Background:
The effectiveness of ultrasound-guided pericapsular nerve group (PENG) blocks for postoperative analgesia following direct anterior total hip arthroplasty under general anaesthesia remains uncertain. We conducted a prospective randomized trial to determine whether a PENG block would reduce postoperative intravenous morphine consumption compared with surgical local anaesthetic infiltration.

Methods:
Consecutive patients were randomized to receive either an ultrasound-guided PENG block after induction of anaesthesia or surgical local anaesthetic infiltration after femoral neck resection. General anaesthesia and perioperative analgesic management were standardized according to institutional practice, and all procedures were performed by a single surgeon. The primary outcome was total intravenous morphine consumption during the post-anaesthesia care unit (PACU) stay. The secondary outcome measure was total oral morphine consumption from PACU discharge to postoperative day 1 (POD#1), expressed in oral morphine equivalents (OME).

Results:
Of the 60 recruited patients, 56 were analysed using a modified intention-to-treat analysis. Median (interquartile range) PACU morphine consumption did not differ significantly between the control and PENG groups (0 [0–6] mg vs. 0 [0–3] mg; median difference 0 mg, 95% confidence interval (CI) −2 to 4.5; P = 0.235). Total OME consumption through POD#1 was lower in the PENG group compared to the control group (0 [0–10] mg vs. 7 [3–20] mg; P = 0.040).

Conclusions:
In patients undergoing direct anterior total hip arthroplasty, PENG block, when implemented as part of a multimodal analgesic pathway, did not reduce PACU intravenous morphine consumption compared with surgical local infiltration.