Specialty Anesthesia and Critical care: Res earch on efficiency of pain relief of patient controlled epidural analges IA with ropivacain or bupivacain combined fentanyl after hip replacement surgery in the elderly

Compare the analgesic and motor block effects of ropivacaine 0.1% - fentanyl 1 mcg/ml with bupivacaine 0.1% - fentanyl 1 mcg/ml in the patient controlled epidural analgesia after hip replacement surgery in the elderly.