These authors proposed several modifications to the Walch classification for arthritic glenohumeral pathoanatomy.
They define a B3 glenoid as being monoconcave and worn preferentially in its posterior aspect, leading to pathologic retroversion of at least 15° or "subluxation" of 70%, or both.
They define a D glenoid as glenoid anteversion or anterior humeral head subluxation.
They redefine a A2 glenoid as having a line connecting the anterior and posterior native glenoid rims that transects the humeral head.
Comment: These authors have obviously put a lot of thought into the description of the arthritic glenohumeral joint building on the original pioneering work of Gilles Walch.
As pointed out in prior posts (see link), there many arthritic forms that lie between and among the classically described glenoid types, so that a categorical system has difficulty capturing them all.
For example in the proposed system, the difference between an
and a
is based on whether or not the retroversion is greater or less than an arbitrarily selected level of 15 degrees.
In addition there is confusion when the term 'subluxation' - which should be used to describe the relationship of the humeral and glenoid articular surfaces - is used to describe the relationship of the humeral head to the scapular plane (see the discussion in this link). The B3
as described does not show the separation of the the humeral and glenoid joint surfaces that characterizes 'subluxation' in the usual sense of the word.
By contrast the B2, B1, and D meet the usual definition of subluxation - "incomplete or partial dislocation of a joint "
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(3) The centering of the humeral head with respect to the glenoid (the distance between the anterior glenoid lip and the center of glenohumeral contact (C) divided by the distance between the anterior and posterior glenoid lips (G)). 0.5 indicates a centered humeral head.
Using this system,
the example "D" glenoid below would be 50% anterior biconcavity, 10 degree retroversion, and decentering of .25 (subluxation).
the example "B3" glenoid below would be 0 biconcavity, 40 degree retroversion, and centering of .5.
the example "A2" glenoid below would be 0 biconcavity, 15 degree retroversion, and centering of .5.
Such a system can provide the information necessary for characterizing the pathology and for planning treatment.
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