Assessing talonavicular joint rotations in three dimension

Introduction The union of the spherical talar head with the cupped shaped navicular shows the general characteristics of a ball-and-socket joint [1]. As such, the talonavicular joint should be expected to demonstrate three rotational degrees of freedom. Yet, conventional approaches to foot motion analysis provide little opportunity to assess motion of the intrinsic foot joints. A new approach, and perspective, is adopted that permits an appreciation of the talonavicular joint that is not restricted to the confines of marker dependence or the orthogonal reference frame. Data will be presented that shows talonavicular rotation about independent axes that possess orientations that are not orthogonal to any conventional reference frame.