Continuous Infusion and Intermittent Bolus Adductor Canal Block for Total Knee Arthroplasty

The investigators believed the analgesic efficacy of adductor canal block on patients receiving total knee arthroplasty. However, the analgesic effects of different delivery regimens and duration of effects are variable. The investigators hypothesize that using continuous infusion and shorter interval bolus of local anesthetics to perform adductor canal block will reduce pain scale and opioid consumption in patients receiving total knee arthroplasty compared with longer interval bolus of local anesthetics.