Posterior stability of the shoulder depends on acromial anatomy: a biomechanical study of 3D surface models

PURPOSE Primary glenohumeral osteoarthritis is commonly associated with static posterior subluxation of the humeral head. Scapulae with static/dynamic posterior instability feature a superiorly and horizontally oriented acromion. We investigated whether the acromion acts as a restraint to posterior humeral translation. METHODS Five three-dimensional (3D) printed scapula models were biomechanically tested. A statistical shape mean model (SSMM) of the normal scapula of 40 asymptomatic shoulders was fabricated. Next, a SSMM of scapular anatomy associated with posterior subluxation was generated using data of 20 scapulae ("B1"). This model was then used to generate three models of surgical correction: glenoid version, acromial orientation, and acromial and glenoid orientation. With the joint axially loaded (100N) and the humerus stabilized, an anterior translation force was applied to the scapula in 35°, 60° and 75° of glenohumeral flexion. Translation (mm) was measured. RESULTS In the normal scapula, the humerus translates significantly less to contact with the acromion compared to all other configurations (p < .000 for all comparisons; i.e. 35°: "normal" 8,1 mm (± 0,0) versus "B1" 11,9 mm (± 0,0) versus "B1 Acromion Correction" 12,2 mm (± 0,2) versus "B1 Glenoid Correction" 13,3 mm (± 0,1)). Restoration of normal translation was only achieved with correction of glenoid and acromial anatomy (i.e. 75°: "normal" 11 mm (± 0,8) versus "B1 Acromion Correction" 17,5 mm (± 0,1) versus "B1 Glenoid Correction" 19,7 mm (± 1,3) versus "B1 Glenoid + Acromion Correction" 11,5 mm (± 1,1)). CONCLUSIONS Persistence or recurrence of static/dynamic posterior instability after correction of glenoid version alone may be related to incomplete restoration of the intrinsic stability that is conferred by a normal acromial anatomy. LEVEL OF EVIDENCE V biomechanical study

Fixation of distal clavicle fractures with coracoclavicular instability: a comparative biomechanical study in human cadavers

Background The need for coracoclavicular (CC) stabilization in the fixation of fractures with CC instability (Neer type IIB and V) was biomechanically demonstrated by higher construct strength than isolated locking plate osteosynthesis. It was the purpose of this study to prove noninferiority of the new cow-hitch suture repair technique compared with the well-established suture tape double-button fixation with regard to overall fixation strength and cyclic loading properties. Methods Twelve human cadaver shoulders (7 right and 5 left) were matched for sex and age (mean age: 75 ± 5 years). An oblique parasagittal fracture line 20 mm medial to the acromioclavicular joint line was created, and the CC ligaments were dissected. Six shoulders were reconstructed by a double FiberTape fixation with two suture buttons (group DB), and the remaining six shoulders by a cow-hitch suture repair using a double FiberWire with only coracoid button fixation (group CH). Both reconstruction techniques were tested in a servo-hydraulic material testing machine for cyclic displacement (mm), stiffness (N/mm), and maximum load-to-failure (N) after 500 cycles at 3 mm/s and inferosuperior load between 15 and 70 N. Superior fragment displacement in space was recorded using a MicroScribe digitizer. Results There were no statistically significant differences regarding cyclic displacement (group DB: 0.7 mm; group CH: 1.3 mm; P = .36), stiffness (group DB: 177 N/mm; group CH: 116 N/mm; P = .17), maximum load-to-failure (group DB: 560 N; group CH: 492 N; P = .59), and superior displacement in space of the medial fragment (group DB: 3.2 mm; group CH: 1.6 mm; P = .48). Conclusion Fixation of unstable distal clavicle fractures using a double FiberWire cow-hitch suture repair with isolated coracoid button fixation for stand-alone CC stabilization resulted in similar biomechanical properties to a double-suture button fixation with FiberTapes while avoiding prominent clavicular implants

Chinese multinationals: host country factors and foreign direct investment location

The study of Chinese multinationals (MNEs) is becoming one of the most promising research topics in the international business literature. After outlining the distinctive characteristics of the internationalization process of Chinese MNEs, this chapter analyzes the influence of various host country factors on the location of Chinese outward foreign direct investment (FDI). From a sample of 189 outward FDI decisions made by 35 mainland Chinese firms in 63 countries, our results show that host market size and the existence of overseas Chinese in the host country are positively associated with the number of Chinese FDIs. However, greater difficulty in doing business and host country political risk have no effect

Structuring for team success:The interactive effects of network structure and cultural diversity on team potency and performance

This longitudinal study used data from 91 self-managed teams (456 individuals, 60 nationalities) to examine the interactive effects of a team’s task (“workflow”) network structure and its cultural diversity (as indexed by nationality) on the team’s “potency” (i.e., the team’s confidence in its ability to perform) and its performance (as rated by expert judges). We found that whereas the emergence of dense task networks enhanced team potency it was the emergence of (moderately) centralized task networks that facilitated team performance. These varied structural effects, moreover, were themselves contingent on team composition: the more culturally diverse a team, the more pronounced were the positive effects of network density on team potency and the higher the level of network centralization required for optimal team performance. The success of a team appears to hinge on the interplay between network structure and team composition

A Chemistry of Organization: Combinatory Structural Analysis and Design

This paper is a response to the call for models of organization design as a science revealing the inner composition of organization and specifying the laws to be respected when crafting it. It maintains that the needed science is a chemistry of organization, addressing the combination of 'organizational elements' playing a role analogous to that of chemical elements in composing a variety of substances. Drawing both on classic organization design theory and on configurational and complementarity-based approaches, the paper specifies a set of basic organizational elements and a set of combinatory laws regulating their effective combinations. Testable propositions are derived on the necessary and sufficient conditions that the composition of organizations should have respect for achieving high levels of efficiency and innovation. These propositions are tested empirically on a sample of firms, using an innovative application of Boolean algebra

Anticipating parenthood among Lesbian, Gay, Bisexual, and Heterosexual young adults without children in Portugal: predictors and profiles

Parenthood is a highly valued life goal, independent of one’s sexual orientation. However, the majority of studies exploring young adults’ parenthood plans have relied exclusively on samples of heterosexual individuals. This study aimed (i) to explore differences in parenthood intentions as a function of sexual orientation, (ii) to investigate to what extent sociodemographic and psychological characteristics predict parenthood intentions of lesbian, gay, bisexual (LGB), and heterosexual individuals, (iii) to test the mediating effect of stigma between sexual orientation and parenthood intentions, and (iv) to identify and characterize profiles of prospective parenthood (through cluster analysis). Data were gathered using an online survey from 375 self-identified LGB and heterosexual young adults without children in Portugal, with a mean age of 25.83 years old (SD = 4.49). Findings indicated that LGB individuals were less likely to intend to have children than heterosexual individuals; furthermore, among LGB individuals, lesbian women expressed stronger intentions to have children than did gay men. Similarities between heterosexual and LGB young adults were observed concerning the psychological determinants of parenthood intentions. Four distinctive profiles of prospective parenthood were identified: aspiring parents not anticipating stigma, aspiring parents anticipating stigma, childfree intent, and childfree ambivalent. Lesbian and bisexual women mostly populated the childfree ambivalent cluster; in contrast, the aspiring parents anticipating stigma cluster contained an overrepresentation of men, including sexual minority men. Professionals may want to attend to communalities and specificities of prospective parenthood as a function of sexual orientation, in order to provide unbiased and culturally competent support to sexual minority individuals

Economics of Literary Translation - A Simple Theory and Evidence

Books are an important factor of cultural transmission, but need, in most cases, to be translated. According to some authors, this may lead to a form of cultural domination of English. The population speaking English as a first language is, with the exception of Mandarin, the largest in the world. It is therefore not surprising that English produces more fiction (and much more scientific literature, as scientists from all countries write in English with increasing frequency) than any other language. We develop a theoretical model of translation, which is estimated on the basis of UNESCO translation data. We show that translations from English are dominated by translations from other languages, including Scandinavian ones and French