Evaluation of rebound characteristics for running-specific prostheses based on strain distribution

Abstract

The objective of this study was to identify a range of the running-specific prostheses which contributed to its rebound characteristics by investigating the relationship between the strain distribution and the rebound characteristics. The blade with random and point patterns on the surface was photographed using two synchronized high-speed video cameras to quantify the dynamic strain and displacement responses of the blade. Strain responses were calculated by differentiating the distribution of displacement which was quantified by recognizing random patterns in the high-speed images using the digital image correlation method. Vertical and horizontal impact loads were measured with a load cell attached on the impactor and the bending strain responses, respectively. As a result, the strain responses on the hindfoot tend to have a greater effect on the impact load than that on the forefoot, and the load tends to increase as the maximum value of the strain decreases. The ratio of velocity, which is defined as one of the rebound characteristics, also tends to increase with the impact load. This trend suggests that the deformation of the hindfoot contributes to the rebound characteristics of the blade and it may be effective to suppress the deformation of the hindfoot for increasing the rebound characteristics.