Evaluation of Usability of the Tiger Full Foot 3D Scanner for the Measurements of Basic Foot Dimensions in Clinical Practice

Background: Foot dimension information is important both for footwear design and clinical applications. In recent years, non-contact three-dimensional foot digitizers/scanners became popular as they are non-invasive and are both valid and reliable for the most of measures. Some of them also offer automated calculations of basic foot dimensions. The study aimed to determine test-retest reliability, objectivity, and concurrent validity of the Tiger full foot 3D scanner as well as the relationship between the manual measures of the medial longitudinal arch of the foot and its alternative parameters obtained automatically by the scanner. Methods: Intraclass correlation coefficients and the values of minimal detectable change were used to assess the reliability and objectivity of the scanner. Concurrent validity and the relationship between the arch height measures were determined by the Pearson's correlation coefficient and the limits of agreement between the scanner and the calliper method. Results: Both the relative and absolute agreement between the repeated measurements obtained by the scanner show excellent reliability and objectivity of linear measures and only good to nearly good test-retest reliability and objectivity of the arch height. Correlations between the values obtained by the scanner and the calliper were generally higher in linear measures (rp{greater than or equal to}0.929). The representativeness of state of bony architecture by the soft tissue margin of the medial foot arch demonstrate the lowest correlations among the all measurements (rp{less than or equal to}0.526). Conclusions: The Tiger full foot 3D scanner offers both excellent reliability and objectivity in linear measures, which correspond to those obtained by the calliper method. However, values obtained by the both methods shouldn't be used interchangeably. The arch height measure is less accurate, which could limit its use in some clinical applications. Orthotists and related professions probably appreciate scanner more than other specialists.

Corresponding Author; email: ondrej.lastovicka@upol.cz