ObjectiveThis study compared the efficacy of ultrasound-guided erector spinae plane block (ESPB) and wound infiltration (WI) for postoperative analgesia in patients who underwent lumbar spinal surgery with instrumentation.MethodsIn this randomized controlled trial, 80 patients were divided into two groups: ESPB (n = 40) and WI (n = 40). Postoperative pain intensity was assessed via the visual analog scale (VAS) at multiple time points within 24 h. Additionally, opioid consumption, time to first rescue analgesia, incidence of postoperative nausea and vomiting (PONV), and patient satisfaction were evaluated.ResultsBoth ESPB and WI provided effective postoperative pain management, with no significant differences in VAS scores. However, the ESPB group demonstrated a significantly longer duration of analgesia, a shorter time to first rescue analgesia, and lower total tramadol consumption (50 ± 60 mg vs. 100 ± 75 mg; p = 0.010) than did the WI group. Furthermore, a trend toward reduced PONV incidence was observed in the ESPB group, likely due to its opioid-sparing effect.ConclusionWhile both ESPB and WI provided effective postoperative pain management, ESPB demonstrated a distinct advantage by offering a longer duration of analgesia and significantly reducing opioid consumption. These findings suggest that ESPB is more effective than WI for postoperative analgesia in lumbar spinal surgeries, providing prolonged pain relief and improving patient outcomes. Further studies are warranted to explore its long-term benefits and cost-effectiveness.Trial RegistrationClinicalTrials.govPRS: NCT06567964 Date: 08/21/2024 Retrospectively registered.