Does Intrathecal Morphine in Spinal Anesthesia Have a Role in Modern Multimodal Analgesia for Primary Total Joint Arthroplasty?

Background: Intrathecal morphine (ITM) combined with bupivacaine spinal anesthesia can improve postoperative pain, but has potential side effects of postoperative nausea/vomiting (PONV) and pruritus. With the use of multimodal analgesia and regional anesthetic techniques, postoperative pain control has improved significantly to a point where ITM may be avoided in total joint arthroplasty (TJA).

Methods: We performed a retrospective study of primary TJA patients who underwent a standardized multimodal recovery pathway and received bupivacaine neuraxial anesthesia with ITM vs bupivacaine neuraxial anesthesia alone (control).

Results: In total, 598 patients were identified (131 controls, 467 ITMs) with similar demographics. On postoperative day 0 (POD 0), ITM patients had significantly lower mean visual analog scale scores (1.5 ± 1.6 vs 2.5 ± 1.9, P < .001) and consumed less oral morphine equivalents (10.5 ± 25.4 vs 16.8 ± 27.2, P = .013). ITM patients walked further compared to controls by POD 1 (133.6 ± 159.6 vs 97.3 ± 141 m, P = .028) and were less likely to develop PONV during their entire hospital stay (38.5% vs 48.6%, P = .043). No significant differences were seen for total morphine equivalents consumption, rate of discharge to care facility, length of stay, and 90-day readmission rates.

Conclusion: ITM was associated with improved POD 0 pain scores and less initial oral/intravenous opioid consumption, which likely contributes to the subsequent improved mobilization and lower rates of PONV. In the setting of a modern regional anesthesia and multimodal analgesia recovery plan for TJA, ITM can still be considered for its benefits.