Comparison of Two Different Concentrations and Volume of Ropivacaine for Continuous Bilateral Adductor Canal Block for Post-operative Analgesia in Primary Total Knee Arthroplasty

Abstract

Total knee arthroplasty (TKA) is associated with varying degree of pain. Using peripheral nerve block after total knee arthroplasty, without impeding mobility, is challenging. Optimal concentration of Ropivacaine for bilateral continuous adductor canal block (ACB) after bilateral total knee arthroplasty is currently unknown during postoperative analgesia. The aim of the study is to compare two different concentrations of Ropivacaine in equianalgesic doses for ultrasound guided continuous adductor canal block for pain management after bilateral total knee arthroplasty. A prospective, double blind, randomized comparative study having ASA 1-3 grades, between 40 to 80 years, 100 patients received ACB of either Ropivacaine 0.1% or 0.2% in equianalgesic doses for 48 hrs after bilateral TKA. We assessed numerical rating scale (NRS) for pain at rest and 45-degree range of motion (ROM) as primary end point, motor power of quadriceps and fentanyl consumption as secondary end point and compared using Mann Whitney test. All patients had received comprehensive multimodal analgesia. Statistical analysis was done by using the SPSS software 22.0. The comparison was made using the Chi square test, unpaired T test and Mann Whitney test. NRS scores at rest and 45-degree ROM were statistically significant decreased in group-A receiving Ropivacaine 0.2% (p < 0.004 and p <0.001). Motor power was higher in group-A (p<0.001) and fentanyl consumption was less in group-A (p<0.001). Ropivacaine 0.2% in equianalgesic dose provides more effective analgesia, preserve quadriceps strength and decreased fentanyl consumption than Ropivacaine 0.1% during first 48 hours for continuous bilateral ACB after primary bilateral total knee arthroplasty.