Table 1. Characteristics of included studies.
| Study | Group | Simple size | Age (Y) | Gender (M/F) | No. of level (Two/Three) | Devices information | Follow-up (months) |
|---|---|---|---|---|---|---|---|
| Hey 2013 | HS | 7 | 51 | 3/4 | 4/3 | ProDisc-C | 48 |
| ACDF | 7 | 48 | 4/3 | 4/3 | cage | ||
| Kang 2013 | HS | 12 | 53.6 | 8/4 | 0/12 | ProDisc-C | 24–48 |
| ACDF | 12 | 55.3 | 7/5 | 0/12 | cage/Zero-plate | ||
| Liu 2012 | HS | 17 | 53.7 | 13/4 | 12/0 | NS | 6 |
| ACDF | 17 | 56.4 | 14/3 | 12/0 | |||
| Shen 2013 | HS | 18 | 54.2 | 11/7 | 18/0 | Bryan | 18–34 |
| ACDF | 30 | 54.9 | 19/11 | 30/0 | cage | ||
| Shin 2009 | HS | 20 | 48 | 10/10 | 20/0 | Mobi-C | >24 |
| ACDF | 20 | 45.7 | 12/8 | 20/0 | cage |
HS: hybrid surgery, ACDF: anterior cervical discectomy and fusion, NS: not state, M: male, F: female, Y: years.