40 patients undergoing arthroscopic acromioplasty were randomized to receive continuous catheter infusion with ropivacaine through either an interscalene or subacromial catheter site. This study evaluated the efficacy of two different catheter sites for local anesthetic infusion to provide pain relief following arthroscopic acromioplastty. The results from this study indicated that use of an interscalene infusion was superior when compared to subacromial infusion for pain relief at rest, during motion, and throughout the night; these measures were assessed during a 43 hour period post-operatively.