Sutures vs. Adhesive Strips in Lumbar Spinal Fusion: Propensity-Matched Non-Inferiority Retrospective Analysis of Surgical Site Infections

Purpose : To compare surgical site infection rates between adhesive strips and sutures in lumbar spinal fusion surgery, using a non-inferiority margin. Methods : This single-center retrospective study compared surgical site infection (SSI) rates between sutures and adhesive strips in lumbar spinal fusion using propensity score matching (PSM) and a 3% non-inferiority margin. Patients undergoing one- or two-level lumbar fusion via an open posterior approach between 2019 and 2022 were included. Data were extracted from a prospectively maintained database, and postoperative SSIs were classified using the KISS surveillance system. Exclusion criteria included patients under 18, pre-existing infections, revision surgeries, and deep organ/space infections. PSM balanced covariates such as age, gender, ASA classification, surgical time, use of drainage, and the number of levels fused. A total of 997 patient records were analyzed. After applying PSM, 608 patients were evenly divided into two groups. Statistical analysis included t-tests, Mann-Whitney U tests, chi-square tests, and a Wald test for non-inferiority, rejecting the null hypothesis if the 95% one-sided confidence interval remained below the 3% margin. Results : Following PSM, infection rates were 1.64% for sutures and 1.97% for adhesive strips. A one-sided Wald test with a 3% non-inferiority margin produced an absolute risk difference of 0.33% (SE 1.1%; z = –2.47; one-sided p = 0.0067) and an upper 95% CI bound of 2.11%. Conclusions : Adhesive strips are non-inferior to sutures in SSI rates for one or two level lumbar spinal fusion. Registered at ClinicalTrials.gov Identifier NCT06664424 on October 15, 2024.