1. Any persons unable to consent, will not be eligible

2. Patients undergoing revision arthroplasty or reverse shoulder arthroplasty

3. Proximal humerus fractures

4. Inability to have interscalene anesthetic catheter placement

5. Compromised baseline renal function (CrCl \< 50)

6. BMI \> 40

7. History of GI bleed, prior duodenal surgery, or gastric sleeve resection

8. Current narcotic use or prior consistent narcotic exposure in the last 6 months

9. Use of perioperative oral steroid medications

10. Active Workman's compensation claim

11. Prior shoulder arthroplasty on the contralateral side in which an interscalene catheter was used

ZYNRELEF vs Continuous Catheter for Pain Management Following Shoulder Arthroplasty