Femoral nerve versus adductor canal block for early postoperative pain control and knee function after anterior cruciate ligament reconstruction with hamstring autografts: a prospective single-blind randomised controlled trial

Introduction The optimal pain management strategy for postoperative pain after anterior cruciate ligament reconstruction (ACLR) remains unclear. This study compared femoral nerve block (FNB) and adductor canal block (ACB) for pain management of early postoperative pain, knee function, and recovery of activity of daily living (ADL) after ACLR using hamstring autografts. Material and methods In this prospective, single-blind, randomised controlled trial, 64 patients aged 12–56 years who underwent anatomical double-bundle ACLR with a hamstring autograft between August 2019 and May 2020 were randomised to undergo preoperative FNB ( n = 32) or ACB ( n = 32). The peripheral nerve block was performed by a single experienced anaesthesiologist under ultrasound guidance. The primary outcomes were postoperative pain as evaluated using the visual analogue scale (VAS) at 3, 6, 12, 24, and 48 h postoperatively and the need for pain relief. The secondary outcome was knee function, including the recovery of range of motion, contraction of the vastus medialis, and stable walking with a double-crutch (ADL), as evaluated by blinded physical therapists. Results There were no significant differences in patient demographics between the two groups. The VAS scores, need for pain relief, knee function, and ADL did not significantly differ between the groups. Conclusion FNB and ACB provided comparable outcomes related to early postoperative pain, knee function, and ADL after double-bundle ACLR using hamstring autografts. Further research is necessary to evaluate the mid- to long-term effect of each block on recovery of knee function and ADL. Level of evidence I.