Use of three-dimensional computed tomography for the analysis of the glenoid anatomy.

Preoperative evaluation for a total shoulder arthroplasty includes 2-dimensional analysis of the glenoid through either standard radiographs or computed tomography (CT) images. Recent evidence suggests that these 2-dimensional images may actually misrepresent the 3-dimensional (3D) anatomy of the glenoid. Because 3D reconstructions of CT images allow 3D visualization and analysis of the scapula as a free body, we hypothesized that they can reflect the true anatomy of the glenoid more accurately. To test this hypothesis, we obtained various glenoid morphometric measurements from excised cadaveric scapulae as well as their respective 3D CT images. On average, the glenoid version angles measured from the 3D CT images were within 1.0 degrees +/- 0.7 degrees (mean +/- SD) of those from the actual specimen (95% confidence limit, <2.2 degrees for all observers). These measurements from the 3D CT images showed high interobserver and intraobserver reliability (interobserver and intraobserver correlation coefficients, 0.983 and 0.978, respectively). Similarly, measured glenoid surface width and length from the 3D CT images were within 1.8 +/- 1.2 mm and 1.4 +/- 1.1 mm, respectively, of those from the actual specimen. In addition, we were able to estimate the glenoid surface area as well as the glenoid vault volume from the 3D CT images. These values were 8.67 +/- 2.73 cm2 and 11.86 +/- 5.06 cm3, respectively. The mean glenoid vault volume with respect to its surface area was 1.35 +/- 0.24 cm3/cm2 (range, 1.06-1.91 cm3/cm2). These data suggest that 3D CT images can accurately reflect the true anatomy of the glenoid and that they can provide valuable information regarding the glenoid surface and vault. As such, 3D CT images may prove to be a useful tool during the preoperative evaluation for a total shoulder arthroplasty, particularly in patients with significant glenoid bone loss.