CT-based preoperative analysis of scapula morphology and glenohumeral joint geometry

To investigate the geometry of the glenohumeral joint using three-dimensional (3D) models; define landmarks, planes, angles and regions of interest; and analyze the exact morphology of the scapula.

We reconstructed 3D scapula models based on computed tomography (CT) data sets of 12 healthy controls. Three-dimensional models were reconstructed using the 3D Slicer2 (Surgical Planning Lab, Boston, MA), which provides interactive measurement. The 3D model and measuring tools can be freely shifted and rotated in all planes.

The average length of the scapulas was 209.58 +/- 26.72 mm (left) and 223.68 +/- 47.74 mm (right); width was 124.03 +/- 13.28 mm (left) and 141.44 +/- 27.78 mm (right); and volume was 121.38 +/- 12.02 ml (left) and 130.24 +/- 20.86 ml (right). The glenoid dimensions were 34.34 +/- 5.62 mm (left) and 36.44 +/- 7.36 mm (right) (anteroposterior); and 49.16 +/- 7.68 mm (left), 51.46 +/- 10.07 mm (right) (superoinferior). For all average values, scapulas from male controls were significantly larger than those from females, and right sides were larger than left sides (p < 0.05). The glenoid version was nearly the same for male/female and left/right (left = 9.02 +/- 3.89 degrees retroversion; right = 8.26 +/- 3.72 degrees retroversion) (p > or = 0.05).

The 3D measurement of scapula morphology compared with geometry of the glenohumeral joint leads to a more precise planning of shoulder surgery. As new shoulder prostheses are intended to reconstruct the normal anatomy as closely as possible, such exact 3D measurements may be used for optimization.