Erector Spinae Plane Block Combined With Local Infiltration Analgesia for Posterior Lumbar Interbody Fusion: Prospective, Double-Blind, Randomized Controlled Trial

Objective: To evaluate whether erector spinae plane block (ESPB) combined with local infiltration analgesia (LIA) provides better postoperative analgesia than ESPB alone, LIA alone, or placebo in patients undergoing posterior lumbar interbody fusion (PLIF).Methods: This prospective, double-blind, randomized controlled trial enrolled adults undergoing open PLIF for degenerative lumbar disease. Patients were randomly assigned in a 1:1:1:1 ratio to placebo, LIA, ESPB, or combined ESPB with LIA. Fluoroscopy-guided ESPB or placebo injection was performed before induction of general anesthesia, while LIA or placebo infiltration was given before wound closure. All patients received standardized general anesthesia and postoperative patient-controlled intravenous analgesia. The primary outcomes were postoperative sufentanil consumption and visual analogue scale (VAS) pain scores at rest and during movement at 4, 8, 12, 24, and 48 hours. Analyses were based on the modified intention-to-treat population. Longitudinal VAS trajectories were assessed using linear mixed-effects models, together with multiplicity-adjusted pairwise comparisons and factorial interaction analyses. A right-censoring sensitivity analysis of time to first patient-controlled intravenous analgesia (PCIA) bolus was performed using Kaplan-Meier, log-rank, and adjusted Cox proportional hazards analyses.Results: Of the 188 randomized patients, 182 were included in the modified intention-to-treat analysis. Baseline characteristics were similar across the 4 groups. Body-weight- and operative-time-normalized remifentanil and propofol consumption rates were lower in the ESPB-containing groups, whereas the rocuronium consumption rate did not differ significantly among groups. Linear mixed-effects models showed significant group×time interactions for both resting and movement VAS scores, indicating different postoperative pain trajectories among the groups. The combined ESPB with LIA group showed the most consistent short-term analgesic benefit, with lower pain scores at several early postoperative time points, lower postoperative sufentanil consumption, fewer analgesia pump activations, and a longer time to first PCIA bolus. After multiplicity adjustment, the postoperative rescue analgesia count was also lower in the combined group than in the control group. Factorial analyses identified a greater-than-additive effect only for time to first PCIA bolus, whereas the other analgesic outcomes showed no consistent evidence of statistical synergy. Right-censoring sensitivity analyses supported the longer time to first PCIA bolus in the combined group. Adverse-event rates were similar among the 4 groups, and no significant between-group differences were observed in VAS or Oswestry Disability Index scores at 3 months.Conclusion: Fluoroscopy-guided ESPB combined with LIA improved short-term postoperative analgesia after open PLIF. The combined regimen reduced postoperative opioid requirements and analgesia pump activations and prolonged the time to first PCIA bolus without increasing adverse events. Its benefit is better interpreted as an incremental, layered multimodal analgesic effect rather than a consistently synergistic effect across outcomes. No between-group differences in pain or functional outcomes were observed at 3 months.