Intra-articular Morphine and Ropivacaine Injection Provides Efficacious Analgesia As Compared With Femoral Nerve Block in the First 24 Hours After ACL Reconstruction: Results From a Bone–Patellar Tendon–Bone Graft in an Adolescent Population

Abstract

Background: Opioid consumption and patient satisfaction are influenced by a surgeon’s pain-management protocol as well as the use of adjunctive pain mediators. Two commonly utilized adjunctive pain modifiers for anterior cruciate ligament (ACL) reconstruction are femoral nerve blockade and intra-articular injection; however, debate remains regarding the more efficacious methodology. Hypothesis: We hypothesized that intra-articular injection with ropivacaine and morphine would be found to be as efficacious as a femoral nerve block for postoperative pain management in the first 24 hours after bone–patellar tendon–bone (BTB) ACL reconstruction. Study Design: Cohort study; Level of evidence, 3. Methods: Charts were retrospectively reviewed for BTB ACL reconstructions performed by a single pediatric orthopaedic surgeon from 2013 to 2019. Overall, 116 patients were identified: 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 (MMEs) consumed were tabulated for each patient. Results: Opioid use was 24.3 MMEs in patients treated with intra-articular injection versus 28.5 MMEs in those with peripheral block ( P = .108). Consumption of MMEs was greater in the intra-articular group in the 0- to 4-hour period (7.1 vs 4.6 MMEs; P = .008). There was significantly less MME consumption in patients receiving intra-articular injection versus peripheral block at 16 to 20 hours (3.2 vs 5.6 MMEs; P = .01) and 20 to 24 hours (3.8 vs 6.5 MMEs; P < .001). Mean pain scores were not significantly different over the 24-hour period (peripheral block, 2.7; intra-articular injection, 3.0; P = .19). Conclusion: Within the limitations of this study, we could identify no significant difference in MME consumption between the single-shot femoral nerve block group and intra-articular injection group in the first 24 hours postoperatively. While peripheral block is associated with lower opioid consumption in the first 4 hours after surgery, patients receiving intra-articular block require fewer opioids 16 to 24 hours postoperatively. Given these findings, we propose that intra-articular injection is a viable alternative for analgesia in adolescent patients undergoing BTB ACL reconstruction.