Ultrasound Guided Femoral Nerve Block and Ultrasound Guided Femoral Nerve Block With Peripheral Nerve Stimulation in Knee Replacement Surgery

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.

Inclusion Criteria:

- 18 to 80 years old at time of surgery.

- Male or female patients undergoing total knee replacement under either general or
neuroaxial anesthesia (spinal or epidural). Intraoperative, patients will receive
spinal anesthetics with 15 mg bupivacaine and 25mcg of fentanyl intrathecally.

Exclusion Criteria:

- Current or recent drug abuse (within past 6 months).

- Pregnancy.

- Patient refuses regional analgesia.