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Chapter 30 Sacropelvic Fixation Techniques

T E C H N I Q U E S

TECH FIG 5 ● (continued) D. A drill is used to tap through the SI articulation.

D

A

B

C

TECH FIG 6 ● A. The drill is removed, and a 1.45-mm guidewire mounted on a handheld driver is advanced into the ilium toward the AIIS. Tapping the S2AI screw hole over the guidewire ( B ) and placement of the S2AI screw ( C ). D,E. Final alignment of the S2AI screw and spinal construct. D E

■ Percutaneous S2 Alar Iliac Technique

(see TECH FIG 5A ), is identified using standard AP and pelvic inlet fluoroscopic views. ■ A Jamshidi needle is angled toward the AIIS and advanced 10–20 mm into the sacral ala. The ideal S2AI trajectory is the same as in the open procedure and averages 40 degrees of lat- eral angulation in the transverse plane and 40 degrees of caudal angulation in the sagittal planes but varies with pelvic obliquity (see TECH FIG 5B,C ). ■ A teardrop view is then obtained to verify the needle trajectory ( TECH FIG 7A ). ■ The teardrop view is a fluoroscopic view obtained by rolling the C-arm roughly 30 degrees over the table, and tilting it roughly 30 degrees cephalad, which creates an overlap of the AIIS and the PSIS and the image of a teardrop.

■ Because the S2AI screw is in line with the spinal construct at- tached to the mobile spine, the S2AI technique is amenable to a minimally invasive percutaneous approach. 17,22 ■ The percutaneous sacropelvic fixation is frequently combined with a minimally invasive percutaneous fixation of the lumbar spine, but this may not be required depending on the indication. ■ The approach to the sacrum is a 3-cm midline incision at the level of the S1 and S2 dorsal foramen ( TECH FIG 7B ). ■ The starting point, located in line with the lateral edge of the S1 foramen and midway between the S1 and S2 dorsal foramina