Table 1.

Basic character of included studies.

Author	Publication year	Country	Mean age (HS/ACDF)	Sample size (HS/ACDF)
Shin et al.	2009	Korea	45.7/48	20/20
Kang et al.	2012	China	53.6/55.3	12/12
Liu et al.	2012	China	53.7/56.4	17/17
Shen et al.	2013	China	54.2/54.9	18/30
Hey et al.	2013	Singapore	51/48	7/7
Grasso	2015	Italy	44.2/47.3	20/20
Ji et al.	2015	Korea	45.7/48	20/20

HS – hybrid surgery of anterior cervical discectomy and fusion combine with artificial arthroplasty; ACDF – anterior cervical discectomy and fusion.