Dexmedetomidine in Spinal Anesthesia for Orthopedic Surgery: Extending Analgesia Beyond the Operating Room

Abstract

Spinal anesthesia is widely used in total knee arthroplasty (TKA) because it provides reliable block characteristics and favorable perioperative outcomes. However, a key limitation is the relatively short duration of local anesthetics, which may require additional analgesia or a switch to general anesthesia. To address this, intrathecal adjuvants are used to extend the duration of the block and enhance postoperative pain management. Dexmedetomidine, a highly selective α₂-adrenergic agonist, has demonstrated sedative and analgesic properties without respiratory depression, making it an attractive alternative to opioids such as fentanyl. In this case series, 10 µg of intrathecal dexmedetomidine was combined with ropivacaine in 20 patients undergoing TKA. Outcomes assessed included onset and regression of sensory and motor block, postoperative pain scores, and hemodynamic stability. Dexmedetomidine produced a rapid block onset, extended sensory block lasting up to 12 hours in some patients, and a predictable pattern of motor regression. Postoperative analgesia was favorable, with most patients remaining pain-free for the first six hours and reporting only mild discomfort at 12 hours. Hemodynamic changes observed included reductions in heart rate (HR) and mean arterial pressure (MAP), with some patients requiring vasopressor support, though no serious adverse events occurred. Our findings align with randomized controlled trials (RCTs) and meta-analyses indicating that intrathecal dexmedetomidine extends block duration, reduces the need for postoperative analgesics, and offers a favorable efficacy and side-effect profile compared to fentanyl. This case series adds to the existing body of evidence by presenting real-world clinical data on the use of intrathecal dexmedetomidine as an adjuvant to ropivacaine in elderly patients undergoing TKA. It demonstrates the adjuvant’s safety, hemodynamic stability, and analgesic effectiveness in a routine hospital setting, supporting the applicability of findings from controlled trials to everyday anesthetic practice. Further large-scale studies are needed to refine dosing strategies and evaluate long-term outcomes in orthopedic populations.