Last updated on July 6 2022
Description
Sagittal plane deformity can be determined clinically and radiographically, evaluating the magnitude of the deformity and the correction degree required to reestablish balance.
Sagittal vertical axis (SVA) is a parameter to characterize the Sagittal Balance and it is identified by a plumb line dropped from C7 to the sacral end plate. To calculate the SVA, it’s required an X-Ray on the lateral view. Sagittal forward (SVA > 5 cm), neutral (0 – 5 cm, ideally 2.5 cm), and sagittal backward (SVA < 0). The distal boundaries of this line can be defined as:
- Positive Sagittal Balance: a plumb line that is anterior to the posterosuperior aspect of the S1 body;
- Negative Sagittal Balance: a plumb line that is posterior to the posterosuperior aspect of the S1 body.
This only influences the reciprocal distance to the SVA but not the principle of measurement.
Measurements
The measurement made by the procedure is displayed in the image:
- Sagittal Vertical Axis (SVA): horizontal offset from the posterosuperior corner of the S1 vertebral body to the plumb line.
Auxiliary references
To show this procedure, PeekMed® needs additional references:
- Plumb Line: a vertical line starting from the midpoint of the C7 vertebral body.
How to perform
After selecting this procedure in the sidebar, you must mark the points to conclude it. To see the caption of each point you need to click on this button 
Beware: you can change the position of the points at this stage or later. To do this, simply click on each handle with the left mouse button and move them to the most suitable position.
This procedure has no advanced configuration.