40 patients with knee osteoarthritis undergoing primary total knee arthroplasty (TKA) were randomized to receive post-operative administration of local infusion analgesia (LIA) or saline using a double lumen catheter. The purpose of this study was to evaluate the effectiveness and safety of this modified LIA for pain relief following TKA procedures. Results indicated that the modified LIA administration technique used in this study safely reduced pain following TKA, resulted in significantly lower serum C-reactive protein (CRP) levels, and significantly more patients treated with modified LIA could perform a straight leg raise on post-operative day 2. There were no significant between-group differences in mean fentanyl consumption or range of motion at any time point.