Use of S2-Alar-iliac Screws Associated With Less Complications Than Iliac Screws in Adult Lumbosacropelvic Fixation

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.