The Reliability of the Divergence Angle for Evaluating Rotational Implant Positioning in Medial Unicompartmental Knee Replacement.

Background Unicompartmental knee arthroplasty (UKA) is a highly effective surgical procedure used to treat patients with osteoarthritis affecting a single knee compartment. UKA has gained significant popularity, accompanied by an expansion of its surgical indications. This increasing trend can be attributed to the consistently excellent clinical outcomes associated with UKA, which rival those achieved with total knee arthroplasty (TKA). However, despite these advancements, implant rotation malposition remains a prevalent factor contributing to early failure in UKA cases. The aim of this study is to analyze the rotational positioning of femorotibial implants in UKA and to identify an appropriate angle formed by the femoral component and the tibial component using a newly described angle. Methods This was a retrospective study of patients' data of 40 medial UKA cases of 33 patients who were operated on in our hospital between October 1998 and March 2019. The study introduces a new angle called the "divergence angle." This angle is formed between the lateral portion of the femoral component and the lateral part of the tibial component, as measured on a patellofemoral Merchant view at 30 degrees of knee flexion. The divergence angle was evaluated through radiographic assessment by two independent reviewers. Results According to statistical analysis, the divergence angle was highly reliable with both intra- and inter-observer reproducibility. Intra-observer reproducibility was excellent with an intra-class correlation coefficient (ICC) between 0.901 and 0.933 (p < 0.001). The inter-observer reproducibility was excellent with an ICC of 0.92 (p < 0.001). The Gaussian curve confirmed the normal distribution of the divergence angle values with moderate dispersion of values. The majority of the angles of divergence (85%) measured between the femoral and tibial components were less than 10 degrees (n = 34), with a mean angle of 6.3 ± 4.5°. Conclusion The divergence angle between the femoral and tibial components, measured at 30 degrees of knee flexion using the Merchant view, is an easily accessible, reliable, and reproducible method. This technique enables the assessment of the optimal rotational positioning of implants in medial UKA.

Spin-Glass-like State and Reversible Room-Temperature Magnetocaloric Effect in Double Distorted Perovskites Nd(Cu3-xMnx)Mn4O12.

The preparation, complex magnetic properties and room-temperature magnetocaloric effect in Nd(Cu3-xMnx)Mn4O12 with cation distribution (Nd3+)A(Cu3-x2+xMnx3+)A'(Mn1+x3+Mn3-x4+)BO122- (x = 1 and 1.5) have been reported. Both compounds show a sharp paramagnetic-ferromagnetic (FM) transition at TC of 300 and 280 K, respectively. The substitution of Cu by Mn at the A' site induces the emergence of a spin glass state below ≈63 K for x = 1 and ≈72 K for x = 1.5 compound. Another antiferromagnetic-like magnetic transition is also observed in both compounds at 23 and 28 K, respectively, which is discussed as the antiferromagnetic coupling between Nd3+ at the A' site and (Mn3+/Mn4+) at the B site. These two compounds exhibit room-temperature magnetocaloric effect. For a small field of 2 T, the maximum magnetic entropy changes -ΔSM are 1.5 J/kg K at 300 K and 1.4 J/kg K at 280 K, respectively. Moreover, the -ΔSM(T) curves show an asymmetric distribution, resulting in high refrigerant capacity values for both compounds. We further demonstrate the distinct roles of the A'- and B-site spins on the magnetic properties and the origin of the spin-glass-like state in double distorted perovskites Ln(Cu3-xMnx)Mn4O12 family of compounds.

Does isolated arthroscopic anterior acromioplasty modify critical shoulder angle?

INTRODUCTION: Critical shoulder angle (CSA)>35° correlates significantly with primary rotator cuff tear and re-tear after repair. Acromial axial orientation varies between individuals. The present study aimed to assess the impact of strictly anterior acromioplasty on CSA. HYPOTHESIS: CSA is reduced by arthroscopic anterior acromioplasty. MATERIAL AND METHODS: A single-center retrospective study included patients receiving isolated arthroscopic acromioplasty between January 2016 and December 2017. Exclusion criteria comprised history of surgery and fracture or dislocation of the shoulder. Pre- and post-operative AP shoulder radiographs were taken. The angle subtended by a line between the inferior and superior edges of the glenoid and a line between the inferior edge of the glenoid and the most lateral point on the acromion was measured. RESULTS: One hundred and two patients were included: mean age, 50.5±10.1 years (range, 23-82 years). Mean CSA was 34.7±4.4° (range, 26-48°) preoperatively and 31.7±3.7° (range, 23-40°) postoperatively (p<0.001). In the group with CSA >35°, the decrease was significant: 34.4±3.2° (range, 28-40°) versus 38.9±2.8° (range, 36-48°) (p<0.001), with 64% CSA <35° after isolated anterior acromioplasty. DISCUSSION: CSA was decreased by arthroscopic acromioplasty. However, in 36% of cases with preoperative CSA >35°, CSA was not normalized. CONCLUSION: Anterior arthroscopic acromioplasty significantly reduced CSA in the overall population, and especially in case of high CSA. LEVEL OF EVIDENCE: IV; retrospective study.

Does anterior arthroscopic acromioplasty modify critical shoulder angle?

INTRODUCTION: Critical shoulder angle (CSA) is measured on AP view in neutral rotation as the angle subtended by the tangent to the glenoid and the lateral edge of the acromion. CSA >35° is a risk factor for primary rotator cuff tear and iterative tear after cuff repair. The aim of the present study was to assess change in CSA following arthroscopic anterior acromioplasty. HYPOTHESIS: CSA is decreased by arthroscopic anterior acromioplasty. MATERIAL AND METHOD: A single-center retrospective descriptive observational study included patients undergoing arthroscopic acromioplasty between January 2016 and December 2017, for whom strictly AP pre- and post-operative radiographs were available. Patients with history of surgery, fracture or dislocation in the same shoulder were excluded. RESULTS: 102 patients were included; mean age, 50.5 years (range, 23-82 years). Mean preoperative CSA was 34.7±4.4° (range, 26-48°) and postoperative CSA 31.7±3.7° (range, 23-40°) (p<0.001). In the pathological CSA group (>35°), the values were 38.9±2.8° (36-48°) and 34.4±3.2° (28-40°) (p<0.001), with a 64.3% rate of correction after acromioplasty. DISCUSSION: CSA decreased after arthroscopic acromioplasty. Even so, 36.7% of pathological CSAs (>35°) were not corrected, with risk of rotator cuff tear. CONCLUSION: Anterior arthroscopic acromioplasty significantly reduced CSA overall, notably in case of high CSA. LEVEL OF EVIDENCE: IV, retrospective study.

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Tetrahedral chain ordering and low dimensional magnetic lattice in a new brownmillerite Sr2ScFeO5.

We report the synthesis, structure and physical properties of a hitherto unreported brownmillerite compound Sr2ScFeO5. We have shown a new ordering sequence of the interlayer iron tetrahedral chains. Reduced dimensionality of the magnetic lattice and the frustration in the two dimensional iron tetrahedral chains originate complex magnetic and magneto-dielectric effects. Our study highlights a novel approach to tailor the magnetic lattice in bulk oxides.

High-Performance Thermoelectric Bulk Colusite by Process Controlled Structural Disordering.

High-performance thermoelectric bulk sulfide with the colusite structure is achieved by controlling the densification process and forming short-to-medium range structural defects. A simple and powerful way to adjust carrier concentration combined with enhanced phonon scattering through point defects and disordered regions is described. By combining experiments with band structure and phonons calculations, we elucidate, for the first time, the underlying mechanism at the origin of intrinsically low thermal conductivity in colusite samples as well as the effect of S vacancies and antisite defects on the carrier concentration. Our approach provides a controlled and scalable method to engineer high power factors and remarkable figures of merit near the unity in complex bulk sulfide such as Cu26V2Sn6S32 colusites.

Structure and Electronic Properties of the Quasi-One-Dimensional Ba2Co1-xZnxS3 Series.

This work focuses on the structure and physical properties of the solid solution Ba2Co1-xZnxS3 (0 ≤ x ≤ 1), a family of quasi-one-dimensional sulfides with end members Ba2CoS3 and Ba2ZnS3. The structure of selected compounds with increasing Zn2+ content has been analyzed using neutron diffraction, transmission electron microscopy, and extended X-ray absorption fine structure, and the physical properties have been analyzed via magnetic susceptibility and resistivity measurements. The progressive substitution of the nonmagnetic Zn2+ cation for Co2+ rapidly destroys the antiferromagnetic transition present at 46 K in the quasi-one-dimensional Ba2CoS3, leading to paramagnetic behavior down to the lowest investigated temperature (5 K) for compounds with x > 0.25. For compounds with x ≥ 0.4, a pure Curie-Weiss regime is recovered around 300 K, yielding effective moments consistent with the g factor of the tetrahedrally coordinated Co2+ previously determined for Ba2CoS3. The substitution of Zn2+ for Co2+ also removes the metallic-like behavior of Ba2CoS3, causing an increase in the value of the resistivity with all the Ba2Co1-xZnxS3 compounds showing semiconducting behavior. The negative magnetoresistance of Ba2CoS3 is improved by the substitution of Zn2+ for Co2+, with values of -6% for Ba2Co0.75Zn0.25S3, -9% for Ba2Co0.5Zn0.5S3, and -8% for Ba2Co0.25Zn0.75S3. However, there does not seem to be a correlation between the values of resistivity and magnetoresistance and the content of Zn2+, leading to the hypothesis that transport properties may be linked more closely to extrinsic properties.

Phase transitions and magnetic structures in MnW1-x Mo x O4 compounds (x ⩽ 0.2).

Temperature-dependent specific heat, magnetization and neutron diffraction data have been collected in zero magnetic field for polycrystalline samples of MnW1-x Mo x O4 (x ⩽ 0.2) solid solution whose end-member MnWO4 exhibits a magnetoelectric multiferroic phase (AF2 phase) between T 1 ≈ 8 K and T 2 = 12.5 K. In MnW1-x Mo x O4, diamagnetic W(6+) are replaced with diamagnetic Mo(6+) cations and magnetic couplings among Mn(2+) (3d (5), S = 5/2) ions are modified due the doping-induced tuning of the orbital hybridization between Mn 3d and O 2p states. It was observed that magnetic phase transition temperatures which are associated with the second-order AF3-to-paramagnetic (T N) and AF2-to-AF3 (T 2) transitions in pure MnWO4 slightly increase with the Mo content x. Magnetic specific heat data also indicate that the first-order AF1-to-AF2 phase transition at T 1 survives a weak doping x ⩽ 0.05. This latter phase transition becomes invisible above the base temperature 2 K for higher level of doping x ⩾ 0.10. Neutron powder diffraction datasets collected above 1.5 K for a sample of MnW0.8Mo0.2O4 were analyzed using the Rietveld method. The magnetic structure below ≈ 14 K is a helical incommensurate spin order with a temperature-independent propagation vector k = (-0.217(6), 0.5, 0.466(4)). This cycloidal magnetic structure is similar to the polar AF2 structure observed in MnWO4. The AF1 up-up-down-down collinear spin arrangement observed in MnWO4 is absent in our MnW0.8Mo0.2O4 sample.

Interplay between 3d-3d and 3d-4f interactions at the origin of the magnetic ordering in the Ba2LnFeO5 oxides.

A new family of oxides in which 3d-3d and 3d-4f interactions are of comparable strength has been synthesized and characterized both from structural and physical viewpoints. These compounds of formulation Ba2LnFeO5 (Ln = Sm, Eu, Gd, Dy, Ho, Er, Yb) are isotypic to the perovskite derivative Ba2YFeO5. They exhibit an original structure consisting of isolated FeO4 tetrahedra linked via LnO6 (or YO6) octahedra. Magnetic and calorimetric measurements show that all these compounds exhibit a unique, antiferromagnetic transition involving both the 3d and 4f ions. The antiferromagnetic properties of the Ln = Y phase (non-magnetic Y(3+)) and of the Ln = Eu (non-magnetic ground state multiplet of Eu(3+)) are ascribed to super-super exchange Fe-O-O-Fe interactions, leading to the lowest T(N) (5.5 K for Y and 4.6 K for Eu). The introduction of a magnetic lanthanide, i.e. Ln = Sm, Gd, Dy, Ho, Er, Yb, in the octahedral sites, leads to larger T(N) values (up to 9.8 K for Ln = Yb). It is found that several mechanisms must be taken into account to explain the complex evolution of the magnetic properties along the Ba2LnFeO5 series. In particular, the super-exchange Ln-O-Fe, as well as the on-site Ln(3+) magnetocrystalline anisotropy, are suggested to play crucial roles. This Ba2LnFeO5 series offers a rare opportunity to investigate experimentally a situation where the 3d-3d and 3d-4f interactions co-operate on an equal footing to trigger a unique long-range magnetic ordering in insulating oxides.

Revisiting some chalcogenides for thermoelectricity.

Thermoelectric materials that are efficient well above ambient temperature are needed to convert waste-heat into electricity. Many thermoelectric oxides were investigated for this purpose, but their power factor (PF) values were too small (∼10-4 W m-1 K-2) to yield a satisfactory figure of merit zT. Changing the anions from O2- to S2- and then to Se2- is a way to increase the covalency. In this review, some examples of sulfides (binary Cr-S or derived from layered TiS2) and an example of selenides, AgCrSe2, have been selected to illustrate the characteristic features of their physical properties. The comparison of the only two semiconducting binary chromium sulfides and of a layered AgCrSe2 selenide shows that the PF values are also in the same order of magnitude as those of transition metal oxides. In contrast, the PF values of the layered sulfides TiS2 and Cu0.1TiS2 are higher, reaching ∼10-3 W m-1 K-2. Apparently the magnetism related to the Cr-S network is detrimental for the PF when compared to the d0 character of the Ti4+ based sulfides. Finally, the very low PF in AgCrSe2 (PF = 2.25 × 10-4 W m1 K-2 at 700 K) is compensated by a very low thermal conductivity (κ = 0.2 W m-1 K-1 from the measured Cp) leading to the highest zT value among the reviewed compounds (zT700K = 0.8). The existence of a glassy-like state for the Ag+ cations above 475 K is believed to be responsible for this result. This result demonstrates that the phonon engineering in open frameworks is a very interesting way to generate efficient thermoelectric materials.

The spin glass delafossite CuFe(0.5)V(0.5)O(2): a dipolar glass?

The ferroelectric and spin glass properties of CuFe(0.5)V(0.5)O(2) have been studied. Magnetization, ac magnetic susceptibility and specific heat measurements reveal a spin glass behavior (T(f) = 20.5 K) for this delafossite. In CuFeO(2), substitution of trivalent diamagnetic cations for Fe(3 + ) is known to change the antiferromagnetic state and induce ferroelectricity. But partial occupation of the Fe(3 + ) site by V(3 + ) is responsible for disordered magnetism in CuFe(0.5)V(0.5)O(2). The dielectric permittivity shows a frequency dependence reminiscent of relaxor ferroelectrics in which different cations occupy the same crystallographic site. Polarization measurements show the existence of a ferroelectric state below T(f) with P(5 K)≈1.3 µC m( - 2). These results point towards a relaxor-type ferroelectricity originating from a disordered array of magnetic cations. A clear coupling between electronic charges and spins is evidenced by the magnetodielectric effect.

Increase in magnetoresistivity in Ba2CoS3 via Zn2+/Co2+ substitution.

We report an increase of negative magnetoresistivity from 1.7% to 9% in the Ba(2)Co(0.5)Zn(0.5)S(3) series (0

Derivation of the heat capacity anomaly at a first-order transition by using a semi-adiabatic relaxation technique.

This paper deals with the problem of determining the heat capacity anomaly associated with a first-order transition when using relaxation calorimetry. A method of data recording and analysis is proposed, which is shown to be well suited to investigate such a feature, including its hysteretical character. This technique is applied to spinel vanadates, allowing us to shed light on a recent controversy about the double-transition which takes place in these oxides.

Negative magnetoresistance in Ba2CoS3.

A small negative magnetoresistance and metallic-like behaviour has been detected for the first time in a one-dimensional sulfide containing Co2+.