Infection Risk of Lumbar Epidural Injection in the Operating Theatre Prior to Lumbar Fusion Surgery

PURPOSE: To determine the association between preoperative lumbar epidural injections (LEIs) in the operating theater (OR) and the occurrence of surgical site infection (SSI) after posterior lumbar instrumented fusion surgery. METHODS: This study was performed from January 2015 to September 2019. We enrolled 2312 patients who underwent lumbar surgery without LEIs (control group) and 469 patients who underwent lumbar surgery after LEIs in the OR. We further separated the patients by the time interval between the LEIs and surgery: 1) for the 0–1 M group, lumbar surgery was performed within 1 month after the LEIs, and 2) for the >1 M group, it was performed more than 1 month after the LEIs. RESULTS: The postoperative infection rate in the 0–1 M group was considerably higher than that in the control group (p = 0.0101). We further subdivided the 0–1 M and >1 M groups into four subgroups: a) the 0–1 MNS group included patients in the 0–1 M group who did not receive steroids; b) the 0–1 MS group who received steroids; c) the >1 MNS group included patients in the >1 M group who did not receive steroids; d) the >1 MS group who received steroids. The postoperative infection rate in the 0–1 MS subgroup was considerably higher than that in the control group (p = 0.0018). However, the infection rate was lower in the >1 MS subgroup (p = 0.1650). There were no statistically significant differences in the postoperative infection rate between the control group and the two non-steroid groups (0–1 MNS group, p = 0.4961; 1 MNS group, p = 0.7381). CONCLUSION: The administration of LEIs without steroids in the OR before lumbar instrumented fusion does not significantly increase patients’ risk of postoperative infection. We recommend avoiding steroid injections administered within 1 month before lumbar instrumented fusion.