In this prospective, comparative, randomized, double blinded, placebo controlled trial, we propose to provide standard therapy for both groups of patients, consisting of interscalene block with 16 ml of standard 0.5% bupivacaine, as well as propofol infusion to provide general anesthesia in the operating room and low doses of ketamine for analgesia. In addition, half of the patients will receive an injection of 266 mg liposomal bupivacaine (FDA approved dosage) into the subacromial space and peri-articular tissues at the end of surgery. The other half of the patients will receive an injection of an inert solution of comparable volume into the peri-articular tissues at the conclusion of surgery (control group).