Expansive pedicle screw placement fixation for the treatment of senile osteoporotic thoracolumbar vertebral fractures: 18-month follow-up data of 16 cases within one year in the same institution  Chinese Journal of Tissue Engineering Research . 2010, (22): 4127 -4130 .  DOI: 10.3969/j.issn.1673-8225.2010.22.035