Peripheral nerve blocks including the lumbar plexus block, the fascia iliaca block, and the femoral nerve block are popular adjuncts to current pain management protocols among patients undergoing hip surgery. However, these may have a limited effect on surgical anesthesia and can be associated with complications such as femoral nerve palsy. Recently, a new regional analgesia technique known as the pericapsular nerve group (PENG) block has been described to target the anterior hip capsule, primarily the articular branches of the femoral nerve and the accessory obturator nerve. To date, the literature describing the PENG block and its use has been primarily limited to case reports and case series. Thus, we aimed to compare the postoperative outcomes between patients who underwent hip arthroscopy with and without the PENG block. Specifically, we compared: 1) postoperative pain scores; 2) opioid consumption; 3) adverse events and complications 5) and time to discharge between patients who underwent hip arthroscopy with and without the PENG block.
A prospectively collected, retrospective chart review was performed to identify patients who underwent hip arthroscopy at a single institution between May 2019 and December 2020. Patients were included if they received general anesthesia and were opioid naïve (n=43). Patients who received a PENG block (n=20) were compared to patients who did not (n=23). No significant differences were found in age (38 ±13 vs 36 ± 13 years; p=0.580), American Society of Anesthesiologists (ASA) score (1.7 ± 0.58 vs 1.6 ± 0.51’ p=0.417), and body mass index (BMI) (26 ± 4 vs 26 ± 4 kg/m2;p=0.580) between the PENG and the no-PENG groups. Pain scores were measured utilizing visual analog scores (VAS) and patient’s lowest and highest pain score was noted. Opioid medications were collected intraoperatively and postoperatively (prior to discharge) and converted to morphine milligram equivalents (MME). Adverse events were defined as the number of patients who required anti-emetic administration due to nausea following surgery. Minutes to discharge was defined as the anesthesia handoff time to the time stamp from the nurse’s discharge note. Student’s t-tests compared patient demographics, pain, and opioid consumption. Fisher’s exact tests were performed to compare adverse events. A p-value of 0.05 was set as the threshold for statistical significance.
On average, the lowest pain score among patients in the PENG group was 2 ± 1.7 versus 2.6 ± 1.6 in the no-PENG group (p=0.27). The highest pain score among patients in the PENG group was 5.5 ± 2.2 versus 7.0 ± 1.9 in the no-PENG group, which was significant (p=0.02). Opioid consumption was significantly lower intraoperatively (11.63 ± 12.2; p<0.001) and postoperatively (12.5 ± 9.4 vs 32.7 ± 21.6; p<0.001) in the PENG group. The number of patients who required anti-emetic administration was lower in the PENG group as well (0 vs 4;p=0.111). No complications including postoperative falls were noted in either groups. The time to discharge was 135 ± 37 in the PENG group versus 157 ± 51 minutes in the no-PENG group (0.114).
In order to optimize perioperative outcomes, peripheral nerve blocks have been employed in hip surgery. We found that the PENG block improves perioperative outcomes by decreasing pain, opioid consumption, and anti-emetic use following hip arthroscopy. Thus, these findings may suggest that the PENG block better targets the anterior hip capsule. Of note, both study groups received midazolam prior to induction. The PENG group also received fentanyl; however, this use was not tallied as part of the total intraoperative opioid consumption. Thus, the average intraoperative opioid consumption may be somewhat underestimated. Nonetheless, larger, prospective randomized controlled studies are necessary to further elucidate how these interventions compare.