Impact of the COVID-19 pandemic and surgical procedure on surgical site infection in adult spinal deformity surgery - a longitudinal trends study.

PURPOSE: To investigate trends in surgical site infections (SSI) in adult spinal deformity (ASD) surgery over 13 years, beginning with three-column osteotomies (3-COs) and continuing through the introduction of lateral lumbar interbody fusion (LLIF) and vancomycin powder, as well as during the COVID-19 pandemic. METHODS: Consecutive 633 patients who underwent corrective and fusion surgeries were enrolled at a single institution between 2010 and 2022. The incidence of SSI and details of patients with SSI were obtained from the surgical records. RESULTS: The overall incidence of SSIs was 6.0% (n = 38). Univariate analysis showed that SSI was significantly associated with older age (p = 0.036), male (p = 0.002), diabetes mellitus (p = 0.002), albumin levels (p = 0.019), revision cases (p = 0.003), surgery performed during the COVID-19 pandemic (p = 0.047), and iliac fusion (p = 0.046). In the multivariate analysis, revision cases (odds ratio, 3.73), male patients (odds ratio, 2.68), diabetes mellitus (odds ratio, 2.56), and albumin level (odds ratio, 0.44) were independent risk factors. The incidence of SSI was highest in the first three years, when 3-COs were the mainstay of the surgical procedure, reaching 10.6%. After the introduction of LLIF and intraoperative vancomycin (VCM) powder, the incidence decreased to 4.8%. During the COVID-19 pandemic, the incidence was lowest at 1.3% compared to other terms. CONCLUSIONS: Lower SSI rates were observed after the introduction of staged LLIF-based surgery and intrawound vancomycin powder and during the COVID-19 period; however, these temporal associations should be interpreted cautiously because multiple changes in practice occurred concurrently.