October 20, 2019
10/20/2019 10:15:00 AM - 10/20/2019 12:15:00 PM
Room WA2 - Area B
Adductor Canal and Distal Femoral Triangle Nerve Blocks Provide Similar Analgesia and Opioid Consumption Following Anterior Cruciate Ligament Surgery
Prianka Desai, M.D., Katherine Chuy, M.D., Shruthima Thangada, M.D., Uchenna O. Umeh, M.D., Arthur Atchabahian, M.D.
NYU Langone Health, New York, New York , United States
Disclosures: P. Desai: None.K. Chuy: None.S. Thangada: None.U.O. Umeh: None. A. Atchabahian: Royalties; Self; McGraw Hill. Honoraria; Self; B Braun, Sintetica.
Anterior cruciate ligament (ACL) reconstruction results in significant post-operative pain that is poorly controlled by opioid analgesics alone. The adductor canal nerve block is routinely performed in our institution for this procedure and has previously been well described to be a beneficial addition to the analgesic regimen for ACL surgery and other knee operations.1,3 Recent literature has revealed that the blocks that many regional anesthesiologists consider to be adductor canal nerve blocks are anatomically distal femoral triangle blocks (DFTB) (and not true adductor canal nerve blocks (TACB)) based on the anatomical definitions of the adductor canal and femoral triangle.4 The apex of the femoral triangle, which marks the end of the femoral triangle and start of the adductor canal, is defined as the intersection between the medial border of the sartorius muscle and the medial border of the adductor longus muscle.4 This study aimed to compare the analgesic efficacy of DFTB and TACB. We hypothesized that more proximal blocks, i.e. DFTB, would provide better analgesia and reduced opioid consumption. Methods: In this IRB approved, prospective, randomized, single blinded, noninferiority trial involving human subjects, 68 patients undergoing unilateral ACL surgery were recruited. Patients received either DFTB or TACB depending on randomization. For all patients, ultrasound was used to identify the border between the adductor canal and apex of the femoral triangle. All patients received 20 cc of bupivacaine 0.5%. The perioperative medications were standardized. Total opioid use for 24 hours from arrival to OR was calculated in morphine equivalents and compared for the two groups. The data was obtained from anesthesia records, PACU medication records, and post-op medications logs that the patients took home to record medications consumed after discharge. Results: A total of 68 patients were recruited and randomized. Of the 44 patients who completed the study, 24 were randomized to the DFTB group and 20 were randomized to the TACB group. 24 patients were withdrawn from the study for multiple reasons including failure to complete post-op opioid consumption medication log, deviation from surgical plan, or deviation from standardized anesthesia protocol. Total opioid consumption for 24 hours from arrival to OR was calculated in morphine equivalents. Wilcoxon’s rank sum test was used and there was no difference between the two groups (Group 1 M= 43.28 SD= 18.09 vs Group 2 M= 41.06 SD= 22.68, p=0.75). Discussion: The adductor canal block is routinely performed for ACL surgery to supplement analgesia since it provides a sensory block with minimal motor block.1,2 However, recent publications describing the true anatomic definition of the adductor canal have caused anesthesiologists to realize that many of the “adductor canal blocks” they have performed, are actually distal femoral triangle blocks.4 Our hypothesis that a more proximal block would provide better pain control was disproven by this study. Instead, the 24 hour opioid consumption in patients undergoing unilateral ACL surgery was the same in patients with distal femoral triangle blocks and true adductor canal nerve blocks. Thus, this anatomical distinction might not have clinical consequences.

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