Two-dimensional glenoid version measurements vary with coronal and sagittal scapular rotation

Area of Science:

• Orthopedic surgery
• Radiology
• Biomechanical analysis

Background:

• Accurate osseous glenoid morphology analysis is vital for treating glenohumeral arthritis and instability.
• Two-dimensional computed tomography (2D CT) is commonly used for evaluating glenoid alignment.
• The accuracy of 2D CT for glenoid version assessment depends on axial reconstruction angle relative to scapular position.

Purpose of the Study:

• To investigate the impact of scapular rotation in coronal and sagittal planes on glenoid version measurements using 2D images.
• To quantify the variability in glenoid version measurements due to scapular malalignment.

Main Methods:

• Generated 3D models of scapulae from CT scans of 36 cadaveric shoulders.
• Validated the anatomic geometry of the 3D models.
• Rotated 3D models in 1-degree increments in coronal and sagittal planes.
• Measured glenoid version on simulated 2D images at each rotation increment and calculated version variability.

Main Results:

• Anatomic glenoid version averaged 2.0° ± 3.8° retroversion.
• Average difference between anatomic and clinical glenoid version was 6.9° ± 5.6° (range 0.1°–22.5°).
• Scapular rotation in coronal (abduction) and sagittal (internal rotation) planes significantly altered glenoid version measurements (p < 0.0001).

Conclusions:

• Malalignment of ≥1° of the scapula in coronal or sagittal planes introduces inaccuracies in glenoid version measurement.
• Aligning the plane of axial reconstruction with the scapula is essential for accurate 2D CT glenoid version assessment.
• Three-dimensional (3D) models are recommended for reliable evaluation of glenoid version.