Results of included studies.
| Author (Year) | Study Time Span, y | Intervention | Age, y, Mean (±SD or range) | Levels Operated | N | Preoperative Score, Mean (±SD) | Postoperative Score, Mean (±SD) | Utility Measurement Tool |
| Comparative studies | ||||||||
| Chen et al (2019) | 3 | ACDF | 46.8 (±6.0) | 1 level | 30 | 7.49 (±2.39) | 14.59 (±1.22) | JOA |
| ACDA | 48.5 (±4.6) | 1 level | 30 | 7.38 (±2.41) | 15.42 (±0.46) | |||
| Cheng et al (2011) | 3 | ACDF | 47.7 (±5.8) | 1 level (n = 21) | 42 | 9.00 (±1.20) | 14.80 (±1.20) | JOA |
| 2 level (n = 17) | ||||||||
| 3 level (n = 4) | ||||||||
| ACDA | 47.2 (±5.7) | 1 level (n = 24) | 41 | 9.00 (±1.20) | 15.20 (±1.20) | |||
| 2 levels (n = 14) | ||||||||
| 3 levels (n = 3) | ||||||||
| Sun et al (2020) | 1 | Normal ACDF | 52.4 (±10.1) | 1 level | 31 | 8.90 (±1.40) | 13.60 (±1.50) | JOA |
| Distraction ACDF | 51.6 (±8.9) | 1 level | 30 | 8.80 (±1.50) | 13.30 (±1.50) | |||
| Sorar et al (2007) | 2.7 | ACDF | 53 | 1 level (n = 5) | 14 | 12.80 (±0.50) | 15.60 (±0.40) | mJOA |
| 2 levels (n = 9) | ||||||||
| Corpectomy | 59.3 | 2 levels (n = 2) | 6 | |||||
| 3 levels (n = 4) | ||||||||
| Pescatori et al (2020) | 3 | Corpectomy (mild/moderate CDM) | 57.4 (±10.6) | 1 level (n = 22) | 30 | 13.23 (-) | 16.00 (-) | mJOA |
| 2 levels (n = 25) | ||||||||
| Corpectomy (severe CDM) | 3 levels (n = 13) | 30 | 7.26 (-) | 12.66 (-) | ||||
| Cohort studies | ||||||||
| Li et al (2019) | 1 | Anterior (anterior cervical discectomy + ACDF + corpectomy) | 50 (±8.55) | 1 level (n = 54) | 117 | 11.47 (±1.27) | 14.67 (±1.27) | JOA1 |
| 54.0 (±8.77) | 2 levels (n = 45) | |||||||
| 57.7 (±9.14) | 3 levels (n = 18) | |||||||
| Pandita et al (2018) | 1 | ACDF | 51.0 (±9.38) | 1 level (n = 23) | 30 | 12.40 (±3.68) | 14.92 (±3.24) | mJOA, Nurick |
| 2 levels (n = 7) | ||||||||
| Zika et al (2020) | 5 | ACDF | 50.8 (39–70) | 1 level (n = 9) | 36 | 10.80 (±1.90) | 15.50 (±3.00) | mJOA |
| 2 levels (n = 17) | ||||||||
| 3 levels (n = 8) | ||||||||
| 4 levels (n = 2) | ||||||||
| Zhang et al (2020) | 5 | ACDF | 54.9 (±9.62) | - | 35 | 11.98 (±2.21) | 16.54 (±1.07) | mJOA |
| Pehlivanoglu et al (2019) | 2 | ACDA | 52.4 (37–69) | 1 level (n = 15) | 18 | 11.30 (±0.30) | 16.60 (±0.10) | JOA |
| 2 levels (n = 3) | ||||||||
| Tian et al (2010) | 3.49 (mean) | ACDA | 50.9 (29–73) | 1 level (n = 39) | 50 | 14.00 (-) | 16.50 (-) | JOA |
| 2 levels (n = 11) | ||||||||
ACDA, anterior cervical discectomy with arthroplasty; ACDF, anterior cervical discectomy and fusion; CDM, cervical degenerative myelopathy; JOA, Japanese Orthopedic Association score; mJOA, modified Japanese Orthopedic Association score.