Effect of a Single Shot Sciatic Nerve Block Combined with a Continuous Femoral Block on Pain Scores After Knee Arthroplasty. A Randomized Controlled Trial

Abstract

Introduction: 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 formajor 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 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 in three occasions until 24h postoperatively, side effects and patient satisfaction are monitored. Results: We hypothesize that the addition of a sciatic block to a femoral nerve block can give a clinical significant reduction in post-operative TKA pain scores (on the Visual Analogue Scale (VAS) of 1.5 or greater between the intervention and control groups). We hope to start statistical analysis soon and finish by December 2011. With the results of this study we hope to give a valuable contribution for the ongoing debate of post-operative analgesia after TKA.