Pericapsular nerve group (PENG) block combined with local infiltration analgesia is not superior to local infiltration analgesia for the management of postoperative pain after primary elective total hip arthroplasty: A prospective, randomized, controlled, single-blind trial

Background: Local infiltration analgesia (LIA) has been advocated for the pain management after total hip arthroplasty (THA). The analgesic benefits of an added pericapsular nerve group (PENG) block remain questionable. Methods: This randomized, single-blind trial enrolled patients undergoing elective THA under general anaesthesia and standardized postoperative analgesia. Patients were allocated to receive either a PENG block (20 mL of ropivacaine 0.475 %) combined with intraoperative LIA (PENG + LIA group, n = 32), or intraoperative LIA alone (LIA group, n = 32). The primary outcome was oral morphine equivalent (OME) consumption at day 1. Secondary outcomes were: pain scores at post anaesthesia care unit (PACU) discharge and on day 2, times for the Timed to Up and Go (TUG) test and measurement of adductor strength on day 1, and patients' satisfaction using the EVAN-G questionnaire. Results: Compared with LIA alone, PENG + LIA resulted in similar OME consumption on day 1 (78 [51-91.5] mg vs 58 [30-80] mg respectively, median difference (95%CI) of -17 (-34 to 1) mg, p = 0.09). Pain scores and morphine consumption were not different between groups at any time point. TUG and thigh adduction tests were similar between LIA and PENG + LIA groups (respectively 35 [25-48.5] vs 31.5 [19.5-46.5] sec, p = 0.39; and 105 [85-150] vs 100 [80-125] mmHg, p = 0.61). No difference in the patients' satisfaction was found. Conclusion: The addition of a PENG block to large-volume LIA did not significantly improve the analgesia for elective THA in the setting of an adequate basic postoperative analgesia regimen. The results of the lower limb functional tests confirmed the PENG block to be motor-sparing.