Aim: To evaluate the usefulness of the apical oblique projection of the shoulder in determining radiographic signs of instability.

Methods: Radiographs from 50 consecutive patients who presented for surgery for treatment of symptomatic unilateral shoulder instability were evaluated. Standard radiographic views had been obtained (anteroposterior [AP], lateral and axillary view) pre-operatively along with an apical oblique. The apical oblique view is obtained by placing the patient in a 45 degrees posterior-oblique position and angling the beam 45 degrees caudad. The radiographs were reviewed independently by two radiologists. Each radiograph was evaluated for evidence of any Hill-Sachs or bony Bankart lesions that were accepted as radiographic signs of anterior instability. Comparison of the diagnostic yield of the standard views and the apical oblique were made.

Results: The radiographs of 32 males and 18 females with an average age of 27 years (range: 17 to 41 years) were included in the series. Pathology (Hill-Sachs, Bankart lesions or both) was seen on an apical oblique in 93% of cases compared with AP (48%), lateral(17%) and axillary(32%) views. Taken collectively the standard views showed pathology in only 72% of cases.

Conclusions: The apical oblique view is easy for the radiographer to obtain, can be performed using standard imaging equipment and can be obtained pain-free in the acute setting. The diagnostic yield was significantly higher than the standard trauma series. The apical oblique view should be added to these in cases of suspected shoulder instability.