The analgesic efficacy of intrathecal morphine compared to peripheral regional analgesia in total hip arthroplasty

BACKGROUND: Following elective total hip arthroplasty, pain continues to be a significant problem. Intrathecal morphine or peripheral regional analgesia, that is local infiltration analgesia or peripheral nerve block, are common analgesic modalities, but it is still not known which is superior. DESIGN: Systematic review and meta-analysis of randomised controlled trials. DATA SOURCES: The following electronic databases were searched from inception to 24 March 2026: CENTRAL; Ovid Embase; Ovid MEDLINE; Scopus; and Web of Science. ELIGIBILITY CRITERIA: Randomised controlled trials that compared intrathecal morphine to peripheral regional analgesia in patients scheduled for elective total hip arthroplasty under general or spinal anaesthesia. RESULTS: Eight trials and 471 patients were included. The peripheral regional analgesia was peripheral nerve block in six trials and local infiltration analgesia in two trials. No difference was demonstrated between intrathecal morphine and peripheral regional analgesia in regard to the first coprimary outcome, the pain score at rest at 24 h. The quality of evidence was moderate. Intrathecal morphine was found to be superior to peripheral regional analgesia with respect to the second coprimary outcome, the cumulative intravenous morphine equivalent consumption at 24 h. Mean difference (95% CI) was 11.38 mg (4.31-18.45; P = 0.002, I2 = 81%). The quality of evidence was low. Intrathecal morphine was revealed to be superior to peripheral regional analgesia at 8-12 h for the pain score at rest, 1.24 (0.60-1.88); P = 0.0001, I2 = 68%; pain score on movement, 1.15 (0.12-2.17), P = 0.03, I2 = 65%; but the rate of in hospital pruritus was reduced with peripheral regional analgesia, 0.31 (0.17-0.58), P = 0.0002, I2 = 0%. No differences in functional status were shown. CONCLUSIONS: We found no difference between intrathecal morphine and peripheral regional analgesia in regard to pain score at rest at 24 h. Intrathecal morphine may lead to a favourable effect on some but not all analgesic indices compared to peripheral regional analgesia in elective total hip arthroplasty. The quality of evidence for these positive effects was low. Intrathecal morphine reduced the systemic opioid consumption, but is not in itself an opioid free strategy. This notion is supported by the increased incidence of in hospital pruritus with intrathecal morphine. The quality of evidence for this was high. In view of the quality of evidence, high quality randomised controlled trials are required to substantiate these results.