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This paper explores how competing interactions in the intermolecular potential of fluids affect their structural transitions. This study employs a versatile potential model with a hard core followed by two constant steps, representing wells or shoulders, analyzed in both one-dimensional (1D) and three-dimensional (3D) systems. Comparing these dimensionalities highlights the effect of confinement on structural transitions. Exact results are derived for 1D systems, while the rational function approximation is used for unconfined 3D fluids. Both scenarios confirm that when the steps are repulsive, the wavelength of the oscillatory decay of the total correlation function evolves with temperature either continuously or discontinuously. In the latter case, a discontinuous oscillation crossover line emerges in the temperature–density plane. For an attractive first step and a repulsive second step, a Fisher–Widom line appears. Although the 1D and 3D results share common features, dimensionality introduces differences: these behaviors occur in distinct temperature ranges, require deeper wells, or become attenuated in 3D. Certain features observed in 1D may vanish in 3D. We conclude that fluids with competing interactions exhibit a rich and intricate pattern of structural transitions, demonstrating the significant influence of dimensionality and interaction features.

Systems of dense spheres interacting through very short-ranged attraction are known from theory, simulations and colloidal experiments to exhibit dynamical reentrance. Their liquid state can thus be fluidized at higher densities than possible in systems with pure repulsion or with long-ranged attraction. A recent mean-field, infinite-dimensional calculation predicts that the dynamical arrest of the fluid can be further delayed by adding a longer-ranged repulsive contribution to the short-ranged attraction. We examine this proposal by performing extensive numerical simulations in a three-dimensional system. We first find the short-ranged attraction parameters necessary to achieve the densest liquid state, and then explore the parameter space for an additional longer-ranged repulsion that could further enhance reentrance. In the family of systems studied, no significant (within numerical accuracy) delay of the dynamical arrest is observed beyond what is already achieved by the short-ranged attraction. Possible explanations are discussed.

Purpose The purpose of this paper is to investigate the current challenges to making individualized men’s dress shirt adjustments, and devised a novel measurement method to assess shoulder shape. Design/methodology/approach To understand the common complaints about ready-to-wear dress shirts, a wear evaluation with 15 Japanese males was performed. The shoulder components of these shirts could not be adjusted using any currently available measurement methods. The three-dimensional body shape of two subjects who had a problem with the shoulder of ready-to-wear shirts was compared with a dummy designed to represent the average Japanese male. Findings The authors determined that one of the subjects with an incompatible shoulder fit had a shoulder point (SP) line that was anterior to the one measured on the average dummy. The other subject had a smaller shoulder angle than the average dummy. To effectively measure the wearer’s shoulder characteristics, the authors devised a new measuring device that can measure the shoulder angle and its degree of forward thrust. With this device, it was possible to understand the wearers’ shoulder types and make appropriate dress shirt adjustments. Originality/value The authors devised a new measuring device to assess shoulder angle and forward thrust, qualities that previously could not be measured without three-dimensional analysis. Using this device, it was possible to understand the wearers’ shoulder types and make appropriate dress shirt adjustments.

In many cases, the stability of complex structures in colloidal systems is enhanced by a competition between different length scales. Inspired by recent experiments on nanoparticles coated with polymers, we use Monte Carlo simulations to explore the types of crystal structures that can form in a simple hard-core square shoulder model that explicitly incorporates two favored distances between the particles. To this end, we combine Monte Carlo-based crystal structure finding algorithms with free energies obtained using a mean-field cell theory approach, and draw phase diagrams for two different values of the square shoulder width as a function of the density and temperature. Moreover, we map out the zero-temperature phase diagram for a broad range of shoulder widths. Our results show the stability of a rich variety of crystal phases, such as body-centered orthogonal (BCO) lattices not previously considered for the square shoulder model.

In the milling process, the friction and wear of the tooth minor flank of the square shoulder milling cutter directly affects the machined surface quality and the cutter’s life. The friction of the minor flank of the cutter tooth presents a nonlinear distribution, and its variation cannot be revealed by using a single parameter. It is difficult to identify the dynamic characteristics of the friction of the minor flank of the cutter tooth. In this work, the friction velocity model for the cutter tooth minor flank was developed by using the relative motion relationship between the flank area element and the workpiece transition surface. In accordance with the atomic excitation theory developed under the potential energy field at the friction interface of the cutter, the model for friction energy consumption under the friction velocity and thermal-stress coupling field on the minor flank of the cutter tooth was developed. Based on the mechanism of the interfacial atomic thermal vibration, the model for the friction coefficient under thermal-stress mechanical coupling was developed. Using the instantaneous friction coefficient and normal stress, the instantaneous friction distribution function of the flank was obtained. Finally, an identification method for the friction dynamic characteristics of the shoulder milling cutter tooth flank under vibration was proposed and verified by experiments.

Background Arthroscopic Bankart repair and open Latarjet bone block procedure are widely considered mainstays for surgical treatment of recurrent anterior shoulder instability. The choice between these procedures depends mainly on surgeon preference or training rather than published evidence. Questions/purposes We compared patients with recurrent posttraumatic anterior shoulder instability treated with arthroscopic Bankart or open Latarjet procedure in terms of (1) frequency and timing of recurrent instability, (2) risk factors for recurrent instability, and (3) patient-reported outcomes. Methods In this retrospective comparative study, we paired 93 patients undergoing open Latarjet procedures with 93 patients undergoing arthroscopic Bankart repairs over the same period for posttraumatic anterior shoulder instability by one of four surgeons at the same center. Both groups were comparable except that patients in the Latarjet group had more glenoid lesions and more instability episodes preoperatively. Minimum followup was 4 years (mean, 6 years; range, 4–10 years). Patients were assessed with a questionnaire, including stability, Rowe score, and return to sports. Recurrent instability was defined as at least one episode of recurrent dislocation or subluxation. Return to sports was evaluated using a 0% to 100% scale that patients completed after recovery from surgery. Various risk factors for recurrent instability were also analyzed. Results At latest followup, 10% (nine of 93) in the Latarjet group and 22% (20 of 93) in the Bankart group demonstrated recurrent instability (p = 0.026; odds ratio, 0.39; 95% CI, 0.17–0.91). Ten recurrences in the Bankart group (50%) occurred after 2 years, compared to only one (11%) in the Latarjet group. Reoperation rate was 6% and 7% in the Bankart and Latarjet groups, respectively. In both groups, patients younger than 20 years had higher recurrence risk (p = 0.019). In the Bankart group, independent factors predictive for recurrence were practice of competitive sports and shoulder hyperlaxity (ie, passive external rotation > 85° in the contralateral uninjured shoulder). Although return to sports was not different between groups, the mean Rowe score was higher in the Latarjet group (78 versus 68, p = 0.018). Conclusions Patients who had the open Latarjet procedure had less recurrent instability and better Rowe scores over a mean 6-year followup. We now perform isolated arthroscopic Bankart repair for carefully selected patients, including patients with an Instability Severity Index Score of 3 or less. Level of Evidence Level III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

The aim of this clinical trial was to evaluate the effectiveness of therapeutic MD on pain, functional capacity, muscle strength, quality of life, and depression in patients with subacromial impingement syndrome (SIS). A total of 40 inpatient subjects with definite SIS were included in this study. These patients were sequentially randomized into 2 groups. Group 1 ( n  = 20) received therapeutic MD. Group 2 ( n  = 20) was served as control group and received sham MD. Superficial heat and exercise program were given to both groups. Both of the programs were performed 5 times weekly for 3 weeks. Patients were assessed before treatment (BT), after treatment (AT), and at a 1-month follow-up (F). Outcome measures included visual analogue scale, goniometry, Shoulder Pain and Disability Index, Shoulder Disability Questionnaire, shoulder isokinetic muscle testing, handgrip strength, Short Form 36, and Beck Depression Index. The patients with SIS in each group had significant improvements in pain, shoulder ROM, disability, shoulder muscles and grip strength, quality of life, and depression AT and F when compared with their initial status ( P  < 0.05). There was no statistically significant difference between the groups according to all the parameters regarding the change scores between AT–BT test and F–BT test ( P  > 0.05). A 2,450-MHz MD regimen showed no beneficial effects in patients with SIS, so the superficial heat and exercise program, as it is efficient, may be preferable for the treatment of SIS, alone.

Background Despite recent advances in the treatment of hepatitis C, it is estimated that nearly 4 million Americans have a chronic form of the disease. Although research in lower-extremity arthroplasty suggests patients with hepatitis C are at risk for increased complications, including postoperative bleeding, acute postoperative infection, and general medical complications, no similar studies have investigated this question in patients undergoing total shoulder arthroplasty (TSA). Questions/purposes We asked whether there is an increased risk of postoperative complications after TSA among patients who have hepatitis C, and if so, what complications in particular seem more likely to occur in this population? Methods Patients who underwent TSA, including anatomic or reverse TSA, were identified in the PearlDiver database using ICD-9 procedure codes. This is a for-fee insurance patient-records database that contains more than 100 million individual patient records from 2005 to 2012. The Medicare data in the database are the complete 100% Medicare Standard Analytical File indexed to allow for patient tracking with time. Patients with hepatitis C who underwent shoulder arthroplasty then were identified using ICD-9 codes. Patients with hepatitis B coinfection or HIV were excluded. A control cohort of patients without hepatitis C who underwent TSA was created and matched to the study cohort based on age, sex, obesity, and diabetes mellitus. A total of 1466 patients with hepatitis C and 21,502 control patients were included. The two cohorts were statistically similar in terms of sex (53% females in study and control groups), age (nearly ½ of each cohort younger than 65 years), obesity (approximately 17% of each cohort were obese), diabetes (approximately 40% of each cohort had diabetes), and followup of each cohort occurred throughout the length of the database from 2005 to 2012. Postoperative complications were assessed using ICD-9 and Current Procedural Terminology codes and compared between cohorts. Results Patients with hepatitis C, when compared with matched control subjects, had greater odds of infection within 3 months (odds ratio [OR], 1.7; 95% CI, 1.1–2.6; p = 0.015), 6 months (OR, 1.7; CI, 1.3–2.4; p = 0.001), and 1 year (OR, 2.1; CI, 1.7–2.7; p < 0.001); revision TSA within 1 year (OR, 1.5; CI, 1.1–2.9; p = 0.008) and 2 years (OR, 1.6; CI, 1.2–2.0; p = 0.001), dislocation within 1 year (OR, 1.6; CI, 1.2–2.2; p < 0.001); postoperative fracture within 1 year (OR, 1.8; CI, 1.2–2.6; p = 0.002); systemic or medical complications within 3 months (OR, 1.3; CI, 1.0–1.6; p = 0.022); and blood transfusion within 3 months (OR, 1.7; CI, 1.4–1.9; p < 0.001). Conclusions Hepatitis C is associated with an increased risk for complications after TSA, including infection, dislocation, fracture, revision TSA, systemic complications, and blood transfusion compared with matched control subjects. Although this study is able to identify increased odds of complications in patients with hepatitis C, the mechanism by which these occur is likely not solely related to the virus, and is more likely related to a higher degree of case complexity in addition to other postoperative socioeconomic factors. Level of Evidence Level III, therapeutic study.

Background Total shoulder arthroplasty (TSA) is an effective treatment for end-stage glenohumeral joint pathology with good long-term results. Previous descriptions of morbidity and blood transfusion in TSA are limited by preoperative risk factors and postoperative complications considered and single-center studies. Questions/purposes The purpose of this study was to define in a group of patients undergoing TSA (1) the type and incidence of complications; (2) the frequency of and risk factors for both minor and major complications; and (3) the risk factors for bleeding resulting in transfusion. Methods We retrospectively queried the National Surgical Quality Improvement Program database using Current Procedural Terminology billing codes and identified 1922 cases of TSA performed between 2006 and 2011. Postoperative outcomes were divided into one of four categories: any complication, major morbidity (systemic life-threatening event or a substantial threat to a vital organ) or mortality, minor morbidity (localized to the operative upper extremity or not posing a major systemic threat to the patient), or bleeding resulting in transfusion. Univariate and multivariate analyses were then used to identify risk factors for complications. Results There were a total of 155 complications (8% of the 1922 patients identified). The most common complication was bleeding resulting in transfusion (82 patients [4.26%]) followed by urinary tract infections (27 patients [1.40%]), return to the operating room (14 patients [0.73%]), pneumonia (10 patients [0.52%]), and peripheral nerve injury (nine patients [0.47%]). The incidence of major morbidity was 2% (44 patients), which included five patients (0.26%) who died; the incidence of any minor morbidity was 7% (136 patients). After controlling for likely confounding variables, we found steroid use (odds ratio [OR], 3; 95% confidence interval [CI], 2–6), hematocrit < 38% (OR, 2; 95% CI, 1–3), American Society of Anesthesiologists (ASA) Class 4 (OR, 3; 95% CI, 1–7), and operating time > 2 hours (OR, 2; 95% CI, 1–3) as independent predictors of complication and congestive heart failure (OR, 12; 95% CI, 1–106) as an independent risk factor for major morbidity or mortality. Hematocrit < 38% (OR, 3; 95% CI, 2–6), resident involvement (OR, 3; 95% CI, 2–5), steroid use (OR, 3; 95% CI, 1–6), and ASA Class 3 versus 1 or 2 (OR, 2; 95% CI, 1–5) were independent risk factors for bleeding resulting in transfusion. Conclusions Short-term morbidity after TSA is higher than previously reported. The prevalence of complications within 30 days of surgery and our outlined risk factors should guide surgeon-driven preoperative patient evaluation, management, and counseling. Surgeons who perform TSA should be aware operative time > 2 hours is associated with increased complications. Patients with preoperative hematocrit < 38%, history of steroid use, ASA Class > 2, and patients with congestive heart failure should receive medical optimization before TSA. Level of Evidence Level III, therapeutic study.

Background A concern regarding reverse shoulder arthroplasty (RSA) is the possibly higher complication rate compared with conventional unconstrained shoulder arthroplasty. Questions/purposes We determined (1) the rate of instability and infection; (2) whether diagnosis influenced instability and infection rates; and (3) whether these complications affect ASES, Constant, and WOOS scores after RSA. Methods A prospective database, clinical charts, and radiographs of 284 patients who had undergone primary (n = 212 patients) or revision (n = 72 patients) RSA were reviewed to identify patients whose postoperative course was complicated by instability or infection. Results The rate of instability was similar in patients with primary (eleven of 212 [5%)] and revision (six of 72 [8%]) reverse arthroplasty. The rate of infection was higher in the revision (five of 72 [7%]) than in the primary (three of 212 [1%]) group. Patients with an irreparable subscapularis tendon had a higher rate of instability (14 of 123 [12%]) compared with patients with a repairable subscapularis tendon (one of 161 [less than 1%]). The fracture sequelae group had the highest rate of instability (seven of 25 [28%]) among diagnoses within the primary group. The rates of infection were similar between the diagnoses within the primary group. The improvements in the ASES score, the Constant score, and the WOOS score from preoperatively to postoperatively were better in the no instability/infection group as compared with the instability/infection group. Conclusions This information confirms the available literature allowing surgeons to give patients realistic expectations regarding the infection and instability rates after RSA. Level of Evidence Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.