Table 3.

Interpretation of pedicle screw misplacement

Severity	Direction
	Lateral	Inferomedial	Medial	Superomedial	Total
Cortical encroachment	52 (10.7%)	0	7 (1.4%)	2 (0.4%)	61 (12.5%)
Frank penetration
Minor (<2 mm)	22 (4.5%)	17 (3.5%)	5 (1.0%)	2 (0.4%)	46 (9.4%)
Moderate (≥2, <4 mm)	2 (0.4%)	3 (0.6%)	2 (0.4%)	0	7 (1.4%)
Severe (≥ 4 mm)	0	0	1 (0.2%)	0	1 (0.2%)
Total	76 (15.6%)	20 (4.1%)	15 (3.1%)	4 (0.8%)	115 (23.6%)

Values are expressed as the number (%) of misplaced screw