Comparison of USG guided adductor canal block vs femoral nerve block for post-operative pain management in total knee arthroplasty: A prospective randomised controlled study

Background: Total knee arthroplasty (TKA) is a markedly invasive surgical intervention associated with postoperative pain, which impedes early ambulation. Optimizing postoperative analgesia is paramount for facilitating enhanced functional recovery. This investigation endeavored to delineate the comparative efficacy of adductor canal block (ACB) versus femoral nerve block (FNB) in the analgesic management of individuals undergoing total knee arthroplasty (TKA). Materials and Methods: A total of 100 ASA grade I–II patients were randomized into two groups (n = 50): Group A received ultrasound-guided femoral nerve block, and Group B received adductor canal block. Both groups were given 15 mL of 0.2% ropivacaine prior to catheter insertion, followed by a continuous infusion at 8 mL/hr. Postoperative VAS scores, analgesia duration, adverse effects, anesthetic requirements, and sensory and motor block characteristics were recorded. Results: In this study, no statistically significant differences were observed between the groups regarding hemodynamic parameters, age, sex, ASA distribution. Group A demonstrated a faster onset of sensory block (7.77±1.27 min) and a shorter duration (510.79±97.60 min) compared to Group B (8.51±1.32 min; 615.64±102.85 min). Similarly, the onset of motor block was slightly shorter and its duration was longer in Group A (10.72±2.09 min; 579.5±92.10 min) relative to Group B (11.04±2.05 min; 565.32±92.78 min). However, the duration of analgesia was notably shorter in Group A (11.04±3.85 hours) compared to Group B (15.59±4.63 hours), accompanied by higher mean VAS scores in Group A. The overall incidence of adverse drug reactions was minimal (3.0%) and comparable between the two cohorts. Conclusion: The present investigation delineated that both adductor canal block and femoral nerve block conferred efficacious postoperative nociceptive attenuation in patients undergoing total knee arthroplasty. Nevertheless, there is motor sparing leading to early mobilization in patients with ACB when compared with FNB.