Effect of a Sciatic Block (SNB) Combined With a Continuous Femoral Block (CFNB) on Pain Scores After Knee Arthroplasty

Study Overview
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Brief Summary
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The purpose of this study is to determine if the addition of a sciatic nerve block (SNB) to a continuous femoral nerve block (CFNB) improves post-operative analgesia after knee arthroplasty.

Detailed Description
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Background: Postoperative pain after total knee replacement /arthroplasty (TKA) is a major concern. It is severe pain in 60% of patients and moderate in 30%. Continuous femoral nerve blocks (CFNB) are considered an excellent choice for regional anesthesia for major knee repair but there are some controversies about the need of supplemental obturator or sciatic nerve blocks for achieving better postoperative analgesia. A recent meta-analysis states there is no sufficient evidence to recommend or discharge these associations. Objectives: We aim to assess the efficacy of the association of a sciatic nerve block (SNB) and a continuous femoral nerve block (CFNB) for reducing postoperative pain in patients submitted to TKA. Methods: A randomized controlled study on 50 patients submitted to TKA. Control group receives a femoral nerve block with a catheter before general anesthesia is induced and the intervention group gets a similar block plus a single shot SNB before general anesthesia. Both groups start a continuous local anesthetic infusion through femoral catheter after the end of surgery and supplemental oral diclofenac and paracetamol. Pain scores are measured until 24h postoperatively, side effects and patient satisfaction are monitored.

Official Title
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Effect of a Single Shot Sciatic Nerve Block (SNB) Combined With a Continuous Femoral Block (CFNB) on Pain Scores After Knee Arthroplasty. A Randomized Controlled Trial

Conditions
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Postoperative Pain

Intervention / Treatment
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* Procedure: SNB plus CFNB
* Procedure: CFNB


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Unilateral total knee replacement Exclusion Criteria: Contra-indication for general anesthesia Infection on puncture site Coagulation disorders Pre-existent neuropathies Allergies to local anesthetics, paracetamol, diclofenac and tramadol Severe dyspepsia Less than 50kg weigh Body Mass Index (BMI) greater than 40 American Society of Anesthesiologists (ASA) Physical Status 4 or 5 Absence of capacity to use the Visual Analog Score (VAS) scale Refusal to give informed consent
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: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Continuous femoral nerve block (CFNB)<br>A continuous femoral nerve block is performed for peri-operative analgesia and a bolus of 30 ml of ropivacaine 0.375% is injected before induction of general anesthesia and surgery starts. An infusion of 8ml/h of ropivacaine 0.2% is started in post anesthesia care unit (PACU) and maintained for 48h | Procedure: CFNB<br>* A continuous femoral nerve block is performed for peri-operative analgesia and a bolus of 30 ml of ropivacaine 0.375% is injected before induction of general anesthesia and surgery starts. An infusion of 8ml/h of ropivacaine 0.2% is started in post anesthesia care unit (PACU) and maintained for 48h<br>* Other names: Femoral nerve block;|
| Experimental: Single shot SNB plus CFNB<br>A single shot sciatic nerve block (SNB) is performed before surgery with 25ml of 0.2% ropivacaine in addition to the continuous femoral nerve block (CFNB) performed in the control group before induction of general anesthesia and surgery starts. An infusion of 8ml/h of ropivacaine 0.2% is started in Post anesthesia care unit (PACU) and maintained for 48h | Procedure: SNB plus CFNB<br>* A single shot sciatic nerve block (SNB) is performed with 25 ml of 0.2% ropivacaine before surgery in addition to an isolated continuous femoral nerve block (CFNB) in the control group<br>* Other names: Sciatic nerve block;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Visual Analogue Scores (VAS) - Pain Scores Measured in mm (0-100) | Pain scores measured by Visual Analogue Score (VAS) scale at 15-30min after Post anesthesia care unit (PACU) arrival VAS is a 100mm scale to measure pain. 0mm - no pain 100mm - worst possible pain | 15-30 min after arrival on post anesthesia care unit (PACU) | 
| VAS Results - Pain Measured in mm (0-100) | VAS pain scores are measured by blinded investigators 12h after surgery . VAS scale: 0 - no pain 100 - worst possible pain | 12h after surgery | 
| VAS Results - Pain Scores Measured in mm (0-100) | VAS pain scores are measured by blinded investigators 24h after surgery . VAS scale: 0 - no pain 100 - worst possible pain | 24h after surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Satisfaction With Anesthesia Technique in Each Arm of the Study | Satisfaction with the anesthesia technique using a categorical scale with three levels: Bad Reasonable Good/Very Good A Fisher's Exact test is made to asses any differences in the distribution of patients in each arm to each level of the categorical scale | 1 month after surgery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Postoperative pain, Knee arthroplasty, Peripheral nerve blocks, Sciatic nerve block, Femoral nerve block