Overview of Spinopelvic Alignment

The two overarching concepts in this section are scoliosis and sagittal balance. A number of specific terms and measurements are shown for reference. Depending on the purpose and practice, radiology reports may remain descriptive.


Reference

Savarse LG et al. Spinopelvic sagittal balance: what does the radiologist need to know? Radiol Brasil 2020;53(3):175-184

Davis DK et al. Spine sagittal balance. StatPearls

Key anatomic points for assessment of spinopelvic alignment include: the C7 vertebral body, S1 superior surface, and femoral head geometric midpoint.

Spinal Alignment-Scoliosis Terms

Apex

End Vertebral body

Cobb Angle

Primary Curve

Secondary Curve

Hemi-vertebrae, Butterfly vertebrae

Acute Upper Thoracic Scoliosis

Lumbar Lordosis

Thoracic Kyphosis

Coronal balance

Sagittal Balance

More important than coronal balance

Associated with pain and disability

Compensatory mechanisms for positive sagittal balance include reduction of thoracic kyphosis and pelvic rotation

Examinations in standing position are useful.

Spinopelvic Alignment-Key Terms

Plumb line. A line from the midportion of the C7 vertebral body extending straight caudally.

Sagittal Vertical Axis

Pelvic Tilt

Sacral Slope. The slope of the superior surface of S1 defined by an angle between a line along the surface and a line perpendicular to the posterior edge of the S1 superior endplate.

Pelvic Incidence

Spinopelvic Angle. An angle formed by a line extending from the C7 vertebral body midpoint to the S1 superior endplate midpoint and a line from the S1 superior endplate midpoint to the femoral head geometric midpoint.


Pelvic Incidence = Sacral Slope + Pelvic Tilt