Statistical analysis
The statistical analysis was performed by SPSS software (version 19.0, IBM, US), and the significance level was set at 5%. After normality test, the measurements were presented as averages and standard deviations. One-way ANOVA test was carried out to compare the difference among all three groups. For further analysis of the difference between the specific two groups, Least-Significant Difference test was performed. The bone repair at different time points in each group was analyzed by repeated measures ANOVA. For data do not follow a normal distribution, measurements were presented as medians (interquartile range), and nonparametric Kruskal-Wallis test was employed for post hoc analysis. In addition, Pearson correlation coefficient was used to depict possible relationship between bone defect and bone repair measurements.