Table 1. Patient, screw, and violation characteristics: Open versus percutaneous screws.

	Open	Percutaneous	P-value
Number of screws	252	306	NA
Mean age	60.1 ± 1.1	61.1 ± 1.1	0.55
Mean BMI	30.9 ± 0.55	29.4 ± 0.51	0.057
Male (n = 133)	50% (n = 63)	45.8% (n = 70)	0.48
Female (n = 146)	50% (n = 63)	54.2% (n = 83)	0.48
Top screws
L1 (n = 29)	7.9% (n = 10)	12.4% (n = 19)	0.22
L2 (n = 56)	14.3% (n = 18)	24.8% (n = 38)	0.029
L3 (n = 52)	24.6% (n = 31)	13.7% (n = 21)	0.020
L4 (n = 111)	42.1% (n = 53)	37.9% (n = 58)	0.48
L5 (n = 31)	11.1% (n = 14)	11.1% (n = 17)	1.0
Fusion length
5 levels (n = 10)	4.0% (n = 5)	3.3% (n = 5)	0.76
4 levels (n = 33)	7.1% (n = 9)	15.7% (n = 24)	0.028
3 levels (n = 37)	13.5% (n = 17)	13.1% (n = 20)	0.92
2 levels (n = 71)	26.2% (n = 33)	24.8% (n = 38)	0.80
1 level (n = 128)	49.2% (n = 62)	43.1% (n = 66)	0.31
Depth of spine [mm] (SD)	79.7 ± 19.5	71.6 ± 18.4	0.0009
Mean facet violation grade	0.45 ± 0.045	0.62 ± 0.053	0.018
Incidence grade 1	63 (25.0%)	82 (26.8%)	0.70
Incidence grade 2	18 (7.1%)	15 (4.9%)	0.34
Incidence grade 3	5 (2.0%)	26 (8.5%)	0.0059
Long-term follow-up	48 (84.2%)	9 (15.8%)	< 0.001