Removal of spinopelvic S2 alar-iliac osseointegrative screws: a case report and surgical technique guide.

Background: Traditional S2 alar-iliac (S2AI) screws have an increased risk of screw loosening compared to iliac screws (IS), leading to advancements in technology with osseointegrative S2AI screws to increase bone integration and stability. Though the overall increased stability is desired, this can also pose an obstacle if removal of the implants are required. Case Description: A 66-year-old female s/p T10-S2 posterior spinal fusion (PSF) nine months prior presented with sepsis, necessitating the removal of the implants including osseointegrative iFuse Granite S2AI implants (SI-BONE, Inc.; Santa Clara, CA). The S2AI implants were unable to be removed with their associated screw driver due to the extensive bone ongrowth and ingrowth, necessitating different techniques for screw removal. The right S2AI screw's inner shank was disengaged from the outer sleeve, followed by removal with an easy out device after the TORQ Trephine (SI-BONE, Inc.; Santa Clara, CA) passed along the outer sleeve. The left S2AI screw's tulip head was in an unfavorable position and therefore cross threaded from the inner shank with a rongeur. The left S2AI screw was then trephined in a similar fashion and removed with its associated driver. Ultimately the operation was successful, and the implants were removed by non-traditional techniques that were unaccounted for. Conclusions: Due to the osseointegrative properties of the implant, removal of screws implanted more than nine months prior using the associated driver is often not possible. The purpose of this report is to highlight tips and challenges in removing osseointegrative spinopelvic screws to improve screw removal techniques and implants.