Inflammatory response analysis will be performed on the first 15 patients in each group (for a total of 30 patients). Before awakening of the patient the surgeon will insert a microdialysis catheter in the fat adjacent to the surgical wound with sterile technique. The microdialysed liquid will be collected in dedicated tubes directly in the infusion pump. The sample of the first hour will be discarded to avoid that microtrauma of catheter positioning influences the study. Sampling will be performed every 6 hours the first day, and every 12 hours in the second and third day. Serum samples will be collected to compare systemic with regional samples. All samples will be stored at -80 ° C until sampling. Concentrations quantification of different cytokines will be analyzed by ELISA Parma Unit will analyze VNTR (variable number of tandem repeats) polymorphism of the ADRB2 gene, directly related to the risk of chronic persistent postoperative pain development; Pavia Unit will take care of genotyping of polymorphic sites in the following genes: OPRM1 (mu-opioid receptor 1), COMT (catecholamine O-methyl transferase), UGT2B7 (UDP-glucuronyl transferase), IL1Ra (interleukin 1receptor alpha). From the blood samples will be extracted DNA and RNA using standard procedures. RNA will be retained for possible future studies on the expression of genes of interest. The DNA will be used instead for the study of genetic polymorphisms.