Comparison of 3 Techniques for Ultrasound-guided Femoral Nerve Catheter Insertion

This is a randomized study which will compare three femoral nerve catheter insertion techniques. Subjects will be randomized into one of thee groups, Group 1: ultrasound guided femoral nerve catheter using a stimulation needle and stimulating catheter, .Group 2: ultrasound guided femoral nerve catheter using a stimulation needle, but non-stimulating catheter, or Group 3: ultrasound guided femoral nerve block without stimulation. * Pain Scores after surgery with be measured using the VAS (Visual Analogue Scale). Subjects will be asked to rate their pain on a scale of 1-10. * Block Performance time is the time from starting the block (after prepping and draping) until catheter is placed. * Opioid requirements will be measured as the total amount of opioids (converted to morphine sulfate equivalents) used both during surgery, and during the first 48 hours after surgery. * Block failure rate will be calculated as the rate of cases that requires repeating the block after surgery.