A Double-Blind Randomized Comparison Trial of Postoperative Pain in Patients Undergoing Total Shoulder Arthroplasty Who Receive Interscalene Blocks with near Equipotent Doses of Plain 0.5% Bupivacaine vs. Liposomal Bupivacaine

Background/Objectives: Interscalene brachial plexus block (ISB) is a common regional anesthesia technique for analgesia in patients undergoing shoulder surgery. Liposomal bupivacaine (LB) was developed to prolong analgesia duration; however, the existing literature demonstrates mixed results regarding its efficacy. This study aimed to compare the analgesic effectiveness of near-equipotent doses of LB and plain bupivacaine (PB) for patients undergoing total shoulder arthroplasty (TSA). Methods: This prospective double-blinded randomized controlled trial enrolled 78 elective TSA patients. Participants were randomized to receive an ISB with either 36 mL of 0.5% PB (180 mg) or a mixture of 10 mL of LB, 20 mL of 0.25% PB, and 6 mL of saline (183 mg). The primary outcome was the proportion of patients with clinically tolerable pain scores (visual analog scale (VAS) ≤ 4) on postoperative day (POD) 1 in each group. Secondary outcomes included the proportion of patients with clinically tolerable pain scores on POD 2–5, overall pain scores in the post-anesthesia care unit (PACU) and on POD 1–5, Quality of Recovery Survey-15 (QoR-15) scores on POD 1–5, analgesic consumption on the day of surgery and on POD 1–5, and adverse events. Results: A total of 67 patients completed the study. There was a statistically significant increase in median body mass index (BMI) in the PB vs. LB group (30.0 (27.4–33.1) vs. 27.0 (24.3–29.4), p = 0.0197). All other demographic characteristics were comparable between groups. There was no difference in the primary outcome or any of the secondary outcomes. Conclusions: LB did not reduce postoperative pain compared to PB. Larger, multicenter studies are warranted to further evaluate the clinical benefit of LB in this population.