Interfascial Spread of Injectate After Adductor Canal Injection in Fresh Human Cadavers

Abstract

The adductor canal block has become a common analgesic technique in patients undergoing knee arthroplasty. Dispersion of local anesthetic outside the adductor canal through interfascial layers and blockade of smaller nerves that confer innervation to the knee could contribute to the analgesic efficacy of the adductor canal block. We studied the diffusion of local anesthetic mixed with dye after injection into the adductor canal in fresh human cadavers. In all 8 legs, injectate was found in the popliteal fossa in contact with the sciatic nerve and/or popliteal blood vessels. Interfascial spread patterns were identified.

The Spread of Ultrasound-Guided Injectate From the Adductor Canal to the Genicular Branch of the Posterior Obturator Nerve and the Popliteal Plexus

“…Injection of 10 mL of dye into the AC did spread consistently via the adductor hiatus into the popliteal fossa and always stained the popliteal vessels. Furthermore, the sciatic nerve was stained in only 1 of 10 cases probably because of injection of a lower volume (10 mL) compared with Goffin et al 18 It can be speculated that an injection of a larger volume would increase the risk of anesthesia of the sciatic nerve with an associated increased risk of fall and reduction of the ability to ambulate. 16 Furthermore, the analgesic effect of a sciatic block after TKA is not even clinically convincing.…”

“…Several studies have reported a spread of injectate to the popliteal fossa after injection into the AC, but none of these studies have assessed whether the injectate reached the popliteal plexus and the genicular branch of the posterior obturator nerve. [15][16][17][18] The latter plays an important clinical role in knee pain after TKA. 3,19,20 The obturator nerve can be anesthetized by an ultrasound-guided subpectineal injection of local anesthetic at the level of the inguinal crease.…”

“…3,21 In addition, anesthesia of the tibial genicular nerve branches of the popliteal plexus with the AC approach might improve analgesia compared with a subpectineal obturator nerve block after TKA. Goffin et al 18 reported spread of injectate into the popliteal fossa after injection of 20-mL dye into the AC and observed staining of the sciatic nerve in all cases, but staining of the popliteal vessels in only 3 of 8 cadavers. The results of Goffin et al 18 do not agree with our present study.…”

“…Goffin et al 18 reported spread of injectate into the popliteal fossa after injection of 20-mL dye into the AC and observed staining of the sciatic nerve in all cases, but staining of the popliteal vessels in only 3 of 8 cadavers. The results of Goffin et al 18 do not agree with our present study. Injection of 10 mL of dye into the AC did spread consistently via the adductor hiatus into the popliteal fossa and always stained the popliteal vessels.…”

Comparison of Continuous Proximal Versus Distal Adductor Canal Blocks for Total Knee Arthroplasty

“…19 While most investigators report a "midthigh" or distal approach to the ACB, 8,9,11,12 the exact location of the block may affect local anesthetic spread to the nerves within and around the adductor canal. [22][23][24] A prior study by Mariano and colleagues 25 comparing proximal and distal ACBs did not show a difference between groups in terms of total opioid consumption; however, it was not powered for this specific outcome. To date, there have been no prospective trials comparing continuous proximal and distal ACBs using opioid consumption as a primary outcome.…”