Caton-Deschamps index (knee)

The Caton-Deschamps index is a ratio that is used in everyday practice as well as in research to measure patellar height and allows the diagnosis of patella alta and patella baja.

Radiographic features

The Caton-Deschamps index is the ratio between the distance between the lower pole of the patella and the upper limit of the tibia, and the length of the patellar joint surface.

Caton-Deschamps index

Caton-Deschamps index can be measured on a lateral radiograph or sagittal knee CT or MRI reconstructions. For measurement it is considered ideal that the knee is flexed at an angle of 30º, although for the original study by Caton-Deschamps the bending angles were between 20º and 80º.

  • A: measure of the distance between the lower pole of the patella and upper limit of the tibia
  • B: measure of patellar articular surface

The mathematical operation performed is A / B:

  • normal range 0.6-1.3
  • patella baja: <0.6
  • patella alta: >1.3

Caton-Deschamps ratio can also be applied to children, but age correction should be applied because patellar ossification begins at its proximal side 1.

Knee pathology

The knee is a complex synovial joint that can be affected by a range of pathologies:

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Article information

rID: 47666
Section: Signs
Tag: cases
Synonyms or Alternate Spellings:
  • Caton-Deschamps ratio
  • Caton Deschamps ratio

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