A preliminary study for a kinematic model of the complex tibia-fibula-talus-calcaneus

The relevance of the articulation passive motion, i. e. the motion in virtually unloaded condition, for the study of human diarthrodial joints has been widely recognized. In particular, passive motion makes it possible to better understand the basic role of the main anatomical structures that guide the relative motion between the articular elements. Recently, it has been shown that equivalent mechanisms allow obtaining fisical-mathematical models that can well replicate the articular passive motion. These models represent also a useful tool for both pre-operation planning and prosthesis design. Although the human ankle joint has been extensively investigated for its strategic importance in human physical activities, studies that examine the kinematic behavior of the tibio-talar joint also outlining the motion of the fibula bone, which is directly involved in the ankle motion, are still lacking. This paper presents a preliminary study for the development of a 3D passive motion model of the articulation that involves four bones, namely tibia, fibula, talus and calcaneus. In this anatomical complex, called TFC for simplicity, the ankle joint is a fundamental part. In particular, this model targets to evaluate the fibula role.