Second-generation uncemented stems: excellent 5-13-year results

Introduction: The purpose of this study was to prospectively evaluate the 5-13-year results of a cementless total hip arthroplasty with a special focus on the survivorship, occurrence of osteolysis, incidence of intraoperative femoral fractures, thigh pain, and cortical hypertrophy of the femoral stem. The femoral component used in this study was titanium fluted, slotted, symmetrical component that was prepared with intraoperative machining. The proximal third of the stem had hydroxyl-apatite coating and horizontal steps. Methods: The clinical and radiographical results of a consecutive series of 157 total hip arthroplasties (124 patients) with this stem were investigated. Minimum follow-up was 5years. The average age of the patients at the time of surgery was 47years. Three patients died and ten patients were lost to follow-up, leaving 142 hips for evaluation. The clinical result was evaluated on the basis of the Merle d'Aubigné score, complications and thigh pain. A detailed radiographic analysis was performed at each follow-up visit. Kaplan-Meier survivorship analysis was performed to evaluate stem, cup, and bearing survivorship. Results: The mean follow-up was 8.5years (range 5-13years). The average Merle d'Aubigné score improved from 10.5 points preoperatively to 17.4 points postoperatively. The cumulative 10-year survival rate was 99% for the femoral component, 99% for the acetabular component, and 69% for the bearing. Thigh pain was identified in three patients (2%). There was no distal femoral osteolysis. Seventy-nine percent of all the hips had endosteal spot welds around the coated, proximal one-third of the prosthesis. 51% had radiodense lines around the distal tip of the prosthesis, and 3% had cortical hypertrophy. One undersized stem and one cup were revised for aseptic loosening, and 25 bearings were exchanged. Conclusions: Uncemented, machined, fluted titanium canal-filling femoral components achieve reliable fixation in this young patient population. They have a decreased incidence of activity-related thigh pain, lower rate of intraoperative femur fractures and cortical hypertrophy with comparable bone-ingrowth in comparison to other second-generation uncemented femoral components described in literature. Bearing wear and the need for bearing exchange was the only limitation of these construct

Statistical Power of Piecewise Regression Analyses of Single-Case Experimental Studies Addressing Behavior Problems

In intervention research, single-case experimental designs are an important way to gain insights into the causes of individual changes that yield high internal validity. They are commonly applied to examine the effectiveness of classroom-based interventions to reduce problem behavior in schools. At the same time, there is no consensus on good design characteristics of single-case experimental designs when dealing with behavioral problems in schools. Moreover, specific challenges arise concerning appropriate approaches to analyzing behavioral data. Our study addresses the interplay between the test power of piecewise regression analysis and important design specifications of single-case research designs. Here, we focus on the influence of the following specifications of single-case research designs: number of measurement times, the initial frequency of the behavior, intervention effect, and data trend. We conducted a Monte-Carlo study. First, simulated datasets were created with specific design conditions based on reviews of published single-case intervention studies. Following, data were analyzed using piecewise Poisson-regression models, and the influence of specific design specifications on the test power was investigated. Our results indicate that piecewise regressions have a high potential of adequately identifying the effects of interventions for single-case studies. At the same time, test power is strongly related to the specific design specifications of the single-case study: Few measurement times, especially in phase A, and low initial frequencies of the behavior make it impossible to detect even large intervention effects. Research designs with a high number of measurement times show robust power. The insights gained are highly relevant for researchers in the field, as decisions during the early stage of conceptualizing and planning single-case experimental design studies may impact the chance to identify an existing intervention effect during the research process correctly. Copyright © 2022 Wilbert, Börnert-Ringleb and Lüke

Phase decomposition and nano structure evolution of metastable nanocrystalline Cu-Co solid solutions during thermal treatment

Nanocrystalline and ultrafine-grained Cu100-xCox (x = 26 and 76) solid solutions have been prepared by severe plastic deformation (SPD) of elemental powder mixtures. For both concentrations a supersaturated solid solution fcc phase was identified after the deformation process with grain sizes of less than 50 nm for Co rich solutions and around 100 nm for Cu rich solutions. Additionally, synthesis of nanocrystalline materials in the Cu-Co alloy system by electrodeposition has been conducted. Microstructural characterization by scanning and transmission electron microscopy, differential scanning calorimetry, and microhardness measurements are used to investigate the structural evolution, the thermal stability and mechanical properties of the different nanocrystalline Cu-Co alloy materials during isothermal and non-isothermal annealing. In this study it is shown that the phase decomposition of the metastable Cu-Co solid solutions has a significant influence on their thermal stability, which can be linked to the underlying microstructure that forms during annealing

Tap Reactor for Temporally and Spatially Resolved Analysis of the CO2_{2} Methanation Reaction

Chemical energy carriers produced according to power-to-X concepts will play a crucial role in the future energy system. Here, CO$_{2}$ methanation is described as one promising route. However, transient operating conditions and the resulting effects on catalyst stability are to be considered. In this contribution, a tap reactor for spatially and temporally resolved analysis of the methanation reaction is presented. The Ni catalyst investigated was implemented as coating. Reaction data as a function of time and reactor coordinate under various operating conditions are presented and discussed. A comparison with simulation data validates the presented tap reactor concept

Poor transcript-protein correlation in the brain: negatively correlating gene products reveal neuronal polarity as a potential cause

International audienceTranscription, translation, and turnover of transcripts and proteins are essential for cellular function. The contribution of those factors to protein levels is under debate, as transcript levels and cognate protein levels do not necessarily correlate due to regulation of translation and protein turnover. Here we propose neuronal polarity as a third factor that is particularly evident in the CNS, leading to considerable distances between somata and axon terminals. Consequently, transcript levels may negatively correlate with cognate protein levels in CNS regions, i.e., transcript and protein levels behave reciprocally. To test this hypothesis, we performed an integrative inter‐omics study and analyzed three interconnected rat auditory brainstem regions (cochlear nuclear complex, CN; superior olivary complex, SOC; inferior colliculus, IC) and the rest of the brain as a reference. We obtained transcript and protein sets in these regions of interest (ROIs) by DNA microarrays and label‐free mass spectrometry, and performed principal component and correlation analyses. We found 508 transcript|protein pairs and detected poor to moderate transcript|protein correlation in all ROIs, as evidenced by coefficients of determination from 0.34 to 0.54. We identified 57‐80 negatively correlating gene products in the ROIs and intensively analyzed four of them for which the correlation was poorest. Three cognate proteins (Slc6a11, Syngr1, Tppp) were synaptic and hence candidates for a negative correlation because of protein transport into axon terminals. Thus, we systematically analyzed the negatively correlating gene products. Gene ontology analyses revealed overrepresented transport/synapse‐related proteins, supporting our hypothesis. We present 30 synapse/transport‐related proteins with poor transcript|protein correlation. In conclusion, our analyses support that protein transport in polar cells is a third factor that influences the protein level and, thereby, the transcript|protein correlation

LCPD: Reduced Range of Motion Resulting From Extra- and Intraarticular Impingement

Background: Legg-Calvé-Perthes disease (LCPD) often results in a deformity that can be considered as a complex form of femoroacetabular impingement (FAI). Improved preoperative characterization of the FAI problem based on a noninvasive three-dimensional computer analysis may help to plan the appropriate operative treatment. Questions/purposes: We asked whether the location of impingement zones, the presence of additional extraarticular impingement, and the resulting ROM differ between hips with LCPD and normal hips or hips with FAI. Methods: We used a CT-based virtual dynamic motion analysis based on a motion algorithm to simulate the individual motion for 13 hips with LCPD, 22 hips with FAI, and 27 normal hips. We then determined the motion and impingement pattern of each hip for the anterior (flexion, adduction, internal rotation) and the posterior impingement tests (extension, adduction, external rotation). Results: The location of impingement zones in hips with LCPD differed compared with the FAI/normal groups. Intra- and extraarticular impingement was more frequent in LCPD (79% and 86%, respectively) compared with normal (15%, 15%) and FAI hips (36%, 14%). Hips with LCPD had decreased amplitude for all hip motions (flexion, extension, abduction, adduction, internal and external rotation) compared with FAI or normal. Conclusions: Hips with LCPD show a decreased ROM as a result of a higher prevalence of intra- and extraarticular FAI. Noninvasive assessment of impingement characteristics in hips with LCPD may be helpful in the future for establishment of a surgical pla

Influence of Electrode Structuring Techniques on the Performance of All-Solid-State Batteries

All-solid-state batteries (ASSBs) offer a promising route to safer batteries with superior energy density compared to conventional Li-ion batteries (LIBs). However, the design of the composite cathode and optimization of the underlying microstructure is one of the aspects requiring intensive research. Achieving both high energy and power density remains challenging due to limitations in ionic conductivity and active material loading. Using structure-resolved simulations, we investigate the potential of perforated and layered electrode designs to enhance ASSB performance. Design strategies showing significant performance increase in LIBs are evaluated regarding their application to ASSBs. Composite cathodes with solid electrolyte channels in the structure do not significantly increase cell performance compared to unstructured electrodes. However, the design with a two-layer cathode proves promising. The layered structure effectively balances improved ionic transport due to increased solid electrolyte fraction at the separator side and substantial active material loading through increased active material fraction at the current collector side of the cathode. Our research highlights key challenges in ASSB development and provides a clear direction for future studies in the field.Comment: 46 pages, 15 figure

The In Vitro Human Fracture Hematoma Model - A Tool for Preclinical Drug Testing

The aim of the study was to establish an in vitro fracture hematoma (FH) model, which mimics the in vivo situation of the human fracture gap in order to assess drug efficacy and effectiveness for the treatment of fracture healing disorders. Therefore, human peripheral blood and mesenchymal stromal cells (MSCs) were coagulated to produce in vitro FH models, incubated in osteogenic medium under normoxia/hypoxia, and analyzed for cell composition, gene expression and cytokine/chemokine secretion. To evaluate the model, we studied the impact of dexamethasone (impairing fracture healing) and deferoxamine (promoting fracture healing). Under hypoxic conditions, MSCs represented the predominant cell population, while the frequencies of leukocytes decreased. Marker gene expression of osteogenesis, angiogenesis, inflammation, migration and hypoxic adaptation increased significantly over time and compared to normoxia while cytokine/chemokine secretion remained unchanged. Finally, dexamethasone favored the frequency of immune cells compared to MSCs, suppressed osteogenic and pro-angiogenic gene expression and enhanced the secretion of inflammatory cytokines. Conversely, deferoxamine favored the frequency of MSCs over that of immune cells and enhanced the expression of the osteogenic marker RUNX2 and markers of the hypoxic adaptation. In summary, we demonstrate that hypoxia is an important factor for in vitro modeling the initial phase of fracture healing, that both fracture-healing disrupting and promoting substances can influence the in vitro model comparable to the in vivo situation. Therefore, we conclude that our model is able to mimic in part the human FH and to reduce the number of animal experiments in early preclinical studies