Continuous Adductor Canal Infusion vs. Single-injection Adductor Canal Block for Total Knee Arthroplasty

The study compares the effect of two multimodal analgesia protocols, the one integrating IVPCA morphine with single-injection adductor canal block and the other integrating continuous adductor canal infusion with timely administered intravenous tenoxicam, on postoperative analgesia and functional activity after TKA. To assess the outcome of both modalities, The investigators can have more comparative result of pain score and other functional parameters like range of motion of knee joint and muscle strength. Based on that, the investigators try to find a better multimodal analgesic approach for postoperative analgesia and functional recovery for patients receiving TKA in Taiwan. The investigators hypothesize that multimodal analgesia using continuous adductor canal infusion and intravenous tenoxicam are as effective as another modality using IVPCA and single-injection adductor canal block for postoperative pain relief after TKA surgery. However, continuous adductor canal infusion integrated with intravenous tenoxicam might reduce the occurrence of opioid-related side effect and enhance the functional recovery. Based on that, the investigators conduct this prospective, randomized controlled trial to examine our hypothesis.