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

Study Overview
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Brief Summary
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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.

Official Title
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Saphenous Nerve Block vs. Femoral Nerve Block for Total Knee Arthroplasty: A Comparative Effectiveness Study in Bilateral Total Knee Arthroplasty Patients

Conditions
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Difference Between Femoral Nerve Block and Saphenous Block

Intervention / Treatment
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* Procedure: Study Technique
* Procedure: Control Technique


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: All patients ages 40-80 undergoing Bilateral Total Knee Replacement Planned use of neuraxial anesthesia Ability to follow study protocol 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

Ages Eligible for Study
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Minimum Age: 40 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Supportive Care
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Study Technique Left Leg, Control Technique Right Leg<br> | Procedure: Study Technique<br>* One leg will receive the saphenous nerve block, at the level of the adductor canal (study technique). The block will be under ultrasound guidance. The local anesthetic will be 15 ml of 0.5% bupivacaine. All study patients, regardless of study arm will receive combined spinal epidural, with 3 ml of 0.5% bupivacaine as the spinal agent. Epidural local anesthetic, if needed, will consist of 2% lidocaine.<br>Procedure: Control Technique<br>* The other leg will receive the femoral nerve block (control technique). The block will be under ultrasound guidance. The local anesthetic will be 30 ml of 0.25% bupivacaine. All study patients, regardless of study arm will receive combined spinal epidural, with 3 ml of 0.5% bupivacaine as the spinal agent. Epidural local anesthetic, if needed, will consist of 2% lidocaine.<br>|
| Experimental: Study Technique Right Leg, Control Technique Left Leg<br> | Procedure: Study Technique<br>* One leg will receive the saphenous nerve block, at the level of the adductor canal (study technique). The block will be under ultrasound guidance. The local anesthetic will be 15 ml of 0.5% bupivacaine. All study patients, regardless of study arm will receive combined spinal epidural, with 3 ml of 0.5% bupivacaine as the spinal agent. Epidural local anesthetic, if needed, will consist of 2% lidocaine.<br>Procedure: Control Technique<br>* The other leg will receive the femoral nerve block (control technique). The block will be under ultrasound guidance. The local anesthetic will be 30 ml of 0.25% bupivacaine. All study patients, regardless of study arm will receive combined spinal epidural, with 3 ml of 0.5% bupivacaine as the spinal agent. Epidural local anesthetic, if needed, will consist of 2% lidocaine.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Visual Analogue Scale Pain Score | 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. | Up to postoperative day 1 | 

Secondary Outcome Measures

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

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Bilateral total knee replacement, Femoral Nerve Block, Saphenous Nerve Block