Comparison of patient demographics by laminoplasty group.
| Demographics | MP Group | LP Group | P Value |
| Number | 22 | 46 | – |
| Age | 61.2 ± 6.4 | 60.9 ± 5.9 | 0.85 |
| Gender (male:female) | (14:8) | (29:17) | 0.96 |
| BMI | 26.6 ± 3.0 | 27.7 ± 2.7 | 0.08 |
| Disc herniation (patients) | 19 | 39 | – |
| OPLL (patients) | 8 | 20 | – |
| Operation level | 0.74 | ||
| C3–C6 | 4 | 8 | – |
| C3–C7 | 16 | 29 | – |
| C2–C6 | 1 | 4 | – |
| C2–C7 | 1 | 5 | – |
| Preoperative JOA | 9.1 ± 7.9 | 8.7 ± 7.2 | 0.84 |
| Preoperative VAS | 5.2 ± 2.5 | 5.4 ± 2.3 | 0.75 |
| Follow-up period (mo) | 15.8 ± 3.8 | 16.8 ± 3.2 | 0.55 |
Abbreviations: BMI, body mass index; JOA, Japanese Orthopaedic Association; LP Group, traditional open-door laminoplasty-treated patients; MP Group, haplo-paraspinal-muscle-preserving laminoplasty-treated patients; OPLL, ossification of posterior longitudinal ligament; VAS, visual analog scale.
Note: Data are shown as the mean ± SD; ‘-’ represents values were not compared for differences.