Table 3.

Comparison of PS Parameters with or without Loosening.

	Loosening		P
	(–) (n=246)	(+) (n=44)
Screw diameter# (mm)	6.34±0.87	6.55±0.87	0.17
Screw length# (mm)	42±3.47	42.7±2.94	0.21
Screw trajectory angle (axial) # (°)	22.3±9.5	18.9±9.1	<0.05*
Screw trajectory angle (sagittal) # (°)	6.63±5.5	5.18±3.82	0.098
Screw pull-out length# (mm)	0.114±0.58	4.31±4.92	<0.0001****
No. of screw pull-out (%)	11 (4.5%)	36 (81.8%)

PS=pedicle screw

^#Mean±standard deviation (SD)

*P<0.05; ****P<0.0001