13th International Conference on Fracture June 16–21, 2013, Beijing, China -8- Figure 12. Scatter plot diagram of rigidity values for each sample The values obtained for rigidity vary substantially, although there does appear to be a trend. The pattern is more evident in the right femurs, where the effect is more acute due to the subtraction osteotomy. The rigidity of the normal fracture is considerably higher than that of the subtraction osteotomy for left and right femurs. These results are expected, as a normal fracture should be more rigid than a bone that has undergone a surgical procedure (subtraction osteotomy). 3.2 Ultra-Micro Indentation Tests 3.2.1 Cortical and Trabecular Hardness UMI tests were carried out to measure cortical and trabecular hardness. Both of the two types of tissue must be represented separately as they have different biological structure. To enable a clearer understanding Figure 13 shows the areas analyzed on the bones. There is a box plot diagram for each of the four groups, enabling a comparison of the data obtained for the same area of different samples. Figure 13. Diagram schematising the various areas used for hardness testing As an example Figure 14 presents the hardness of one area depicted in Figure 13. The boxes represent the interquartile ranges (25 and 75%), the horizontal line the median and the unfilled square the mean. The whiskers are outliers. Crosses indicate the minimum and maximum points. To compare the treatments to the control group a two-sample t-test was used. The null hypothesis of this test is that the means of the two groups compared are equal. Using a level of 0.05, if the p parameter is lower than 0.05, the two sample groups compared are significantly different. F+S OS+S OS+A OS+B Trabecular Cortical
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