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Study Design: Retrospective comparative study., Objective: To compare clinical and radiographic outcomes between the S2-alar-iliac (S2AI) and the iliac screw (IS) techniques in the adult population and clarify the clinical strength of S2AI screws., Summary of Background Data: S2AI screws have been described as an alternative method for lumbosacropelvic fixation in place of ISs. The S2AI technique has several advantages with lower prominence, increased ability to directly connect to proximal instrumentation, less extensive dissection of tissue, and enhanced biomechanical strength over the IS technique. However, the clinical significance of these advantages remains unclear., Methods: A single-center retrospective review of patients who underwent lumbosacropelvic fixation yielded 25 IS group patients and 65 S2AI group patients. Baseline demographic information, postoperative complications, pain and functional outcomes, and screw-related outcomes were collected., Results: The S2AI group had lower rates of reoperation (8.8% vs. 48.0%, P < 0.001), surgical site infection (SSI) (1.5% vs. 44.0%, P < 0.001), wound dehiscence (1.5% vs. 36.0%, P < 0.001), and symptomatic screw prominence (0.0% vs. 12.0%, P = 0.02) than the IS group, whereas rates of L5-S1 pseudarthrosis, proximal junctional failure, and sacroiliac joint pain were similar in both groups. Statistically significant pain relief and functional recovery were achieved in both groups without any significant intergroup differences. On multivariate analyses, age [odds ratio (OR) = 0.91, P = 0.004] and S2AI instrumentation (OR = 0.08, P < 0.001) were protective of reoperation, whereas diabetes mellitus (OR = 10.9, P = 0.03) and preoperative diagnosis of tumor (OR = 12.3, P = 0.04) were associated with SSI, and S2AI instrumentation (OR = 0.09, P < 0.001) was protective of SSI., Conclusion: The use of the S2AI technique over the IS technique was an independent predictor of preventing reoperation and SSI, while achieving similar clinical and functional outcomes., Level of Evidence: 4.

Background: In sacropelvic fixation, the iliac screw technique offers biomechanically strong constructs, but its disadvantages include screw prominence, wound dehiscence, and postoperative pain secondary to the high profile nature. To overcome this drawback, S2-alar-iliac (S2AI) screws were developed as an alternative technique for sacropelvic fixation. This study aimed to compare the S2AI screw technique with the iliac screw technique in terms of postoperative symptomatic screw prominence., Methods: A retrospective review of the records of sacropelvic fusion procedures performed at a single institution between October 2010 and January 2015 identified 32 patients with 72 iliac screws and 68 patients with 148 S2AI screws, and clinical and radiographic data were collected. If a patient had wound dehiscence and/or tenderness in the buttock immediately overlying a pelvic screw head postoperatively, it was defined as symptomatic screw prominence. The minimal distance from screw head to skin (MDSS) on postoperative computed tomography scans was measured for each patient to clarify the relationship between symptomatic screw prominence and MDSS., Results: Mean follow-up period was 22.0 months. There was significantly more symptomatic pelvic screw prominence in the iliac screw group (11.1% vs. 1.4%, P = 0.002). MDSS ≤23 mm was the strongest predictor of symptomatic pelvic screw prominence, which yielded sensitivity of 100%, specificity of 94.1%, positive predictive value of 47.6%, and negative predictive value of 100%., Conclusions: The use of the S2AI screw technique resulted in a reduced rate of symptomatic screw prominence. MDSS ≤23 mm was the strongest predictor of symptomatic screw prominence., (Published by Elsevier Inc.)