Surgical Site Infection After Posterior Lumbar Instrumented Fusions

Background: Minimally invasive surgery (MIS) has shown the potential in reducing surgical site infection (SSI); however, its impact on instrumented lumbar fusion procedures remains unclear. Purpose: We sought to investigate the difference in SSI rates for open, mini-open, and MIS techniques in patients who underwent posterior lumbar instrumented fusions. Methods: We conducted a retrospective review of all patients at a single academic institution who underwent instrumented 1- or 2-level posterior lumbar fusion between January 2019 and June 2022. Cases were allocated to 1 of 3 mutually exclusive surgical cohorts (MIS, mini, or open). SSIs were diagnosed based on the National Healthcare Safety Network criteria. Results: A total of 1352 patients were reviewed for a total of 1382 lumbar fusion operations included in this study. The mean age was 61.5 ± 12.8 years, and the mean body mass index was 28.7 ± 5.67 kg/m². The largest cohort was open (39.3%, 543), followed by mini (33.1%, 458) and MIS (27.6%, 381). Thirteen patients (0.94%) developed an SSI. There were no statistically significant differences in the infection rates between the cohorts; SSI rates were MIS (0.3%, 1), mini (1.1%, 5), and open (1.3%, 7). Twelve (92%) of the patients with an SSI underwent a subsequent irrigation and debridement procedure; on average, this occurred 42.2 ± 25 days postoperatively. Conclusions: This retrospective review found that 0.94% of patients developed an SSI following a 1- or 2-level posterior lumbar instrumented fusion. Although the observed SSI rate in the open cohort was 4 times higher than in the MIS cohort, the sample sizes were insufficient to determine statistically significant differences between the 3 surgical approaches. Nonetheless, our data suggests that all 3 techniques evaluated had exceptionally low infection rates.