Analgesic efficacy of ultrasound-guided genicular nerve block in combination with adductor canal block in total knee arthroplasty: A randomised, double-blind, placebo-controlled trial

Background and Aims: Distal motor-sparing nerve blocks are increasingly popular for knee arthroplasty pain. Genicular nerve ablation, initially proposed for knee osteoarthritis, is also currently used for postoperative pain management. We hypothesised that superior postoperative analgesia can be achieved by combining genicular nerve block with adductor canal block (ACB) by reducing 24-hour opioid consumption. Methods: Fifty patients were assigned to Group I (ultrasound-guided ACB with 20 mL of 0.25% ropivacaine and 4 mg dexamethasone and ultrasound-guided superomedial (SM), superolateral (SL), and inferomedial (IM) GNB with 5 mL of 0.25% ropivacaine and 2 mg of dexamethasone at each location and Group II (ultrasound-guided ACB with 20 mL of 0.25% ropivacaine, 4 mg dexamethasone, and ultrasound-guided three-location GNB with 15 mL of 0.9% saline). The outcomes measured were 24-hour morphine consumption, pain scores over 24 hours, and the time to rescue analgesia. The continuous data were analysed using an unpaired t -test or the Mann-Whitney U test, and the Chi-square test was used to analyse the categorical variables. Results: The mean total consumption of morphine (mg) was 5.96 standard deviation (SD): 2.73 in Group I and 15.52 (SD: 2.67) in Group II, with a mean difference of 9.56 95% confidence interval (CI): -4.66, −2.39 ( P < 0.001, Cohen’s d = 3.54). In Group II, the mean time for first rescue analgesia was 20.73 (SD: 7.28) hours, whereas it was 24.00 (SD: 0.00) hours in Group I, with a mean difference of −3.27 (95% CI: −11.33, 4.783) ( P = 0.034, Cohen’s d = 0.45). Pain severity at rest was substantially lower in Group I at 6 hours ( P = 0.020), 12 hours ( P = 0.003), and 24 hours ( P = 0.002). Pain score with movement in Group I was considerably lower at 6 hours ( P = 0.008) and 12 hours ( P < 0.001). Conclusion: Combining genicular block with ACB provided superior postoperative analgesia and reduced opioid consumption compared to ACB alone.