Abstract: Objective   To investigate the effect of continuous lumbar plexus block in postoperative analgesia in patients with hip arthroplasty and its effect on inflammatory factors.  Methods   A retrospective analysis of 114 patients who underwent hip arthroplasty from November 2018 to December 2019 was used as the object,and they were divided into the control group and the observation group according to the postoperative analgesia,there were 57 patients in each group.The control group received patient-controlled intravenous analgesia after operation,and the observation group received continuous lumbar plexus block.The effect of the patients was evaluated 3 days after operation,and the visual analog pain (VAS) scores,postoperative inflammatory factor levels,and cognitive function levels were compared between the two groups.and safety.  Results   The VAS scores of the observation group were lower than those of the control group on the 1st,2nd and 3rd days after operation.The levels of inflammatory factors TNF-ɑ and IL-6 in the observation group[（3.26±0.19）ng/L,（1.55±0.12）ng/L] were lower than the control group patients[（5.49±0.23）ng/L,（2.63±0.14）ng/L](P<0.05).In the observation group,the IL-10 level of the patients was (4.79±0.23) ng/L,which was higher than that of the control group [(2.48±0.19) ng/L,P<0.05].The MMSE scores of the observation group at 1d and 2d before surgery were (20.30±2.32) score and (21.35±2.33) score,which were higher than the MMSE score of the control group; the incidences of lower limb numbness,urinary retention,nausea and vomiting and respiratory depression in the observation group after analgesia were lower than those in the control group (P<0.05).  Conclusion   Continuous lumbar plexus block can reduce pain and reduce inflammatory factor levels in patients undergoing hip arthroplasty after analgesia.It has less effect on patients’ cognitive function and can reduce complications

Key words: continuous lumbar plexus block, hip replacement, postoperative analgesia, application effect, visual simulated pain score, inflammatory factors, cognitive function