Background: Total knee arthroplasty (TKA) surgery is associated with severe postoperative pain. Currently, adductor canal block (ACB) is a widely used method to provide analgesia after TKA.

Objective: The primary objective was to study the analgesic efficacy of perineural dexmedetomidine with bupivacaine in ACB in patients undergoing TKA, and the secondary objectives were to investigate the ambulation ability and the side effects.

Methods: Sixty patients aged 18-85 years, ASA status I-III underwent primary, unilateral TKA under spinal anesthesia. They were randomized into two groups; Group C received 20 mL of 0.25% bupivacaine and Group D received 20 mL of 0.25% bupivacaine plus 0.5 mcg/kg dexmedetomidine for ACB. The time to first rescue analgesia, 24-hour morphine consumption, postoperative pain score, quadriceps strength, the Timed Up and Go (TUG) test, patient satisfaction, and adverse outcomes were assessed.

Results: The patient demographic and intraoperative data were comparable in both groups. The median time to first rescue analgesia (group C: 196 [89, 363], group D: 184 [105, 267], and P-value = 0.112), 24-hour morphine consumption (group C: 6.5 [4, 10], group D: 9 [3.25, 14.50] and P-value = 0.245) and postoperative pain score at rest and on movement (P-value = 0.829 and 0.888, respectively) showed no significant differences between groups. There were no significant differences in TUG test, quadriceps strength, adverse events, and patient satisfaction between groups.

Conclusion: The addition dexmedetomidine to bupivacaine was not better than single-shot ACB regarding postoperative analgesia and ambulation ability following TKA.