Oxycodone Versus Intravenous Morphine for Postoperative Analgesia After Hip Surgery

Inclusion Criteria: * The patient must have given his/her informed and signed consent * The patient must be insured or beneficiary of a health insurance plan * The patient is available for a 4 month follow-up * The patient weight between 50 and 100 kg * Patient scheduled for unilateral hip arthroplasty * Patient has creatinine clearance \> 50 ml/min (Cockroft) * Patient with ASA-PS score of 1, 2 or 3 (American Society Anesthesiology - Physical Status) Exclusion Criteria: * The patient is participating in another study * The patient is in an exclusion period determined by a previous study * The patient is under judicial protection, under tutorship or curatorship * The patient refuses to sign the consent * It is impossible to correctly inform the patient * The patient is pregnant, parturient, or breastfeeding * Patient with ASA score of 4 * Patient has a known deficit in cytochrome P450 * Uncontrolled epilepsy * Chronic alcoholism * Patient already taking opiate agonist on a long term basis (codeine, dextromoramide, dihydrocodeine, oxycodone po, morphine-like antitussif) * Patient already taking agonist-antagonists on a long term basis (buprenorphine, nalbuphine, pentazocine) * The patient is under treatment for liver inducing enzyme cytochrome P450: anti-infectives (e.g. rifampicin, rifabutin, nevirapine, griseofulvin), antiepileptic (phenobarbital, phenytoin) * the patient has an allergy to opiates * the patient has chronic renal insufficiency: creatinine clearance \< 50 ml / min (Cockroft formula) * the patient has severe hepatic insufficiency(transaminase and/or alkaline phosphatase x 3/nal)) * patient with porphyria, intracranial hypertension, a syndrome subocclusive or ileus