Intramedullary nailing versus external ring fixator for treatment of tibial fractures - a study protocol for a randomised clinical trial.

INTRODUCTION: Tibial shaft fractures are among the most common lower extremity fractures. Treatment of tibial shaft fractures with intramedullary nailing has become the treatment of choice in adults. However, commonly reported outcomes include knee pain, limitations in activities of daily living and reduction in quality of life (QOL). The literature lacks high-quality studies to document superiority of intramedullary nailing versus other surgical treatment methods. The present study aims to compare the 12-month Knee Injury and Osteoarthritis Outcome Score (KOOS) - sport and recreation activities (sport/rec) after standard intramedullary nailing with external ring fixation for adult patients with isolated tibial shaft fractures. METHODS: This study is a multicentre randomised, prospective clinical trial. A total of 67 patients will be included in the study, and the primary outcome will be the KOOS-sport/rec at 12 months after surgery. CONCLUSIONS: With KOOS-sport/rec as the primary outcome, the findings of the present study are expected to advance our understanding of knee pain, function and QOL, regardless of the treatment option and the outcome of the study. FUNDING: The project is partially funded by the Independent Research Found Denmark. CLINICALTRIALS: gov ID: NCT-03945669, version 1.1, 21 September 2022.

Correlation between stoichiometry and surface structure of the polar MgAl2O4(100) surface as a function of annealing temperature.

The correlation between surface structure, stoichiometry and atomic occupancy of the polar MgAl2O4(100) surface has been studied with an interplay of noncontact atomic force microscopy, X-ray photoelectron spectroscopy and surface X-ray diffraction under ultrahigh vacuum conditions. The Al/Mg ratio is found to significantly increase as the surface is sputtered and annealed in oxygen at intermediate temperatures ranging from 1073-1273 K. The Al excess is explained by the observed surface structure, where the formation of nanometer-sized pits and elongated patches with Al terminated step edges contribute to stabilizing the structure by compensating surface polarity. Surface X-ray diffraction reveals a reduced occupancy in the top two surface layers for both Mg, Al, and O and, moreover, vacancies are preferably located in octahedral sites, indicating that Al and Mg ions interchange sites. The excess of Al and high concentration of octahedral vacancies, very interestingly, indicates that the top few surface layers of the MgAl2O4(100) adopts a surface structure similar to that of a spinel-like transition Al2O3 film. However, after annealing at a high temperature of 1473 K, the Al/Mg ratio restores to its initial value, the occupancy of all elements increases, and the surface transforms into a well-defined structure with large flat terraces and straight step edges, indicating a restoration of the surface stoichiometry. It is proposed that the tetrahedral vacancies at these high temperatures are filled by Mg from the bulk, due to the increased mobility at high annealing temperatures.

Noncontact atomic force microscopy study of the spinel MgAl(2)O(4)(111) surface.

Based on high-resolution noncontact atomic force microscopy (NC-AFM) experiments we reveal a detailed structural model of the polar (111) surface of the insulating ternary metal oxide, MgAl(2)O(4) (spinel). NC-AFM images reveal a 6√3×6√3R30° superstructure on the surface consisting of patches with the original oxygen-terminated MgAl(2)O(4)(111) surface interrupted by oxygen-deficient areas. These observations are in accordance with previous theoretical studies, which predict that the polarity of the surface can be compensated by removal of a certain fraction of oxygen atoms. However, instead of isolated O vacancies, it is observed that O is removed in a distinct pattern of line vacancies reflected by the underlying lattice structure. Consequently, by the creation of triangular patches in a 6√3×6√3R30° superstructure, the polar-stabilization requirements are met.

Stable cation inversion at the MgAl2O4(100) surface.

From an interplay of atom-resolved noncontact atomic force microscopy, surface x-ray diffraction experiments, and density functional theory calculations, we reveal the detailed atomic-scale structure of the (100) surface of an insulating ternary metal oxide, MgAl2O4 (spinel). We surprisingly find that the MgAl2O4(100) surface is terminated by an Al and O-rich structure with a thermodynamically favored amount of Al atoms interchanged with Mg. This finding implies that so-called Mg-Al antisites, which are defects in the bulk of MgAl2O4, become a thermodynamically stable and integral part of the surface.

Stabilization principles for polar surfaces of ZnO.

ZnO is a wide band gap metal oxide with a very interesting combination of semiconducting, transparent optical and catalytic properties. Recently, an amplified interest in ZnO has appeared due to the impressive progress made in nanofabrication of tailored ZnO nanostructures and functional surfaces. However, the fundamental principles governing the structure of even the clean low-index ZnO surfaces have not been adequately explained. From an interplay of high-resolution scanning probe microscopy (SPM), X-ray photoelectron spectroscopy (XPS), near edge X-ray absorption fine structure (NEXAFS) spectroscopy experiments, and density functional theory (DFT) calculations, we identify here a group of hitherto unresolved surface structures which stabilize the clean polar O-terminated ZnO(0001) surface. The found honeycomb structures are truly remarkable since their existence deviates from expectations using a conventional electrostatic model which applies to the opposite Zn-terminated (0001) surface. As a common principle, the differences for the clean polar ZnO surfaces are explained by a higher bonding flexibility of the exposed 3-fold coordinated surface Zn atoms as compared to O atoms.