Reproducible measurements for radiographically assessing longitudinal tarsal axes of severe cavus or flatfoot deformity

Abstract

Category: Other Introduction/Purpose: Calcaneal pitch and Meary’s angles are commonly used to assess longitudinal foot arches on lateral-view radiographs. Several different methods have been described in literatures to obtain the talar, first metatarsal, calcaneal, and plantar axes, but their reliability and reproducibility still remain to be evaluated. The aim of this study was to determine the most reproducible methods for radiographically evaluating the longitudinal axes. Methods: Standing radiographic images of 40 feet from consecutive outpatients, 22 feet with a severe cavus deformity and 48 feet with a severe flatfoot deformity, were obtained to measure the longitudinal axes of the talus, first metatarsal, calcaneus and plantar surface by using six, five, four and three different methods, respectively, that were described in the previous reports (Figure). Interobserver and intraobserver correlation coefficients were calculated by three observers. Results: The best interobserver and intraobserver correlation coefficients were obtained for methods that used a line bisecting the angle formed by the lines tangential to the superior and inferior margins of the talus (Method B), a line connecting the center of the first metatarsal head and the midpoint of the visualized base of the first metatarsal (Method J), and a line drawn tangential to the inferior surface of the calcaneus (Method L). For the plantar axis, the method that used the horizontal plane [reference axis] was considered the best. Conclusion: The above mentioned methods were considered ideal for the radiographic assessment of longitudinal foot arches, even in severely deformed feet. This study could contribute to standardized assessments of foot deformities.