TABLE 4.

Results of the Gertzbein-Robbin Grade of the drilled screw on the ex-vivo ovine spines and the corresponding clinical accuracy. $\ast$ refers to the proper screw diameter based on the pedicle size.

Screw diameter	NO. of screws				Clinical accuracy [%]
$\left[\mathrm{m}\mathrm{m}\right]$	A	B	C	D	(A + B)/total
4	44	4	0	0	100
5	41	6	1	0	97.91
6	32	13	3	0	93.75
7	19	23	6	0	87.50
$\ast$	35	11	2	0	95.83