Combination of Continuous Femoral Block and Intravenous Parecoxib For Postoperative Analgesia After Total Knee Arthroplasty

Inclusion Criteria: * PATIENTS ASA I-II UNDERGOING TOTAL KNEE ATRTHROPLASTY Exclusion Criteria: Exclusion criteria for both groups included: * Age younger than 40 years old or older than 80 years old * ASA \> III * Obesity (\>140 kg body weight) * Allergy to local anesthetics * History dependence on opioids * Contraindications for subarachnoid anesthesia or femoral block (coagulopathy, local infection, pre-existing neurological problems, patient refusal) * Contraindications to the administration of parecoxib * Severe hepatic or renal disease (serum creatinine ≥ 1.7 mg/dl)