The reduced local anesthetic requirement is of particular advantage in patients who are discharged home with a nerve block catheter in situ as the supplied reservoir of local anesthetic will last longer. Ambulatory infusion pumps with both PIB and PCA features are now commercially available. The investigators hypothesize that a PIB+PCA dosing regimen using one of these new ambulatory infusion pumps will provide more effective postoperative analgesia with less local anesthetic consumption than the CI+PCA dosing regimen.