A new single-center, double-blind, prospective, superiority randomized controlled trial published in Regional Anesthesia & Pain Medicine compares continuous femoral nerve blocks (CFNB) and continuous adductor canal blocks (CACB) for outpatient anterior cruciate ligament (ACL) surgery.
The researchers, noting that the “comparative opioid-sparing and functional outcomes” of the two approaches are “unclear,” randomized 60 adults undergoing ACL reconstruction at Stanford Outpatient Surgery Center between June 2018 and April 2023 to receive either CFNB or CACB. All patients received a 20 mL loading dose of 0.5% ropivacaine and were discharged with a 0.2% ropivacaine infusion.
The study’s primary outcome was average numeric rating scale (NRS) pain scores analyzed using a linear mixed-effects repeated-measures model over 48 hours, with secondary outcomes including cumulative morphine milligram equivalents (MME), continuous passive motion (CPM) usage, CPM compliance, and Quality of Recovery-15 (QoR-15) scores.
Among the 57 patients who completed the study, mixed-effects repeated-measures analysis of average NRS pain scores at 24 and 48 hours “showed no significant difference between CFNB and CACB.”
The researchers concluded that “CFNB was not superior to CACB on the primary pain outcome over 48 hours. In secondary analysis, CFNB catheters were associated with lower immediate postoperative pain. In exploratory analyses, fewer patients required more than 50 MME over 48 hours. This finding is hypothesis-generating and requires confirmation in an adequately powered trial. There were no differences in quality of recovery or CPM compliance. Whether any opioid-related differences between techniques outweigh concerns about motor blockade warrants further investigation.”
Read the full study here.
