Objective:To investigate the impact of central screw size on the stability of the glenoid baseplate in reverse shoulder arthroplasty using a finite element analysis.Methods:Four sizes of central screws (length × diameter) were designed: 25.0 mm×5.5 mm (G1), 30.0 mm×5.5 mm (G2), 25.0 mm×6.5 mm (G3), and 30.0 mm×6.5 mm (G4), along with a glenosphere, a baseplate, and peripheral screws. The central screw of group G1 was selected for a biomechanical test along with a set of customized prosthesis. The results were used to validate a finite element model. The validated finite element model was employed to analyze the central screws of 4 different sizes under a vertically downward 490 N load in simulation. After the model calculation was completed, the total displacement of each model, the maximum Von Mises stress on the bone surface at the baseplate-bone contact interface, the maximum Von Mises stress on the bone tissue around the screw-bone interface, the maximum value of the maximum principal strain (tensile strain), the maximum value of the minimum principal strain (compressive strain), the total volume of bone damage, and the volume of bone damage around the central screw were analyzed.Results:Insignificant differences were found in the total displacement and total volume of bone damage across the 4 models. On the bone surface at the baseplate-bone contact interface, the maximum Von Mises stress in G3 and G4 (11.26 MPa and 9.88 MPa, respectively) was slightly higher than that in G1 and G2 (9.11 MPa and 8.90 MPa, respectively). On the bone tissue around the screw-bone interface, G4 exhibited significantly higher maximum stress (15.82 MPa) and significantly higher maximum value of the maximum principal strain (10.09×10 -2) than G1 (8.51 MPa, 3.88×10 -2), G2 (9.45 MPa, 4.29×10 -2), and G3 (9.92 MPa, 3.92×10 -2), while the maximum value of the minimum principal strain in G3 (12.12×10 -2)was significantly higher than that in G1 (8.23×10 -2), G2 (8.10×10 -2), and G4 (8.34×10 -2). The volume of bone damage around the central screw in G3 (11.4 mm 3) was significantly smaller than that in G1 (24.9 mm 3), G2 (28.5 mm 3), and G4 (20.3 mm 3). Conclusions:In reverse shoulder arthroplasty, to a certain extent, increasing the length of a central screw amplifies bone damage volume around the screw. Conversely, increasing only the diameter of a central screw reduces bone damage volume around the screw, consequently lowering the loosening risk of a central screw.

Objective:To investigate the impact of central screw size on the stability of the glenoid baseplate in reverse shoulder arthroplasty using a finite element analysis.Methods:Four sizes of central screws (length × diameter) were designed: 25.0 mm×5.5 mm (G1), 30.0 mm×5.5 mm (G2), 25.0 mm×6.5 mm (G3), and 30.0 mm×6.5 mm (G4), along with a glenosphere, a baseplate, and peripheral screws. The central screw of group G1 was selected for a biomechanical test along with a set of customized prosthesis. The results were used to validate a finite element model. The validated finite element model was employed to analyze the central screws of 4 different sizes under a vertically downward 490 N load in simulation. After the model calculation was completed, the total displacement of each model, the maximum Von Mises stress on the bone surface at the baseplate-bone contact interface, the maximum Von Mises stress on the bone tissue around the screw-bone interface, the maximum value of the maximum principal strain (tensile strain), the maximum value of the minimum principal strain (compressive strain), the total volume of bone damage, and the volume of bone damage around the central screw were analyzed.Results:Insignificant differences were found in the total displacement and total volume of bone damage across the 4 models. On the bone surface at the baseplate-bone contact interface, the maximum Von Mises stress in G3 and G4 (11.26 MPa and 9.88 MPa, respectively) was slightly higher than that in G1 and G2 (9.11 MPa and 8.90 MPa, respectively). On the bone tissue around the screw-bone interface, G4 exhibited significantly higher maximum stress (15.82 MPa) and significantly higher maximum value of the maximum principal strain (10.09×10 -2) than G1 (8.51 MPa, 3.88×10 -2), G2 (9.45 MPa, 4.29×10 -2), and G3 (9.92 MPa, 3.92×10 -2), while the maximum value of the minimum principal strain in G3 (12.12×10 -2)was significantly higher than that in G1 (8.23×10 -2), G2 (8.10×10 -2), and G4 (8.34×10 -2). The volume of bone damage around the central screw in G3 (11.4 mm 3) was significantly smaller than that in G1 (24.9 mm 3), G2 (28.5 mm 3), and G4 (20.3 mm 3). Conclusions:In reverse shoulder arthroplasty, to a certain extent, increasing the length of a central screw amplifies bone damage volume around the screw. Conversely, increasing only the diameter of a central screw reduces bone damage volume around the screw, consequently lowering the loosening risk of a central screw.

OBJECTIVE: To assess the public health risk to Singapore posed by the Middle East respiratory syndrome (MERS) outbreak in the Republic of Korea in 2015. METHODS: The likelihood of importation of MERS cases and the magnitude of the public health impact in Singapore were assessed to determine overall risk. Literature on the epidemiology and contextual factors associated with MERS coronavirus infection was collected and reviewed. Connectivity between the Republic of Korea and Singapore was analysed. Public health measures implemented by the two countries were reviewed. RESULTS: The epidemiology of the 2015 MERS outbreak in the Republic of Korea remained similar to the MERS outbreaks in Saudi Arabia. In addition, strong infection control and response measures were effective in controlling the outbreak. In view of the air traffic between Singapore and MERS-affected areas, importation of MERS cases into Singapore is possible. Nonetheless, the risk of a serious public health impact to Singapore in the event of an imported case of MERS would be mitigated by its strong health-care system and established infection control practices. DISCUSSION: The MERS outbreak was sparked by an exported case from the Middle East, which remains a concern as the reservoir of infection (thought to be camels) continues to exist in the Middle East, and sporadic cases in the community and outbreaks in health-care settings continue to occur there. This risk assessment highlights the need for Singapore to stay vigilant and to continue enhancing core public health capacities to detect and respond to MERS coronavirus.

We conducted in-depth analysis on the use of a popular Chinese social networking and microblogging site, Sina Weibo, to monitor an avian influenza A(H7N9) outbreak in China and to assess the value of social networking sites in the surveillance of disease outbreaks that occur overseas. Two data sets were employed for our analysis: a line listing of confirmed cases obtained from conventional public health information channels and case information from Weibo posts. Our findings showed that the level of activity on Weibo corresponded with the number of new cases reported. In addition, the reporting of new cases on Weibo was significantly faster than those of conventional reporting sites and non-local news media. A qualitative review of the functions of Weibo also revealed that Weibo enabled timely monitoring of other outbreak-relevant information, provided access to additional crowd-sourced epidemiological information and was leveraged by the local government as an interactive platform for risk communication and monitoring public sentiment on the policy response. Our analysis demonstrated the potential for social networking sites to be used by public health agencies to enhance traditional communicable disease surveillance systems for the global surveillance of overseas public health threats. Social networking sites also can be used by governments for calibration of response policies and measures and for risk communication.