Non-invasive Biomechanical Analysis Of Joint Motion

This study investigated a novel non-invasive method designed to characterize the spatial position of small bones and joints in vivo. CAT scans of discrete joint positions were used to determine incremental joint-motion parameters. Use of the method is illustrated and validated by an in vitro analysis of subtalar joint motion (inversion-eversion). Body principal axes were used to define the location and orientation of the talus and calcaneus. Three-dimensional talar motion was defined with reference to a fixed calcaneus. Preliminary results correlate strongly with prior studies, suggesting that the unique non-invasive methods used are accurate and reliable to define relative joint motion. Suggestions for further development and clinical application are presented. defined, volume and mass properties were then computed. This allowed location of the center of mass (CM) and the orientation of the body principal axes. Because the CM and the principal axes are fixed in the body, they provide a singular reference for describing changes in position. The principal axes transform the inertia tensor (I) into a diagonalized matrix (I’) whose elements are the principal moments of inertia. The principal moments of inertia and the corresponding pMCipal axes were obtained by solving the eigenvalue problem