Intra-and inter-observer reliability and repeatability of the metatarsus adductus angle in childhood: A concordance study

Abstract

Background

Metatarsus adductus is a relatively common congenital foot deformity often unrecognized at birth. There is adduction of the metatarsals, supination of the subtalar joint, and plantar flexion of the first ray.

Objective

The objective of this study was to utilize the most commonly used methods for assessing metatarsus adductus deformity in children and to identify the measurements with the least intra- and inter-observer variability.

Materials and methods

All consecutive patients between 2 and 9 years of age with metatarsus adductus by roentgenographic evaluation on weight-bearing dorsoplantar images were included in this cross-sectional study. Measurements included 32 radiographs, 18 feet from 14 girls with a mean age of 3.73 ± 2.53 years, and 14 feet corresponding to 11 boys with a mean age of 5.21 ± 2.15 years. We identified and assessed all radiographic measurements to evaluate the metatarsus adductus with the different measurements commonly used today, including the Berg, Kilmartin, Laaveg & Ponseti, rearfoot, Root, and Simons’ angles.

Results

The reliability of the variables measured in 32 weight-bearing dorsoplantar foot radiographs showed excellent reliability ranging in Laaveg-Ponseti and rearfoot angles with low standard error of measurement (SEM), coefficient of variation (CV), and minimum detectable change (MDC) with intraclass correlation coefficient (ICC) higher than 0.990. Kilmartin, Root, and Simons’ angles showed good intra- and inter-observer reliability, with ICC values greater than 0.900; however, they also exhibited systematic differences between sessions or between observers (P < 0.05), or a high MDC value, which may limit their reproducibility.

Conclusion

Based on the results obtained in this study from the different measurements performed, the rearfoot measurement and the method proposed by Laaveg and Ponseti can be considered the most reliable, as they showed the highest intra- and inter-observer reliability.