Fifty-six patients with ASA I–II status scheduled for unilateral primary TKA were randomized to receive intravenous dexmedetomidine 0.5 µg/kg plus ACB with levobupivacaine (n=28) or perineural dexmedetomidine 0.5 µg/kg added to levobupivacaine in the ACB with intravenous saline (n=28). The primary outcome was shivering incidence 1 hour after spinal anesthesia. Secondary outcomes included shivering severity, hemodynamics, pain scores at rest and with movement, duration of postoperative analgesia, rescue analgesic use, and sedation scores over 24 hours. Overall, the results revealed equal intraoperative shivering incidence (50%) but lower postoperative shivering and greater sedation with intravenous dosing, whereas perineural dosing produced faster sensory block onset, longer analgesia, lower pain scores, and reduced opioid use. In short, perineural dexmedetomidine as an ACB adjuvant improved postoperative analgesia but offered less postoperative shivering control than intravenous dexmedeto