The relevance of human joint models has been shown in the literature. They can help in
diagnosis, in prostheses and ortheses design and in predicting the joints’ behavior.
Recently a sequential approach for the modeling of the human diarthrodial joints composed
of three steps has been proposed. At each step the role of some anatomical structures is
considered. Starting from a limited number of structures, the model gets more and more
sophisticated until all the components, both passive (articular surfaces, ligaments and
tendons) and active (muscles), are incorporated in the final model.
According to this procedure, the behavior of the human ankle during passive motion (no
loads applied) has been previously modeled by a one degree of freedom 5-5 fully parallel
mechanism. Starting from this model, the kinetostatic model of the human ankle joint that
replicates its behavior when external loads are applied is developed. The anatomical and
mechanical characteristics and the role of the passive structures are considered; a multifiber
model is developed and an optimization criteria based on experimental data is
proposed.
Finally an application of the developed model to an amputated ankle is presented, together
with the results obtained from the optimization of the geometrical and mechanical
Parameters. Although some improvements can be achieved, the model is satisfactorily able
to replicate the behavior of the human ankle subject to the anterior drawer and the inversion
clinical tests applied in the neutral position