Objective To compare the analgesic effects of epidural Morphine versus lumbosacral plexus block in patients undergoing hip joint replacement.Methods A total of 94 ASA Ⅰ ～ Ⅱpatients undergoing hip surgery with combined spinal epidural anesthesia(CSEA) were selected and randomized into 4 groups:Group M received a single epidural injection of 2 mg Morphine for analgesia,Group MN1 received an epidural injection of 1 mg Morphine combined with lumbosacral plexus block,Group MN2 received an epidural injection of 2 mg morphine combined with lumbosacral plexus block,and Group N received lumbosacral plexus block.All patients were administered intramuscular parecoxib for 3 days after surgery and,if the visual analogue scale(VAS)≥4,additional intramuscular tramadol.Patient-controlled intravenous analgesia(PCIA) was applied if pain relief was insufficient after Tramadol treatment.Postoperative analgesic effects,the ability to ambulate and side effects were monitored.Results VAS scores gradually increased in the 4 groups after surgery and were higher between the morning of the 1st day and the evening of the next day than at 4 hours after surgery in all the 4 groups.There were no significant differences in VAS scores between rest and exercise conditions in any of the 4 groups.Ambulatory VAS scores were lower in Groups MN1 and MN2 than in Groups M and N 6 hours after surgery,while resting VAS scores had no significant differences between the 4 groups.Resting and ambulatory VAS scores were both lower in Groups MN1 and MN2 than in Groups M and N 6 hours after surgery,while they had no significant differences between either Groups MN1 and MN2 or Groups M and N 4-8 hours after surgery.Resting and ambulatory VAS scores were lower in Groups M,MN1 and MN2 than in Group M on the morning of the day after surgery,and more patients in Group N needed early tramadol and PCIA for rescue analgesia.Muscle strength was lower in Groups MN1 and MN2 than in Groups M and N 4 hours and on the morning of the day after surgery.No significant differences between the groups were found in standing ability 6 hours after surgery and in motor activity on the morning of the day after surgery.The incidence of urinary retention was higher in Groups M and MN2 than in Groups MN1 and N,and was higher in Group MN1 than in Group N.The incidence of pruritus was higher in Groups M and MN2 than in Group N.There was no significant difference in Ramsay sedation scores and postoperative nausea and vomiting (PONV) between the groups.Conclusions Epidural morphine combined with lumbosacral plexus nerve block can provide better analgesic effects than a single dose of epidural morphine or lumbosacral plexus nerve block in elderly patients undergoing hip joint replacement.Although the synergy of the combination has certain influence on early muscle strength recovery,it does not affect early postoperative rehabilitation training.With the combined use of parecoxib and lumbosacral plexus nerve block,epidural injection of 1 mg and 2 mg morphine provides similar analgesic effects,but epidural injection of 2 mg morphine results in a higher incidence of urinary retention.Thus,a small dose of epidural morphine combined with lumbosacral plexus nerve block is recommended for postoperative analgesia in elderly patients receiving hip joint replacement.