Intraoperative landmark-based genicular nerve block versus periarticular infiltration for postoperative analgesia in total knee arthroplasty: a randomized non-inferiority trial.

Introduction: Genicular nerve blocks (GNBs) are an emerging technique that have been used as a part of multimodal analgesia for total knee arthroplasty. The efficacy of intraoperative landmark-based GNBs, a recently introduced technique, has been established. We hypothesized that it would provide non-inferior postoperative analgesia compared with periarticular infiltration (PAI) when combined with continuous adductor canal block.

Methods: This study randomized 140 patients undergoing total knee arthroplasty to receive either intraoperative landmark-based GNB (GNB group) or PAI (PAI group), with 139 completing the study. The primary outcomes were the pain scores at rest and during movement at 12 hours postoperatively on an 11-point Numerical Rating Scale; the non-inferiority margin was 1. Pain scores at additional time points, intravenous morphine consumption, time to first rescue analgesia, functional performance and muscle strength tests, and sleep disturbance were also assessed.

Results: At 12 hours postoperatively, the PAI and GNB groups had median resting pain scores of 0 (0-2) and 0 (0-2), respectively. The median difference was 0 (95% CI -0.4 to 0.4, p=1), with the 95% CI upper limit below the prespecified non-inferiority margin. The median pain score during movement was 1.5 (0-2.3) and 2 (1-3.1) in the PAI and GNB groups, respectively. The median difference was 0.9 (95% CI 0.3 to 1.6, p=0.004), failing to demonstrate non-inferiority. The GNB group had higher intravenous morphine consumption at 12 hours postoperatively and a shorter time to first rescue analgesia.

Conclusions: GNB compared with PAI provides non-inferior resting pain relief. Non-inferiority was not established for pain during movement.

Trial registration number: TCTR20220406001 (www.thaiclinicaltrials.org).