The Normal 3D Gleno-humeral Relationship and Anatomy of the Glenoid Planes

Figures

• 

  Figure 1. Shoulder function as described by Codman. The rear axis of the car represents the plane of the glenoid (yellow) and the axis of the trailer represents the plane of the humerus (red). The centre of rotation of the shoulder joint is the trailer hook in the figure (green).

• 

  Figure 2. The glenoid version is the angulation of the glenoid to the transverse axis of the scapula in the axial plane of the body. In this example, the glenoid version measures 3° retroversion.

• 

  Figure 3. Position of the patient in CT-scan gantry. This position mimics the operative conditions and keeps the gleno-humeral joint in a neutral position.

• 

  Figure 4. Humeral plane. This is a circular plane when a cut is made at the level of the anatomical neck of the humeral sphere.

• 

  Figure 5. The inferior glenoid plane, created with an anterior (A), posterior (P) and inferior (I) point at the bony rim of the inferior two quadrants of the glenoid.

• 

  Figure 6. The gleno-humeral angle. This is the angle between the humeral plane (red plane) and the glenoid plane (green plane).

• 

  Figure 7. The centre of the glenoid was determined by two different methods. The first method defines the centre as the midpoint of the greatest antero-posterior en supero-inferior distance of the glenoid (top figures). With this method (according to Saller) we defined a triangular-shaped plane (Saller’s inferior and superior plane). For the second method we used circular planes. The circular planes are defined by the best-fitting circle constructed with three points. The Circular Max plane (bottom left) takes the whole glenoid into account and the Circular Inferior plane is located at the inferior two quadrants of the glenoid (bottom right).

• 

  Figure 8. Position of the centre of rotation of the humerus (CR) to the centre of the inferior glenoid plane (CIc). The angle in the X-axis is 91.66° and in the Y-axis 91.7°. The distance is 24.8 mm. With this description, we quantified the position of the axis of the car and the trailer, and the position of the trailer hook with an angle and a distance.

• 

  Figure 9. (a, b) Direction from the midpoint of the inferior glenoid circular plane to the most medial point of the scapula. The angle is 93.43° in the X-axis (left figure) and 111.36° in the Y-axis (right figure).

• 

  Figure 10. Correlation of the radius of the inferior circular plane with the spinal scapular length (r = 0.75).

• 

  Figure 11. (a, b) Glenoid aiming device with its several components: K-wire, glenoid components, and the device.

• 

  Figure 12. Fixed retroversion of the glenoid components of 3.4° and a fixed inclination of 111.36°.