Effects of Catheter Location Relative to Femoral Artery on Postoperative Analgesia for Continuous Adductor Canal Blocks

Adductor canal (AC) nerve block is a commonly used modality for postoperative pain control after total knee arthroplasty (TKA). When the adductor canal is viewed by ultrasound, the femoral artery and femoral vein can easily be identified, however, the nerve that is to be blocked is often not visible. For this reason, the femoral artery is used as a landmark for the block. There currently are no studies examining the optimal placement of the nerve block catheter relative to the femoral artery in the canal. The goal of this study will be to examine the relationship between nerve catheter tip location relative to femoral artery within the adductor canal for continuous AC nerve blocks. The investigators specifically will compare postoperative pain as well as incidence of vascular puncture during the procedure and time to complete the procedure for two different catheter locations.