Sagittal Balance: How to perform

Last updated on July 6 2022

Description

Sagittal balance forms part of the plain radiographic assessment of spinal deformity including kyphotic or lordotic deformities and scoliosis. There are numerous ways of assessing this, using various bony landmarks and angles to evaluate whether or not a normal distribution of weight and stresses is present through the axial skeleton. Individuals with abnormal sagittal balance (positive or negative) are at risk of progressive spinal deformity and pain.

By these means, to evaluate a patient’s sagittal balance, it will include the following procedures:

• Sagittal Vertical Axis
• Lumbar Lordosis Angle
• Pelvic Angles
• Thoracic Kyphosis Angle

Measurements

The measurement made by the procedure is displayed in the image: 

• Sagittal Vertical Axis (SVA): the horizontal offset from the posterosuperior corner of S1 vertebral body to the plumb line;
• Lumbar Lordosis Angle (LLA): the angle formed between the superior end plate of L1 and the superior end plate of S1;
• Sacral Slope (SS): the angle between the line along with the S1 end plate and the reference horizontal line;
• Pelvic Tilt (PT): the angle between the reference vertical line that crosses the femoral heads’ midpoint and the line that goes from the femoral heads’ midpoint to the S1 end plate’s midpoint;
• Pelvic Incidence (PI): the angle between the line that goes from the femoral heads’ midpoint to the S1 end plate’s midpoint and a perpendicular line to the S1 end plate’s midpoint;
• Thoracic Kyphosis Angle (TKAG): the angle formed by the superior end plate of the T1 vertebra and the inferior end plate of the T12 vertebra.
  
  

Auxiliary references

To show this procedure, PeekMed® needs additional references:

• Plumb line: a vertical line starting from the midpoint of the C7 vertebral body;
• Center of the S1 end plate: the midpoint between the anterior and posterior edges of the superior end plate of S1;
• Femoral heads midpoint (MP): the midpoint between the left and right femoral heads.