Shoulder replacement surgery is recognized as having the potential to cause a considerable amount of postoperative pain. Adequate management of pain after surgery is necessary not only to improve the patient's wellbeing but also to facilitate recovery. Several regional anesthesia techniques are available to combat postoperative pain in the shoulder replacement surgery patient, however, which method provides superior pain relief remains unknown. The purpose of this study is to examine the effectiveness of a continuous interscalene block versus a single shot interscalene block for postoperative pain relief in the shoulder replacement patient.

Patients undergoing shoulder replacement surgery will experience more effective pain relief with a continuous interscalene block versus and single shot interscalene block.

This is a prospective randomized controlled trial. 76 patients receiving either primary total shoulder replacement, hemiarthroplasty, or reverse total shoulder replacement will be randomized to a regional anesthesia technique as part of their surgical procedure. 38 patients will receive a single shot interscalene block containing ropivicaine and 38 patients will receive a continuous interscalene block containing ropivicaine.

Inclusion Criteria:

• Surgical candidate for primary total shoulder replacement, hemiarthroplasty, or reverse total shoulder replacement
• patient must be 18 years or older and willing to sign and date an Institutional Review Board informed consent form, and
• must be able to understand and agree to follow study protocol.

Exclusion Criteria:

• severe bronchopulmonary disease,
• oxygen dependent,
• existing nerve injury,
• BMI > 40,
• coagulation disorders,
• allergy to ropivicaine,
• history of drug or alcohol abuse,
• American Academy of Anaesthesiologists physical status classification > lll,
• pregnant women.