A randomized double-blind clinical trial was performed. There were 4 groups according to catheter placement and infusion constituents: 1) Intraarticular catheter + anesthetics; 2) Intraarticular catheter +placebo; 3) Subfascial catheter + anesthetics; 4) Subfascial catheter + placebo. The anesthetics infusion contained bupivacaine (bolus + continuous perfusion up to 36 hours). The placebo solution consisted in physiological serum (bolus + continuous perfusion up to 36 hours). Randomization was performed in the hospital pharmacy and the surgeon kept out the surgical field when the resident placed the catheter. The same conventional analgesic schedule was prescribed to all patients: PCA (patient controlled analgesia) + paracetamol 1g/6h + dexketoprofen 50mg/12h. The pain was evaluated by means of PCA (patient controlled analgesia) shots and the VAS (visual analog scale). Side effects, time to start rehabilitation and time to discharge were also analyzed. A statistical analysis was performed to compare all this variables between the 4 groups (SPSS 18.0).

Inclusion Criteria:

• Primary total Hip Replacement

Exclusion Criteria:

• Allergic to Bupivacaine