Evaluation of Analgesic Efficacy of Ultrasound-Guided Adductor Canal Block With 20 mL of 0.5% Ropivacaine in Patients Undergoing Knee Surgeries-A Randomized Control Trial.

Background: Adductor canal block (ACB) is a motor sparing block providing analgesia for surgeries involving anterior part of the knee. The aim of our study was to evaluate the analgesic efficacy of ACB to reduce pain in arthroscopic knee surgeries done under spinal anesthesia. Our primary objective was to evaluate the 24 hours postoperative morphine consumption. The secondary objectives were to evaluate the visual analog scale (VAS) scores at rest and during knee flexion, hemodynamics and side effects of the block.

Methods: In this prospective randomised controlled trial, 70 patients who underwent arthroscopic knee surgeries were randomly divided into two groups, A and C. Surgeries were done under spinal anesthesia. Group A patients received ACB with 20 mL of 0.5 % ropivacaine using ultrasound postoperatively. Block was not performed in group C. The amount of morphine consumption in PCA pump, duration of analgesia, mean VAS scores at rest and flexion, hemodynamics and adverse effects were monitored.

Results: The average morphine consumption was significantly lesser with a P-value ＜ 0.001 in group A (8.628 ± 2.001 mg) when compared to group C (21.914 ± 5.118 mg). The duration of analgesia was longer in group A (365.71 ± 53.648 min vs. 150.429 ± 22.537 min) with highly significant P-value of ＜ 0.001. Group A patients had significantly decreased VAS scores at rest and knee flexion and better haemodynamic stability.

Conclusions: We conclude that ultrasound-guided ACB resulted in significantly lesser morphine consumption after arthroscopic knee surgeries. ACB prolonged the duration of analgesia with better hemodynamics, lesser VAS pain scores and with no complications.