Comparison of Ultrasound-Guided Adductor Canal Block Versus Femoral Nerve Block for Postoperative Analgesia in Total Knee Arthroplasty

Background: Total Knee Arthroplasty (TKA) is a procedure that causes a great deal of postoperative pain which can hinder early mobilization and functional recovery. Femoral Nerve Block (FNB) has been for many years been utilized for postoperative pain relief, but may be associated with some weakness of the quadriceps muscle that can impede early mobilization. The Adductor Canal Block (ACB) has proven to be an alternative that is motor-sparing, and may allow for adequate postoperative pain management without sacrificing muscle function. Ultrasound guided Adductor Canal Block is as effective as Femoral Nerve Block for Postoperative Analgesia after Total Knee Arthroplasty. Hypothesis Testing: A comparison between Ultrasound guided Adductor Canal Block and Femoral Nerve Block for Postoperative Analgesia following Total Knee Arthroplasty. Material and Methods: This prospective randomized comparative study compared 80 patients who had unilateral TKA under spinal anesthesia. The patients were randomly divided into two groups: Group A (ACB) received ultrasound-guided Adductor Canal Block (20 mL of 0.25% bupivacaine) and Group F (FNB) received ultrasound-guided Femoral Nerve Block (20 mL of 0.25% bupivacaine). The Visual Analogic Scale (VAS) was used for the assessment of postoperative pain. Secondary outcomes were: 24-hour opioid consumption, quadriceps strength, time to ambulation, hospital stay, patient satisfaction, and adverse events. Results: Demographic and baseline characteristics were comparable between groups (p>0.05). VAS pain scores at 6, 12, 24, and 48 hours postoperatively were similar in both groups (p>0.05). Twenty-four-hour morphine consumption was comparable between Group A and Group F (12.8±4.3 mg vs. 13.4±4.7 mg; p=0.56). Quadriceps muscle strength was significantly better preserved in the ACB group (4.3±0.6 vs. 2.9±0.8; p<0.001). Patients receiving ACB achieved earlier ambulation (18.2±3.1 h vs. 26.7±4.5 h; p<0.001) and had a shorter hospital stay (4.2±0.9 days vs. 5.1±1.1 days; p=0.002). Patient satisfaction scores were comparable between groups. Conclusion: Ultrasound-guided Adductor Canal Block provides postoperative analgesia comparable to Femoral Nerve Block while preserving quadriceps strength and facilitating earlier ambulation after TKA. ACB may therefore be preferred as part of enhanced recovery protocols.

Keywords: Adductor Canal Block, Femoral Nerve Block, Total Knee Arthroplasty, Postoperative Analgesia, Ultrasound Guidance.