Carpal height

Carpal height is used to diagnose and assess the severity of carpal collapse. It is defined as the distance between the base of third metacarpal and the subchondral bony cortex of the distal radius. But due to variations between individuals, it is more appropriate to calculate the carpal height ratio.

Measurement

On a neutral dorsovolar radiograph of the wrist, two methods can be used:

Method of Youm

It is calculated by dividing the carpal height by the length of the third metacarpal 1.

Its normal range is between 0.51 and 0.57.

Method of Natrass

It is an alternative method for used in radiographs of the wrist that do not fully include the third metacarpus.

It is calculated by dividing carpal height (measured in line with the third metacarpal axis) by the greatest length of the capitate 2.

The capitate length is measured from the subchondral cortex adjacent to the bases of the second and third metacarpus to the proximal cortex along a line that passes through the center of the bone head.

Normal range: 1.57 +/- 0.05 3

Interpretation

These ratios change in diseases that cause carpal collapse, such as rheumatoid arthritis, Kienböck disease, traumatic injuries, and scapholunate advanced collapse

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rID: 44108
Synonyms or Alternate Spellings:
  • Carpal height ratio

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Cases and Figures

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    Method of Youm - ...
    Figure 1: Youm method
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    Method of Natrass...
    Figure 2: Natrass method
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    Diminished carpal...
    Figure 3: diminished carpal height ratio in SLAC
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