Radiographic and Clinical Results of Freehand S2 Alar-Iliac Screw Placement for Spinopelvic Fixation: An Analysis of 45 Consecutive Screws

Study design This was a retrospective clinical case series. Objective The purpose of this study was to evaluate mid-term outcomes of S2 ala-iliac (S2AI) screw fixation in patients who underwent multilevel posterior spinal fusion surgery. Summary of background data There have been few reports on radiographic and clinical outcomes in patients who underwent spinopelvic reconstruction surgery using S2AI screw installation. Materials and methods Twenty-three patients were treated by a single spinal surgeon between September 2013 and June 2014 utilizing segmental instrumentation with pedicle and S2AI screw. Instrumentation including S2AI screw was performed by a freehand technique. Surgical, radiographic, clinical outcomes and complications were evaluated to determine surgical results of S2AI screw fixation. Results The mean follow-up period was 16.9 months (ranged, 13-22 mo). The average number of fusion levels was 7.9 vertebral bodies. There were no cases of neurological deficit and violation of acetabulum or sciatic notch. A peri-screw halo was found in 1 patient and cortical wall violation was observed in 4 patients. The number of lateral and medial breaches was 2 and 3, respectively. All of them were asymptomatic. One patient experienced sacroiliac joint pain after S2AI screw installation. There was no case of screw/rod fracture and revision surgery for S2AI screw. Conclusions Radiographic and clinical outcomes of freehand S2AI screw fixation was acceptable. Sacroiliac joint irritation symptoms after S2AI screw fixation were rare. S2AI screw instrumentation can be a good alternative for spinopelvic fixation. Level of evidence Level 4.