Postoperative pain monitor after total knee replacement.

Aim of this work was to study the postoperative pain within the first week of a total knee replacement by comparing three different forms of administration of analgesia. We proposed to verify the correspondence between a subjective pain assessment made by the patient on a Visual Analogic Scale (VAS) and an objective assessment made by assaying the serum algogenic cytokines interleukin-1 (IL1), interleukin-6 (IL6), and tumor necrosis factor-alpha (TNF-alpha). Statistical analysis of the data on the VAS and the three cytokine assays done preoperatively and on the third and seventh days postoperatively showed that while the VAS declined progressively postoperatively, IL6 tended to be higher on the third postoperative day and then lower on the seventh. The other two cytokines showed no differences preoperatively and postoperatively. On the basis of our results, we support the validity of IL6 dosage to monitor the postoperative pain during future studies.