Intraarticular analgesia after arthroscopic knee surgery: comparison of neostigmine, clonidine, tenoxicam, morphine and bupivacaine

We conducted a randomized, placebo-controlled, double blinded study to compare the analgesic effects of intraarticular neostigmine, morphine, tenoxicam, clonidine and bupivacaine in 150 patients undergoing arthroscopic knee surgery. General anaesthesia protocol was same in all patients. At the end of the surgical procedure, patients were randomized into six intraarticular groups equally. Group N received 500 μg neostigmine, Group M received 2 mg morphine, Group T received 20 mg tenoxicam, Group C received 1 μg kg⁻¹ clonidine, Group B received 100 mg bupivacaine and Group S received saline 20 ml. Visual analog scale scores 0, 30 and 60 min and 2, 4, 6, 12, 24, 48 and 72 h, time to first analgesic need, analgesic consumption at 48 h and 72 h and side effects were noted. Demographic and operational parameters were similar in six groups. All study groups provided analgesia when compared with saline group (P<0.05). Duration of analgesia in Group N and C was longer than other groups (P<0.001). Analgesic consumptions of Group N, C and T were lower than other groups (P<0.01). Pain scores during 2 h postoperatively were lower in all study groups than the control group (P<0.001). In Group B, median pain scores were higher than Groups N and C at 0 min and 30 min postoperatively (P<0.001). Side effects were not significantly different among the six groups. We conclude that the most effective drugs that are administered intraarticularly are neostigmine and clonidine among the five drugs we studied. Tenoxicam provided longer analgesia when compared with morphine and bupivacaine, postoperatively.