Effect of intra-articular dexmedetomidine on postoperative analgesia after arthroscopic knee surgery

Alpha-2-adrenergic agonists have peripheral analgesic effects. We have assessed the potential analgesic effect of dexmedetomidine after intra-articular administration in arthroscopic knee surgery. Sixty patients undergoing arthroscopic knee surgery were randomly assigned into three groups in a double-blind placebo controlled study. The control group received i.v. and intra-articular saline, the intra-articular group received i.v. saline and intra-articular dexmedetomidine, and the i.v. group received i.v. dexmedetomidine and intra-articular saline. Haemodynamic changes, pain visual analogue scale (VAS), sedation score, the time to first postoperative analgesic request, and the total postoperative analgesic use during the first 24 h were evaluated. Dexmedetomidine administration resulted in a significant reduction in pain scores for 6 h after operation in the intra-articular group but only for 1 h in the i.v. group. The time to first postoperative analgesic request was longer in the intra-articular group [312.0 (sd 120.7) min] compared with the control group [71.0 (50.1) min] and the i.v. group [102.1 (54.4) min] (P