Previous studies suggest that an automated periodic infusion (API) regimen is superior to CI. It seems that an API produces better pain control, a lower analgesic consumption over time and less motor inhibition. This is well-described for epidural catheters for laboring women, but evidence is also apparent in PRA. Adding a PCA bolus option to a catheter-based nerve block treatment may even out the difference in pain scores between API and CI. However, it seems that API groups require less LA via PCA function. Reducing LA consumption is of great importance for ambulatory patients whose LA reservoir is limited, but also for all other orthopedic patients whose motor block should be minimized in order to optimize rehabilitation.