Adductor Canal Block Provides Noninferior Analgesia and Superior Quadriceps Strength Compared with Femoral Nerve Block in Anterior Cruciate Ligament Reconstruction

Abstract

Background By targeting the distal branches of the femoral nerve in the mid-thigh, the adductor canal block (ACB) can preserve quadriceps muscle strength while providing analgesia similar to a conventional femoral nerve block (FNB) for inpatients undergoing major knee surgery. In this randomized, double-blind, noninferiority trial, the authors hypothesized that ACB provides postoperative analgesia that is at least as good as FNB while preserving quadriceps strength after outpatient anterior cruciate ligament reconstruction. Methods A total of 100 patients were randomized to receive ACB or FNB with 20 ml ropivacaine 0.5% (with epinephrine). The authors sequentially tested the joint hypothesis that ACB is noninferior to FNB for cumulative oral morphine equivalent consumption and area under the curve for pain scores during the first 24 h postoperatively and also superior to FNB for postblock quadriceps maximal voluntary isometric contraction. Results The authors analyzed 52 and 48 patients who received ACB and FNB, respectively. Compared with preset noninferiority margins, the ACB–FNB difference (95% CI) in morphine consumption and area under the curve for pain scores were −4.8 mg (−12.3 to 2.7) (P = 0.03) and −71 mm h (−148 to 6) (P < 0.00001), respectively, indicating noninferiority of ACB for both outcomes. The maximal voluntary isometric contraction for ACB and FNB at 45 min were 26.6 pound-force (24.7–28.6) and 10.6 pound-force (8.3–13.0) (P < 0.00001), respectively, indicating superiority of ACB. Conclusion Compared with FNB, the study findings suggest that ACB preserves quadriceps strength and provides noninferior postoperative analgesia for outpatients undergoing anterior cruciate ligament reconstruction.

Relieving Pain After Arthroscopic Knee Surgery: Ultrasound-Guided Femoral Nerve Block or Adductor Canal Block?

“…Our study results do not contradict the recently published study by Abdallah et al (16), which showed that ACB was not inferior to FNB for analgesia following arthroscopic repair of the anterior cruciate ligament while preserving muscle strength. Using the weaker clinical criteria and combining it with preserved anterior muscle strength allowed the authors to reach a conclusion of non-inferiority in providing postoperative pain relief.…”

Lower extremity regional anesthesia: essentials of our current understanding

“…Expectedly, in both studies, patients randomized to the former displayed superior quadriceps strength as assessed by straight leg raise during the first 24 hours392 or maximal voluntary isometric contraction at 45 min 393. However, the findings pertaining to pain control differed between the two trials.…”

“…Whereas Abdallah et al 393 found that femoral triangle/adductor canal blocks resulted in non-inferior analgesia and opioid consumption compared to femoral blocks, El Ahl392 reported lower pain scores (at 18 and 24 hours) as well as decreased morphine consumption in patients receiving femoral blocks. This discrepancy could be attributed to the nature of the graft: patellar392 versus hamstring or bone–tendon–bone 393. Nonetheless, in light of these contradictory results, additional trials are needed to compare femoral triangle/adductor canal and femoral blocks for the different types (grafts) of ACL repair.…”

“…In recent years, El Ahl392 and Abdallah et al 393 set out to investigate the benefits of quadriceps-sparing femoral triangle/adductor canal blocks compared with femoral blocks for ACL reconstruction. Expectedly, in both studies, patients randomized to the former displayed superior quadriceps strength as assessed by straight leg raise during the first 24 hours392 or maximal voluntary isometric contraction at 45 min 393.…”

Comparison of femoral block and adductor canal block in the postoperative analgesia of patients undergoing arthroscopic knee surgery

“…In their 54 patient series, both groups were shown to be similar in terms of opioid consumption [7]. Similarly, in a series of 100 patients undergoing anterior ligament repair, adductor canal block and femoral nerve block were found to be equal in terms of cumulative oral morphine consumption [15]. In the same way as our subjects, Dong et al [16] reported that adductor canal block (ACB) shows no superiority than femoral nerve block (FNB) group regarding muscle strength and pain control.…”