Is anterior glenoid bone block position reliably assessed by standard radiography? A cadaver study.

BACKGROUND: Standard radiography with an antero-posterior view and Bernageau's glenoid profile view is the method most widely reported in the literature to assess coracoid bone block position and fusion.

OBJECTIVE: The aim of this cadaver study was to determine whether the antero-posterior and Bernageau's radiographs provide a reliable and reproducible evaluation of the position of a coracoid bone block and its fixation screws.

METHOD: An isolated scapula showing no evidence of osteoarthritis or other abnormalities was used. The coracoid process was transferred to the anterior glenoid rim. Fixation was with two slightly diverging malleolar screws, chosen of different sizes for ease of identification. Computed tomography (CT) was performed as the reference imaging technique. The standard radiographs were then obtained, using fluoroscopy to accurately position the scapula for the antero-posterior and Bernageau's views. This position was defined as 0°, and radiographs were taken at angles of 5°, 10°, and 15° in all three planes. All radiographs were taken during a single session to ensure that the distance separating the tube from the scapula remained unchanged. The images were exported to OsiriX for analysis. We measured the angles formed by the screws and the glenoid surface, as well as bone block position and overhang. Finally, we used 1-mm thick disks to evaluate bone-to-bone contact.

RESULTS: No correlations were found between values by CT and by standard radiography (both views) for the screw angles or overhang. A space≤1mm between the neck of the scapula and the bone block was not visible on the standard radiographs in any of the positions.

CONCLUSION: Standard radiography does not provide an accurate analysis of bone block position or bone-to-bone contact. CT is needed to assess bone block and screw position and bone-to-bone contact.

LEVEL OF EVIDENCE: Level III.