The analgesic effect of obturator nerve block added to a femoral triangle block after total knee arthroplasty a randomized controlled trial

Background and Objectives: Total knee arthroplasty (TKA) is associated with severe pain, and effective analgesia is essential for the quality of postoperative care and ambulation. The analgesic effects of adding an obturator nerve block (ONB) to a femoral triangle block (FTB) after TKA have not been tested previously. We hypothesized that combined ONB and FTB will reduce opioid consumption and pain compared with those of a single FTB or local infiltration analgesia (LIA). Methods: Seventy-eight patients were randomized to combined ONB and FTB, single FTB, or LIA after primary unilateral TKA. The primary outcome was morphine consumption during the first 24 postoperative hours. Secondary outcomes included morphine consumption during the first 48 postoperative hours, pain at rest and passive knee flexion, nausea and vomiting, cumulated ambulation score, and Timed Up and Go test. Results: Seventy-five patients were included in the analysis. The total intravenous morphine consumption during the first 24 postoperative hours was 2 mg (interquartile range [IQR], 0-15) in the combined ONB and FTB group, 20 mg (IQR, 10-26) in the FTB group (P = 0.0007), and 17 mg (IQR, 10-36) in the LIA group (P = 0.002). The combined ONB and FTB group displayed reduced pain, nausea, and vomiting compared with the other groups. The ambulation tests showed no statistically significant differences between the groups. Conclusions: Addition of ONB to FTB significantly reduced opioid consumption and pain after TKA compared with a single FTB or LIA, without impaired ambulation.