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Chapter 30 Sacropelvic Fixation Techniques

T E C H N I Q U E S

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TECH FIG 3 ● A. Extension of the midline incision out to the PSIS for place- ment of the iliac screws. The paraspinal muscles are held out of the field with a clamp, and the PSIS is marked by the forceps. An oblique incision is made in the fascia overlying the PSIS. B. Subsequently, the pedicle seeker is driven into the table of the ilium, angled toward the ASIS. C. Placement of a finger into the greater sciatic notch can help guide the pedicle seeker. D. Line diagram of trajectory. E,F. The iliac screw is attached to the main spinal construct by using a modular connector system, which is tunneled anterior to the paraspinous muscles. ( B,C,E: From Moshirfar A, Rand FF, Sponseller PD, et al. Pelvic fixa- tion in spine surgery. Historical overview, indications, biomechanical relevance, and current techniques. J Bone Joint Surg Am 2005;87[suppl 2]:89–106.)

F

resected depends on the bulkiness of the implant, and the goal should be to minimize implant prominence. 15 ■ With a pedicle seeker or curette, the path into the ilium down toward the AIIS is then developed ( TECH FIG 3B ). ■ The path averages 25 degrees lateral to midsagittal plane and 30 to 35 degrees caudal to the transverse plane toward the

ASIS ( TECH FIG 3C ). Fluoroscopy can be used to confirm the path. Alternatively, placement of a finger into the sciatic notch provides an anatomic landmark that can help guide the path 20 ( TECH FIG 3D ). ■ The path is palpated with a ballpoint probe to verify that neither the medial nor lateral iliac crest cortex has been breached.