Sagittal vertical axis

Last revised by Henry Knipe on 11 May 2024

Citation, DOI, disclosures and article data

Citation:

Knipe H, Sagittal vertical axis. Reference article, Radiopaedia.org (Accessed on 03 Jun 2024) https://doi.org/10.53347/rID-189184

DOI:

https://doi.org/10.53347/rID-189184

Permalink:

https://radiopaedia.org/articles/189184

rID:

189184

Article created:

10 May 2024, Henry Knipe ◉

Disclosures:

At the time the article was created Henry Knipe had the following disclosures:

Integral Diagnostics, Shareholder (ongoing)
Micro-X Ltd, Shareholder (ongoing)

These were assessed during peer review and were determined to not be relevant to the changes that were made.

View Henry Knipe's current disclosures

Last revised:

11 May 2024, Henry Knipe ◉

Disclosures:

At the time the article was last revised Henry Knipe had the following disclosures:

Integral Diagnostics, Shareholder (ongoing)
Micro-X Ltd, Shareholder (ongoing)

These were assessed during peer review and were determined to not be relevant to the changes that were made.

View Henry Knipe's current disclosures

Revisions:

1 time, by 1 contributor - see full revision history and disclosures

Systems:

Musculoskeletal, Spine

Sections:

Approach

Tags:

cases

Synonyms:

Sagittal vertical axis (SVA)
Sagittal vertical alignment (SVA)
Sagittal vertical alignment
C7 plumb line

Sagittal vertical axis/alignment (SVA) is one of the simplest and most widely used methods to assess sagittal balance ^1-3.

Measurement

This measurement is performed on lateral standing full-length spine x-rays. A plumb line is drawn vertically from the middle of the C7 vertebral body ^1,2 or the midpoint of the C7 inferior endplate ³ to S1, and the distance is measured between the plumb line and the posterosuperior corner of S1 ^1-3.

Interpretation

The position of this line can be positive, neutral or negative:

positive balance: the plumb line passes >2 cm in front of the posterosuperior corner of the S1 vertebral body
neutral balance: C7 plumb line intersects the posterosuperior corner of S1 (mean SVA in asymptomatic adults is 0.5 cm +/- 2.5 cm) ¹
negative balance: the plumb line passes more than 2 cm behind the posterosuperior corner of the S1 vertebral body