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

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 ml of normal saline, group II patients received 150 µg of clonidine in 20 ml of normal saline and group III patients received 20 ml 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 µg 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.