Polyether ⁃ ether ketone bar versus titanium bar in lumbar fusion：A meta ⁃ analysis 

SONG Zhenjie, LIU Hongjiang, TANG Hanwu, WANG Liren, YUAN Chao.
The Journal of Practical Medicine . 2021, (12): 1580 -1586 .  DOI: 10.3969/j.issn.1006⁃5725.2021.12.014