Comparative efficacy of S2-alar-iliac versus iliac screw techniques in treating adult spinal deformity: a meta-analysis of postoperative outcomes and complications

Pelvic fixation has become increasingly important in treating spinal deformities that affect the lumbosacral junction. The sacral 2 alariliac screw (S2AI) and iliac screw (IS) fixations are two commonly used techniques. This meta-analysis aimed to systematically compare the clinical outcomes of S2AI and IS techniques in adult spinal deformity. This meta-analysis followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A comprehensive literature search was conducted across PubMed, Embase, Cochrane Library, and Web of Science databases, using combinations of keywords such as "S2-alar-iliac," "iliac screw," "spinopelvic fixation," "lumbosacral surgery," and "clinical outcomes." The search was restricted to articles published up to October 2024. Sixteen studies were included in the analysis. The S2AI cohort showed significant advantages in terms of reduced estimated blood loss (mean difference [MD], -140.70; p=0.006), shorter hospital stays (MD, -1.50; p=0.01), and improved ambulatory status (MD, 0.22; p=0.004). Additionally, the S2AI group had significantly lower incidence of complications, including screw prominence (odds ratios [OR], 0.08; p=0.001), wound infection (OR, 0.24; p=0.0001), wound dehiscence (OR, 0.14; p=0.0001), and reduced need for revision surgeries (OR, 0.32; p=0.0001). There were no significant differences between the S2AI and IS cohorts regarding the sagittal vertical axis (MD, 1.49; p=0.23), Visual Analog Scale pain scores (MD, 0.01; p=0.94), operation time (MD, -31.23; p=0.28), postoperative Oswestry Disability Index (ODI) (MD, 0.14; p=0.84), implant failure (OR, 0.74; p=0.23), pelvic tilt (MD, -0.44; p=0.65), sacral slope (MD, -0.82; p=0.46), lumbar lordosis (MD, -0.19; p=0.89), or pelvic incidence (MD, -0.38; p=0.78). This meta-analysis suggests that while both S2AI and IS fixations have similar outcomes in terms of implant failure, operation time, and postoperative ODI, S2AI may have better outcomes in terms of revision, screw prominence, and wound complications.