Powers ratio

Atlanto-occipital
dissociation injuries • Base of skull lines (annotated images) - Ganzer Fall bei Radiopaedia
Hacking C, Base of skull lines (annotated images). Case study, Radiopaedia.org (Accessed on 05 Jan 2023) https://doi.org/10.53347/rID-40491 • CC by-nc-sa 3.0 (modified)
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The Powers ratio is a measurement of the relationship of the foramen magnum to the atlas, used in the diagnosis of atlanto-occipital dissociation injuries.

The ratio, AB/CD, is measured as the ratio of the distance in the median (midsagittal) plane between the:

  • basion (A) and the posterior spinolaminar line of the atlas (B) and,
  • opisthion (C) and the anterior arch of the atlas (D)

    • Normal values are <1 on plain radiographs and <0.9 on CT . If this ratio is >1, then the anterior atlanto-occipital dissociation should be suspected.

    History and etymology

    Barry Powers, American radiologist, described his ratio in a paper published in 1979 .

    Siehe auch:
    Assoziationen und Differentialdiagnosen zu Power-Quotient:
    atlantookzipitale
    Subluxation
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