Comparative Study of Morphine and Dexmedetomidine as Adjuvants to Bupivacaine in Ultrasound-Guided Adductor Canal Block for Postoperative Analgesia After Knee Surgeries

Knee surgeries are frequently performed operations that can lead to intense pain after the procedure (1). Early mobilization following knee surgery is associated with improved functional outcomes and a reduction in postoperative complications. As a result, achieving effective pain relief while preserving motor function is a primary goal in postoperative care for knee procedures (2).

A variety of strategies are employed for managing postoperative pain, including systemic opioid administration, epidural anesthesia, peripheral nerve blocks, and local infiltration of anesthetics (3).

However, systemic opioids are linked to several undesirable side effects such as nausea, vomiting, itching, sedation, and respiratory depression, which may hinder rehabilitation.

Similarly, epidural analgesia often results in complications like hypotension, urinary retention, and pruritus. The use of long-acting intrathecal opioids has also been associated with adverse events including bilateral motor blockade, tremors, and hypotension. Due to these issues, the reliance on systemic and intrathecal methods for postoperative pain control has been declining (4).

The adductor canal block (ACB), which targets the Hunter's canal, anesthetizes the saphenous and vastus medialis nerves, along with partial coverage of other sensory nerves like the femoral nerve, medial cutaneous nerve, and branches of the obturator nerve as they traverse the distal canal (5). ACB is largely considered a sensory block, affecting only the motor nerve to the vastus medialis, making it advantageous in preserving quadriceps strength during recovery (6, 7). Bupivacaine, a widely used long-acting amide local anesthetic, is frequently employed in peripheral nerve blocks such as the ACB due to its favorable pharmacokinetics.