Effects of Different Volumes of Ropivacaine for Pericapsular Nerve Group Block on Incidence of Quadriceps Weakness and Analgesic Efficacy Following Hip Arthroplasty: A Randomized Controlled Trial.

Introduction: The pericapsular nerve group (PENG) block has been shown to be an effective approach to alleviating pain and reducing the need for opioids among older adults following hip surgery, with possible motor-sparing effects. No reports to date, however, have described appropriate ropivacaine volumes for use in the context of PENG block. The present prospective randomized controlled study was thus developed to assess the quadriceps muscle strength and analgesic efficacy associated with PENG block performed using three different volumes of 0.33% ropivacaine following general anesthesia in older adults undergoing hip arthroplasty.

Methods: In this prospective randomized double-blind controlled clinical study, 60 patients were assigned at random to undergo ultrasound-guided PENG block for hip arthroplasty using different volumes of ropivacaine. Specifically, these patients were administered 10 ml (Group A, n = 20), 20 ml (Group B, n = 20), or 30 ml (Group C, n = 20) of 0.33% ropivacaine. Quadriceps muscle strength was evaluated at 6 h post-surgery. Visual analog scale (VAS) scores at rest and with movement were assessed at 4, 6, 12, and 24 h post-surgery. Block duration, adverse event incidence, and patient satisfaction were evaluated at 24 h post-surgery.

Results: Quadriceps motor block incidence rates at 6 h post-surgery in the 10 ml, 20 ml, and 30 ml groups were 5%, 20%, and 75%, respectively. Quadriceps muscle weakness at 6 h post-surgery was significantly more common in the 30 ml group relative to the others (p < 0.001). Patients administered 10 ml 0.33% ropivacaine exhibited significantly higher VAS pain scores at rest and with movement relative to those patients in the 20 ml and 30 ml treatment groups at all time points (p < 0.05). No apparent differences in analgesic efficacy were observed when comparing the 20 ml and 30 ml groups at 4, 6, 12, and 24 h post-surgery. No significant differences in block duration, satisfaction, or adverse event incidence were observed among groups.

Conclusions: The preservation of motor function in the 20 ml 0.33% ropivacaine group was superior to that in the 30 ml 0.33% ropivacaine group. Relative to the group that received 10 ml 0.33% ropivacaine during PENG block, those elderly patients administered 20 ml and 30 ml volumes of 0.33% ropivacaine experienced superior postoperative pain relief following hip arthroplasty.