Liposomal Bupivacaine Interscalene Nerve Block in Shoulder Arthroplasty is Not Superior to Plain Bupivacaine: A Double Blinded Prospective Randomized Control Trial.

Abstract Introduction Interscalene brachial plexus blocks are a common modality utilized to provide adjunctive pain relief with shoulder replacement surgery. In 2018 the Federal Drug Administration approved the use liposomal bupivacaine (LB) for such nerve blocks. We sought to evaluate whether this formulation of bupivacaine would provide superior pain relief for shoulder replacement patients over standard bupivacaine alone. Our hypotheses were that in the LB cohort the average postoperative pain score over the first 72 hours would be significantly lower, time to block cessation would be longer, total opioid consumption would be lower, and the average patient satisfaction score regarding their pain management would be higher. Materials and Methods A randomized, double-blinded study was designed comparing primary shoulder replacement surgery after an interscalene block with 25 ml of 0.5% plain bupivacaine versus 133 mg of LB with 7.5 ml of 0.5% and 7.5 ml of 0.25% plain bupivacaine. A total of 104 patients were included in the study, with an equal number in each study arm. Patients’ visual analogue pain scores were followed for their inpatient stay, first three full outpatient days, and at a three week follow-up. Use of opioid medication was recorded for the same intervals, and converted to morphine milligram equivalents (MME). The time to first opioid rescue was documented, as well as the patients’ satisfaction with their pain management at both the 3 day and 3 week intervals. Results No clinically relevant advantage to the use of liposomal bupivacaine over plain bupivacaine was found. During the second postoperative day, the mean Visual Analogue Pain Score was 2.4 with liposomal bupivacaine versus 3.3 in the standard cohort. (p=0.0409) The only other statistically significant finding was a higher VAPS with LB during the third full day home compared to standard bupivacaine. (4.0 vs 2.8 respectively, p=0.0197) Both of these differences were less than the minimal clinically important difference of 2 for the VAPS. Analysis of the VAPS for the 1st and 3rd postoperative days, the 1st and 2nd full days home, and at 3 weeks revealed no significant difference. Similarly, there was no significant difference in time to first opioid rescue, total MME use, and patient satisfaction with pain management. Conclusion When used for an interscalene block to provide adjunctive pain relief in shoulder replacement surgery, the addition of liposomal bupivacaine to plain bupivacaine provides no additional clinically important benefit to the patient’s pain experience over standard bupivacaine. Level of evidence Level I; Randomized Controlled Trial; Treatment Study