The established definition of "subluxation" is:
"Subluxation of the shoulder is a partial dislocation of the shoulder. A humeral head subluxation occurs when the ball of the shoulder doesn't fully dislocate from the glenoid fossa but has shifted out of its normal position". (Massachusetts General Hospital)
"When the ball of the upper arm comes partially out of the socket, this is called a subluxation." (AAOS).
"Subluxation of the shoulder is a partial dislocation of the shoulder. A humeral head subluxation occurs when the ball of the shoulder doesn't fully dislocate from the glenoid fossa but has shifted out of its normal position". (Massachusetts General Hospital)
"When the ball of the upper arm comes partially out of the socket, this is called a subluxation." (AAOS).
This definition is clearly met by the case below, showing decentering of the humeral head in the glenoid.
As pointed out by Walch et al (see Morphologic study of the Glenoid in primary glenohumeral osteoarthritis) anteroposterior subluxation (or decentering) of the humeral head is commonly seen the arthritic shoulder. The measurements and clinical significance are straightforward
and can easily be obtained on the axillary truth view (see Answering the critical question: "To what degree is the humeral head functionally centered on the glenoid?" in 6 easy steps. and Natural history of glenoid bone loss in primaryglenohumeral osteoarthritis: how does bone loss progress over a decade?)
Recently, however, the term "subluxation" has been confusingly applied to something completely different. Rather than the clinically relevant relationship of the humeral head to the glenoid socket, some have redefined "subluxation" in terms of the relationship of the humeral head to the plane of the scapular body - a relationship of undetermined clinical significance.
The Evolution of the Walch Classification for PrimaryGlenohumeral Arthritis
Measurement of "humeral head subluxation according to the scapula axis method".
Measurement of "humeral head subluxation according to the scapula axis method".
Measurement of "humeral head subluxation according to the scapula axis method".
Radiographic Severity May Not be Associated with Pain and Function in Glenohumeral Arthritis
Measurement of "humeral head subluxation according to the scapula axis method"..
Focusing on the alignment of the humeral head to the plane of the scapula can lead to the use of augmented components that may not be necessary for centering the head on the glenoid fossa.
Typical (A) preoperative and (B) 2-year postoperative axillary lateral radiograph showing the "correction of posterior subluxation" with the posterior augmented all polyethylene glenoid component.
Augmented glenoid components may not be necessary for obtaining a good clinical outcome.
Do glenoid retroversion and humeral subluxation affect outcomes following total shoulder arthroplasty?
An example of a patient with advanced glenoid retroversion and posterior displacement of the humeral head in relation to the plane of the scapula both before and after total shoulder arthroplasty, but with postoperative centering of the humeral head on the gleonoid. (A) The preoperative axillary radiograph showed retroversion of 38°; (B) the postoperative axillary radiograph showed retroversion of 36°. The ASES score at 5-year follow-up was 98.33.
It is interesting to compare these two postoperative axillary radiographs. The first represents the "corrector" philosophy while the second represents the "acceptor" philosophy (see "acceptors vs correctors"). Which looks more robust?
For more on this important topic, see Subluxation in the arthritic shoulder - what is it and what should be done about it?
You can support cutting edge shoulder research and education that are leading to better care for patients with shoulder problems, click on this link.
Follow on twitter: https://twitter.com/RickMatsen or https://twitter.com/shoulderarth
Follow on facebook: click on this link
Follow on twitter: https://twitter.com/RickMatsen or https://twitter.com/shoulderarth
Follow on facebook: click on this link
Follow on facebook: https://www.facebook.com/frederick.matsen
Follow on LinkedIn: https://www.linkedin.com/in/rick-matsen-88b1a8133/
Follow on LinkedIn: https://www.linkedin.com/in/rick-matsen-88b1a8133/
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).
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).
