Left shoulder

[Michael Shilton]

Hi Steve
This patient has psoriatic arthritis and is complaining of 2 months of shoulder pain. She’s not had pain in this joint before. On examination she is restricted to about 110 degrees abduction and 160 flexion. He main muscular dysfunction was her biceps the rest tested pretty good functionally. The scan of the tendons looked surprisingly normal to me there is some blood flow and cortical irregularity near the greater tuberosity and I didn’t now if the flow was a normal vessel?? She has some restriction to external rotation as well so I’m wondering if this is a slow onset adhesive capsulitis or something related to her psoriatic arthritis? Any thoughts? Thanks, Mike

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[Stephen Bird]

Hi Mike,

Psoriatic arthritis is an attacker of the enthesis organ unit.
So you need to be vigilant of the enthesis of supra, subscap, infra etc.
If the seronegative psoriatic arthritis is attacking this shoulder I would expect these enthesis to show signs of erosive change and sub-periosteal cost formation.
In the MSK pathology principles webinar or perhaps even in the Joints webinar I discuss seronegative arthritis and have a great example of a youngish man who has multi enthesis destruction in the shoulder as result of his seronegative psoriatic arthritis despite a sedentary job.

In your case the enthesis of supra looks normal.

The flow you have is along the edge of the biceps tendon and seems to be arising from he greater tuberosity immediately adjacent to the biceps tendon.
This is a common spot for a small bony irregularity and personally I don’t put too much emphasis on it.
I am currently working on a presentation for the website that is called “what is that bony irregularity”. It will explore enthesis traction injuries, OA changes, gout and RA erosions as well as normal pits in the bone surface from synovial herniation pits. In the end it is all about location, location, location!

O in this location I often see what I believe to be a normal synovial herniation pit at the point where the SGHL is inserting into the humerus. So the bony chink is not necessarily pathological.
But you have flow arising from the enthesis and this raises further questions.
Is the flow due to a pathological enthesis as a result of the seronegative arthritis?
Or is the flow simply a normal vessel?

It is a good question.

I feel the chink in the bone is normal, but the presence of the blood vessel is more concerning as flow across any enthesis is in my view abnormal and consistent with either traction induced enthesopathy or a pathological enthesis due to the seronegative arthritis.

So I am suspicious.

Let’s monitor the other enthesis in the shoulder and see if any other erosions or vessels appear.

You can also monitor other articulations for the same thing.

Steve.

[Michael Shilton]

Hi Steve, many thanks. I’ve just taken a look at the joints webinar which was very informative. I’m having a little difficulty with my terminology/anatomy. Where does the enthesis start and end with LHB? Is there attachment into the bone at this point in the groove thereby classifying it as enthesitis? Good to know your opinion regarding the small c shaped herniation pit looking structure on the axial view, is there more suspicious possible erosive cortex on the long view do you think?
In terms of the other tendons they looked okay to me, I’ll recheck periodically if the patient is willing. Do you know if there tends to be a multi joint systemic coordination of flaring so that if I check her painful ankles for example and they are actively inflamed then that would increase the chance of her shoulder being due to her Psoriatic arthritis or are they independent of each other in terms of the activeness?
I’ll write to her rheumatologist and I’m considering reporting “there is some increased blood flow in the LHB enthesis adjacent to the greater tuberosity with possible cortical erosion which, given the known psoriatic arthritis, is suspicious for pathological enthesitis.” Sound okay, or is the erosion to strong and it’s still a normal pit?
Mike

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[Stephen Bird]

Hi Mike,

The LHBT enthesis is actually the superior labrum of thew GH joint.
It is an unusual tendon to not have a traditional bony enthesis at its origin.
The small herniation pits that you may notice adjacent to the LHBT in the region of the rotator cuff interval are actually from the joint capsule attachments where the SGHL attaches.
In your case there is flow across the enthesis of the SGHL attachment.
There is also excess flow in the LHBT sheath.
Given the seronegative history it is all likely related to this condition.
Whenever i see multi locational disease I think about the possibility of an underlying mechanism like rheumatoid, gout out seronegative disease.
In seronegative it is the enthesis that is mainly affected.

Like rheumatoid, seronegative patients will get occasional flare ups in different locations from time to time. Not necessarily all at the same time.

I would tell the rheumatologist that the SGHL enthesis has a small pit in the bone and flow across the enthesis as well as increased flow in the LHBT sheath consistent with the known seronegative condition.

Steve

[Michael Shilton]

That’s great Steve, many thanks as always.

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