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

Not Applicable

Completed

Brief Summary: 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 (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.

Recruitment & Eligibility

Inclusion Criteria

Exclusion Criteria

Contraindication to a spinal or epidural anesthestic
Not a candidate for bilateral total knee replacement
Chronic opioid use (defined as daily or almost daily use of opioids for >3 months)
Hypersensitivity and/or allergy to local anesthetics
Intraoperative use of any volatile anesthetic
Patients with pre-existing neuropathy on the operative limb
Contraindication to femoral nerve block or saphenous nerve block
Allergy to any of the study medications
American Society of Anesthesiologists (ASA) Class 4-5
Non-English speaking patients

Arm && Interventions

Group	Intervention	Description
Study Technique Right Leg, Control Technique Left Leg	Study Technique	-
Study Technique Right Leg, Control Technique Left Leg	Control Technique	-
Study Technique Left Leg, Control Technique Right Leg	Control Technique	-
Study Technique Left Leg, Control Technique Right Leg	Study Technique	-

Primary Outcome Measures

Name	Time	Method
Visual Analogue Scale Pain Score	Up to postoperative day 1	The primary outcome is the postoperative pain in each leg within the first 24 hours postoperatively. VAS pain scores could range from 0 to 10. Higher values represent a worse outcome.

Secondary Outcome Measures

Name	Time	Method
Preoperative and Postoperative Thigh Muscle Strength in Both Legs	Up to postoperative day 2	This was measured with a dynamometer to gauge strength.
Postoperative Complications	Up to postoperative day 2
Duration of Motor and Sensory Blockade	Up to postoperative day 2
Tracking Total Opioid Usage	Up to postoperative day 2
Rating the Success of the Nerve Blocks	Up to postoperative day 2
Patient Satisfaction With Nerve Blocks	Up to postoperative day 1	Rated on a 0-10 scale, with a higher score representing greater satisfaction.