Tehran University of Medical Sciences Archives of Anesthesiology and Critical Care 2423-5849 10 3 2023 11 19 239 246 EN Moloud Zolfaqari Department of Anesthesiology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. Mehrdad Mokaram Dori Department of Anesthesiology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. Seyed Hossein Khademi Department of Anesthesiology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. Mehryar Taghavi Gilani Lung Diseases Research Center. Mashhad University of Medical Sciences, Mashhad, Iran. Maliheh Ziaee Department of Community Medicine, School of Medicine, Social Determinants of Health Research Center, Gonabad University of Medical Sciences, Gonabad, Iran. Tayyebe Ghanei Mashhad University of Medical Science, Mashhad, Iran. 2023 06 19 2023 07 25 Background: Perioperative pain management can improve surgery results and patient outcomes. Moreover, multimodal methods for pain control have been advised so this study was conducted to assess the beneficial impact of preoperative ultrasound-guided femoral nerve blocks in hip replacement surgery. Methods: This study is a double-blinded clinical trial including 60 individuals who were candidates for joint replacement surgery. The intervention group (n = 30) received a femoral nerve block prior to general anesthesia. Results: After surgery, patients received morphine, Apotel, and morphine + Apotel, all of which were administered at lower doses in the intervention group (femoral nerve block) than in the control group. Pain intensity in first hour (P= 0.01), 4 hours (P= 0.003), 8 hours (P= 0.01), 12 hours (P= 0.001), and 24 hours (P= 0.01) after surgery and average pain 4 hours (P= 0.01), 8 hours (P = 0.01), 12 hours (P = 0.02), and 24 hours (P= 0.01) after surgery was significantly less in the intervention group (femoral nerve block) than in the control group. Conclusion: The findings of our investigation demonstrated the efficacy of ultrasound-guided femoral nerve blocks in the improvement of pain control following hip replacement surgery.   https://aacc.tums.ac.ir/index.php/aacc/article/view/793