Sacral Alar Iliac Fixation for Spine Deformity.

Abstract

As the anatomy of the lumbosacral junction presents a unique challenge for the spine surgeon with regard to achieving a solid fusion, we describe the sacral alar iliac (SAI) technique, which can be used for the placement of pelvic anchors during posterior spinal arthrodesis. Position the patient prone on a radiolucent table. In approaching the starting point, perform limited dissection of the soft tissue between the S1 and S2 dorsal foramina, while taking care to minimize unnecessary dissection and blood loss. As the ideal screw pathway is one-third in the sacral ala and two-thirds in the ilium, start at the junction between the 1st and 2nd sacral segments, cross the sacroiliac joint, travel caudally toward the sciatic notch, cross between the inner and outer table of the ilium, and end close to the anterior inferior iliac spine cranial to the acetabular roof (Figs. 5-A and 5-B). In most children and adults, use screws with an outer diameter ≥9 mm, which are recommended to prevent screw breakage. Ensure that the SAI screws are in line with the remainder of the spinal anchors to allow for ease of rod insertion. Perform carefully layered wound closure per routine at the end of the case, with special attention to meticulous hemostasis. In a review of the cases of 32 pediatric patients treated with SAI fixation, Sponseller et al.27 reported a mean pelvic obliquity correction of 70% and a mean major coronal Cobb angle correction of 67%.