Abstract: Objective To compare the effects of ropivacaine combined with different concentrations of methylene blue for fascia iliaca block on postoperative analgesia, cognitive function and hip joint function recovery in the patients undergoing hip arthroplasty. Methods A total of 81 patients undergoing hip arthroplasty were enrolled and divided into three groups using a random number table: L group was given 30 mL of 0.25% ropivacaine;Y₁ group was given 30 mL of mixture of 0.25% ropivacaine with 20 mg methylene blue;Y₂ group was given 30 mL of mixture of 0.25% ropivacaine with 40 mg methylene blue.All the groups received ultrasound-guided fascia iliaca block before the induction of general anesthesia.The scores of pain Visual Analogue Scale(VAS) at rest and activity 1, 3 and 7 days after surgery, the scores of Mini-Mental State Examination(MMSE) 1 day before surgery and 7 days after surgery, the Harris score 7 days safter surgery,the distance of the first postoperative walk, the number of activities to get out of bed within 7 days postoperatively, the number of cases requiring intravenous rescue analgesia, and the incidence of adverse reactions within 7 days postoperatively were recorded. Results Among the initial 81 patients, 4 cases were lost to follow-up, and 2 cases were excluded for voluntarily requesting intravenous patient-controlled analgesia. Ultimately, 75 patients were included, with 25 cases in each group.Compared with L group, the scores of VAS at rest and activity 1, 3 and 7 days after surgery were significantly lower in Y₁and Y₂ groups(P<0.05);Compared with Y₁ group, the scores of VAS in Y₂ group were significantly lower at rest 1 day after surgery and at activity 1, 3 and 7 days after surgery (P<0.05).Compared with L group, the Harris scores were significantly higher 7 days after surgery, the first walk distance after surgery was significantly longer, the number of activities to get out of bed within 7 days postoperatively was significantly higher, and the number of patients requiring intravenous rescue analgesia after surgery was less in Y₁ and Y₂ groups(P<0.05).There were no statistically significant differences in preoperative and postoperative MMSE scores,and the incidence rate of postoperative adverse reactions among the three groups. Conclusions Iliofascial block with ropivacaine and methylene blue for postoperative pain relief after hip replacement is more effective than ropivacaine alone, and the analgesic time is longer, which is more conducive to the rapid recovery of postoperative hip joint function, and the analgesic effect of methylene blue shows dose-dependence with a certain extent.

Key words: hip arthroplasty, methylene blue, ropivacaine, fascia iliaca compartment block, analgesia, aged