For the continuous block: The catheter will be introduced and advanced 2-3 cm beyond the tip of the needle under ultrasound visualization. The needle was withdrawn over the catheter. Injection of a bolus of 5 ml of ropivacaine 0.5% will take place through the catheter while observing the spread of local anesthetic under ultrasound. The catheter hub will be affixed to the upper lateral thigh with sterile occlusive dressings and an anchoring device.