Foot Build Registration System (FBRS) to evaluate foot posture: a reliability study with healthy subjects and patients with Charcot-Marie-Tooth disease

BackgroundTo follow the weight bearing foot posture in subjects, a measurement tool using digital photography was developed, Foot Build Registration System (FBRS) (Fig. 1) [M. Van der Cruijsen, Voetvorm registratie systeem, Boxmeer (1999).]. This study's objective was to investigate the reproducibility of FBRS measurements in healthy feet and feet of patients with Charcot-Marie-Tooth disease (CMT).MethodsReproducibility and reliability studies were performed in several foot views in healthy and CMT patients.ResultsThese studies showed that the variability of the 95% prediction limit depended upon the foot view being studied and whether markers had been drawn. Some individuals had a higher intra-individual variability than others. Limiting data collection to those individuals with a SD <3.5° for a series of five or more photographs per view improved the 95% prediction limits. These varied between 2.8° and 7.7°.ConclusionsIf the differences found between registration are greater than the abovementioned, values can be attributed to time or operative management for healthy and CMT patients and not to measurement error.