The axillary truth view is the workhorse of assessing preoperative and postoperative glenoid and glenohumeral pathoanatomy.
Understanding the arthritic shoulder and planning its management depends in large part on determining the anteroposterior position of the humeral head on the glenoid in a position of function.
Documenting the effectiveness of surgical management of the arthritic shoulder depends in large part on determining the postoperative anteroposterior position of the humeral head on the glenoid using the same method that was used preoperatively.
As explained in this video, these goals can most practically be accomplished by obtaining the axillary "truth" view taken with the arm forwardly elevated in a position of function. A proper axillary "truth" view will show the "eye" of the spinoglenoid notch (see arrow).
The axillary "truth" view can reveal the wide range of posterior decentering encountered in clinical practice as shown here (note the "eye" on each of these views):
Quantitating the amount of posterior decentering is easily measured on a properly taken axillary "truth" view using 6 straightforward steps:
1. A line segment (AC) is drawn from the anterior (A) to the posterior (C) edges of the glenoid.
2. A perpendicular bisector to this line is drawn from the midpoint (B) of AC.
3. X is the center of a circle fit to the humeral articular surface
4. A diameter of the circle (DF) is drawn through X and parallel to AC
5. E is the intersection of DF with the perpendicular bisector drawn from B.
6. The percentage of posterior decentering is (EF/DF – 0.5) × 100%.
This particular shoulder demonstrates a preoperative posterior decentering of 24%.
Unfortunately, many axillary views are not "truth" views, see such an example below. Functional decentering cannot be measured on such a view.
Unfortunately, decentering in a position of function cannot be measured on a CT scan obtained with the arm at the side (see below):
The amount of decentering preoperatively in a position of function can be compared before and after surgery using the axillary "truth" view.
Examples of the utility of the axillary "truth" view can be seen in "Management of intraoperative posterior decentering in shoulder arthroplasty using anteriorly eccentric humeral head components" and in "Total shoulder arthroplasty with an anterior-offset humeral head in patients with a B2 glenoid"
It is always nice to hear from our colleagues from across the pond. Recently, Angus Wallace, surgeon to Nottingham, posted on ResearchGate: "I agree with Rick Matsen and Bob Neviaser, you should train your radiographer to provide high quality AP and Axillary or Axial radiographs. I carry out 110 shoulder Arthroplasties per year and only order CT scans about twice per year, even for difficult cases." As Mr Wallace says, it is essential that the techs take the films properly as shown here.
We refer to the axillary view as the 'truth' view because it often lets us know what's really going on. Here's an example from our clinic yesterday. An active person in the mid 60s is having difficulty kayaking. The range of motion was restricted by about 20% in all planes. The AP view in the plane of the scapula looked unremarkable except for a small inferior osteophyte.
However, the axillary view showed posterior displacement of the humeral head on the glenoid and bone on bone contact between the center of the humeral head and the posterior glenoid - indicating complete loss of cartilage in these areas.
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