Continuous versus single shot adductor canal block for postoperative pain relief after total knee arthroplasty: A protocol for randomized controlled trial

BACKGROUND: Adductor canal block has become a popular mode of pain management after total knee arthroplasty. This study compared a single-injection adductor canal block (SACB) with continuous adductor canal block (CACB). The hypothesis was that the 2 groups would have equivalent analgesia at 48 hours post-neural blockade. METHODS: This is a double-blinded, randomized, controlled, equivalency trial that is conducted at a single university hospital in China. A total of 60 patients who meet inclusion criteria are randomized in a ratio of 1:1 to either CACB (0.5% ropivacaine 20 mL followed by continuous infusion of 0.2% ropivacaine at 5 mL/h for 48 hours) or SACB (0.5% ropivacaine 20 mL) group. The primary outcome is pain scores at 48 hours utilizing the visual analog scale, whereas the secondary outcomes include opioid consumption, Timed Up & Go test, ambulation distances at discharge, length of stay, and maximal flexion at discharge. All pain scores are assessed by an independent observer who is blinded to the allocation of groups. RESULTS: This study has limited inclusion and exclusion criteria and a well-controlled intervention. This clinical trial is expected to provide evidence of better therapy for the pain management after total knee arthroplasty. TRIAL REGISTRATION: This study protocol was registered in Research Registry (researchregistry5431).