Functionality is available in the Pro edition
To plan pedicle screws installation:
- Activate the tool Pattern screw installation by clicking on the button on the
- In accordance with the scheme in Fig. 7.1 put the following points on the axial plane C1,
B1 (axis of screw #1), C2, B2 (axis of screw #1). Screws scheme similar to shown in
Fig. 7.5 will be displayed on the axial plane.
- If necessary, set the properties of the Pattern screw installation tool. The tool
properties are similar to properties of other measurement tool (see Section 2.15.7).
- Adjust the positions of the points if necessary. To do this, Locate the cursor on the
point to magnify the cross, marking the point, and move it holding the left mouse
- Points C1 and C2 must match with the tips of screws if you want to calculate the
length of the screws.
- Points A1 and A2 denote points of screws introduction. The points move only along
the axis of the screws.
- Point O should be placed on the vertebral axis (shown by the dotted line in Fig. 7.1)
on the border of the spinous process.
Adjusted screws installation scheme is shown in Fig. 7.6.
- If necessary, change the angles of inclination of the axial plane so that it is parallel to the
plane in which the screws must be installed. Working with the planes is described in
- If necessary, move the axial plane so that it coincides with a plane in which the screws must be
- If necessary, move the measurements results (see Section 2.15.9). The measurement results are
connected to points of the dashed lines tool follows:
- point C1: the length of the segment A1C1 (the length of the screw #1);
- point C2: the length of the segment A2C2 (the length of the screw #2);
- point A2: the length of the segment A1A2 (the distance between the screws
- point B1: the length of the segment B1O (the length of the segment connecting the
axis of the screw #1 to the center of the spinous process). Need for deflection of the
drill to the desired angle in the axial plane;
- point B2: the length of the segment OB2 (the length of the segment connecting the
axis of the screw #2 to the center of the spinous process). Need for deflection of the
drill to the desired angle in the axial plane.
Figure 7.5: The original screws installation scheme with letter according to the scheme (the
letters are not available in the program)
Figure 7.6: The adjusted screws installation scheme