Impact of adductor canal block vs. femoral nerve block for postoperative analgesia in total knee arthroplasty

Background: Patients undergoing Total Knee Arthroplasty (TKA) benefit from peripheral nerve blocks as a part of multi-modal analgesia. Femoral Nerve Block (FNB) and Adductor Nerve Block (ACB) are very common blocks used in postoperative analgesia. We compared the impact of the two nerve blocks on the postoperative analgesia in total knee arthroplasty under spinal anesthesia. Method: This prospective double blind randomized controlled trial evaluated 60 patients, ASA PS I and II, randomized either to receive a single shot ACB (Group A, n = 30) or FNB (Group B, n = 30) for postoperative analgesia following TKA in reducing postoperative morphine consumption. Both groups also received infiltration of the local anesthetic by the operating surgeon. Total morphine consumption during first 24 h postoperatively, and pain scores at rest and on flexion of the knee joint at 6, 12, 18 and 24 h were recorded in both groups. Results: Mean morphine consumption at 24 h in Group A and B was 3 mg and 2.75 mg respectively. There was no difference statistically (P = 0.994). Mean pain scores at rest and on knee flexion at specified intervals of 6, 12, 18 and 24 h were statistically not different. Time to initial ambulation in Group A and B was 238.3 and 406.6 min (P = 0.015), and it was significantly prolonged in Group B. Conclusion: The results of this study conclude that adductor nerve block is an effective pain relief technique with comparable opioid sparing effect and with minimal quadriceps weakness and decreased time to early initial ambulation when compared to femoral nerve block, as a part of multimodal analgesia, in knee arthroplasty under spinal anesthesia. It offers good patient satisfaction and early ambulation. Abbreviations: ACB: Adductor Nerve Block, FNB: Femoral Nerve Block, NRS: Numerical Rating Scale, PACU: Post Anesthesia Care Unit, PCA; Patient Controlled Analgesia, TKA: Total Knee Arthroplasty, Citation: Venkatesan S, Mallik M, Mohammed S, Narayan P, Adeel S. Impact of adductor canal block vs. femoral nerve block for postoperative analgesia in total knee arthroplasty. Anaesth. pain intensive care 2025;29(2):40-46. DOI: 10.35975/apic.v29i2.2721 Received: July 30, 2024; Reviewed: August 12, 2024; Accepted: August 12, 2024