Patients undergoing total shoulder arthroplasty commonly receive an interscalene block using ropivacaine to provide analgesia. To provide analgesia for up to 48 hours postoperatively, an indwelling catheter can be placed and a constant infusion of ropivacaine given. This is a safe and very effective technique for managing postoperative pain in this population. This procedure is associated with reduced need for narcotics and improved patient satisfaction. Side effects are uncommon and include catheter displacement and failure of the block. A consequence of this procedure is that it causes paralysis or weakness of the affected arm until the catheter is removed and the drug wears off.