Statistical analysis
The database was established in Excel using SPSS 20.0 statistical software. All the data were tested for homogeneity of variance and sphericity. Further, analysis of variance (ANOVA) and chi-square tests were used for comparison of preoperative basic condition in the two groups, and repeated measures analysis of variance (rANOVA) and one-way ANOVA were used for postoperative comparison between groups; 