Table 1. Summary of univariate analysis of bone union.
| Variables | Fusion | Non-fusion | P |
|---|---|---|---|
| Age | 48.9±1.9 | 68±5.3 | <0.01* |
| Gender (M;F) | 47;14 | 3;5 | 0.07* |
| Fusion level | 0.77 | ||
| L1/2 | 0 | 0 | |
| L2/3 | 1 | 0 | |
| L3/4 | 3 | 1 | |
| L4/5 | 44 | 6 | |
| L5/S | 13 | 1 | |
| BMD | 0.71±0.02 | 0.74±0.05 | 0.58 |
| Cage | 0.18* | ||
| PEEK | 31 | 6 | |
| Titanium | 30 | 2 | |
| Vertebral slip (neutral, mm) | 1.77±0.40 | 3.49±1.10 | 0.14* |
| Translational motion (anterior/posterior, mm) | 1.21±0.22 | 1.99±0.60 | 0.23 |
| Angular motion (flexion/extension; degrees) | 10.9±0.7 | 9.7±2.0 | 0.59 |
| Screw depth into the vertebral body (% depth; %) | 28.5±1.4 | 21.2±3.9 | 0.08* |
| Interval of bilateral screw head (mm) | 28.2±0.6 | 26.5±1.7 | 0.34 |
| Cage position | <0.01* | ||
| Anterior 1/4 | 44 | 2 | |
| Others | 17 | 6 |
*, P<0.20. PEEK, polyether-ether-ketone.