Adductor Canal Block Versus Femoral Nerve Block for Pain Control After Anterior Cruciate Ligament Reconstruction: A Prospective Randomized Trial

Abstract

Background: Femoral nerve block (FNB) is a commonly performed technique that has been proven to provide effective regional analgesia after anterior cruciate ligament (ACL) reconstruction. The adductor canal block (ACB) uses a similar sensory block around the knee while avoiding motor blockade of the quadriceps muscles. Purpose/Hypothesis: The purpose of our study was to compare the efficacy of FNB versus ACB for pain control after ACL reconstruction. It was hypothesized that there would be no difference in pain levels or opioid requirements between the 2 groups. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: We performed a prospective, double-blinded, randomized controlled trial. Sixty patients undergoing primary ACL reconstruction with bone-patellar tendon-bone autograft were randomized to receive either an ACB or an FNB preoperatively. The primary outcomes assessed were pain levels (visual analog scale) and narcotic requirements for 4 days after surgery. Secondary outcomes included ability to perform a straight leg raise in the recovery room and difference in thigh circumference between the operative and nonoperative leg measured at 7 days postoperatively. Results: Morphine requirements were less in the ACB group in the first 4 hours postoperatively ( P = .02). Aside from this time interval, no differences were found between the 2 groups with regard to opioid requirements and pain scores at any other time. Similarly, no differences were noted in patients’ ability to perform a straight leg raise in the recovery room ( P = .13) or in thigh circumference at the first postoperative visit ( P = .09). Conclusion: The results of our study suggest similar efficacy in perioperative pain control with the use of an ACB for ACL reconstruction when compared with FNB. The potential long-term benefit of quadriceps preservation with the ACB is worthy of future study. Registration: NCT03033589 (ClinicalTrials.gov identifier).

Does Rebound Pain after Peripheral Nerve Block for Orthopedic Surgery Impact Postoperative Analgesia and Opioid Consumption? A Narrative Review

“…Pain outcomes following femoral nerve blocks done at the adductor canal are similar to conventional femoral nerve blocks in patients undergoing arthroscopically assisted anterior cruciate ligament repair under general anesthesia [74]. While rebound pain was not mentioned for either group, the adductor canal block group had better pain control and less opioid consumption in the first four hours post-operatively ( p = 02).…”

“…Rebound pain has also been reported in lower limb nerve blocks [14,15,19,73]. Femoral nerve blocks provide effective analgesia for knee surgeries with limitations being rebound pain and increased risks of falls due to quadriceps weakness [19,74,75]. Xing et al described superior pain control with femoral nerve block when compared to general anesthesia alone in the first 6 h post-operatively [19].…”

Untitled

“…As ACB is a purely sensory block, the motor function of only the rectus medialis is affected 35 . A study was done on healthy individuals; quadriceps strength due to ACB was reduced by 8%, whereas FNB initially reduced quadriceps strength by 49% 36 . So, ACB can be used as a single-shot injection or continuous infusion.…”

Femoral nerve block vs adductor canal block after anterior cruciate ligament reconstruction under general anesthesia

“…As peripheral nerve blocks provide effective analgesia, they are considered an essential part of the current multimodal pain management protocol following ACLR. [ 3 , 4 ]…”

“…Some of the high quality studies have confirmed that ACB and FNB, in ACLR, can achieve similar postoperative analgesic effect, but patients with ACB can obtain better early rehabilitation compared with those with FNB. [ 1 – 4 ] However, these studies suffer from several important methodologic shortcomings. Therefore, the question of potential analgesic and motor-sparing benefits of ACB in the setting of ACL reconstruction remains unanswered.…”