INTRA-ARTICULAR MORPHINE AND ROPIVACAINE INJECTION PROVIDES EFFICACIOUS ANALGESIA COMPARED TO FEMORAL NERVE BLOCK IN THE FIRST 24 HOURS POST-OPERATIVELY AFTER ACL RECONSTRUCTION WITH BTB IN AN ADOLESCENT COHORT

Abstract

Background:Opioid consumption and patient satisfaction are influenced by a surgeon’s pain management protocol and the use of adjunctive pain mediators. Two commonly utilized adjunctive pain modifiers for anterior cruciate ligament (ACL) reconstruction include femoral nerve blockade and intra-articular injection; however, debate remains as to the most efficacious methodology.Hypothesis/Purpose:We hypothesize that intra-articular injection with ropivacaine and morphine is as efficacious as a femoral nerve block injection of ropivacaine, dexamethasone, and dexmedetomidine for post-operative pain management in the first 24 hours after bone-patellar tendon-bone (BTB) ACL reconstruction.Methods:Charts were retrospectively reviewed for a single pediatric orthopedic surgeon performing BTB ACL reconstructions from 2013-2019. One hundred sixteen patients were identified, of whom 58 received intra-articular injection and 58 received single shot femoral nerve block. All patients were admitted for 24 hours. Pain scores were assessed every 4 hours. Morphine milligram equivalents (MME) consumed were tabulated for each patient.Results:Opioid use was 24.3 MMEs in patients treated with intra-articular injection vs 28.5MMEs in those with peripheral block (p=0.108). Consumption of MMEs was greater in the intra-articular group in the 0-4 hours period (7.1 MMEs vs. 4.6 MMEs, p=0.008). There was significantly less MME consumption in patients receiving intra-articular injection compared with peripheral block at 16-20 and 20-24 hours (3.2 MMEs vs. 5.6 MMEs, p=0.01; 3.8 MMEs vs. 6.5 MMEs, p<0.001 respectively). Mean pain scores were not significantly different over the 24-hour period (peripheral block=2.7, intra-articular injection=3.0, p=0.19).Conclusion:Moving away from the use of peripheral nerve block as an analgesic modality may be challenging given the multidisciplinary role of pain management in these patients. However, as Ramlogan et al. succinctly noted in their recent editorial “Anterior cruciate ligament repair and peripheral nerve blocks: time to change our practice?” in the British Journal of Anesthesia, both orthopedic and anesthesia colleagues alike are beginning to recognize that it is a change that may benefit our patients. Our study strengthens this argument and shows that there is no significant difference in MME consumption between the femoral nerve block and intra-articular injection groups in the first 24 hours post-operatively. While peripheral block is associated with lower opioid consumption in the first 4 hours after surgery, patients receiving intra-articular block require less opioids 16-24 hours post-operatively. Given these findings, we propose that intra-articular injection is a viable alternative for analgesia in pediatric patients undergoing BTB ACL reconstruction.Figure 1.2.Morphine milligram equivalent consumption trend during 24-hour post-operative period. PB=peripheral nerve block; IA=intra-articular injection