. We evaluate this advanced model on three climatically distinct sites : two in Greenland (Nuuk and Zackenberg) and one in Siberia (Chokurdakh). The model realistically reproduces methane and carbon dioxide emissions from both permafrosted and nonpermafrosted sites. The evolution and vertical characteristics of the underground processes leading to these fluxes are consistent with current knowledge. Results also show that physics is the main driver of methane fluxes, and the main source of variability appears to be the water table depth.

Solid wall boundary conditions have been an area of active research within the context of Smoothed Particle Hydrodynamics (SPH) for quite a while. Ferrand et al. (Int. J. Numer. Methods Fluids 71(4), 446---472, 2012) presented a novel approach using a renormalization factor in the SPH approximation. The computation of this factor depends on an integral along the boundary of the domain and in their original paper Ferrand et al. gave an analytical formulation for the 2-D case using the Wendland kernel. In this paper the formulation will be extended to 3-D, again providing analytical formulae. Due to the boundary being two dimensional a domain decomposition algorithm needs to be employed in order to obtain special integration domains. For these the analytical formulae will be presented when using the Wendland kernel. The algorithm presented within this paper is applied to several academic test-cases for which either analytical results or simulations with other methods are available. It will be shown that the present formulation produces accurate results and provides a significant improvement compared to approximative methods.

International audience; We describe the concept and properties of a new electrostatic optic which aims to provide a 2π sr instantaneous field-of-view to characterize space plasmas. It consists of a set of concentric toroidal electrodes that form a number of independent energy selective channels. Charged particles are deflected towards a common imaging planar detector. The full 3D distribution function of charged particles is obtained through a single energy sweep. Angle and energy resolution of the optics depends on the number of toroidal electrodes, on their radii of curvature, on their spacing, and on the angular aperture of the channels. We present the performances, as derived from numerical simulations, of an initial implementation of this concept that would fit the need of many space plasma physics applications. The proposed instrument has 192 entrance windows corresponding to 8 polar channels each with 24 azimuthal sectors. The initial version of this 3D plasma analyzer may cover energies from a few eV up to 30 keV, typically with a channel dependent energy resolution varying from 10% to 7%. The angular acceptance varies with the direction of the incident particle from 3° to 12°. With a total geometric factor of two sensor heads reaching ~ 0.23 cm2 · sr · eV/eV, this “donut” shape analyzer has enough sensitivity to allow very fast measurements of plasma distribution functions in most terrestrial and planetary environments on three-axis stabilized as well as on spinning satellites.

Dysthyroid Optic Neuropathy (DON) can lead to irreversible visual loss. We report risk features correlated with poor visual recovery despite an intensive treatment in a series of patients with DON.Retrospective analysis of a non-comparative interventional series.Between 1997 and 2007, 300 consecutive patients with Graves' orbitopathy were seen at the Rothschild Foundation (Paris). Medical records of all consecutive patients who developed a DON were reviewed. Demographic, clinical features and visual function were collected at the time of the first onset, one month follow-up after medical and sometime surgical treatment and at the last examination. Statistical analysis (reflected as p values) gathered the significant observations into detrimental visual recovery prognostic factors for DON.Fifty-six eyes of 29 patients developed a DON. Sixteen eyes (28%) did not improve vision despite usual treatment (intravenous steroids and surgical decompression when necessary). An inferior altitudinal visual field defect (AVF, p=0.0004) and/or a lack of response to intravenous steroids boluses (p= 0.011) were related to a poor recovery.DON prognosis is highly variable. Our results suggest that a non-inflammatory element, probably vascular could be involved in atypical DONs. An earlier recognition could prompt to rapid surgical treatment for these patients.

Due to the Lagrangian nature of SPH, treating inlet/outlet boundaries (that are intrinsically Eulerian) is a challenging issue. An extension to the Unified Semi-Analytical boundary conditions is presented to deal with unsteady open boundaries in confined and free-surface flows. The presented method uses Riemann invariants to calculate flow properties near the open boundaries, thus allowing the possibility to treat complex shapes. Furthermore, details are presented for a parallel implementation of this method, including particle creation and deletion , updating properties of vertices and segments, and additional constraints on the time step. Simple validation cases are then displayed to illustrate the performance of the proposed method as well as the ability to deal with complex problems such as generation of water waves and free outlets.

Arctic and boreal peatlands play a major role in the global carbon (C) cycle. They are particularly efficient at sequestering carbon because their high water content limits decomposition rates to levels below their net primary productivity. Their future in a climate-change context is quite uncertain in terms of carbon emissions and carbon sequestration. Nuuk fen is a well-instrumented Greenlandic fen with monitoring of soil physical variables and greenhouse gas fluxes (CH4 and CO2) and is of particular interest for testing and validating land-surface models. But knowledge of soil carbon stocks and profiles is missing. This is a crucial shortcoming for a complete evaluation of models, as soil carbon is one of the primary drivers of CH4 and CO2 soil emissions. To address this issue, we measured, for the first time, soil carbon and nitrogen density, profiles and stocks in the Nuuk peatland (64∘07′51′′ N, 51∘23′10′′ W), colocated with the greenhouse gas measurements. Measurements were made along two transects, 60 and 90 m long and with a horizontal resolution of 5 m and a vertical resolution of 5 to 10 cm, using a 4 cm diameter gouge auger. A total of 135 soil samples were analyzed. Soil carbon density varied between 6.2 and 160.2 kg C m−3 with a mean value of 50.2 kg C m−3. Mean soil nitrogen density was 2.37 kg N m−3. Mean soil carbon and nitrogen stocks are 36.3 kg C m−2 and 1.7 kg N m−2. These new data are in the range of those encountered in other arctic peatlands. This new dataset, one of very few in Greenland, can contribute to further development of joint modeling of greenhouse gas emissions and soil carbon and nitrogen in land-surface models. The dataset is open-access and available at https://doi.org/10.1594/PANGAEA.909899 (Morel et al., 2019b).