Surgeon-Administered Anterolateral Geniculate Nerve Block as an Adjunct to Regional Anesthetic for Pain Management Following Anterior Cruciate Ligament Reconstruction

Abstract

Regional anesthetic blockade of the adductor canal following anterior cruciate ligament reconstruction has gained popularity due to theoretical benefit of improved patient experience, decreased requirement for pain medication and maintained motor function. However, this block does not cover the anterior and lateral genicular innervation to the knee, which may lead to persistent pain postoperatively. The following Technical Note details the genicular nervous system and provides rationale and technique for performing a simple surgeon-administered regional anesthetic at the completion of anterior cruciate ligament reconstruction to address the anterior and lateral genicular nervous system.

© 2021 Published by Elsevier on behalf of the Arthroscopy Association of North America.

Figures

Fig 1

Drawing of the relevant neural anatomy as well as anatomic landmarks as viewed from anterior (A) and lateral (B). The anterior injection of the lateral geniculate nerve block is placed 2 to 3 fingerbreadths above the superior pole of the patella in-line with the lateral one-third of the patella. This injection targets branches of the nerve to vastus lateralis as well as the nerve to vastus intermedius. The nerve to the vastus lateralis is a terminal branch of the femoral nerve that runs obliquely along the periosteum of the metaphysis at the anterolateral aspect of the knee. It gives off a transverse superficial retinacular branch as well as a longitudinal deep capsular branch. This branch is not anesthetized by the typical adductor canal block. The articular branch of the nerve to the vastus intermedius runs along the anterior aspect of the distal femur towards the supra-patellar pouch of the knee capsule and is variably anesthetized by a typical adductor canal block. Meanwhile, the lateral injection of the lateral geniculate nerve block is placed 5 cm proximal to joint line, 2 to 3 fingerbreadths above the lateral epicondyle and 2 fingerbreadths lateral to the “anteroposterior injection site.” This injection targets branches of the lateral genicular nerve as well as some variant branches of the nerve to vastus lateralis. The lateral retinacular nerve is a branch of the superolateral genicular nerve and contributes to lateral knee sensation. The branch point has been found to be located approximately 2 to 2.5 cm proximal to the tip of the lateral femoral epicondyle and 4 to 5.5 cm proximal to the lateral joint line. Neither of these branches is anesthetized by the typical adductor canal block.

Fig 2

Clinical figure of the left knee with the patient positioned supine and the head at the top right. Identifying and marking relevant anatomic landmarks is crucial to performing the lateral geniculate nerve block accurately. At the completion of the surgical intervention and following closure of the wounds, the knee placed over a bump in slight flexion. The procedure is started by marking the patella (red star), lateral joint line (curved red line), and lateral epicondyle (red arrow) as reference points.

Fig 3

Clinical figure of the left knee demonstrating the anterior injection of the lateral geniculate nerve block, targeting branches of the nerve to the vastus lateralis and vastus intermedius. (A) The injection point (red arrow) is marked out 2 to 3 fingerbreadths above the superolateral pole of the patella (red star). (B) A 22-gauge needle is inserted down to periosteum, retracted 1 to 2 mm, and the area infiltrated with local anesthetic.

Fig 4

Clinical figure of the left knee demonstrating the lateral injection of the lateral geniculate nerve block, targeting branches to the nerve to the vastus lateralis and the lateral retinacular nerve. (A) The injection point (red arrow) is marked out 5 cm above the joint line (curved red line), 2-3 fingerbreadths above the lateral epicondyle (red star) and 2 fingerbreadths lateral to the AP injection site (black marker “x”) along the lateral femur. The injection should be in line with the lateral femur, which can be palpated manually moving proximally from the lateral epicondyle. (B) A 22-gauge needle is inserted down to periosteum, retracted 1-2 mm, and the area infiltrated with local anesthetic.