Stress analysis of glenoid component in design of reverse shoulder prosthesis using finite element method.

BACKGROUND: This study aims to clarify the effect of various designs of reverse shoulder prosthesis (RSP) on stress variation of its glenoid component using 2-dimensional (2D) finite element analysis (FEA). This FEA study provides future reference for the optimal design of glenoid component of RSP. MATERIALS AND METHODS: In this study, a 2D finite element (FE) model of human shoulder with implementation of RSP was developed by commercial FE software. The proper material properties were adopted in our model. Various design factors were simulated and all the mechanical profile data were investigated by FEA. RESULTS: Both distal placement and increased lateral offset of glenosphere induce higher stress over glenoid-baseplate junction. Increased thickness of graft, inferiorly tilting of the baseplate, and adoption of BIO-RSA (bony increased-offset reverse shoulder arthroplasty) incur higher stresses over glenoid screws. The inferior screw attains more stress than superior screw. Maximum stress occurs at the base of inferior screw. CONCLUSION: Increased eccentric offset and lateral offset of glenosphere, although being able to reduce notching, may pay the penalty of significant stress concentration over glenoid and its subsequent loosening. Maximum stress occurs at the base of inferior screw elucidate the direct contact failure mode at the middle of inferior screw. This study provides an alternative tool for the optimal design of glenoid component of RSP in the future.

Color temperature tunable white light emitting diodes packaged with an omni-directional reflector.

This study proposed a correlated color temperature (CCT) tunable phosphor-converted white light emitting diode (LED) with an omni-directional reflector (ODR). Applying current to each individual InGaN based ultraviolet, purple and blue source LED chip of the white LED package, we can achieve the CCT tunability. The optimum color properties of the resulting white light are (0.3347, 0.3384), 5398 K, 81, 3137-8746 K for color coordinates, CCT, color rendering index (CRI) and CCT tuning range, respectively. Roughening the ODR substrate, we solve the non-uniformity color distribution caused by the reflectance of the ODR and positioning of source LED chips.

Design and fabrication of white light emitting diodes with an omnidirectional reflector.

This study investigates white light emitting diodes (LEDs), packaged with an omnidirectional reflector (ODR) and UV LED of 378 nm. The current work designs an ODR to solve the problems of UV leak and low phosphors conversion efficiency with a thin film structure of S/(HLH)n/air modified from a quarter-wave stack. Since an ODR is a perfect dielectric mirror for UV light, the UV leak can be eliminated and recycled to enhance phosphors conversion efficiency. By measuring the emission spectrum of a white LED with an ODR, the orientation distribution of the color properties, and the radiation power, the current study did not detect any UV leak. The average luminous intensity enhancement is 15%.