Direct assessment of foot kinematics during human gait using a dynamic cadaver simulator and a biplane X-ray fluoroscopy

Direct measurement of detailed kinematics of individual anatomical structures in the foot during human locomotion is crucial for understanding morphofunctional roles of the human foot structure that mechanically interacts with the ground in a favourable manner to maintain stable gait. In the present study, we constructed a dynamic gait simulator to load and mobilize the cadaver foot and directly measured the three-dimensional kinematics of foot bones using a biplane X-ray fluoroscopy. A robotic gait simulator was developed to load and mobilize the cadaver foot in a manner similar to the way human foot actually moves and interacts with the ground during walking. The simulator has three legs, fore, middle and hind legs, with the cadaver foot fixed to the middle leg (Figure 1A). After the middle cadaver foot contacts the ground, the hind leg departs from the ground. The fore leg replicates the foot-contact with the ground in the next step and toe-off of the middle cadaver foot follows afterward. Tendons of tibialis anterior and soleus were connected to pneumatic actuators to apply forces at the appropriate moment to reproduce how the foot would function during walking.