I received a bunch of helpful comments.
Phil Tirman:
I think the excessive widening of the RI is due to long term stretching as a baseball player with a lot of forceful external rotation in his athletic career.Nice POLPSA Lesion.
As an aside I don’t diagnose tendinitis, especially mild, in a 19y/o. I’ve had call backs asking to change wording as tendinitis connotes degenerative disease which can be harmful to have in an athletes record when it could be a strain (which connotes something that will resolve)
***Given the implication of tendinosis implying degeneration rather than acute injury, I changed my report to say "low grade subscapularis tendon strain" rather than tendinosis
Ming Huang:
I think the large RI is contributing to the posterior instability.
I remember reading that the capsule at RI is important for posterior stability.
I double checked:https://radsource.us/polpsa-lesion/
the reference The role of the rotator interval capsule in passive motion and stability of the shoulder. Journal of Bone and Joint Surgery 74A:53-66, 1992.
Greg:
Interesting case and subject Hillary. This research was presented at a Ortho meeting in 2011. I think the jury is still out on the significance of a wide Rotator interval its association with multidirectional instability. I have noticed however, a widened interval, particularly in female overhead athletes – volleyball, water polo and swimmers. Often times with no other pathology seen.
As for your POLPSA lesion, since the labrum is not medialized I’ve been calling those reverse Perthes lesions and save the POLPSA for when the labral tear is medialized. I’m sure many however, would disagree.
****So, being easily pursuaded, I addended my report to say that it might be more appropriate to report the posterior labral lesion as a "Reverse Perthes" rather than POLPSA lesion.
But the more I think about it….I’m really not sure.
With POLPSA you typically see mild displacement but not "medialization" of the posterior labrum (as we see in ALPSA).
Plus, the posterior capsule is totally lax give the excessive degree of external rotation, I’m not sure lack of displacement is reliable.
Thoughts?
On Tue, Aug 19, 2025 at 2:56 PM hilary wrote:
I injected the arthrogram under fluoro guidance.We routinely inject lidocaine to assess pain response, he had complete pain relief.
There is mild marrow edema at the anterior greater tuberostity and mild subscapularis tendinosis.
The rotator interval looks excessively wide, but…
They positioned him in tremendous external rotation
The red arrow indicates the POLPSA lesion
My question is if the RI can be that wide from the excessive external rotation, or is it pathologic?Thanks
Hilary
