Eighty-seven patients undergoing a primary arthroscopic rotator cuff repair were randomized to receive a periarticular injection of liposomal bupivacaine and plain bupivacaine (n=42) or an interscalene block of plain bupivacaine (n=45). The outcomes of interest included opioid usage in oral morphine equivalents, pain on a Visual Analog Scale (VAS), clinical improvement on the Single Assessment Numeric Evaluation (SANE) scale, and cost. Outcomes were assessed up to 12 weeks post-operation. Results revealed significantly less pain and opioid use on the day of surgery in the interscalene block group, however at 1 and 2 days post-operation, opioid usage was significantly lower in the periarticular group. No significant differences in SANE scores at 12 weeks were observed. Peri-articular injection was $290 cheaper than interscalene block.