Table 2.

rating of implanted screws and comparison of facet joint violation.

Index	Navigation group	Tinavi group	t/Z/χ2	P
Screw rating
0 level	75	105	0.08	0.775
1 level	5	6
0 + 1 level	80	111	0.02	0.879
2 level	4	5
3 level	0	0
Invasion of facet joint violation
A	76	113	4.51	0.034
B	8	3
C	0	0

Grade 0: the pedicle screw is completely in the pedicle.

Grade 1: screw perforation of the pedicle cortex < 2 mm.

Grade 2: screw piercing pedicle cortex ≥ 2 mm and < 4 mm.

Grade 3: the screw penetrated the pedicle cortex ≥ 4 mm (or the screw deviated completely).

A grade of 0 was considered the ideal screw position, a grade of 0 was considered to indicate clinically acceptable precision, and a grade of 3 was considered unacceptable.

Grade A, without proximal joint invasion; Grade B, with proximal articular surface invasion < 1 mm; and Grade C, with proximal articular surface invasion.