Abstract:
This study presents a biomechanical analysis of the human calcaneus (heel bone) to determine the internal forces and stresses it experiences during walking and running. To achieve this, a contact-coupled finite element model (FEM) of the foot was developed, with its inputs derived from experimentally measured data. High-speed cineradiography and force plate measurements were used to simultaneously capture the kinematics (bone motion) and kinetics (ground reaction forces) of a subject walking at 1.62 m/s and running at 3.71 m/s.
The model, which included the calcaneus, talus, and a lumped forefoot, as well as major ligaments and the Achilles tendon, was used to solve for the internal loads at discrete points throughout the stance phase. The results indicate that the internal forces on the joints, ligaments, and Achilles tendon follow the time-history of the moment about the ankle joint, peaking late in the stance phase. The model predicted peak talocalcaneal and calcaneocuboid joint loads of 5.4 and 4.2 body weights (BW) during walking, which increased dramatically to 11.1 and 7.9 BW during running. The maximum Achilles tendon force was 3.9 BW in walking and 7.7 BW in running. Crucially, the analysis showed that the calculated principal stress trajectories within the calcaneus qualitatively matched the bone's actual trabecular architecture, providing a strong validation of the model's physiological relevance.
