Pelvic Fixation With a Quad-Rod Technique Using S2 Alar Iliac and Medialized Entry Iliac Screws for Long Fusion Constructs

Abstract

Purpose: Patients with adult spinal deformity (ASD) may have risk factors for nonunion and subsequent instrumentation failure. This study reviews a novel surgical technique for a quad-rod construct to the pelvis using both S2 alar iliac (S2AI) screw fixation and medialized entry iliac screw fixation as described through three separate cases and a review of the literature. Methods: This technique facilitates alignment of the construct and rod insertion into the tulip heads. The medialized iliac screw technique also avoids the potential soft-tissue complications of the conventional iliac screw bolt given that it is deeper and has more soft-tissue coverage. Results: Three cases performed by the most senior author (V.A.) in which this novel technique was used are presented in this report along with clinical and radiographic images to educate the reader on appropriate execution of this technique. A review of the existing literature regarding pelvic fixation techniques for ASD was also done. Conclusion: Quad-rod augmentation of long thoracolumbar spinal constructs with two independent SI anchoring points is potentially an effective technique to increase lumbar sacral construct rigidity, thereby promoting fusion rates and decreasing revision rates. The described technique provides spine surgeons with an additional tool in their armamentarium to treat patients with complex ASD.