Comparison of the 4-in-1 block technique with femoral and adductor canal blocks in arthroscopic anterior cruciate ligament reconstruction: a randomized controlled trial

Abstract Objectives The aim of this study was to compare the 4-in-1 block technique with femoral nerve block (FNB) and adductor canal block (ACB) in terms of perioperative pain and opioid consumption in patients undergoing arthroscopic anterior cruciate ligament reconstruction (ACLR). Methods The trial was retrospectively registered. In this randomized controlled trial, patients scheduled for ACLR under general anesthesia were randomly assigned to one of three groups: 4-in-1 block, FNB, or ACB. All blocks were performed under ultrasound guidance with 20 mL of 0.25% bupivacaine approximately 45 min before surgery. Intraoperative remifentanil use, postoperative 24-hour intravenous morphine equivalents (IME) consumption, and pain scores measured by the numerical rating scale (NRS) were recorded. Overall postoperative pain burden was additionally assessed using the 0–24-hour NRS area under the curve (AUC). An exploratory post-hoc non-inferiority analysis was performed. Results A total of 60 patients were equally divided among the groups. Intraoperative remifentanil consumption, postoperative 24-hour IME consumption, and the 0–24-hour NRS AUC values did not differ significantly among the groups ( p = 0.842, p = 0.502, and p = 0.958, respectively). Compared with the ACB group, the 4-in-1 block group used, on average, 0.8 mg less postoperative 24-hour IME (90% confidence interval [CI], − 5.61–4.01). Compared with the FNB group, 24-hour IME use was 2.8 mg greater (90% CI, − 1.48–7.08). In both comparisons, the upper bounds of the two-sided 90% CIs did not exceed the exploratory post-hoc non-inferiority margin (Δ = 10 mg). Conclusion In patients undergoing ACLR, the 4-in-1 block did not differ significantly from FNB or ACB in terms of analgesic outcomes. These exploratory findings require further investigation to clarify the role of the 4-in-1 block in perioperative pain management for ACLR. Trial registration ClinicalTrials.gov identifier: NCT05643040. Registered 23 November 2022. Retrospectively registered.