Rockwood Adults CH34

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CHAPTER 34 • Glenohumeral Instability

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D Figure 34-16.  ( Continued ) C: Scapular “Y” view. D: Axillary view which is considered the standard view for the evaluation of the relationship of the humeral head to the glenoid.

(true AP view) is oriented to the scapula with the radiographic beam centered onto the glenohumeral joint line (Fig. 34-17B). In patients who are able to abduct the arm, an axillary view must be obtained in order to evaluate for anterior or posterior humeral head subluxation or dislocation (Fig. 34-17C). This view is centered on the epicenter of the humeral head and the glenoid and provides an unambiguous view of anteroposterior glenohu- meral alignment. Clinical concerns of anterior or posterior gle- nohumeral subluxation/dislocation and osseous Bankart lesions can best be evaluated with the axillary view. Alternatively, if the patient is unable to abduct their arm due to the acuity of injury, a scapular “Y” view must be obtained to evaluate the relationship of the humeral head to the glenoid (Figs. 34-17C and 34-18A). In a systematic review of posterior shoulder dislocations, Xu et al. 269 reported a missed initial diagnosis in 73% of patients (150) due to the lack of an axillary view, Y view, or computed tomography (CT) imaging. Of these 150 patients, almost all (147/150 or 98%)

had only AP or lateral views of the shoulder. When the axillary or Y-view radiographs were made subsequently, the diagnosis of posterior dislocation was confirmed in 100% of patients. In the subset of patients who present acutely with guarding and are unable to abduct the shoulder to obtain the axillary view, the scapular “Y” view (Figs. 34-17C and 34-18A) or a Velpeau view must be obtained to evaluate for subluxation or dislocation (Fig. 34-18B). Silfverskiold et al. 213 compared the axillary and scapular “Y” view in 75 consecutive patients with suspected shoulder dislocations and found that in 69 patients (92%), both views resulted in the same diagnosis. However, 81% of patients preferred the scapular “Y” view because of less pain, and the radiology technician also preferred the “Y” view due to the ease of obtaining the image compared to the axil- lary view. Additionally, a Velpeau view can also be obtained in these patients who are guarding. This is done with the patient in the sling and the radiographic plate positioned posteriorly and

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Figure 34-17.  A: Anteroposterior radiographic view is performed with the beam aligned to the body. B: Grashey view is done with the beam centered with the glenohumeral joint line. C: Axillary view is done with the arm in abduction and the plate is placed behind the patient’s shoulder in the supine position. The radiographic beam is aimed 45 degrees to the axilla.