Abstract
Background
Exparel (Pacira Pharmaceuticals, Parsippany, NJ, USA) is a long-acting liposomal Bupivacaine extended release compound that can be used as peri-articular injection (PAI) or regional nerve block. The purpose of this study was to compare the post-operative analgesic efficacy of Exparel as a single administration adductor canal block (ACB) varsus PAI.
Methods
From May 2016 to June of 2017, 70 patients with primary knee osteoarthritis undergoing unilateral knee replacement were prospectively randomized into two cohorts: 1) PAI (Exparel 266 mg (20 ml vial) with 20 ml of 0.5% bupivacaine HCl, and normal saline to a total volume of 120 ml); 2) ACB (Subsartorial saphenous nerve using Exparel 266 mg in 20 ml vial). All patents underwent spinal anesthesia with comprehensive pre-emptive and postoperative multimodal pain protocol. All opioids given were converted to morphine equivalents. Pain was recorded at 4 – 12 hrs (day of surgery), post-operative day (POD) 1, 2, and 3 after surgery.
Results
There was no statistical significance between the pain scores during the first 12 hrs (day 0) after surgery. We found a trend towards a significance on POD # 1, as PAI group had less pain (5.3 vs 4.2, p=0.09). The mean pain score in ACB group increased on POD # 3 while in PAI continued a decrease (4.8 vs 1.8, p=0.03). There was no statistical significance between the 2 groups regarding the accumulative daily converted Morphine equivalent consumption or total consumption.
Conclusion
We found similar results between PAI and ACB using Exparel after TKA up to 48 hours.
