Total knee arthroplasty (TKA) is a frequent performed surgery. Many institutions are implementing fast track programs for this surgery and adequate pain management is an important feature. Analgesic duration of single shot nerve blocks is limited to no more than 24h. Conversely, the use of continuous nerve block (CNB) through a perineural catheter and infusion of local anesthetic may increase duration of analgesia and provide better outcomes. The purpose of this study is to evaluate effectiveness and safety of using CNB in patients undergoing ambulatory TKA, and its effects on patients' quality of recovery. Investigators hypothesize that continuous adductor canal block would lead to decrease in opioid consumption in patients undergoing fast track TKA. Significance There are no published prospective randomized controlled trials to assess patient's reported quality of recovery after receiving CACB in same day primary knee arthroplasties. As this is a frequent type of surgery and has the prediction to increase its incidence for the next years, there is significant importance in investigations about interventions which may improve its recovery in a fast track regime. A postoperative analgesic technique that offers better pain control, has less adverse effects, reduces the opioid analgesia requirement and is safe to be used in a fast track setting may have additional impact on decreasing health care cost and may lead to an enhanced recovery and better quality of life. Objectives To evaluate effectiveness and safety of using CACB in patients undergoing ambulatory TKA, in comparison to SACB. Primary objective is opioid consumption (in oral morphine equivalent doses) Secondary objectives are to evaluate postoperative QoR-15 scores (10), pain scores, opioid-induced adverse effects (measured via validated opioid symptom distress scale), postoperative functional status, complications relating to the perineural catheter and readmissions.