Effectiveness of Ultrasound-guided Adductor Canal Block for Postoperative Pain Management in below Knee Orthopaedic Surgeries: A Randomised Controlled Study

Abstract

Introduction: The sensory innervation below the knee is provided by the saphenous nerve and sciatic nerve. Drugs deposited in the Adductor Canal (AC) at the Adductor Hiatus (AH) level spread both proximally up to the mid-canal and distally to the popliteal fossa through the perivascular space. The Adductor Canal Block (ACB) is a newer technique by which both nerves can be blocked in a single procedure. Aim: To evaluate the efficacy of ACB for postoperative pain management in below knee surgeries. Materials and Methods: This randomised controlled study was conducted in a tertiary care hospital. A total of 81 patients with American Society of Anaesthesiologists (ASA) I and II physical status were randomly allocated to either group A (ACB) or group B (Control), scheduled for below knee orthopaedic surgery. Group A patients received a mixture of 40 mL of 0.125% bupivacaine and 8 mg dexamethasone in the AC at the hiatus level under ultrasound guidance. Group B patients received standard care for pain management. The duration of sensory and motor block, mean Visual Analogue Scale (VAS) scores, amount of opioid drug requirement, drug-related side-effects, and satisfaction scores were compared between the two groups. Data were presented as mean±Standard Deviation (SD) for continuous variables and frequency (%) for categorical data and were analysed using t-tests and Chi-square tests. Results: The mean age in group A was 42.9±13.5 years and in group B was 46.3±13.1 years. In group A, there were 30 males and 11 females, while in group B, there were 32 males and 8 females. The mean Body Mass Index (BMI) between group A and B was 27.4±3.2 kg/m2 and 26.3±3.1 kg/m2 , respectively. The mean duration of sensory block was longer in group A (12.3±4.6 hours) compared to group B (4.7±0.7 hours). The mean VAS scores (1.351±0.659 vs 3.240±0.590) were significantly lower in group A. The total opioid requirement was 42.9±73.6 mg vs 205.9±26.0 mg between the two groups, which was significantly lower in group A. Conclusion: In distal ACB, a single procedure with 40 mL of 0.125% bupivacaine significantly reduces postoperative VAS scores and analgesic requirements while increasing patient satisfaction levels. Therefore, this block is safe and recommended for postoperative pain management in below knee surgeries.