Anatomy of the Adductor Canal

[BLADEMDA]

I'm very familiar with this block and have performed many of them. But, I'd like a answer to the exact anatomical relationship of my needle to the saphenous nerve for the Perifemoral/Subsartorial approach in the mid thigh.

Is my needle starting Anterior to the artery and ending up posterior? To be precise is the needle Anteromedial or Anterolateral to the Femoral Artery and does it end up Posterolateral? I know this is just minutia but I would like the answer.

http://www.asra.com/display_spring_2011.php?id=18 (take a look at this)

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[BLADEMDA]

 

[BLADEMDA]

So the needle starts out Anterior-Lateral and ends Up Posterior Medial ?

 

[BLADEMDA]

 

[pjl]

Blade I am no master and learned from Internet like you, but I start anterior and lateral then end post medial/posterior

 

[deleted162650]

The way I was trined to do this block was to enter anterol-lateral rather steeply at first and then flatten out so than my needle is coming in relatively "horizontal". I aim to enter the adductor canal just under the saphenous nerve and park the tuohy tip at approx 6 o'clock on the artery (right between artery and vein) which I guess I would call posterior, but not really medial.

 

[BLADEMDA]

This thread isn't about doing the block itself but rather the correct anatomical description of the needle as it enters the tissue and separates the femoral artery from the fibrous sheath of the Sartorius muscle. I'm quite good at getting the needle to across the top of the artery and placing local in an arc over the vessel.

I'm just curious if the anatomical description we use for the needle trajectory from anterolateral to posteromedial is indeed correct.

 

[BLADEMDA]

In 9 dissections the SAPH was identified running from lateral to the SFA in the proximal adductor canal, to anterior or anteromedial to the SFA at the adductor hiatus

SAPH=Saphenous Nerve

 

[BLADEMDA]

 

[sevoflurane]

I actually look for the saph nerve itself. I scan up and down and see where it is the most prominant. Then hit it.
It is often on two separate sides of the FA, so that means that I pull the needle back and get it from a different angle/approach. I carefully tent the FA at times. Push a couple of ccs and watch the hydrodissection pull the saph nerve off the fascia of the FA. If I don'l like what I see on the USD machine, I readjust.

 

[BLADEMDA]

This is a distal adductor canal block where the Saphenous nerve is near the Superficial Descending Genicular Artery. Based on Anatomic reports this description of the location of the saphenous nerve is NOT posteromedial as show above but rather Anteromedial.

 

[BLADEMDA]

I actually look for the saph nerve itself. I scan up and down and see where it is the most prominant. Then hit it.
It is often on two separate sides of the FA, so that means that I pull the needle back and get it from a different angle/approach. I carefully tent the FA at times. Push a couple of ccs and watch the hydrodissection pull the saph nerve off the fascia of the FA. If I don'l like what I see on the USD machine, I readjust.

Don't need help with the block just the correct anatomical position of the needle in relationship to the muscles/artery. Thanks.

 

[Oggg]

The probe faces the medial thigh. I deposit local around the saphenous nerve, anterior to the artery. Sometimes I advance my needle superficial to the artery (or medial to the artery) to put local on the posterior side of the artery. I never go deep to the artery (lateral to the artery) because the vein is right there.

 

[sevoflurane]

Don't need help with the block just the correct anatomical position of the needle in relationship to the muscles/artery. Thanks.

Kew. I know you rock these.

Sometimes I do one or the other or both. Just depends on the patients anatomy. If I feel I have a better trajectory going posteromedial (most of the time), I'll do that.

 

[BLADEMDA]

The probe faces the medial thigh. I deposit local around the saphenous nerve, anterior to the artery. Sometimes I advance my needle superficial to the artery (or medial to the artery) to put local on the posterior side of the artery. I never go deep to the artery (lateral to the artery) because the vein is right there.

Yes, I get it. I know how to do this basic block. I start Anteriolateral to the artery and place local (2 mls) to dissect the artery off the Fibrous sheath of the Sartorius muscle. I place more local at noon over the artery and advance my needle until I'm on the other side of the artery. I place additional local on the other side. I pull back my needle and place additional local at 10:00 on the artery. When I'm done the Artery is surrounded in a SEMI-LUNAR fashion with local and separated from the Sartorious muscle. This is Perifemoral approach to the Saphenous nerve.

 

[BLADEMDA]

 

[BLADEMDA]

I start with needle at about 11:00 in this picture. I'm careful to inject small volumes at first in order to avoid intraneural injection. I separate the artery off the Fibrous sheath of the Sartorius muscle. I inject local at noon and at 1300 in relationship to the artery. The local ends up moving the artery away from the Sartorius muscle. I place a few mls at around 9:00-10:00 as my last injection and avoid the now very clearly delineated Saphenous nerve.

 

[BLADEMDA]

I'm pretty comfortable now with the anatomic description of this block both midthigh and the more distal adductor canal block near the Genicular artery.

 

[pjl]

Can you label your picture with where you think the posterior/ posterior medial areas are?

 

[RxBoy]

This picture helps show why the anatomy in the adductor canal anatomy is tricky. The saphenous nerve (technically the femoral nerve but thats a whole other discussion) is sometimes anterior or posterior to the superficial femoral artery depending on where you are scanning. It starts in a more anterior lateral position and ends in a more posterior medial position as you get closer to the hiatus. This is because it crosses the superficial femoral artery within the canal.

THis is also why it is crucial to deposit local on both sides of the artery. I never look for the nerve, there are way too many hyperechoic structures from the fascial layers. Sometimes the nerve is clear as day but in my experience its usually the exception. I scan up and down the sartorius until the artery is smack in the middle of the sartorius then deposit local both sides (3 and 9 oclock). My goal is to "push" the artery on US as this gives me 3 reassuring signs. 1) I know Im within the canal 2)Its not intraarterial/IV and 3) Im not injecting in the nerve . Success rate for me is almost 100% as the block is easy to test by looking for sensation discrimination in the medial calf.

THe contents of the adductor canal also have a branch of the obturator nerve which is not included in that figure.

 

[Oggg]

I've seen ppl inject anterior only, or both sides. Any research on this? It seems like if local can spread in the canal, it would be able to spread up and done to catch the nerve. Then you wouldn't need to Hydrodissect posterior to the artery. Minor time savings and less needling near the artery.

 

[RxBoy]

I've seen ppl inject anterior only, or both sides. Any research on this? It seems like if local can spread in the canal, it would be able to spread up and done to catch the nerve. Then you wouldn't need to Hydrodissect posterior to the artery. Minor time savings and less needling near the artery.

I have no data to refute you but I can tell you based on my clinical experience that there is a difference between single vs double injection technique. I do about 30+/week and I found that there are 2 instances where the block doesnt work so well....

1) The really obese. And its not just a technical issue cause ive seen it not work so well with perfect spread/imaging.
2) Unilateral spread or spread that doesn't push the artery (spreads opposite or posterior to artery ).

The block takes me 30 seconds total with a redirect. Its way easier than a femoral with experience. No pannus to deal with and no assistance needed. Honestly I feel like I can almost do it blind at this point. When i put the probe down, the femoral artery is always right there. The pop into the canal is subtle but distinct. Almost like when you do enough spinals, you always know when you hit the SA space without having to remove the stylet every couple mm's..

Anecdotally Ive asked pts who had a previous knee arthroplasty with femoral and compare the results to the adductor in the opposite knee arthroplasty. Most tell me the pain is LESS with the adductor. Of course my anecdotal evidence means nothing but def gives me reassurance the block works well.

 

[BLADEMDA]

I have no data to refute you but I can tell you based on my clinical experience that there is a difference between single vs double injection technique. I do about 30+/week and I found that there are 2 instances where the block doesnt work so well....

1) The really obese. And its not just a technical issue cause ive seen it not work so well with perfect spread/imaging.
2) Unilateral spread or spread that doesn't push the artery (spreads opposite or posterior to artery ).

The block takes me 30 seconds total with a redirect. Its way easier than a femoral with experience. No pannus to deal with and no assistance needed. Honestly I feel like I can almost do it blind at this point. When i put the probe down, the femoral artery is always right there. The pop into the canal is subtle but distinct. Almost like when you do enough spinals, you always know when you hit the SA space without having to remove the stylet every couple mm's..

Anecdotally Ive asked pts who had a previous knee arthroplasty with femoral and compare the results to the adductor in the opposite knee arthroplasty. Most tell me the pain is LESS with the adductor. Of course my anecdotal evidence means nothing but def gives me reassurance the block works well.

I always go Anterior and posterior as a good block requires diligence. I don't like "shortcuts" for my blocks unless I am having technically difficulty.
FYI, an Adductor Canal is a good block for analgesia but it is NOT as good as a Femoral block.

 

[Jay K]

Skip to the 4:00 mark on this video and tell me if this block is being done correctly, or whether the local is still above the fascial plane.



From what I'm reading here, most of you like to place local superficial and deep to the artery.

In the block shown in the video, I'm not certain the artery is imaged at all. Perhaps the block is being performed distal to the mid-thigh and more proximal to the knee?

 

[BLADEMDA]

Skip to the 4:00 mark on this video and tell me if this block is being done correctly, or whether the local is still above the fascial plane.



From what I'm reading here, most of you like to place local superficial and deep to the artery.

In the block shown in the video, I'm not certain the artery is imaged at all. Perhaps the block is being performed distal to the mid-thigh and more proximal to the knee?

Auyong is doing a distal adductor canal block and not a midthigh peri femoral block at the start of the video. The distal adductor canal block involves locating the superficial genicular artery and not the femoral artery.

A midthigh block involves placing local in a semilunar position on top of the femoral artery thereby displacing the artery from the sartorious muscle. Auyong is doing the perifemoral block a bit more distal than many of us usually do. I'm uncertain if his injection is actually pushing the femoral vessel away from the sartorius muscle. This can be tricky as local is sometimes injected into the sartorius muscle.

I'm curious if a more distal midthigh perifemoral block is more reliable in blocking the nerve to posterior branch of the obturator nerve vs a true midthigh perifemoral block where the femoral artery is in the middle/center of the sartorious muscle.

 

[Jay K]

In combination with a popliteal n. block, I've been performing the distal adductor canal block, as in Auyong's video, for ankle surgeries with success.

I suppose if I start using it for knees, I'll perform it mid-thigh with local superficial and deep to the artery.

 

[kmurp]

May I ask what total volume of local you all are using?

 

[BLADEMDA]

May I ask what total volume of local you all are using?

I use 15 mls (up to 20 mls if the surgeon doesn't inject or local toxicity isn't an issue) with excellent results. IMHO, a well placed adductor canal block should be successful and long lived with at least 10 mls of local.