Reliability and Validity of the Footprint Assessment Method Using Photoshop CS5 Software in Young People with Down Syndrome.

BACKGROUND

People with Down syndrome present skeletal abnormalities in their feet that can be analyzed by commonly used gold standard indices (the Hernández-Corvo index, the Chippaux-Smirak index, the Staheli arch index, and the Clarke angle) based on footprint measurements. The use of Photoshop CS5 software (Adobe Systems Software Ireland Ltd, Dublin, Ireland) to measure footprints has been validated in the general population. The present study aimed to assess the reliability and validity of this footprint assessment technique in the population with Down syndrome.

METHODS

Using optical podography and photography, 44 footprints from 22 patients with Down syndrome (11 men [mean ± SD age, 23.82 ± 3.12 years] and 11 women [mean ± SD age, 24.82 ± 6.81 years]) were recorded in a static bipedal standing position. A blinded observer performed the measurements using a validated manual method three times during the 4-month study, with 2 months between measurements. Test-retest was used to check the reliability of the Photoshop CS5 software measurements. Validity and reliability were obtained by intraclass correlation coefficient (ICC).

RESULTS

The reliability test for all of the indices showed very good values for the Photoshop CS5 method (ICC, 0.982-0.995). Validity testing also found no differences between the techniques (ICC, 0.988-0.999).

CONCLUSIONS

The Photoshop CS5 software method is reliable and valid for the study of footprints in young people with Down syndrome.