Abstract:Objective To investigate the therapeutic difference between single?injection of bupivacaine liposome versus ropivacaine for combined pericapsular nerve group （PENG） and lateral femoral cutaneous nerve （LFCN） blocks in postoperative motor-sparing analgesia in elderly patients undergoing total hip arthroplasty （THA） . Methods A prospective randomized controlled study design was used to include 60 elderly patients （ASA grade Ⅱ?Ⅲ, aged 60?80years） who underwent lateral approach THA in Guangdong Second Traditional Chinese Medicine Hospital from June to August 2024, and were randomly divided into observation group （n=30） and control group （n=30） . PENG+LFCN block was performed in both groups before combined spinal ? epidural anesthesia, and bupivacaine liposome and ropivacaine hydrochloride were used as nerve block drugs in the observation group and the control group, respectively. Outcomes were observed including visual analog scale （VAS） scores during rest and movement （VASrest and VASmove） at 12, 24, 36, 48, 60 and 72 h postoperatively, time to first rescue analgesia, cumulative sufentanil consumption within 72 h, and the indexes were evaluated including quadriceps strength, and postoperative adverse events［postoperative nausea/vomiting （PONV） , delirium, pulmonary infection］. Results There was no significant difference in VASrest and VASmove between the two groups within 24 h after operation （P>0.05） . Compared with the control group, the VASrest was significantly reduced at 36?60 h after surgery［48 h:2.0 （2.0, 2.2） point vs 3.0 （3.0, 4.0） point, Z=6.045, P<0.01］, and the VASmove decreased significantly［48 h:3.0 （2.0, 3.2） point vs 4.0 （4.0, 5.0） point, Z=5.621, P<0.01］in the observation group. Compared with the control group, the time of first rescue analgesia was delayed in the observation group［ （60.10±7.78） h vs （20.83±5.76） h, t=15.241, P<0.01］, and the dose of sufentanil within 72 h after surgery was reduced［5.0 （3.0, 6.0） μg vs 10.0 （5.8, 13.2） μg, Z=3.183, P<0.01］, and the incidence of PONV was significantly decreased （6.67% vs 33.33% , χ2=6.667, P<0.05） . All patients achieved ambulation by 24 h without quadriceps motor block. Conclusion A single administration of bupivacaine liposome for PENG combined with LFCN blocks can provide effective analgesia for more than 60 h in elderly THA patients, reduce postoperative opioid need, and reduce the incidence of PONV.