Wednesday, July 3, 2024

B0 glenoid with functional decentering in a 44 year old man - what to do?

A 44 year old man had a previously asymptomatic left shoulder until he attempted to separate to young boys who were fighting at school. Since then he has had pain in his left shoulder, especially when he attempts to push with the arm in forward elevation. His ranges of motion are full and symmetrical to the opposite side. His pain is aggravated with cross body adduction and when he pushes forward and upward against resistance. Instability tests were all unremarkable.

An MRI taken with the arm at the side shows the humeral head centered in the glenoid. His posterior labrum appears somewhat hypertrophic (as seen in glenoid dysplasia) and appears detached from his glenoid.



His axillary "truth" view taken in the position of function and in the position most painful for him shows functional posterior decentering of the humeral head on a glenoid lacking a bony concavity posteriorly.




This case may meet the definition of a Walch B0 glenoid: pre-osteoarthritic posterior subluxation of the humeral head. The authors of that article state: "It appears that Walch B0 glenoid is a pathologic condition (initially dynamic, eventually evolving into a static condition) that may lead to posterior erosion of the glenoid, taking place once there is asymmetric increased posterior glenohumeral contact forces and possibly associated with increased glenoid retroversion."

Further discussion of this pathoanatomy can be found at
The B0 glenoid: why does the back of the glenoid wear out?

In the relevant and interesting ASES Podcast - Episode 107 - Glenohumeral Osteoarthritis Etiology Dr. Peter Chalmers and Dr. Brian Waterman conduct a roundtable interview on the etiology of glenohumeral osteoarthritis with Drs. Ben Zmistowski and Jean-David Werthel.

For our patient the question becomes "what can be done to prevent this shoulder from becoming arthritic? Will a posterior labral repair address the functional posterior decentering? Is there a bony procedure that would be more effective?

We are wondering. Share your thoughts at shoulderarthritis@uw.edu

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Here are some videos that are of shoulder interest
Shoulder arthritis - what you need to know (see this link).
How to x-ray the shoulder (see this link).
The ream and run procedure (see this link).
The total shoulder arthroplasty (see this link).
The cuff tear arthropathy arthroplasty (see this link).
The reverse total shoulder arthroplasty (see this link).
The smooth and move procedure for irreparable rotator cuff tears (see this link).

Shoulder rehabilitation exercises (see this link).