Stress distribution within the plantar aponeurosis during walking - A dynamic finite element analysis

Excessive and repeated loading of the plantar aponeurosis (PA) is believed to be the most likely risk factor for developing plantar fasciitis. This study provided a novel approach to investigate the biomechanical responses of the PA during the entire stance phase of gait. One healthy subject was recruited for all the experimental measurements to validate the approach in this study. A three-dimensional (3D) finite element (FE) foot model representing this individual, with emphasis on the PA as a transversely isotropic tissue, was constructed. Kinematic data of foot motions were collected during a walking trial to serve as input conditions for the model. A peak tensile force of 922 N on the PA was found during the terminal-stance phase rather than during the mid-stance phase. The maximal peak von Mises stresses in the PA from the medial to lateral regions of the foot measured 15.61, 14.98 and 11.4 MPa at 74%, 77% and 82% of the stance phase, respectively. These peak stresses all occurred near the proximal calcaneal bony insertion site of the PA and correspond closely with the location where plantar fasciitis develops. Future work should include more subjects and clinical trials before applying these findings to the treatment of plantar fasciitis.