Anatomical Location of the Common Iliac Veins at the Level of the Sacrum: Relationship between Perforation Risk and the Trajectory Angle of the Screw

Table 3

Locations of the right and left common iliac veins based on vertical insertion screw trajectory.

	Trajectory toward tip of promontorium (°)		Trajectory parallel to S1 endplate (°)
	Mean ± SD	ICC (95% CL)	Mean ± SD	ICC (95% CL)
A1(R)°		0.74 (0.58–0.84)		0.74 (0.58–0.84)
A2(R)°		0.79 (0.66–0.88)		0.79 (0.66–0.88)
A1(L)°		0.78 (0.64–0.87)		0.78 (0.64–0.87)
A2(L)°		0.92 (0.87–0.95)		0.92 (0.87–0.95)

A1R°: angle between vertical line (passing from insertion point toward anterior wall of S1) and medial border of the right common iliac vein; A2R°: angle between vertical line and lateral border of the right common iliac vein; A1L° and A2L°: same definitions but on the left side; SD: standard deviation.