Background We hypothesized that the addition of a preoperative pericapsular nerve group (PENG) block to intra-articular local anesthetic injection would improve analgesia after total hip arthroplasty.

Method In this double-blinded trial, 71 patients scheduled for primary total hip arthroplasty were randomized to receive preoperative PENG block with 20 mL 0.5% ropivacaine (PENG group) or 20 mL saline (placebo group). All the patients received an intra-articular injection of 20 mL 0.5% ropivacaine by surgeon after the completion of the procedure. The primary outcome was the highest pain score reported in the recovery room. The secondary outcomes included quadriceps strength, pain scores, opioid use, and opioid-related side effects up to 48 hours after surgery.

Results Seventy patients were included in the final analysis. The highest visual analog scale in the recovery room showed significant intergroup difference (placebo: 5.2±3.1 vs PENG: 3.3±2.7, p<0.01) but the difference did not persist after discharge from the recovery room. The two groups’ postoperative pain scores at rest were similar. A lower intraoperative morphine equivalent dose and lower postoperative vomiting were found in the PENG group. There were no differences in the other outcomes.

Conclusion The addition of a preoperative PENG block to intra-articular injections of local anesthetic provides a limited benefit to postoperative analgesia in the recovery room with no discernible benefits thereafter.

Trial registration number NCT04480320.