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

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).