S2AI and iliac screw prominence and removal for symptomatic prominence: a systematic review

Purpose: Sacropelvic fixation plays a crucial role in complex spinal surgeries, particularly in adult spinal deformity (ASD) and other conditions requiring lumbosacral stabilization. This systematic review and meta-analysis aims to compare the rates of symptomatic screw prominence and screw removal between S2-alar-iliac (S2AI) and iliac screws, as well as those examining each screw type independently, to provide a comprehensive understanding and guide surgical decision-making and improve patient outcomes. Methods: A systematic review following PRISMA guidelines was conducted using Medline, SPORTDiscus, Cochrane Library, and Scopus databases. Inclusion criteria encompassed studies evaluating screw prominence or removal rates for S2AI and iliac screws, individually or in comparison, involving adult patients with sacropelvic fixation. Data on demographics, comorbidities, surgical characteristics, and outcomes were extracted. Statistical analysis included relative risk difference (RR) calculations using a random effects model, with heterogeneity assessed via the I² statistic. Results: Eighteen studies were included, comprising 1462 patients: 648 with S2AI screws and 814 with iliac screws. Symptomatic screw prominence was significantly lower for S2AI screws (1.9%, 12/648) compared to iliac screws (6.3%, 51/814), with a pooled RR difference of 0.08 (95% CI 0.04, p < 0.001). Screw removal rates due to prominence were 0% (0/12) for S2AI screws versus 27.5% (14/51) for iliac screws. Low heterogeneity was observed for both outcomes (I² = 3.32% for prominence, I² = 0.0% for removal). Conclusion: S2AI screws demonstrate significantly lower rates of symptomatic prominence and screw removal compared to iliac screws, supporting their clinical and economic advantages in sacropelvic fixation for ASD. Technological advancements and innovations in implant design further enhance the efficacy of S2AI screws. These findings advocate for their adoption as an effective fixation technique, reducing hardware complications and improving patient outcomes. Future studies will aim to explore factors influencing prominence risk and optimize surgical strategies in ASD treatment.