Intra-articular clonidine vs. morphine for post-operative analgesia following arthroscopic knee surgery (a comparative evaluation

In a prospective, double-blind, randomised study, 30 ASA I patients were allocated to three groups in an attempt to find out the best post-operative analgesic following arthroscopic knee surgery under epidural anaesthesia. Group I patients received 5 mg of preservative-free morphine in 20 mi of normal saline, group II patients received 150 mu g of clonidine in 20 mi of normal saline and group III patients received 20 mi of normal saline only. The post-operative pain was evaluated by a visual analogue scale and the need for rescue analgesic was assessed post-operatively for 12 h. We conclude that intra-articular administration of 150 mu g of clonidine gives a longer lasting pain relief post-operatively (4-12 h) as compared to 5 mg of preservative-free morphine (3 h). No side effects were noted with either of the drugs. (C) 2000 Elsevier Science B.V. All rights reserved.