A randomized comparison of pain control and functional mobility between proximal and distal adductor canal blocks for total knee replacement

Abstract

Background:Adductor canal blocks (ACBs) have become a popular technique for postoperative pain control in total knee arthroplasty patients. Proximal and distal ACB have been compared previously, but important postoperative outcomes have yet to be assessed.Aims:The primary objective of this study is to compare postoperative analgesia between proximal and distal ACB. Secondary outcomes include functional mobility, length of stay (LOS), and adverse events.Settings and Design:This study was a single-center, assessor-blinded, randomized trial.Subjects and Methods:Fifty-seven patients were randomly assigned to receive a proximal (n = 28) or distal (n = 29) ACB. A 20 mL bolus of 5 mg/mL ropivacaine was injected at the respective location followed by 2.0 mg/mL ropivacaine infusion for 24 h.Statistical Analysis:The primary outcome was intra- and postoperative 24-h opioid consumption in intravenous (IV) morphine equivalents. Secondary outcomes include percentage change in timed “Up and Go” (TUG) times, LOS, and average postoperative pain scores. Continuous variables were compared using Student's t-test.Results:The mean (±standard deviation) 24-h intra-and postoperative opioid consumption showed no difference between the proximal and distal groups (39.72 ± 23.6 and 41.28 ± 19.6 mg IV morphine equivalents, respectively, P = 0.793). There was also no significant difference in the median [minimum, maximum] percentage change in TUG times relative to preoperative performance comparing proximal and distal ACB (334.0 [131, 1084] %-change and 458.5 [169, 1696] %-change, respectively, P = 0.130). In addition, there were no differences in postoperative pain scores or LOS.Conclusions:ACB performed at either proximal or distal locations shows no difference in postoperative pain measured by opioid consumption or pain scores. Better TUG performance seen in the proximal group was not statistically significant but might represent a clinically important difference in functional mobility.

Continuous Block at the Proximal End of the Adductor Canal Provides Better Analgesia Compared to that at the Middle of the Canal After Total Knee Arthroplasty: A Randomized, Double-blind, Controlled Trial

“…The discrepancies between the present study and these three RCTs can likely be attributed to the different de nitions of the AC [5][6][7] . Base on their description, these studies actually compared the distal FT 5,6 or the proximal AC 7 with a more cephalad injection in the FT 5-7 , instead of the distal AC with the proximal AC. In another study with the similar purposes, Sztain8 compared the analgesic effect of continuous ACB at the mid-thigh level (termed "proximal AC" in their study), de ned as the midpoint between the anterior superior iliac spine and the patella 12,27,28 which recently has been proved to actually indicate a cranial location to the proximal end of AC and inside the distal FT in most subjects, 11 with a more distal insertion closer to the adductor hiatus.…”

“…RCTs by Mariano 5 , Romano 6 and Meier 7 had investigated the "proximal AC" and "distal AC" and failed to detect signi cant differences in regard to 24 h postoperative opioid consumption, as well as in quadriceps strength or motor function. The discrepancies between the present study and these three RCTs can likely be attributed to the different de nitions of the AC [5][6][7] .…”

“…RCTs by Mariano 5 , Romano 6 and Meier 7 had investigated the "proximal AC" and "distal AC" and failed to detect signi cant differences in regard to 24 h postoperative opioid consumption, as well as in quadriceps strength or motor function. The discrepancies between the present study and these three RCTs can likely be attributed to the different de nitions of the AC [5][6][7] . Base on their description, these studies actually compared the distal FT 5,6 or the proximal AC 7 with a more cephalad injection in the FT 5-7 , instead of the distal AC with the proximal AC.…”

“…4 The optimal location for continuous ACB for TKA has been investigated by previous randomized clinical trials (RCTs). [5][6][7][8] However, identi cation of the adductor canal (AC) was not consistent, [5][6][7][8] and the results differed. The AC is a musculoaponeurotic tunnel that runs proximally from the apex of the femoral triangle (FT)/proximal end (entrance opening) of the AC where the medial borders of the sartorius muscle (SM) and adductor longors muscle (ALM) align, to the adductor hiatus distally where the femoral artery (FA) diverges from the SM and becomes deep.…”

Adductor Canal Blocks: An Observational Ultrasound Study in Volunteers to Identify the Relationship of the True Adductor Canal to Commonly Described Block Approaches and a Review of the Literature

“…Case reports, retrospective studies, cadaveric studies, non-English articles, review articles and meta-analyses were excluded (N = 69) (Included articles are listed in Supplemental Digital Content). The points of needle entry were grouped into 3 different regions ( Figures 4A and 4B): i) proximal blocks, 20,21 including block entry points that target the SFA after it has just beneath the medial border of the sartorius muscle, or the proximal-thigh approach by Meier et al involving the needle insertion at a location where the SFA is underneath the medial third of the sartorius muscle; ii) mid-thigh blocks, 3,10,20,22 including blocks performed at the midthigh level (between ASIS and base of patella), and the distal approach described Meier et al where the SFA lies underneath the middle third of sartorius; and iii) distal blocks, 11,22,23 including blocks performed at the dACB and other true AC blocks . Figure 4A shows the anatomical locations and Figure 4B shows the corresponding ultrasound image of the levels of these blocks.…”