Randomized Controlled Trial of Interscalene Block Compared with Injectable Liposomal Bupivacaine in Shoulder Arthroplasty

Abstract

Background: Shortcomings of interscalene brachial plexus blockade include technical failure and rebound pain. Bupivacaine liposome injectable suspension, a sustained release preparation, is used for surgical-site administration. The purpose of this study was to evaluate these 2 postoperative pain management strategies in patients undergoing shoulder arthroplasty.

Methods: In a non-blinded, randomized controlled trial of participants undergoing primary shoulder arthroplasty, patients were randomized to interscalene brachial plexus blockade or intraoperative soft-tissue infiltration of bupivacaine liposome injectable suspension. The primary outcome variable was morphine equivalent units consumed over the first 24 hours postoperatively. Secondary outcomes included morphine equivalent units consumed intraoperatively and a visual analog scale (VAS) for pain at 0, 8, 16, and 24 hours.

Results: Seventy-eight patients were randomized to interscalene brachial plexus blockade treatment (the blockade group) and 78 patients were randomized to bupivacaine liposome injectable suspension treatment (the suspension group). The mean total postoperative narcotic consumption (and standard deviation) over 24 hours after the surgical procedure was 14.8 ± 11.3 morphine equivalent units in the blockade group compared with 14.4 ± 16.8 morphine equivalent units in the suspension group (p = 0.849). Intraoperative narcotics were significantly lower (p < 0.001) in the blockade group (8.9 ± 4.1 morphine equivalent units) compared with the suspension group (16.2 ± 7.0 morphine equivalent units). The mean VAS pain score was significantly lower in the blockade group than in the suspension group at 0 hours postoperatively (0.8 ± 2.2 compared with 3.3 ± 2.7 points; p < 0.001) and at 8 hours postoperatively (1.4 ± 2.4 compared with 3.2 ± 2.2 points; p < 0.001), but it was not significantly different at 16 hours postoperatively (4.3 ± 2.8 compared with 3.8 ± 2.4 points; p = 0.348). The VAS pain scores were significantly higher (p = 0.021) in the blockade group (4.9 ± 2.7 points) compared with the suspension group (3.9 ± 2.3 points) at 24 hours postoperatively.

Conclusions: Patients treated with bupivacaine liposome injectable suspension required an equivalent amount of postoperative narcotics and greater intraoperative narcotics compared with patients treated with interscalene brachial plexus blockade. Although interscalene brachial plexus blockade provided improved pain scores for the first 8 hours after the surgical procedure, pain scores were worse at 24 hours. The optimal postoperative pain regimen for shoulder arthroplasty and the cost-effectiveness of analgesic techniques require further investigation.

Level of evidence: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.