Adductor Canal Block - Does Nerve to Vastus Medialis Have To Be SEPARATELY Targeted?

The nerve to vastus medialis (NVM) contributes to sensation in the medial knee joint. However I don't believe that it needs to be specifically located and targeted with the needle for separate injection (which increases technical complexity and the risk of mechanical needle-nerve injury) in an adductor canal block . Post-block scanning shows that local anesthetic injected within the adductor canal, even at a distal location, almost always spills out to surround the NVM, as shown in this #short video.

[@armuk]

Good to see the sono-anatomy to support this approach.
Any circumstances in which you'd change the volume from 20ml?

[@DSmith-xf5xi]

You consider the arterial "wink" or compression to signify that you are underneath the vastoadductor membrane, thus in the space where the nerves lie correct? Furthermore - do you think theres any benefit to having this local anesthetic spread medially and perhaps blocking aspects of the subsartorial plexus?

[@KiJinnChin]

Arterial "wink" is a great term! I use it to confirm that I am truly injecting within the canal. In addition, because I am hoping to get the LA to track along the artery into the popliteal fossa, I want it to be deposited as close to the artery as possible.
I'm not sure about your second point - I have not really thought about it up to now; but will definitely ponder whether or not (a) this happens and (b) whether it is one mechanism for additional analgesic benefit.

[@DSmith-xf5xi]

Amit Pawa mentioned it at ASRA at one point regarding the medial spread, so I cannot take credit for it. Thank you for your reply and your excellent videos!@@KiJinnChin

[@zakalobi80]

Sorry, one more question. How do you know with ultrasound imaging the proper level of injection in AC?

[@KiJinnChin]

You can scan in a proximal-distal direction along the canal. For a distal approach, I aim to identify where the artery drops away into the adductor hiatus, as the distal end of the canal. I retrace a little more proximally to where I can see the arterial wall very clearly, and then I approach the artery in this plane as you see in the video.

[@zakalobi80]

Do you recommend this approach for analgesia for high tibial osteotomy? thanks.

[@KiJinnChin]

yes I think it's reasonable

[@zakalobi80]

Thank you, sir.@@KiJinnChin

[@uramalakia]

Sufficient volume is key for this?

[@KiJinnChin]

I generally only inject 20ml and I usually see this pattern. Logically a larger volume will enhance spread both proximally, and distally towards the popliteal plexus (my main reason for preferring a distal ACB). So you could do 30ml if you like.

[@KiJinnChin]

See my reply to a similar comment from @uramalakia. I guess if you really wanted to enhance the effect AND you are willing to accept the possibility of quads weakness (from excessive proximal spread). You could also do a dual injection approach as outlined in this interesting article - pubmed.ncbi.nlm.nih.gov/35282508/

[@erickim1830]

Runge and Nystaad's work appears to support Sonowane's proposal that local spread at very distal peri-femoral arterial does capture some coverage of the posterior knee. But IPACK remains a nice option too.
pubmed.ncbi.nlm.nih.gov/29797704/
ua-cam.com/video/lf312uzZaDQ/v-deo.html