Damping and elastic response of the human ankle to in vivo sudden eversion motion

The mechanics of the human subtalar joint was studied in sudden eversion motion of the foot. Experimental data collected from a specially constructed apparatus were fed into a quasi-linear second-order underdamped system model. The following parameters were determined as a function of the joint´s angle: ankle moment, elastic stiffness, damping coefficient and moment of inertia. The effects of the tested leg´s weight bearing capacity and of protective footwear on the results were also studied. The following ranges were found; elastic stiffness: 15-65 Nm/rad; damping coefficient; 0.11-2.89 Nm-s/rad.<>