Serum interleukin-6 response to elective total hip replacement surgery

The focus of this work was to study the serum interleukin-6 (IL-6) response to total hip replacement. Twenty-one patients received an uncemented total hip prosthesis. Venous samples for IL-6 determination were drawn before and after surgery. The IL-6 response was significant, and a peculiar heterogeneity of response was apparent: the medians of peak levels (82.3 pg/ml) and of areas under the response curve (51.8 pg/ml) distinguished between IL-6 high responders (HR) and IL-6 low responders (LR; p<0.0001). No difference was found in the gender composition of these groups, whereas the HR patients were older than the LR patients (p<0.05). The amount of IL-6 increase was found to correlate with patient age, whereas its slope was found to correlate with the duration of the surgical procedure. Moreover, the HR group presented a higher degree of hyperthermia in the days after surgery compared with the LR patients, without evidence of differences in postoperative complications, time to mobilisation, or length of stay in hospital. The main finding of our study was the evidence of a remarkable variability between individuals in the IL-6 response to surgery. Future studies are needed to identify the factors involved in the regulation of the cytokine response to surgery.