title: The assessment of scapular radiographs: analysis of anteroposterior radiographs of the shoulder and the effect of rotational offset on the glenopolar angle.
abstract: 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.
authors.affiliation: Steadman Philippon Research Institute, Department of BioMedical Engineering, 181 W Meadow Dr., Vail, CO 81657, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Wijdicks
authors.forename: J
authors.initials: J
authors.lastname: Anavian
authors.forename: B W
authors.initials: BW
authors.lastname: Hill
authors.forename: B M
authors.initials: BM
authors.lastname: Armitage
authors.forename: S
authors.initials: S
authors.lastname: Vang
authors.forename: P A
authors.initials: PA
authors.lastname: Cole
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005471:Fluoroscopy / Q000379:methods; D050723:Fractures, Bone / Q000000981:diagnostic imaging*; D061165:Glenoid Cavity / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012189:Retrospective Studies; D012399:Rotation; D012540:Scapula / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D012784:Shoulder Fractures / Q000000981:diagnostic imaging; D000070599:Shoulder Injuries; D012785:Shoulder Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D055815:Young Adult
keywords: Glenopolar angle; Grashey view; Radiological landmarks; Scapula; Shoulder radiograph; True anteroposterior