modified Insall-Salvati index

Intra-articular
loose bodies • Patellar dislocation with chondral injury - Ganzer Fall bei Radiopaedia
Feger J, Patellar dislocation with chondral injury. Case study, Radiopaedia.org (Accessed on 23 Nov 2022) https://doi.org/10.53347/rID-76304 • CC by-nc-sa 3.0 (modified)
Radiopaedia • CC-by-nc-sa 3.0 • de

The modified Insall-Salvati ratio or index is another technique to assess patellar height.

Usage

It was proposed to avoid mismeasurement due to the variable shape of the inferior patella pole , however, the Insall-Salvati ratio has been demonstrated to be more reproducible .

Measurement

The modified Insall-Salvati ratio is applied on a lateral 30° flexed knee radiograph like the Insall-Salvati ratio but is measured differently:

  • A: distance from the inferior margin of the patellar articular surface (as opposed to the lower pole of the patella itself) to the patellar tendon insertion
  • B: length of the patellar articular surface

Modified Insall-Salvati ratio = A/B

Interpretation

  • normal: 1.25 (range 1.2-2.1)
  • patella alta: >2
    • at this cut-off, 3% of normal knees will be classified as patella alta
Siehe auch:
und weiter:
Assoziationen und Differentialdiagnosen zu Modified Insall-Salvatti index: