Adductor canal block combined with local infiltration analgesia with morphine and betamethasone show superior analgesic effect than local infiltration analgesia alone for total knee arthroplasty: a prospective randomized controlled trial

BACKGROUND: Local infiltration analgesia (LIA) and adductor canal block (ACB) provide postoperative analgesia for total knee arthroplasty (TKA). ACB blocks the saphenous nerve and has smaller impacts on quadriceps muscle weakness. ACB theoretically does not have enough analgesic effects on posterior sensory nerves. LIA may increase its analgesic effects on the posterolateral knee. The purpose of this study was to evaluate whether ACB combined with a LIA cocktail of ropivacaine, morphine, and betamethasone has superior analgesic effect than LIA for TKA. METHODS: A total of 86 patients were assessed for eligibility from February 2019 to May 2019. 26 of those were excluded, and 60 patients were divided into 2 groups by computer-generated random number. Group A (LIA group) received LIA cocktail of ropivacaine, morphine and betamethasone. Group B (LIA+ ACB group) received ultrasound-guided ACB and LIA cocktail of ropivacaine, morphine and betamethasone. Postoperative visual analogue scale (VAS) resting or active pain scores, opioid consumption, range of motion (ROM), functional tests, complications and satisfaction rates were measured. The longest follow-up was 2 years. RESULTS: Two groups have no differences in terms of characteristics, preoperative pain or function (P > 0.05). ACB combined with LIA had significantly lower resting and active VAS pain scores, better ROM, better sleeping quality and higher satisfaction rates than LIA alone within 72 h postoperatively (P < 0.05). Complications, or adverse events and HSS score, SF-12 score were observed no significant differences within 2 years postoperatively. CONCLUSIONS: Adductor canal block combined with Local infiltration analgesia provide better early pain control. Although the small statistical benefit may not result in minimal clinically important difference, Adductor canal block combined with Local infiltration analgesia also reduce opioid requirements, improve sleeping quality, and do not increase the complication rate. Therefore, Adductor canal block combined with Local infiltration analgesia still have good application prospects as an effective pain management for total knee arthroplasty. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR1900021385, 18/02/2019.