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Background: High tibial osteotomy (HTO) aims to realign the varus knee to alleviate stress in the medial compartment. However, detailed information on the impact of HTO on stress distribution across the tibiofemoral joint surface still needs to be completely elucidated. Purpose/Hypothesis: The present study aimed to analyze the subchondral bone density distribution to validate the alignment threshold causing paradoxical changes. We hypothesized that there would be a paradoxical stress change in the medial compartment beyond a specific threshold for lower limb realignment after HTO. Study Design: Case series; Level of evidence, 4. Methods: A retrospective clinical study of 32 knees from 30 patients who underwent medial opening-wedge HTO between 2015 and 2019 was conducted at Hokkaido University Hospital. The subchondral bone density across the tibiofemoral joint was analyzed using computed tomography–osteoabsorptiometry before and after HTO. The high-density area (HDA) within the medial and lateral compartments and their subregions, which were quartered in the coronal plane, was specifically examined. Results: The hip-knee-ankle angle, medial proximal tibial angle (MPTA), joint line obliquity (JLO), and joint line convergence angle significantly changed after HTO (P <.01). The HDA of the medial compartment to the total HDA ratio decreased from 83% to 77%. Paradoxically, the HDA in the most central subregion of the medial compartment increased from 24% to 30%. There were significant differences between MPTA and JLO in patients with and without paradoxical changes in the HDA. MPTA and JLO cutoff values causing paradoxical changes in the HDA were 94° and 4°, respectively. Conclusion: There was a paradoxical stress increase in the M4 region at the medial compartment associated with the MPTA and JLO beyond specific thresholds. Therefore, surgical planning should be cautiously performed to prevent overcorrection, which can lead to adverse stress distribution changes. [ABSTRACT FROM AUTHOR]

Production of formic acid (FA) by hydrogenation of CO2 using a ternary hybrid catalyst, poly(ethyleneimine)-tethered Ir-iminophosphine complex (Ir-PN-PEI) immobilized in titanate nanotubes (TNTs), is reported. On the basis of comprehensive structural analyses, we show that Ir-PN-PEI is tightly immobilized within the cavity space of TNT without affecting the electronic/coordination states of Ir atoms. Liquid-phase CO2 hydrogenation under pressurized CO2 and H2 demonstrates that the Ir-PN-PEI catalyst immobilized in Na+-type TNT exhibits the highest FA yields (TON>1000 for 20 h under mild reaction conditions (2.0 MPa, 140 °C)) and improved reusability, which far outperform those of unimmobilized prototype Ir-PN-PEI. The improved catalytic performance is attributed to the ability of TNT to efficiently capture CO2 and to stabilize PEI, with Na+-type TNT with higher basic property providing a more productive effect. The catalyst is reusable over multiple cycles with activity comparable to those of heterogeneous catalysts previously reported, rendering this material suitable for efficient transformation of CO2 into FA. [ABSTRACT FROM AUTHOR]

The Front Cover shows the production of formic acid from CO2 and H2 by a ternary hybrid catalyst composed of an Ir complex, poly(ethyleneimine) and titanate nanotubes (TNTs).In their Full Paper, Y. Kuwahara et al. demonstrate that immobilization of a poly(ethyleneimine)‐tethered Ir complex catalyst inside the cavity space of TNTs can afford efficient catalysts with both improved activity and reusability, owing to the CO2 adsorption capacity of poly(ethyleneimine) and stabilizing effect of TNTs. This study can potentially offer a generalized method to capture and convert CO2, which is particularly desirable for sustainable formic acid production. More information can be found in the Full Paper by Y. Kuwahara et al. on page 1906 in Issue 11, 2017 (DOI: 10.1002/cctc.201700508). [ABSTRACT FROM AUTHOR]