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Abstract

Study Objective: This narrative review discusses the anatomy, mechanism of action, techniques, indications and complications of the pericapsular nerve group block in a hip surgery setting. Interventions:The MEDLINE, EMBASE and Google Scholar databases (inception to the first week of March 2023) were searched. For anatomy, mechanism of action, techniques, and complications, cadaveric research, randomized trials, retrospective studies and case series were considered. Nonetheless, for surgery indications, to highlight the best evidence available, only randomized trials without major discrepancies with their prospective registration, blinded assessment and sample size justification were retained for analysis. Main Results:The anatomical studies suggest that pericapsular nerve group block may work through a combination of different mechanisms (i.e., blocking lateral capsule nerves, local anesthetic spread to the femoral nerve, spread towards medial capsule nerves). Compared to alternatives, except for the periarticular local anesthetic infiltration, pericapsular nerves group block results in similar or improved postoperative analgesia in total hip arthroplasty. It should be noted that the motor blockade has not been completely circumvented and the scarcity of adequate studies on other surgical procedures prevents from obtaining further conclusions about its indications. Conclusions:The pericapsular nerve group block has become very popular after its first description as an analgesic motor-sparing technique for hip fractures. However, without an absolute motor-sparing effect, its current indication is better supported in postoperative analgesia for total hip arthroplasty. Therefore, further investigation is required to find the optimal motor-sparing analgesic block for hip surgery. AbbreviationsAIIS= anteroinferior iliac spine; AON= accessory obturator nerve; FN= femoral nerve; FNB= femoral nerve block; IAI= intraarticular injection; IM= Iliacus muscle; ImM= iliacus minor muscle; IPE= iliopubic eminence; IPB= iliopsoas plane block; IPM= iliopsoas muscle; IPP iliopsoas plane=; IPT= iliopsoas tendon; LA= local anesthetic; LFCN= lateral femoral cutaneous nerve; ON= obturator nerve; PAI= periarticular local anesthetic infiltration; PACU= postanesthetic care unit; PeM= pectineus muscle; PENG= pericapsular nerve group; PMM= psoas major muscle; PPI= periportal local anesthetic infiltration; POD= postoperative day; RCT= randomized controlled trial; SIFIB= suprainguinal fascia iliaca block; THA = total hip arthroplasty; USG = ultrasound-guided; WI= wound local anesthetic infiltration.