Background: The accurate measurement of flatfoot on standing radiographs allows correct diagnosis of the condition and evaluation of reconstructive procedures.
Method: The standing radiographic measurements of patients with symptomatic, adult flatfoot were compared to controls using blinded observers.
Results: On the lateral radiograph, the talar-to-first metatarsal angle, the calcaneal pitch angle, and the medial cuneiform-fifth metatarsal height differed significantly between the patient group and the controls. The difference in the talar-to-first metatarsal angles on lateral radiographs was the most statistically significant (patient group 21.1 +/- 10.8 degrees and control 7.1 +/- 10.7 degrees, p < 0.0001) with good correlation between readings (intraobserver 0.75, interobserver 0.83). On the anteroposterior (AP) radiograph, the talar head uncoverage distance was the most significantly different measurement between these groups.
Conclusions: These findings support the hypothesis that the talar-first metatarsal angle is an accurate radiographic identifier of patients with symptomatic, adult flatfoot.