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