Clinical Assessment of the Medial Longitudinal Arch in Children: Rater Agreement and Relationship to Objective Foot Arch Measurements

The purpose of this study was to (1) investigate the agreement among clinical experts regarding the classification of the medial longitudinal arch in children and to (2) examine the relationship between the expert ratings and the static and dynamic foot arch measurements. Eleven foot experts were asked to identify foot arches of seventy-four children (mean ± SD age of 9.0 ± 1.81 years) using three categories (low, normal, and high arch). Additionally, dynamic footprint data of all children were captured with a pedobarographic platform. For static arch measurements, a specially constructed caliper was used to assess heel-to-toe length and dorsum height. Agreement among raters was determined using the kappa statistic. For comparisons between clinical rating and diagnostic systems, receiver operating characteristic (ROC) curves and ordinal logistic regression were calculated. The combined kappa score for all three arch types (0.422, 32.8%) shows borderline moderate agreement between raters. Area under the curves (AUC) values of the ROC curves ranging from 0.48 to 0.68 show poor relationship between quantitative and qualitative arch height measurements. The highest agreement was found for the dynamic arch index and foot experts’ ratings for low arched vs non-low arched feet (AUC = 0.68) and normal vs low arched feet (AUC = 0.67). The results of this study showed borderline moderate agreement among clinical experts in the clinical assessment of the medial longitudinal plantar arch in children. Also, only a poor relationship between the clinical foot arch assessments and the static and dynamic foot measurements was revealed. Further research is necessary to establish an accurate and consistent diagnostic system for the measurement of the medial longitudinal arch in children.