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S E P T E M B E R 2 0 1 5 | O U T P AT I E N T S U R G E R Y M A G A Z I N E O N L I N E
The goal is to place the needle tip and local anesthetic adjacent to the
saphenous nerve in the space deep to sartorius muscle and antero-lat-
eral to the femoral artery.
4. Having identified this space in the short axis, I rotate my probe 45
degrees to achieve an oblique view of the adductor canal. This accom-
plishes 2 goals. First, it forces my needle insertion to be a little more
proximal in the thigh and therefore not below the expected lower
margin of the tourniquet (if the insertion is 3 hands' breadths above
the patella, you can safely ensure you are above the lower margin of
the tourniquet). Second, it lets the catheter eventually be threaded
down (parallel to) the adductor canal, especially if the curved Touhy
bevel is rotated to face down the thigh.
5. After placing a small lidocaine skin wheal with a 25g needle, I
insert an 18g Touhy needle several centimeters away from the trans-
ducer in-plane and obliquely towards the canal. The blunt Touhy nee-
dle passes through the sartorius muscle and when it penetrates the
deep border of the sartorius, I can usually feel a distinct pop.
6. I then have the block nurse inject several milliliters of local
anesthetic to confirm that I am in the canal. If I've succeeded, I'll see
the anesthetic spread and open up the canal by pushing the sartorius
more superficially, the vastus medialis more deeply and the femoral
artery postero-medially away from the injection. Often I'll also see
the saphenous nerve move away from the injection, although this
isn't necessary to achieve a successful block.
7. Depending on the quality of the spread, I bolus up to 20 ml of
0.25% bupivacaine. But we've demonstrated that as little as 10 ml can
result in adequate spread throughout the adductor canal (bit.ly/block-
jockscadaver).
8. I rotate the needle 90 degrees so the Touhy bevel faces down the
leg. Then I thread the catheter 3 to 4 centimeters down the canal.
