Introduction and purpose: In this study we present the comparative results of two prospective studies carried out on 236 patients, treated with 5 different types of intravenous analgesia after knee arthroplasty, with the aim of detecting any differences.

Materials and methods: We designed 5 different analgesia protocols that were approved by the Ethics Committee of our Hospital. Protocol A: Tramadol and Ketorolac. Protocol B: Meperidine and Ketorolac. Protocol C: PCA pump administration of Morphine Chloride and Magnesium Metamizol Protocol D: Tramadol and Dexketoprofen Trometanol Protocol E: Meperidine and Dexketoprofen Trometanol. We measured the following variables at 6, 24 and 48 hours: VAS (visual analog scale), nausea and vomiting as well as the rescue medication used, time to walking, patient satisfaction and hospital stay.

Results: The 236 patients were distributed in groups of 40, except for group C in which there were 38 patients. Forty patients were lost to follow-up or did not comply with the inclusion criteria. With dexketoprofen trometanol associated with an opioid – tramadol or meperidine- pain control was satisfactory, whereas in the other 3 groups during the first 6 hours analgesic control was insufficient; the differences found were statistically significant. With the addition of an antiemetic (metoclopramide) there was a decrease in nausea and vomiting. Hospital stay was also shorter in patients with protocols D and E.

Conclusion: On the basis of the data obtained in our study, we can conclude that dexketoprofen trometanol – in association with an opiate (tramadol or meperidine) is the NSAID of choice for intravenous analgesia after primary knee arthroplasty, since it shows good analgesic control, shortens hospital stays and has fewer secondary effects.