Identification of Threshold Pathoanatomic Metrics in Primary Glenohumeral
In their classic article, Primary glenohumeral osteoarthritis: clinical and radiographic classification. TheAequalis Group, these authors applied the standard definition of "subluxation": a partial dislocation, i.e.a separation of the joint surfaces." They provided a diagram showing non-subluxated joint with the humeral head centered on the glenoid articular surface.
Importantly, the authors of this classic article pointed out that there was no statistical correlation between the amount of posterior subluxation and glenoid version. They reported that, "Posterior subluxation existed in 45% of cases of primary osteoarthritis and did not occur because of excessive humeral retroversion, as there was no statistical correlation between these two factors."
In their recent article, these authors sought to identify the morphometric differences for the different glenoid types.
They analyzed CT scans from 707 shoulders of which 585 were obtained from shoulders with primary glenohumeral arthritis and 122 from shoulders without glenohumeral pathology.
They found that among the arthritic shoulders, 90% of the glenoids were retroverted and 85% of humeral heads were posterior to the plane of the scapular body.
From their data it can be seen that the percent of the humeral head posterior to the plane of the scapula is determined predominantly by the retroversion of the glenoid.
From these to articles, one can conclude that the term "subluxation" is properly applied to decentering of the humeral head on the glenoid. Posterior displacement of the humeral head in relation to the plane of the scapula is mostly a result of glenoid retroversion and is not properly referred to as "subluxation".
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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).
