On the fracture behavior of cortical bone microstructure: The effects of morphology and material characteristics of bone structural components.

Bone encompasses a complex arrangement of materials at different length scales, which endows it with a range of mechanical, chemical, and biological capabilities. Changes in the microstructure and characteristics of the material, as well as the accumulation of microcracks, affect the bone fracture properties. In this study, two-dimensional finite element models of the microstructure of cortical bone were considered. The eXtended Finite Element Method (XFEM) developed by Abaqus software was used for the analysis of the microcrack propagation in the model as well as for local sensitivity analysis. The stress-strain behavior obtained for the different introduced models was substantially different, confirming the importance of bone tissue microstructure for its failure behavior. Considering the role of interfaces, the results highlighted the effect of cement lines on the crack deflection path and global fracture behavior of the bone microstructure. Furthermore, bone micromorphology and areal fraction of cortical bone tissue components such as osteons, cement lines, and pores affected the bone fracture behavior; specifically, pores altered the crack propagation path since increasing porosity reduced the maximum stress needed to start crack propagation. Therefore, cement line structure, mineralization, and areal fraction are important parameters in bone fracture. The parameter-wise sensitivity analysis demonstrated that areal fraction and strain energy release rate had the greatest and the lowest effect on ultimate strength, respectively. Furthermore, the component-wise sensitivity analysis revealed that for the areal fraction parameter, pores had the greatest effect on ultimate strength, whereas for the other parameters such as elastic modulus and strain energy release rate, cement lines had the most important effect on the ultimate strength. In conclusion, the finding of the current study can help to predict the fracture mechanisms in bone by taking the morphological and material properties of its microstructure into account.

A finite element study on femoral locking compression plate design using genetic optimization method.

The locking compression plate (LCP) and screw sets are widely used as internal fixator assemblies to treat long bone fractures. However, the surgeon's critical challenge is choosing the implant set (plate and screws) for each patient. The present study introduces a parametrized simulation-based optimization algorithm for determining an LC system with the best bone-implant stability. For this purpose, a three-dimensional fractured bone supported by an LC system was generated, and the discrete genetic optimization approach was utilized to design the optimum implant. Initially, an algorithm was developed to optimize the optimum layouts for different numbers of screws. For the middle third transverse fracture, six screws were selected as the optimal number of the screws. In a second stage, the model was run to determine the best LC plate dimensions for desired fractured bones. Finally, optimal plates were identified for simple middle third transverse, 60° middle third oblique, and distal third transverse femoral fractures. The results of these simulations and those for other fracture types can be exploited to achieve improved surgical outcomes by selecting proper implants and screws configurations.

[Surveillance system OKkio alla SALUTE: the role of primary school in the promotion of healthy life style--results in 2008]. / Il sistema di sorveglianza OKkio alla SALUTE: il ruolo della scuola primaria nella promozione di stili di vita salutari. Risultati 2008.

In 2007 the Italian Ministry of Health/CCM promoted and funded the project "System of surveys of behavioral risks in ages 6-17", coordinated by the National Institute of Health. One of the aims of the project is the definition and implementation of a data collection system on the weight of primary school children, their eating habits, physical activity and school initiatives favoring the healthy growth of children, called "OKkio alla SALUTE". In 2008 the first survey of OKkio was conducted in 18 Italian regions. 45,590 third grade school children in 2610 classes participated. Information was collected from 2461 schools. The responses of the head teachers showed that 64% of the schools have a canteen, used by 70% of children. Only 12% of schools include the provision of a balanced mid-morning snack. Frequently there are educational activities related to physical activity and healthy eating that, in some cases, also involve the families of the children. 29% of the schools cannot guarantee two hours of physical activity as suggested by the school curriculum because of the lack or inadequacy of the gym or the structure of the timetables. The information gathered through the cooperation of school administrators, teachers and health workers, has helped to describe the major health educational activities of the school, that is confirmed to be the ideal venue for promoting healthy lifestyles in young people.