Sonographic appearances of groin anatomy

[Linh]

Hi Steve,

Hope you are doing well.

Excellent presentations on hernia assessment!

I was wondering if you can do a short “How to” video/images/explanations on locating:
– the lacunar ligament and its relationship to a more medial femoral hernia.
– the conjoint tendon & pubic aponeurosis at the Symph Pubis (also their clinical significance?)
– the anatomy of paramidalis
– the obturator nerve (as a source of medial groin/hip pain)

Best regards,
Linh

[Stephen Bird]

Hi Linh,

They are a few good topics,

I will get around to making material on them,

but for now some comments:

The Lacunar ligament is not a structure I see with ultrasound but I know where it lives and I can see if it fails.

Imagine the apex of a triangle being made by the inguinal ligament and the anterior surface of the pectinous muscle (with the bony iliopectineal eminence beneath it). This triangular area is where the lunar ligament lives and when it fails peritoneal content can pass deep to the inguinal ligament and superficial to the pectinous muscle through the defect. So it is sort of a really medially placed femoral hernia just lateral to the pubic tubercle.

The pubic aponeurosis is the combined collagen anterior to the symphysis pubis. It has contributions from the right and left inguinal legs, conjoint tendons, rectus abdominus and the adductor longus from below. So that is 8 structures in total and they all blend together interdigitating anterior to the symphysis pubis forming the pubic aponeurosis.

The conjoint tendon is the collagen from transversus abdominus and internal oblique (which make the posterior wall of the intgional canal) then blend with the pubic aponeurosis just medial to the attachment of the inguinal ligament. If you scan the right pubic tubercle for example and have the transducer straight sagittal pointing towards the patients chin you will see the rectus abdominus tendon blending into the pubic aponeurosis with the pyramidalis muscle sitting anterior to it. If you then slide the transducer to the lateral edge of the pubic tubercle and then rotate the transducer slightly anticlockwise so the probe is pointing to the patients ipsilateral shoulder tip you will see another structure that looks similar to the rectus abdominus tendon, but this time it is the conjoint tendon.
The conjoint tendon is much talked about, however I don’t personally see many cases where it looks abnormal sonographically. It certainly makes up part of my athletic pubalgia examination.

The pyramidalis is on no concern to me. It can be of varying sizes as an anatomical variation between individuals and it can be absent congenitally. It is always a fairly small muscle so doesn’t have a lot of strength.

You see it anterior to the rectus abdominus tendons and distal muscle bellies and it is triangular in shape. I have never seen this published, but I observe the tendon of rectus abdominus being longer in patients with a larger pyramidalis and the rect and tendon is shorter (with a longer muscle extension) in patients with an absent pyramidalis.

The obturator nerve can indeed be a source of pain in the upper inner thigh area.
I don’t see an abnormal nerve sonographically, however we do see where the nerve runs.
If you scan sagittal just lateral to the edge of the pubic tubercle you will see the pectinous muscle originating from the iliopectineal eminence. Deep to this muscle is the obturator externes muscle and the 2 branches of the obturator nerve run 1: between pectinous and obturator externes and 2: immediately deep to obturator externus. You can see the adjacent artery with colour Doppler. Both of these locations can be injected under ultrasound guidance.

Steve

[Linh]

Hi Steve,

Thanks for your detail response. Can’t wait for more visual input from you.

What are the possible injuries we might find on the pubic aponeurosis? For example, would an apophyseal fracture at the pubic symph on a teenage footballer affect this structure?

Also, if say a patient who previously had a mesh hernia repair, would you expect the conjoint to be thickened and scarred later on?

With groin hernias, do you just do ballooning and erect? Do you do crunching/half sit-ups – Do you think this is helpful at all if I already perform ballooning and erect sequence?

Best regards,
Linh

[Stephen Bird]

Hi Linh,

The pubic aponeurosis certainly can tear and we see this with traction injuries mainly generated by adductor longus or rectus abdominus.

With the adductor longus tears or the pubic aponeurosis when you scan the adductor longus in ling axis you can see it separating from the undersurface of the pubic tubercle with a cleft developing. On MRI this is seen as a secondary cleft sign.

When rectus abdominus causes the tear we see this more anteriorly about half way between the central axis of the symphysis pubis and the lateral edge of the pubic tubercle. You see again a cleft forming and also bony change from the avulsion. It is usually asymmetrical which makes it easy to notice.

Apophyseal injuries in young athletes are quite different as this is a bony injury rather than an aponeurosis failure.

I don’t see conjoint tendon problems with mesh repairs particularly. Others may have a different opinion, however after a mesh repair I am more interested in neural entrapment from the fastening clips rather than conjoint tendon problems. The conjoint tendon is really just the pubic aponeurosis end of the posterior wall and after a mesh repair the posterior wall has been replaced / reinforced by mesh.

I use 2 techniques for increasing abdominal pressure.

The first technique I have the bed tilted at 45 degrees so it is comfortable for me to scan and also I have some gravitational pressure. I ask the patient to put their thumb on their lips and blow on it like they are blowing up a balloon. I can ask them to blow harder or softer so I can control the pressure.

The second technique is to do the same trick with the patient standing erect.
In the erect position it is technically difficult to scan and navigate, however you do have maximum pressure.

The combination of these 2 techniques covers all bases.

Steve

[Linh]

Thanks Steve for your explanation 🙂

[Linh]

Hi Steve,

I tried using your tips above on this 7 year old Groin study. Can you please critique if I got the right landmarks/anatomy?

I can’t imagine the pubic aponeurosis. Is it a bright thick band across the 2 pubic tubercles?

Also did I differentiate the RA insertion and conjoint tendon correctly?

Bets regards,
Linh

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[Linh]

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[Stephen Bird]

I think your images are excellent,

The pubic aponeurosis is all of the collagen anterior to the bony symphysis pubis so it is quite thick.

I think you have imaged the rectus abdominus and conjoint components nicely.

Good work,

Steve

[Linh]

Hi Steve,

Same patient, he had non specific fluid going into his inguinal canal and stops at the superficial ring. Is this a form of funicular hydrocele?

Best regards,
Linh

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[Stephen Bird]

Yes 100% I would call this a funicular hydrocele.

Nice example,

Steve

[Linh]

Thank you so much Steve! I’m impressed you are able to guide others scan without even showing them visually!

[Stephen Bird]

Your images made it easy,

They are great images and show really classic appearances as I would expect from someone who has great skills.

Lovely work,

Steve

[Linh]

You’re too kind! 🙂

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