The validity and day-to-day reliability of a shoe-embedded sensor module for estimating foot progression angle during over-ground walking

Foot progression angle (FPA) is the angle of the foot when in contact with the ground, relative to the direction of walking. Modification of FPA is a possible management strategy for knee osteoarthritis; however, measurement of FPA is typically confined to the lab environment. We have tested the validity and reliability of a custom-built shoe-embedded sensor module. The sensor module uses a 9-axis sensor (3D accelerometer, gyroscope and magnetometer) and a custom algorithm to calculate the step-by-step FPA during non-lab (real-world) walking. Our experiment found the sensor module to exhibit good to excellent validity and day-to-day reliability.