Fig. 1

Pictures representing the process from CBCT scans to the embedded bone reference frames. Pictures representing the process from CBCT scans to the embedded bone reference frames, through the definitions of 3D models of the bone surface. The patient in single-leg weight-bearing during the CBCT scan (a). The 3D data-set including volume rendering available at the interactive screen (b). The result of the process of bone segmentation (Amira): all foot and ankle bone segments were modeled separately (different colors), and the ground segment is also identified and depicted (c). The overall bone models in the foot anatomical reference frame, here in a nearly lateral view (d). Construction of the three anatomical axes by means of the PCA technique, an exemplary application to the calcaneus model; the origin at the centroid of the bone model and the three corresponding co-ordinate axes are depicted (e). The same, for all foot bone models (f)