Randomised Controlled Trial between Ultrasound Guided Femoral Nerve Block and Adductor Canal Block for Postoperative Pain and Functional Outcome in Anterior Cruciate Ligament Reconstruction

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Introduction: Femoral Nerve Block (FNB) is used as an adjunct to postoperative analgesia in Anterior Cruciate Ligament (ACL) reconstruction surgeries. However, it causes a reduction in quadriceps strength following use. To mitigate the loss in muscle function and patient safety, surgeons and anaesthesiologists have recently been exploring the potential benefits of a motor sparing Adductor Canal Nerve Blockade (ACB). To date, few comparative studies exist to determine its clinical utility. Aim: To compare the efficacy of femoral nerve block versus ACB for postoperative pain and functional outcome in patients undergoing ACL reconstruction. Materials and Methods: This prospective, randomised controlled trial was done after approval from Institutional Ethics Committee, Kasturba Medical College, Mangalore, Karnataka, India, 76 ASA Class 1 and 2 patients posted for ACL reconstruction, aged 18-60 years were chosen after consent and were randomised into two groups using computer-generated block randomisation. Group F received femoral nerve block and Group A received adductor canal block postoperatively. Visual analogue scale score at 0, 12 and 24 hours and Medical Research Council grading at 2, 12 and 24 hours post-block were measured and compared between both groups. Data analysis was done using student unpaired t-test, student paired t-test and chi-square test. Results: Visual analogue scale scores at 0, 12 and 24 hours postoperative was 2.29, 3.26 and 3.86 in Group A and 2.59, 3.61 and 4.49 in Group F (statistically non significant). Average time for rescue analgesia was 1 hour and 8 hours in Group A and F respectively. Medical research council grading 2, 12 and 24 hours postoperative was 2.6, 4.09 and 4.77 in Group A and 2.8, 3.15 and 4.05 in Group F (statistically significant). Conclusion: Compared with femoral nerve block, the study suggests that adductor canal block preserves quadriceps strength but is equianalgesic for patients undergoing anterior cruciate ligament reconstruction.