We will analyze A: the difference in consumption of local anesthetic in the two different groups B: the difference of "insensate limb" in the post-operative home as described by Ilfeld(inability to perceive the sense of touch throughout the area of distribution of the sciatic nerve) C: rate of foot drop D: numeric rate scale (NRS) for pain assessment, rate of dislodgment of the catheters, patient satisfaction, need for intervention by the anesthesiologist after discharge.