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

Multimodal analgesia (MMA) has been endorsed to improve postoperative analgesia and functional activity after surgery, and integrating regional analgesia to reduce the consumption of opioid has also been used in postoperative pain management. The investigator try to find a better combination of MMA for postoperative analgesia and functional recovery for patients receiving TKA in Taiwan, therefore the effect of single-injection and continuous infusion of peripheral nerve block is compared in patient undergoing unilateral TKA. The investigators hypothesize that continuous adductor canal infusion is as effective as single-injection adductor canal block for postoperative pain relief under intravenous PCA after TKA surgery. Based on that, the investigators conduct this prospective, randomized controlled trial to examine our hypothesis.

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.

Eligibility Criteria:
Inclusion Criteria

* Clinical diagnosis of knee osteoarthritis
* Must be aged between 20 to 90 years old
* Must be scheduled for unilateral total knee arthroplasty surgery
* Must agree to enroll into the clinical trial and have signed the written informed consent

Exclusion Criteria:

* American Society of Anesthesiologists physical status class IV-V
* Elevated liver enzymes or liver failure
* Renal dysfunction (serum creatinine level ≥ 1.5 mg/dL)
* Cardiac failure
* Organ transplantation recipient
* Stroke
* Major neurological deficit with lower extremity muscle weakness
* Sensory and motor disorders in lower limb
* Coagulopathy or thrombocytopenia
* Previous drug dependency
* Patients who used illicit drugs within six months
* Chronic use of opioids
* Allergy to local anesthetics and drug used in experiment
* Inability to walk independently
* Inability to comprehend pain assessment
* Refusal for implanting a continuous peripheral nerve catheter
* Refusal for enrolling in study