Statistical analysis
The primary endpoints of change in BMD in the lumbar spine were used as the basis for a sample size calculation. According to Coco et al. [The Kolmogorov–Smirnov test was performed to determine whether data were normally distributed. Mean (standard deviation) or median (interquartile range) and frequency (percentage) were reported for quantitative and qualitative variables, respectively. The continuous variables were compared between groups using independent t-test or Mann–Whitney U test when appropriate, and frequencies were compared using the Chi-square test. 