Coupling biplanar videoradiography with the unified deformable power model to quantify foot and talocrural joint power

Analysis of the power produced by the foot and ankle during locomotion can provide insights into their function. Foot power is often quantified by applying the unified deformable (UD) power model to the hindfoot while ankle power is quantified by performing three or six degree-of-freedom joint power calculations. These measurements are possible with optical motion capture. Biplanar videoradiography (BVR) provides new opportunities for quantifying foot and ankle power as it provides highly accurate measurements of the individual foot bones that are not possible with optical motion capture. In this paper, we apply the UD power model to the talus to quantify foot power. This novel application of the UD power model also allows us to quantify talocrural joint power. We compared this new method of calculating foot and ankle power with the methods possible with optical motion capture. We found similar trends between the two methods, suggesting that applying the UD power model to the talus can quantify foot and talocrural power. Key differences between the two methods included the magnitude of power and work, as well as the timing of the power curves. These findings support the idea that the foot can actively produce power during propulsion and that the timing of arch and ankle mechanics, and their synchronization, is important for propulsion across locomotor modes.