The glenopolar angle assesses the rotational
alignment of the glenoid and may provide prognostic information
and aid the management of scapula fractures. We have analysed the
effect of the anteroposterior (AP) shoulder radiograph rotational
offset on the glenopolar angle in a laboratory setting and used
this to assess the accuracy of shoulder imaging employed in routine
clinical practice. Fluoroscopic imaging was performed on 25 non-paired scapulae
tagged with 2 mm steel spheres to determine the orientation of true
AP views. The glenopolar angle was measured on all the bony specimens
rotated at 10° increments. The mean glenopolar angle measured on
the bone specimens in rotations between 0° and 20° and thereafter
was found to be significantly different (p <
0.001). We also obtained
the AP radiographs of the uninjured shoulder of 30 patients treated
for fractures at our centre and found that none fitted the criteria
of a true AP shoulder radiograph. The mean angular offset from the
true AP view was 38° (10° to 65°) for this cohort. Radiological
AP shoulder views may not fully project the normal anatomy of the scapular
body and the measured glenopolar angle. The absence of a true AP
view may compromise the clinical management of a scapular fracture. Cite this article:
