Opioid Sparing at 24 h after Total Shoulder Arthroplasty by Undiluted Liposomal Bupivacaine Single Shot Interscalene Block: A Randomized Clinical Trial, First Results

Background: The purpose of this study was to compare postoperative opioid consumption following total shoulder arthroplasty, after: (A) a single-shot undiluted liposomal bupivacaine (LB; commercial name: Exparel) interscalene block, or (B) a Ropivacaine block (R), supplemented with continuous catheter infusion. Methods: This prospective, randomized study (NCT03739021) compared postoperative analgesic requirements in Morphine Milligram Equivalent (MME) during the first 24 h after discharge from the post-anesthesia care unit (PACU) in patients receiving total shoulder arthroplasty. Two similar groups of 30 patients each received equivalent general operative anesthesia. Preoperative interscalene block was performed with either 10mL of undiluted liposomal bupivacaine (LB) or ropivacaine (R) 0.5% plus continuous catheter infusion. Results: There were no differences between the two groups regarding age, gender, length of surgery, intraoperative narcotic usage, or length of hospital stay. The time required to administer (LB) compared to (R) was significantly reduced (5 min vs. 15 min). The LB group experienced a reduction in MME during the first 24 h after PACU discharge (25 vs. 41 MME). Conclusion: A single shot of undiluted liposomal bupivacaine (LB) provided a significant (p = 0.045) reduction in opioid use during the first 24 h after shoulder replacement surgery compared to ropivacaine (R) with continuous catheter infusion. A larger sample group will be required to bolster these results. There was no measured difference in reported pain level. LB also took less time to administer.