From: The technical feasibility and preliminary results of minimally invasive endoscopic-TLIF based on electromagnetic navigation: a case series
Grade
Accuracy of PPSP according to Neo et al. [15]
0
No deviation; the screw was contained in the pedicle
1
Deviation < 2 mm (i.e., less than half of the screw diameter)
2
Deviation > 2 and < 4 mm
3
Deviation > 4 mm (i.e., complete deviation)