Comparative Evaluation Of 0.25% Levobupivacaine with and Without Dexmedetomidine for Ultrasound-Guided Adductor Canal Block In Postoperative Analgesia for Knee Surgeries: A Randomized Controlled Trial

Abstract

Background: The Adductor Canal Block (ACB) is an effective regional anesthesia technique for managing postoperative pain following knee surgeries. It provides sensory analgesia while preserving quadriceps motor function. Levobupivacaine, a commonly used local anesthetic, offers a moderate duration of pain relief. Dexmedetomidine, an alpha-2 adrenergic receptor agonist, has the potential to prolong the duration of nerve blocks. Therefore, perineural administration of dexmedetomidine may enhance the quality and duration of analgesia when used as an adjuvant.

Objective: To compare the efficacy and duration of postoperative analgesia using 0.25% levobupivacaine alone versus 0.25% levobupivacaine combined with dexmedetomidine (0.5 micrograms per kilogram) for Adductor Canal Block (ACB) in patients undergoing Total Knee Replacement (TKR) or knee arthroscopy.

Methods: In this prospective, double blind, randomized study, 60 ASA I–II adults scheduled for elective unilateral knee surgery under spinal anaesthesia were allocated to Group L (20 mL levobupivacaine 0.25%) or Group LD (20 mL levobupivacaine 0.25% + dexmedetomidine 0.5 mg/kg-1). Primary outcome was time to first rescue opioid (NRS > 3). Secondary outcomes included pain scores (NRS 0–10) at predefined intervals, haemodynamics, opioid consumption, and adverse events.

Results: Baseline demographics were comparable between groups. Median (IQR) time to first rescue analgesia was significantly longer in Group LD for both TKR [7.7 (6.0–9.0) h vs 6.3 (5.0–7.5) h; p = 0.036] and arthroscopy [11.3 (9.3–12.5) h vs 8.6 (7.1–10.0) h; p < 0.001]. Group LD demonstrated lower NRS scores from 4 h to 12 h post block (all p < 0.05). Total 24 h morphine requirement was reduced by 29% in Group LD. Haemodynamic variables remained within 20% of baseline; systolic blood pressure was modestly lower in Group LD at 2–6 h. No hypotension, bradycardia, nausea, vomiting, or neurological deficits were recorded.

Conclusion: Addition of 0.5 µg kg⁻¹ dexmedetomidine to levobupivacaine for ACB significantly prolongs analgesia and decreases opioid consumption without compromising haemodynamic stability or increasing adverse effects. Dexmedetomidine enhanced ACB represents an effective component of multimodal analgesia after knee surgery.