STT joint OA treatment

[David Smith]

Hi Steve,
I’m wondering whether there is an US guided technique to target the rest of the STT joint for interventional treatment. I’m very familiar with injecting the CMC joint, but I wondered whether there might be a way for me to target the STT joint in those patients that have this problem as well.
Thanks,
Dave

[Stephen Bird]

Hi Dave,

It is really common for these 2 joints to be involved in arthritis and synovitis together and hence we often inject the 1st CMC and STT joints at the same time.

I have attached some images from my teaching material.

Scan the FCR tendon in the long axis and you can see it passing between the scaphoid and the trapezium. At this level inject between the bones and you have done an STT joint injection.
Some may flow into the FCR tendon sheath and I think this is OK as synovitis of this sheath goes along with STT joint arthritis and the sheath often communicates with the degenerative joint.
The photo I have attached is from a journal article, however I am concerned about the location of the radial artery if you use such a flat approach so we use a more vertical approach and check the location of the radial artery.

Steve.

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[David Smith]

Great answer Stephen! I will be adding this to my treatments of CMC joint OA. Beautiful tip!
Dave

[Stephen Bird]

It is a common combination. Your patients will love it. Just watch for the position of the radial artery,

Steve

[David Smith]

Hi Steve,
Do you inject in the area shown in the article, or do you move more medially where the FCR is passing over the scaphoid and trapezium? When I scan, it seems that the trapezium as a taller bone process to the radial side of the FCR, and the FCR travels over the two bones just ulnar to that. In the article, they are injecting using the same view used when injecting the CMC joint.
Thanks
Dave

[Stephen Bird]

You are correct the trapezium is the taller bone and you inject between the scaphoid and the trapezium.
Distal to this you can see the 1st CMC joint.

I think when we do this the transducer is placed slightly more to the ulnar side so you see the FCR tendon in long axis and the scaphoid and trapezium bones. To then show the 1st CMC you slide the transducer slightly radially and distally.

If you get the needle between the scaphoid and trapezium you will be in the STT joint.

Steve

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