Efficiency of Femoral Nerve Block for Recovery after Primary Total Knee Arthroplasty

Abstract

Purpose The aim of our study is to evaluate the efficiency of femoral nerve block on recovery after primary total knee arthroplasty. Our primary goal is to provide adequate analgesia with a lower concentration of bupivacaine (0.125%) as well as the usual concentration (0.25%). Comparing the degree of motor block, side effects, postoperative pain scores, opioid consumption, and ambulation and discharge times are our secondary goals. Methods The study was conducted as randomized, controlled and double blind. Sixty three patients were randomised into three groups: G125(n:21) received FNB with 20ml of 0,125% bupivacaine, G25(n:21) received 10ml of 0,25% bupivacaine and GCont(n:21) received no block. FNB was applied with ultrasound guidance after the operation. Pain scores(NRS) at certain time intervals, total opioid consumption, motor block, knee flexion and discharge times were recorded. Results For GCont, pain scores were significantly higher at 2nd, 6th, 12th and 24th hour postoperatively, total opioid consumption was higher(G125:75mg, G25:0mg, GCont:280mg) and first opioid demand time was earlier(G125:12th hour, G25:21st hour GCont:2nd hour). First knee flexion time and mobilization time were also delayed for GCont. G25 had lower scores for quadriceps muscle strength(G25:3/5, G125:4/5, GCont:5/5, Manual Test at 6th Hour), but this did not affect mobilization compared to G125. Conclusion G125 had lower quadriceps muscle strength loss compared to the G25 and earlier mobilization and flexion times, low opioid consumption and low pain scores compared to the control group. In this respect, we believe the femoral nerve block with 0,125% bupivacaine proves to be a suitable option for analgesia with the potential of maintaining enough movement for recovery after TKA.