Comparison of Ultrasound-Guided Anterior and Posterior Approaches to Sciatic Nerve Block for Lower Limb Surgeries: A Randomised Clinical Study

Abstract

Introduction: Sciatic nerve block is used for anaesthesia and analgesia in lower limb surgeries. The anterior approach to the sciatic nerve is rarely performed due to unreliable anatomical surface markings. Aim: To compare the anterior and posterior approaches to sciatic nerve block in terms of patient comfort and technical difficulty. Materials and Methods: This randomised clinical study was conducted at the Department of Anaesthesiology, BLDE (Deemed to be University) Shri BM Patil Medical College, Hospital and Research Centre, Bijapur, Karnataka, India. A total of 84 patients who underwent lower limb surgeries from November 2020 to August 2022 were included. Informed consent was obtained, and patients were randomised into two groups-Group-A and Group-P-using the card method. Ultrasound-guided sciatic nerve block was performed using the anterior approach in Group-A and the posterior approach in Group-P. Sensory and motor blockade, time to perform the block, number of attempts, duration of analgesia, and patient satisfaction were recorded. Statistical analysis was performed using the Chi-square test, Analysis of Variance (ANOVA), student t-test, and the results were represented in tables. Results: The median age in Group-A was 42.95±12.69 years, and in Group-P was 43.95±8.68 years. Males were higher in number with 26 (31%) in Group-A and 23 (27%) in Group-P, respectively. Patient satisfaction, duration of analgesia (10.3±3.5 years Group-P and 10.5±4.0 years Group-A), onset of sensory (11.85±7.35 years Group-P and 9.53±5.40 years Group-A), and motor blockade (18.67±7.05 years Group-P years and 17.82±5.70 years Group-A) were similar in both groups. The number of attempts (2.85±0.90 years Group-P and 3.05±0.91 years Group-A) and time taken for performing the sciatic nerve block (6.75±1.10 years Group-P and 7.44±1.00 years Group-A) was higher in the anterior approach compared to the posterior approach. Conclusion: Although both approaches to sciatic nerve block are equally effective, this study concludes that the posterior approach is simpler to perform, requires less time, and provides better patient comfort and satisfaction. Ultrasound-guided posterior sciatic nerve block offers effective anaesthesia and excellent post-operative analgesia.

Keywords

• beck’s anterior approach
• labat’s posterior approach
• peripheral nerve block
• regional anaesthesia