Intra-rater and inter-rater reliability of the five image-based criteria of the foot posture index-6.

Purpose/background: The Foot Posture Index-6 (FPI-6) is considered a simple quantification tool to assess static foot alignment. Palpation of the foot is required for assessment of one of the six criteria that comprise the FPI-6; the remaining five criteria may be evaluated using still-frame photographs. Using only the image-based criteria may allow multiple clinicians to evaluate large groups of patients quickly.