The PENG Block in Elective Primary Anterior Total Hip Arthroplasty Is Associated with Reduced Length of Stay

Background: The pericapsular nerve group (PENG) block has been shown to reduce pain and opioid consumption in posterior total hip arthroplasty (THA). The present study assessed the effects of the PENG block versus a placebo on postoperative (1) pain, (2) morphine consumption, and (3) length of stay in patients undergoing primary anterior THA. Methods: This was an institutional review board-approved, single-center, parallel-group, prospective, randomized, double-blinded, controlled trial of patients undergoing primary anterior THA between June 2022 and April 2023. Both groups underwent ultrasound-guided injection of a 20-mL solution (0.5% ropivacaine in the PENG group, 0.9% NaCl in the placebo group), according to the PENG block procedure. Sixty patients were included (32 in the PENG group, 28 in the placebo group). We assessed (1) postoperative pain at 1, 6, 12, and 24 hours with use of the visual analogue scale; (2) total morphine consumption as the morphine-equivalent dose (MED) during the first 24 hours postoperatively; and (3) the length of stay in days. Results: For the primary outcome, the median visual analogue scale pain score was 3.5 (range, 0 to 10) in the PENG group versus 4 (range, 0 to 10) in the placebo group at 1 hour postoperatively (p = 0.335); 1 (range, 0 to 7) versus 2 (range, 0 to 6) at 6 hours postoperatively (p = 0.306); 1 (range, 0 to 8) versus 1 (range, 0 to 6) at 12 hours postoperatively (p = 0.895); and 1.5 (range, 0 to 6) versus 1.5 (range, 0 to 6) at 24 hours postoperatively (p = 0.914). For secondary outcomes, the mean ± standard deviation 24-hour morphine consumption was 24 ± 17 MED in the PENG group versus 35 ± 29 MED in the placebo group (p = 0.110). The median length of stay was 2 days (range, 2 to 5 days) in the PENG group versus 4 days (range, 2 to 7 days) in the placebo group (p = 0.003). Conclusions: In this trial, the PENG block showed a significant decrease in hospital length of stay; however, no significant difference was found for visual analogue scale pain scores or morphine consumption following primary anterior THA compared with a placebo. Level of Evidence: Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.