Efficacy and safety of intrathecal morphine in total knee arthroplasty: A systematic review and meta-analysis

Abstract

Objective: Morphine is a potent analgesic used to manage the pain following total knee arthroplasty (TKA). We aim to assess the safety and efficacy of intrathecal morphine (ITM) compared with placebo following TKA.Methods: We systematically searched four databases for trials that study the safety and efficacy of ITM in TKA. From relevant studies, data were extracted and pooled as mean difference (MD) or standardized mean difference (SMD) with 95 percent confidence interval (CI) using Review Manager software (Version 5.3).Results: We included six randomized controlled trials in our study. ITM significantly reduced pain scores at 4 hours (SMD = –0.82, 95 percent CI [–1.52, –0.12], p = 0.02) and 24 hours (MD = –2.01, 95 percent CI [–2.93, –1.09], p = 0.0001) after surgery compared to placebo. No statistically significant difference in cumulative morphine use or nausea episodes was observed after 24 hours. ITM increased the risk of pruritus more than placebo (relative risk [RR] = 4.82, 95 percent CI [2.34, 9.93], p 0.0001).Conclusion: ITM reduces pain at 4 and 24 hours post-operatively with no effect on cumulative morphine consumption. The only feared side effect is pruritus.

Analgesic efficacy and risk of low-to-medium dose intrathecal morphine in patients undergoing cardiac surgery: An updated meta-analysis

“…Intrathecal morphine (ITM), which enables rapid action of morphine on the central nervous system by enhancing its access to the cerebrospinal fluid, is being increasingly used in a variety of surgeries to provide effective analgesia and decrease opioid consumption ( 12 – 15 ). In addition to its analgesic advantages, other beneficial effects may include a potentially reduced hospital length of stay (LOS) and enhanced recovery after surgery ( 15 – 17 ).…”

“…In addition to its analgesic advantages, other beneficial effects may include a potentially reduced hospital length of stay (LOS) and enhanced recovery after surgery ( 15 – 17 ). However, its use may be associated with side effects such as nausea, vomiting, itching, and even respiratory depression ( 12 – 15 ). Although ITM has been used for decades in patients undergoing cardiac surgery, its possible association with respiratory depression as reported in a previous meta-analysis (i.e., odds ratio of 7.86) has raised a clinical concern that may restrict its application in this patient population ( 18 ).…”