Prospective Evaluation of Interscalene Nerve Catheters vs. Single Injection Blocks

Inclusion Criteria: * American Society of Anesthesiologists (ASA) physical status 1-3 * 18-79 years of age, inclusive * body mass index of \< 36 kg/m2. * The ability to understand local anesthetic related complications and care of a CPNB * Presence of a caretaker with them during the first 24 hours of local anesthetic infusion, and on a daily basis. * The ability to communicate with the practitioner managing the catheter. * Residence within 2 hours of University of Wisconsin Hospital and Clinics Exclusion Criteria: * Any contraindication to a continuous interscalene catheter placement * Clinically significant pulmonary disease * Clinically significant cardiac disease * Allergy to ropivacaine * Peripheral or central nervous system disease * Current (or planned) anticoagulation therapy or disease * Local infection over area of catheter placement * Renal or hepatic failure * History of opioid dependence * Significant psychiatric disease * Pregnancy or lactation (Subjects will be asked if it is possible they could be pregnant. If a subject responds in the affirmative, a pregnancy test will be done.) * Seizure Disorder