The over-the-top subscapularis repair in reverse shoulder arthroplasty: biomechanical evaluation of a novel technique.

Background: We evaluate the effect of repairing the upper subscapularis tendon at an alternative location on the anterior greater tuberosity above the center of rotation using a reverse shoulder arthroplasty (RSA) muscle model.

Methods: We compared an innovative subscapularis repair on the anterior aspect of the greater tuberosity with the standard repair on the lesser tuberosity in a previously validated digital linear RSA muscle model. Standard repair vs.

Using Two-Dimensional Correlation Size Exclusion Chromatography (2D-CoSEC) and EEM-PARAFAC to Explore the Heterogeneous Adsorption Behavior of Humic Substances on Nanoparticles with Respect to Molecular Sizes.

The adsorption behaviors of different constituents within bulk humic substances (HS) on two nanoparticles, TiO and ZnO, were examined by using two-dimensional correlation size exclusion chromatography (2D-CoSEC) and excitation emission matrix-parallel factor analysis (EEM-PARAFAC), which separated bulk HS into different size fractions and fluorescent components, respectively. Subtle changes in the size distributions of HS with increasing adsorbents were successfully identified and tracked via the 2D-CoSEC. From adsorption isotherm experiments, three different HS constituent groups with respect to sizes and fluorescence features were identified by the 2D-CoSEC and EEM-PARAFAC, respectively.

Non-catalytic and catalytic degradation of effluent dissolved organic matter under UVA-and UVC-irradiation tracked by advanced spectroscopic tools.

Non-catalytic and catalytic photodegradation of effluent dissolved organic matter (EfDOM) was examined under two different light sources (UVA and UVC). The degradation behavior was tracked by dissolved organic carbon (DOC), UV absorbance, and different fluorescent components. Catalytic UV irradiation resulted in much higher degradation rates than those without photocatalysts (TiO and ZnO) regardless of the tracking variables.

Impact of Posterior Wear on Muscle Length with Reverse Shoulder Arthroplasty.

The use of reverse total shoulder arthroplasty (rTSA) in patients with posterior glenoid wear can be challenging. Implanting a baseplate in the correct version may require significant eccentric reaming, which further medializes the joint line and results in greater rotator cuff muscle shortening. To restore the joint line, bone graft may be required, though it is associated with additional risks.

Optimizing Deltoid Efficiency with Reverse Shoulder Arthroplasty Using a Novel Inset Center of Rotation Glenosphere Design.

Introduction: Paul Grammont's hemispherical gleno sphere concept medializes the center of rotation (CoR) to the glenoid face to increase deltoid abductor moment arms and improve muscle efficiency. Reducing glenosphere thickness to less than half its spherical radius further medializes the CoR and offers the potential for even greater improvements in efficiency. To that end, this study quantifies deltoid abducttor moment arms for six different rTSA prostheses during scapular abduction from 0° to 140°.

Insight into photocatalytic degradation of dissolved organic matter in UVA/TiO₂ systems revealed by fluorescence EEM-PARAFAC.

Photocatalytic degradation of dissolved organic matter (DOM) using TiO2 as a catalyst and UVA as a light source was examined under various experimental settings with different TiO2 doses, solution pH, and the light intensities. The changes in UV absorbance and fluorescence with the irradiation time followed a pseudo-first order model much better than those of dissolved organic carbon. In general, the degradation rates were increased by higher TiO2 doses and light intensities.

Effect of reverse shoulder design philosophy on muscle moment arms.

This study analyzes the muscle moment arms of three different reverse shoulder design philosophies using a previously published method. Digital bone models of the shoulder were imported into a 3D modeling software and markers placed for the origin and insertion of relevant muscles. The anatomic model was used as a baseline for moment arm calculations.

Spatial variability in chromophoric dissolved organic matter for an artificial coastal lake (Shiwha) and the upstream catchments at two different seasons.

Selected water quality parameters and spectroscopic characteristics of dissolved organic matter (DOM) were examined during two different seasons for an artificial coastal lake (Shiwha Lake in South Korea), which are affected by seawater exchange due to the operation of a tidal power plant and external organic loadings from the upstream catchments. The coastal lake exhibited much lower concentrations of organic matter and nutrients than the upstream sources. The spectroscopic properties of the lake DOM were easily distinguished from those of the catchment sources as revealed by a lower absorption coefficient, lower degree of humification, and higher spectral slopes.

Impact of inferior glenoid tilt, humeral retroversion, bone grafting, and design parameters on muscle length and deltoid wrapping in reverse shoulder arthroplasty.

Purpose: This study quantifies the ability of humeral retroversion, glenoid tilt, bone graft, and varying prosthesis design parameters to restore anatomic muscle length and deltoid wrapping with reverse shoulder arthroplasty.

Methods: A computer model simulated abduction and internal and external rotation for a normal shoulder, the RSP reverse shoulder, the Equinoxe reverse shoulder, and the Grammont reverse shoulder when implanted using various implantation methods. The length of eight different muscles and the deltoid wrapping angle were quantified to evaluate the ability of each implantation method and design to restore anatomic muscle tensioning.

Comparison of bone removed with reverse total shoulder arthroplasty.

Introduction: A computer model quantified glenoid base - plate surface contact area and the amount of humeral and glenoid bone removed by three different reverse shoulder prosthesis designs when implanted with various techniques.

Methods: The computer model quantified differences in glenoid baseplate contact area and the cortical and cancellous humeral and glenoid bone removed to implant the 36 mm Depuy Delta III, 32 mm neutral DJO RSP, and the 38 mm Exactech Equinoxe reverse shoulders when each was implanted along the inferior glenoid rim of a normal and 10 mm medially eroded scapula in 20° of humeral retroversion. The impact of inferior glenoid tilt was also quantified.

Effect of prosthesis design on muscle length and moment arms in reverse total shoulder arthroplasty.

The purpose of this article is to compare the effect reverse shoulder design philosophy has on the lengths and moment arms of the external rotators of the shoulder (i.e. posterior deltoid, infraspinatus, and teres minor).

Design rationale for a posterior/superior offset reverse shoulder prosthesis.

Introduction: A computer model quantified and compared muscle lengths and moment arms of two different reverse shoulder arthroplasty humeral tray designs during two different motions.

Methods: The computer model simulated internal/ external rotation and abduction in the scapular plane for the normal shoulder, the 38 mm non-offset, and the 38 mm posterior-superior offset reverse shoulders. Muscle lengths were directly measured for seven muscles during each motion.

Biomechanical impact of posterior glenoid wear on anatomic total shoulder arthroplasty.

Introduction: This study quantified bone removed to correct three different sizes of posterior glenoid defects and also quantified the change in rotator cuff muscle length resulting from correction of each defect using three different glenoid designs.

Methods: A 3-D computer model quantified the cortical and cancellous bone removed when correcting three sizes of posterior glenoid defects and simulated internal/external rotation to quantify changes in rotator cuff muscle length when correcting glenoid retroversion in three sizes of posterior glenoid defects using three different glenoid prostheses: 1. eccentric reaming using a non-augmented glenoid (Equinoxe standard pegged), 2.

Computing the viscosity of supercooled liquids: Markov Network model.

The microscopic origin of glass transition, when liquid viscosity changes continuously by more than ten orders of magnitude, is challenging to explain from first principles. Here we describe the detailed derivation and implementation of a Markovian Network model to calculate the shear viscosity of deeply supercooled liquids based on numerical sampling of an atomistic energy landscape, which sheds some light on this transition. Shear stress relaxation is calculated from a master-equation description in which the system follows a transition-state pathway trajectory of hopping among local energy minima separated by activation barriers, which is in turn sampled by a metadynamics-based algorithm.

Computing the viscosity of supercooled liquids. II. Silica and strong-fragile crossover behavior.

A recently developed atomistic method capable of calculating the fragile (non-Arrhenius) temperature behavior of highly viscous liquids is further tested by studying a model of SiO(2), a glass former well known for its Arrhenius temperature behavior (strong). The method predicts an Arrhenius temperature variation, in agreement with experiments, the origin of which is revealed by both quantitative and qualitative results on transition state pathways, activation barrier analysis, energy landscape connectivity, and atomistic activation mechanisms. Also predicted is a transition from fragile to strong behavior at a lower viscosity, below the range of measurements, which had been previously suggested on the basis of molecular dynamics simulations.

Computing the viscosity of supercooled liquids.

We describe an atomistic method for computing the viscosity of highly viscous liquids based on activated state kinetics. A basin-filling algorithm allowing the system to climb out of deep energy minima through a series of activation and relaxation is proposed and first benchmarked on the problem of adatom diffusion on a metal surface. It is then used to generate transition state pathway trajectories in the potential energy landscape of a binary Lennard-Jones system.