Ultrasound-guided continuous femoral nerve block for analgesia after total knee arthroplasty: catheter perpendicular to the nerve versus catheter parallel to the nerve.

Background And Objectives: This study tested the hypothesis that, in continuous femoral nerve block (CFNB) under ultrasound guidance, placing a catheter perpendicular to the nerve can shorten the time of catheter insertion while providing a similar quality of analgesia compared with placing a catheter parallel to the nerve.

Methods: Fifty patients undergoing total knee arthroplasty were randomly assigned to receive ultrasound-guided CFNB either with the catheter parallel to the nerve technique (parallel group, n = 25) or with the catheter perpendicular to the nerve technique (perpendicular group, n = 25). Patient-controlled morphine analgesia pumps were available to all the patients after surgery.