Saphenous Nerve Block vs. Femoral Nerve Block for Total Knee Arthroplasty

Currently, the regional anesthetic standard of care for total knee replacement surgery is
combined spinal/epidural to provide long-lasting pain relief with or without a femoral nerve
block, or FNB. The femoral nerve block refers to a technique that your anesthesiologist can
use to numb the thigh muscle for approximately 18 hours after surgery. While this technique
offers significant pain relief, it is possible it may cause muscle weakness and increase
patients' recovery times. Hence there is a need for an alterative anesthetic technique, one
that may help minimize postoperative pain as effectively as a femoral nerve block, while not
causing weakness of the thigh muscle.

The saphenous nerve, a branch of the femoral nerve, provides sensation to the knee. Thus it
is hypothesized by "blocking" or anesthetizing the saphenous nerve with local anesthetic
closer to where it branches off, the area around and below the knee will feel numb. Yet
unlike the femoral nerve block, the thigh muscle itself will still be able to function.

For patients undergoing two total knee replacements at one time or bilateral total knee
replacement, they will be randomly assigned to receive a femoral nerve block on one leg and
a saphenous block on the other. Pain levels will be measured and thigh muscle strength will
be tested using a dynamometer before surgery, 6-8 hours following anesthesia administration,
and on postoperative days 1 and 2.