Tehran University of Medical Sciences Archives of Anesthesiology and Critical Care 2423-5849 9 Supp. 1 2023 07 19 375 379 Mehrdad Mokarram Dori Department of Anesthesiology and critical care medicine, Imam Reza Hospital, Mashhad University of Medical Science, Mashad, Iran. Fateme Dehghan Tafti Department of Anesthesiology and Critical Care Medicine, Imam Reza Hospital, Mashhad University of Medical Science, Mashad, Iran. Alireza Bameshki Department of Anesthesiology and Critical Care Medicine, Imam Reza Hospital, Mashhad University of Medical Science, Mashad, Iran. Maliheh Ziaee Department of Community Medicine, School of Medicine, Social Determinants of Health Research Center, Gonabad University of Medical Sciences, Gonabad, Iran. 2022 10 25 2023 01 15 Background: The aim of this study was to evaluate the effect of combined lumbar plexus – para sacral nerve block (LP/NB) and spinal anaesthesia (SA) on the duration and intensity of postoperative pain in patients with Tibia fracture requiring surgery. Methods: In this clinical trial, 40 patients with tibial fractures requiring surgery, who were admitted to a referral hospital in north-eastern Iran from 2020 to 2021, and randomly subjected to LP/NB or spinal anaesthesia. Pain intensity and duration of anaesthesia in the two groups were compared based on a numerical rating scale within 4, 6 and 12 hours from the induction of anaesthesia. Clinical demand for analgesics following surgery was also recorded. Data were statistically analysed with IBM SPSS. Results: The mean age of participants was 37.4 ±14.4, with 29 (72.5%) and 11 (27.5%) male and female patients, respectively. There were no significant differences in age and sex ratio between the two groups. The mean pain intensity within 4 hours from surgery was lower in the LP/NB group, however, this difference was not statistically significant (p-value: 0.054). Likewise, there were also no significant differences between the values reported for 6 (p-value: 0.303) and 12-hour (p-value: 0.523) post-surgery pain intensity for each group. Overall, the mean pain intensity at any given time was not significantly different between the two groups of LP/NB and SA (p-value: 0.671). Conclusion: There was no significant difference between the two groups in terms of mean pain intensity at 4, 6 and 12 hours after the onset of the block. No side effects were observed in any of the patients. https://aacc.tums.ac.ir/index.php/aacc/article/view/657