Analgesic effect of continuous adductor canal block versus continuous femoral nerve block for knee arthroscopic surgery: a randomized trial

BACKGROUND AND OBJECTIVES: Anterior cruciate ligament reconstruction (ACLR) is one of the most frequently performed orthopedic procedures. The ability to perform ACLR on an outpatient basis is largely dependent on an effective analgesic regimen. The aim of the study was to compare the analgesic effect between continuous adductor canal block (cACB) and femoral nerve block (cFNB) during arthroscopy guided ACLR. METHOD: In this prospective, randomized, controlled clinical trial, 60 ASA I/II patients for arthroscopic ACLR were recruited. Patients in Group I received cACB and those in Group II cFNB. A bolus dose of 20 cc 0.5% levobupivacaine followed by 0.125% 5 mL.h(-1) was started for 24 hours. Rescue analgesia in the form of paracetamol 1 g intravenous (IV) was given. Parameters assessed were time of first rescue analgesia, total analgesic requirement in 24 hours, and painless range of motion of the knee (15 degrees of flexion to further painless flexion). RESULTS: The time-to-first postoperative analgesic request (hours) was earlier in Group II (14.40 ± 4.32) than Group I (16.90 ± 3.37) and this difference was statistically significant (p < 0.05). The cumulative 24-h analgesic consumption (paracetamol in g) was 0.70 ± 0.47 in Group I and 1.70 ± 0.65 in Group II (p < 0.001). The painless range of motion (degree) was 55.67 ± 10.40 in Group I and 40.00 ± 11.37 in Group II (p < 0.001). CONCLUSION: The findings of this study suggest that continuous adductor canal block provides superior analgesia in patients undergoing arthroscopic ACLR when compared to continuous femoral nerve block.