Clinical Comparison of Femoral Nerve Versus Adductor Canal Block Following Anterior Ligament Reconstruction (FNB vs ACB)

Clinical Comparison of Femoral Nerve Versus Adductor Canal Block Following Anterior Ligament Reconstruction

This study will examine the potential differences between femoral nerve blockade (FNB) and adductor canal blockade (ACB) for pain control and quadriceps muscle activation for patients following anterior cruciate ligament (ACL) reconstruction.

Adequate pain control following anterior cruciate ligament reconstruction (ACL) often requires a regional nerve block. The femoral nerve block (FNB) has been traditionally employed. More recently, ultrasound application to regional nerve blocks allows for the use of alternatives such as the adductor canal block following ACL reconstruction. In 2009, Manickam et al. were the first to describe the ultrasound guided adductor canal technique for the purposes of knee joint analgesia. Unlike other traditional techniques that seek to cause a sensory as well as a motor blockade, the adductor canal block attempts to spare the motor block of the neighboring distributions in an attempt to offer selective analgesia and strength preservation. Chisholm et al demonstrated the adductor canal block provides similar and adequate postoperative analgesia when compared to the FNB, following arthroscopic ACL reconstruction with patellar tendon autograft. Their study focused on analgesia and did not evaluate quadriceps function or impact on rehabilitation. Sharma et al drew the first association between femoral nerve blocks and increased fall risk due to muscle weakness in total knee arthroplasty population. A randomized, blinded study to compare quadriceps strength following adductor canal versus FNB was performed by Kwofie et al. They showed that compared with FNB, adductor canal block results in significant quadriceps motor sparing and significantly preserved balance. These studies focused on acute muscle weakness after regional anesthesia and its relation to safety. Quadriceps function is very important in rehabilitation of ACL reconstruction. Luo et al demonstrated long term deficits related to FNB. They demonstrated that patients treated with FNB after ACL reconstruction had significant isokinetic deficits in knee extension and flexion strength at 6 months when compared with patients who did not receive a nerve block. Patients without a block were 4 times more likely to meet criteria for clearance to return to sports at 6 months. In addition, Krych et al found significantly inferior quadriceps strength and function at 6 months in FNB group. Based on the available literature, we aim to compare femoral nerve versus adductor canal block in regards to pain control and muscle strength in ACL reconstruction patients until return to sport.

Ultrasound guided FNB (30 ml of 0.2% ropivacaine with 100 mcg clonidine using a 22-gauge 40 mm ProBloc II insulated needle; Kimberly-Clark, Roswell, Georgia) below the inguinal ligament using a high-frequency linear ultrasound transducer (4-12 Hz; Mindray M7; Mindray North America, Mahwah, NJ) with stimulator confirmation.

Ultrasound guided ACB (15 ml of 0.2% ropivacaine with 100 mcg clonidine using a 22-gauge 40 mm ProBloc II insulated needle; Kimberly-Clark, Roswell, Georgia) at the mid-thigh using a high-frequency linear ultrasound transducer (4-12 Hz; Mindray M7; Mindray North America, Mahwah, NJ).

Quadriceps muscle activation was examined using surface electromyography (sEMG) of the vastus medialis oblique muscle. Peak sEMG activity was recorded in microvolts (uV) on the surgical and contralateral limbs while performing five maximal effort isometric contractions in full knee extension--the reported values are equal to the quadriceps sEMG in uV of the contralateral limb minus the quadriceps sEMG in uV of the surgical limb.

Quadriceps muscle activation was examined using surface electromyography (sEMG) of the vastus medialis oblique muscle. Peak sEMG activity was recorded in microvolts (uV) on the surgical and contralateral limbs while performing five maximal effort isometric contractions in full knee extension--the reported values are equal to the quadriceps sEMG in uV of the contralateral limb minus the quadriceps sEMG in uV of the surgical limb.

Quadriceps muscle activation was examined using surface electromyography (sEMG) of the vastus medialis oblique muscle. Peak sEMG activity was recorded in microvolts (uV) on the surgical and contralateral limbs while performing five maximal effort isometric contractions in full knee extension--the reported values are equal to the quadriceps sEMG in uV of the contralateral limb minus the quadriceps sEMG in uV of the surgical limb.

The straight leg raise assessment was performed in a standardized long-sitting position with well-knee flexed to 90 degrees. Patients were asked to complete 30 repetitions of straight leg raises with a small bolster supporting the heel using the following criteria; (1) perform with no visible quad lag (2) reach the height of the opposite tibial tubercle and (3) maintain a controlled rate of 30 hertz for the ascending and descending phases. The examination was only performed on the surgical limb and the absolute number of successful repetitions is reported.

The straight leg raise assessment was performed in a standardized long-sitting position with well-knee flexed to 90 degrees. Patients were asked to complete 30 repetitions of straight leg raises with a small bolster supporting the heel using the following criteria; (1) perform with no visible quad lag (2) reach the height of the opposite tibial tubercle and (3) maintain a controlled rate of 30 hertz for the ascending and descending phases. The examination was only performed on the surgical limb and the absolute number of successful repetitions is reported.

The straight leg raise assessment was performed in a standardized long-sitting position with well-knee flexed to 90 degrees. Patients were asked to complete 30 repetitions of straight leg raises with a small bolster supporting the heel using the following criteria; (1) perform with no visible quad lag (2) reach the height of the opposite tibial tubercle and (3) maintain a controlled rate of 30 hertz for the ascending and descending phases. The examination was only performed on the surgical limb and the absolute number of successful repetitions is reported.

morphine equivalents consumed during the entire post-anesthesia care unit (PACU) visit post surgery will be obtained from the All-scripts electronic medical record (EMR) system.

Inclusion Criteria: Males & Females ages 16-30 yrs Undergoing ACL reconstruction by Co-Investigator (Walter Lowe) Receiving peri-operative FNB or ACB Exclusion Criteria: Not enrolled within the COFAKS study Receiving intrathecal nerve blockade or no blockade

Bailey L, Weldon M, Kleihege J, Lauck K, Syed M, Mascarenhas R, Lowe WR. Platelet-Rich Plasma Augmentation of Meniscal Repair in the Setting of Anterior Cruciate Ligament Reconstruction. Am J Sports Med. 2021 Oct;49(12):3287-3292. doi: 10.1177/03635465211036471. Epub 2021 Sep 3.

Worsham J, Lowe WR, Copa D, Williams S, Kleihege J, Lauck K, Mascarenhas R, Bailey L. Subsequent Surgery for Loss of Motion After Anterior Cruciate Ligament Reconstruction Does Not Influence Function at 2 Years: A Matched Case-Control Analysis. Am J Sports Med. 2019 Sep;47(11):2550-2556. doi: 10.1177/0363546519863347. Epub 2019 Jul 26.

Bailey L, Griffin J, Elliott M, Wu J, Papavasiliou T, Harner C, Lowe W. Adductor Canal Nerve Versus Femoral Nerve Blockade for Pain Control and Quadriceps Function Following Anterior Cruciate Ligament Reconstruction With Patellar Tendon Autograft: A Prospective Randomized Trial. Arthroscopy. 2019 Mar;35(3):921-929. doi: 10.1016/j.arthro.2018.10.149. Epub 2019 Feb 4.