The Design and Validation of a Low-Cost Foot Measurement System

It is estimated that approximately 40% of the population suffers from abnormal foot posture, specifically high arched or low arched feet. While the evaluation of foot posture can involve many aspects, it commonly requires the measurement of basic dimensions of the foot. Clinicians and researchers often rely on the use of specialized devices or three-dimensional (3D) scanners to evaluate specific aspects of a patient's foot posture. However, current technologies are extremely expensive, therefore highlighting the need for a cost-effective device to be used in rural and clinical settings. As a result, the purpose of this study was to develop an inexpensive system to measure total foot length, truncated length, dorsum height, navicular height, and foot width. Bland-Altman plots showed significant differences between this measurement system and a 3D scanner for total foot length, truncated length, and navicular height (p < 0.001) and significant differences when assessing the repeatability of dorsum height (p = 0.022). However, the magnitudes of these differences were minimal compared to the overall measurement. Additionally, interclass correlation coefficients revealed that this system had excellent validity when compared to a 3D scanner (interclass correlation coefficients = 0.908-0.994), and good to excellent repeatability when compared between days (interclass correlation coefficients = 0.867-0.996). These results demonstrate that it is possible to design an inexpensive, valid, and repeatable system that can be used in clinical, research, and rural settings to successfully evaluate basic dimensions of the foot that can be used for the determination of foot type.