Treatment of spondylolisthesis using titanium posterior pedicle screw-rod fixation system combined with intervertebral bone grafting: A 5-year follow-up in the same institute for 36 cases Chinese Journal of Tissue Engineering Research . 2010, (13): 2429 -2432 .  DOI: 10.3969/j.issn.1673-8225.2010.13.037