All popliteal blocks will be performed preoperatively by 1 of 4 staff anesthesiologists with substantial expertise in both peripheral nerve localization techniques. Patients will be in the supine position with a bolster below the calf keeping the tibia parallel to the floor. This allows placement of the ultrasound probe in the popliteal region in the ultrasound group. An ultrasound machine and a nerve stimulator will be set up in both groups and the patient will be blinded on the technique used for nerve localization. The ultrasound machine will be turned on and placed perpendicular to the anesthesiologist performing the block on the opposite side of the leg being blocked. The nerve stimulator will be turned on and a grounding lead place on the side of the leg being blocked for both groups. The anesthesiologist performing the block will be given the allocation only after the set up of both systems and just prior to commencement of the block. The patient will be sedated with 2-5mg midazolam and 50-200 ug fentanyl to achieve anxiolysis while maintaining verbal contact. A screen will be set up to prevent the patient or the person assessing the block from seeing the block or the ultrasound screen.